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| author | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:42:36 -0700 |
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| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:42:36 -0700 |
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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/13640-0.txt b/13640-0.txt new file mode 100644 index 0000000..73fe796 --- /dev/null +++ b/13640-0.txt @@ -0,0 +1,4828 @@ +*** START OF THE PROJECT GUTENBERG EBOOK 13640 *** + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 821 + + + + +NEW YORK, September 26, 1891 + +Scientific American Supplement. Vol. XXXII, No. 821. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + * * * * * + + + + +TABLE OF CONTENTS. + + +I. Architectural.--The New Labor Exchange in Paris.--With + views of the interior and exterior of the building + +II. Electrical.--The Construction and Maintenance of Underground + Circuits.--By S.B. FOWLER.--A comprehensive article, + discussing at length the various devices for protecting underground + circuits, methods _of_ inserting the cables, etc. + +III. Engineering.--Railroads to the Clouds.--Sketches of a number + of mountain railroads + +IV. Marine Engineering.--The French Armored Turret Ship + the Marceau.--1 engraving.--A full description of the vessel, giving + dimensions and cost + + A Review of Marine Engineering during the Past Decade.--A + paper read before the Institution of Mechanical Engineers by Mr. + Alfred Blechynben, of Barrow-in-Furness.--This paper, which + is continued from Supplement No. 820, treats on steam pipes, + feed water heating, twin screws, etc. + +V. Miscellaneous.--The Little House.--An article giving various + hints about the arrangement and management of small + dwellings, with special view to the best sanitary arrangements + + Stilt Walking.--A sketch, with engraving, of Sylvain Dornon, + the stilt walker of Landes + + Remains of a Roman Villa in England + + Gum Arabic and its Modern Substitutes.--A continuation of a + paper by Dr. S. Rideal and W.E. Youle.--With 26 tables + + A New Method of Extinguishing Fires.--Invented by George + Dickson and David A. Jones, of Toronto, Canada.--Apparatus designed + to utilize a mixture of water and liquefied carbonic acid + +VI. Medicine and Hygiene.--The Hygienic Treatment of + Obesity.--By Dr. Paul Chebon.--Methods of eating, drinking, + and exercising for the purpose of reducing fat.--An extended + article, giving valuable information to people troubled with too + much flesh + +VII. Photography.--Spectroscopic Determination of the Sensitiveness + of Dry Plates.--A full description of the new plan of + Mr. G.F. WILLIAMS, for determining the sensitiveness of dry + plates by the use of a small direct vision pocket spectroscope + +VIII. Physics.--A Physical Laboratory Indicator.--By J.W. + MOORE, of Lafayette College.--1 engraving.--This is a modification + of the old peg board adapted to use in the laboratory.--It indicates + the names of the members of the class, contains a full + list of the experiments to be performed, refers the student + to the book and page where information in reference to experiments + or apparatus may be found, it shows what experiments + are to be performed by each student at a given time, etc. + + Cailletet's Cryogen.--A description, with one engraving, of Mr. + Cailletet's new apparatus for producing temperatures from 70 + degrees to 80 degrees C., below zero, through the expansion of + liquid carbonic acid + +IX. Technology.--The Manufacture of Roll Tar Paper.--An extended + article containing a historical sketch and full information + as to the materials used and the methods of manufacture + + Smokeless Gunpowder.--By Hudson Maxim.--A comprehensive + article on the manufacture and use of smokeless gunpowder, + giving a sketch of its history, and describing the methods of + manufacture and its characteristics + + Method of Producing Alcohol.--A description of an improved + process for making alcohol.--Invented by Mr. Alfred Springer, + of Cincinnati, Ohio + + * * * * * + + + + + +[Illustration: INTERIOR OF THE NEW LABOR EXCHANGE, PARIS.] + +[Illustration: NEW LABOR EXCHANGE, PARIS.] + +THE NEW LABOR EXCHANGE, PARIS. + + +The new Labor Exchange is soon to be inaugurated. We give herewith a +view of the entrance facade of the meeting hall. The buildings, which +are the work of Mr Bouvard, architect, of the city of Paris, are +comprised within the block of houses whose sharp angle forms upon +Place de la Republique, the intersection of Boulevard Magenta and +Bondy street. One of the entrances of the Exchange is on a level with +this street. The three others are on Chateau d'Eau street, where the +facade of the edifice extends for a length of one hundred feet. From +the facade and above the balcony that projects from the first story, +stand out in bold relief three heads surrounded by foliage and fruit +that dominate the three entrance doors. These sculptures represent the +Republic between Labor and Peace. The windows of the upper stories are +set within nine rows of columns, from between the capitals of which +stand out the names of the manufacturers, inventors, and statesmen +that have sprung from the laboring classes. Upon the same line, at the +two extremities of the facade, two modillions, traversed through their +center by palms, bear the devices "Labor" and "Peace." Above, there is +a dial surmounted by a shield bearing the device of the city of Paris. + +The central door of the ground floor opens upon a large vestibule, +around which are arranged symmetrically the post, telegraph, +telephone, and intelligence offices, etc. Beyond the vestibule there +is a gallery that leads to the central court, upon the site of which +has been erected the grand assembly hall. This latter, which measures +20 meters in length, 22 in width, and 6 in height, is lighted by a +glazed ceiling, and contains ten rows of benches. These latter contain +900 seats, arranged in the form of circular steps, radiating around +the president's platform, which is one meter in height. A special +combination will permit of increasing the number of seats reserved for +the labor associations on occasions of grand reunions to 1,200. The +oak doors forming the lateral bays of the hall will open upon the two +large assembly rooms and the three waiting rooms constructed around +the faces of the large hall. In the assembly rooms forming one with +the central hall will take place the deliberations of the syndic +chambers. The walls of the hall will, ere long, receive decorative +paintings.--_L'Illustration._ + + * * * * * + + + + +MANUFACTURE OF ROLL TAR PAPER. + + +Roofing paper was first used in Scandinavia early as the last century, +the invention being accredited to Faxa, an official of the Swedish +Admiralty. The first tar and gravel roofs in Sweden were very +defective. The impregnation of the paper with a water-proofing liquid +had not been thought of, and the roofs were constructed by laying over +the rafters a boarding, upon which the unsaturated paper, the sides of +which lapped over the other, was fastened with short tacks. The +surface of the paper was next coated with heated pine tar to make it +waterproof. The thin layer of tar was soon destroyed by the weather, +so that the paper, swelled by the absorption of rain water, lost its +cohesiveness and was soon destroyed by the elements. This imperfect +method of roof covering found no great favor and was but seldom +employed. + +In Germany the architect Gilly was first to become interested in tar +paper roofing, and recommended it in his architecture for the country. +Nevertheless the new style of roof covering was but little employed, +and was finally abandoned during the first year of the 19th century. +It was revived again in 1840, when people began to take a renewed +interest in tar paper roofs, the method of manufacturing an +impermeable paper being already so far perfected that the squares of +paper were dipped in tar until thoroughly saturated. The roof +constructed of these waterproof paper sheets proved itself to be a +durable covering, being unimpenetrable to atmospheric precipitations, +and soon several factories commenced manufacturing the paper. The +product was improved continually and its method of manufacture +perfected. The good qualities of tar paper roofs being recognized by +the public, they were gradually adopted. The costly pine tar was soon +replaced by the cheaper coal tar. Square sheets of paper were made at +first; they were dipped sufficiently long in ordinary heated coal tar, +until perfectly saturated. The excess of tar was then permitted to +drip off, and the sheets were dried in the air. The improvement of +passing them through rollers to get rid of the surplus tar was +reserved for a future time, when an enterprising manufacturer +commenced to make endless tar paper in place of sheets. Special +apparatus were constructed to impregnate these rolls with tar; they +were imperfect at first, but gradually improved to a high degree. Much +progress was also made in the construction of the roofs, and several +methods of covering were devised. The defects caused by the old method +of nailing the tar paper direct upon the roof boarding were corrected; +the consequence of this method was that the paper was apt to tear, +caused by the unequal expansion of the roofing boards and paper, and +this soon led to the idea of making the latter independent of the +former by nailing the sides of the paper upon strips running parallel +with the gable. The use of endless tar paper proved to be an essential +advantage, because the number of seams as well as places where it had +to be nailed to the roof boarding was largely decreased. The +manufacture of tar paper has remained at about the same stage and no +essential improvements have been made up to the present. As partial +improvement may be mentioned the preparation of tar, especially since +the introduction of the tar distillery, and the manufacture of special +roof lacquers, which have been used for coating in place of the coal +tar. As an essential progress in the tar paper roofing may be +mentioned the invention of the double tar paper roof, and the wood +cement roof, which is regarded as an offshoot. + +The tar paper industry has, within the last forty years, assumed great +dimensions, and the preferences for this roofing are gaining ground +daily. In view of the small weight of the covering material, the wood +construction of the roof can be much lighter, and the building is +therefore less strained by the weight of the roof than one with the +other kind, so that the outer walls need not be as heavy. Considering +the price, the paper roof is not only cheaper than other fireproof +roofs, but its light weight makes it possible for the whole building +to be constructed lighter and cheaper. The durability of the tar paper +roof is satisfactory, if carefully made of good material; the double +tar paper roof, the gravel double roof, and the wood cement roof are +distinguished by their great durability. + +These roofs may be used for all kinds of buildings, and not only are +factories, storehouses, and country buildings covered with it, but +also many dwellings. The most stylish residences and villas are at +present being inclosed with the more durable kinds; the double roof, +the gravel double roof, and the wood cement roof. For factory +buildings, which are constantly shaken by the vibrations of the +machinery, the tar paper roof is preferable to any other. + +In order to ascertain to what degree tar paper roofs would resist +fire, experiments were instituted at the instigation of some of the +larger manufacturers of roofing paper, in the presence of experts, +architects, and others, embracing the most severe tests, and it was +fully proved that the tar paper roof is as fireproof as any other. +These experiments were made in two different ways; first, the +readiness of ignition of the tar paper roof by a spark or flame from +the outside was considered, and, second, it was tested in how far it +would resist a fire in the interior of the building. In the former +case, it was ascertained that a bright, intense fire could be kept +burning upon the roof for some time, without igniting the woodwork of +the roof, but heat from above caused some of the more volatile +constituents of the tar to be expelled, whereby small flames appeared +upon the surface within the limits of the fire; the roofing paper was +not completely destroyed. There always remained a cohesive substance, +although it was charred and friable, which by reason of its bad +conductivity of heat protected the roof boarding to such an extent +that it was "browned" only by the developed tar vapors. A fire was +next started within a building covered with a tar paper roof; the +flame touched the roof boarding, which partly commenced to char and +smoulder, but the bright burning of the wood was prevented by the +air-tight condition of the roof; the fire gases could not escape from +the building. The smoke collecting under the roof prevented the +entrance of fresh air, in consequence of which the want of oxygen +smothered the fire. The roofing paper remained unchanged. By making +openings in the sides of the building so that the fire gases could +escape, the wood part of the roof was consumed, but the roofing paper +itself was only charred and did not burn. After removing the fire in +contact with the paper, this ceased burning at once and evinced no +disposition whatever to spread. In large conflagrations, also, the tar +paper roofs behaved in identically a similar manner. Many instances +have occurred where the tar paper roof prevented the fire from +spreading inside the building, and developing with sufficient +intensity to work injury. + +As it is of interest to the roofer to know the manner of making the +material he uses, we give in the following a short description of the +manufacture of roofing paper. At first, when square sheets were used +exclusively, the raw paper consisted of ordinary dipped or formed +sheets. The materials used in its manufacture were common woolen rags +and other material. In order to prepare the pulp from the rags it is +necessary to cut them so small that the fabric is entirely dissolved +and converted into short fibers. The rags are for this purpose first +cut into pieces, which are again reduced by special machines. The rags +are cut in a rag cutting machine, which was formerly constructed +similar to a feed cutter; later on, more complicated machines of +various constructions were employed. It is not our task to describe +the various kinds, but we remain content with the general remark that +they are all based on the principles of causing revolving knives to +operate upon the rags. The careful cleansing of the cut rags, +necessary for the manufacture of paper, is not required for roofing +paper. It is sufficient to rinse away the sand and other solid +extraneous matter. The further reduction of the cut rags was formerly +performed in a stamp mill, which is no longer employed, the pulp mill +or rag engine being universally used. + +The construction of this engine may be described as follows: A box or +trough of wood, iron, or stone is by a partition divided into two +parts which are connected at their ends. At one side upon the bottom +of the box lies an oakwood block, called the back fall. In a hollow of +this back fall is sunk the so-called plate, furnished with a number of +sharp steel cutters or knives, lying alongside of each other. A roller +of solid oakwood, the circumference of which is also furnished with +sharp steel cutters or knives, is fastened upon a shaft and revolves +within the hollow. The journal bearings of the shaft are let into and +fastened in movable wooden carriers. The carriers of the bearings may +be raised and lowered by turning suitable thumbscrews, whereby the +distance between the roller and the back fall is increased or +decreased. The whole is above covered with a dome, the so-called case, +to prevent the throwing out of the mass under the operation of +grinding. The roller is revolved with a velocity of from 100 to 150 +revolutions per minute, whereby the rags are sucked in between the +roller and the back fall and cut and torn between the knives. At the +beginning of the operation, the distance between the roller and the +back fall is made as great as possible, the intention being less to +cut the rags than to wash them thoroughly. The dirty water is then +drawn off and replaced by clean, and the space of the grinding +apparatus is lessened gradually, so as to cut the rags between the +knives. The mass is constantly kept in motion and each piece of rag +passes repeatedly between the knives. The case protects the mass from +being thrown out by the centrifugal force. The work of beating the +rags is ended in a few hours, and the ensuing thin paste is drawn off +into the pulp chest, this being a square box lined with lead. + +From the pulp chest it passes to the form of the paper machine. This +form consists of an endless fine web of brass wire, which revolves +around rollers. The upper part of this form rests upon a number of +hollow copper rollers, whereby a level place is formed. The form +revolves uniformly around the two end rollers, and has at the same +time a vibratory motion, by which the pulp running upon the form is +spread out uniformly and conducted along, more flowing on as the +latter progresses. The water escapes rapidly through the close wire +web. In order to limit the form on the sides two endless leather +straps revolve around the rollers on each side, which touch with their +lower parts the form on both sides and confine the fluid within a +proper breadth. The thickness of the pulp is regulated at the head of +the form by a brass rule standing at a certain height; its function is +to level the pulp and distribute it at a certain thickness. The +continually moving pulp layer assumes greater consistency the nearer +it approaches to the dandy roll. This is a cylinder covered with brass +wire, and is for the purpose of compressing the paper, after it has +left the form, and free it from a great part of the water, which +escapes into a box. The paper is now freed of a good deal of the +fluid, and assumes a consistency with which it is enabled to leave the +form, which now commences to return underneath the paper, passing on +to an endless felt, which revolves around rollers and delivers it to +two iron rolls. The paper passes through a second pair of iron +rollers, the interiors of which are heated by steam. These rollers +cause the last of the water to be evaporated, so that it can then be +rolled upon reels. A special arrangement shaves the edges to the exact +size required. + +The paper is made in different thicknesses and designated by numbers +to the size and weight. + +Waste paper, bookbinders' shavings, etc., can be used for making the +paper. As much wool as possible should be employed, because the wool +fiber has a greater resistance than vegetable fiber to the effects of +the temperature. By wool fiber is understood the horny substance +resembling hair, with the difference that the former has no marrowy +tissue. The covering pellicle of the wool fiber consists of flat, +mostly elongated leaves, with more or less corners, lying over each +other like scales, which makes the surface of the fiber rough; this +condition, together with the inclination of curling, renders it +capable of felting readily. Pure wool consists of a horny substance, +containing both nitrogen and sulphur, and dissolves in a potash +solution. In a clean condition, the wool contains from 0.3 to 0.5 per +cent. of ash. It is very hygroscopical, and under ordinary +circumstances it contains from 13 to 16 per cent. humidity, in dry air +from 7 to 11 per cent., which can be entirely expelled at a +temperature of from 226 to 230 degrees Fahrenheit. Wool when ignited +does not burn with a bright flame, as vegetable fiber does, but +consumes with a feeble smouldering glow, soon extinguishes, spreading +a disagreeable pungent vapor, as of burning horn. By placing a test +tube with a solution of five parts caustic potash in 100 parts water, +a mixture of vegetable fibers and wool fibers, the latter dissolve if +the fluid is brought to boiling above an alcohol flame, while the +cotton and linen fibers remain intact. + +The solubility of the woolen fibers in potash lye is a ready means of +ascertaining the percentage of wool fiber in the paper. An exhaustive +analysis of the latter can be performed in the following manner: A +known quantity of the paper is slowly dried in a drying apparatus at +temperature of 230° Fahrenheit, until a sample weighed on a scale +remains constant. The loss of weight indicates the degree of humidity. +To determine the ash percentage, the sample is placed in a platinum +crucible, and held over a lamp until all the organic matter is burned +out and the ash has assumed a light color. The cold ash is then +moistened with a carbonate of ammonia solution, and the crucible again +exposed until it is dark red; the weight of the ash is then taken. To +determine the percentage of wool, a sample of the paper is dried at +230° Fahrenheit and weighed, boiled in a porcelain dish in potash lye +12° B. strong, and frequently stirred with a glass rod. The wool fiber +soon dissolves in the potash lye, while the vegetable fiber remains +unaltered. The pulpy mass resulting is placed upon a filter, dried at +212° Fahrenheit, and after the potash lye has dripped off, the +residue, consisting of vegetable fiber and earthy ash ingredients, is +washed until the water ceases to dissolve anything. The residue dried +at 212° Fahrenheit is weighed with a filter, after which that of the +latter is deducted. The loss of weight experienced is essentially +equal to the loss of the wool fiber. If the filtrate is saturated with +hydrochloric acid, the dissolved wool fiber separates again, and after +having been collected upon a weighed filter, it may be weighed and the +quantity ascertained. + +The weight of the mineral substances in the raw paper is ascertained +by analyzing the ash in a manner similar to that above described. The +several constituents of the ash and the mineral added to the raw paper +are ascertained as follows: Sufficient of the paper is calcined in the +manner described; a known quantity of the ash is weighed and thrown +into a small porcelain dish containing a little distilled water and an +excess of chemically pure hydrochloric acid. In this solution are +dissolved the carbonates, carbonate of lime, carbonate of magnesia, a +little of sulphate of alumina, as well as metallic oxides, while +silicate of magnesia, silicic acid, sulphate of lime (gypsum) remain +undissolved. The substance is heated until the water and excess of +free hydrochloric acid have been driven off; it is then moistened with +a little hydrochloric acid, diluted with distilled water and heated. +The undissolved residue is by filtering separated from the dissolved, +the filter washed with distilled water, and the wash water added to +the filtrate. The undissolved residue is dried, and after the filter +has also been burned in due manner and the ash added, the weight is +ascertained. It consists of clay, sand, silicic acid and gypsum. + +The filtrate is then poured into a cylinder capable of holding 100 +cubic centimeters, and furnished with a scale; sufficient distilled +water is then added until the well-shaken fluid measures precisely 100 +cubic centimeters. By means of this measuring instrument, the filtrate +is then divided into two equal portions. One of these parts is in a +beaker glass over-saturated with chemically pure chloride of ammonia, +whereby any iron of oxide present and a little dissolved alumina fall +down as deposit. The precipitate is separated by filtering, washed, +dried at 212° Fahrenheit and weighed. To the filtrate is then added a +solution of oxalate of ammonia until a white precipitate of oxalate of +lime is formed. This precipitate is separated by filtering, washed, +dried and when separated from the filter, is collected upon dark +satinized paper; the filter itself is burned and the ash added to the +oxalate of lime. This oxalate of lime is then heated to a dark red +heat in a platinum crucible with lid until the oxalate of lime is +converted into carbonate of lime. By the addition of a few drops of +carbonate of ammonia solution and another slight heating of the +crucible, also the caustic lime produced in the filter ash by heating, +is reconverted into carbonate of lime, and after cooling in the +exsiccator, the whole contents of the crucible is weighed as +carbonate of lime, after deducting the known quantity of filter ash. + +Any magnesia present in the filtrate of the oxalate of lime is by the +addition of a solution of phosphate of soda separated as phosphate of +ammonia and magnesia, after having stood twenty-four hours. The +precipitate is filtered off, washed with water to which a little +chloride of ammonia is added, dried, and after calcining the fiber and +adding the filter ash, glow heated in the crucible. The glowed +substance is weighed after cooling, and is pyrophosphate of magnesia, +from which the magnesia or carbonate of magnesia is calculated +stoichiometrically. All the ascertained sums must be multiplied by 2, +if they are to correspond to the analyzed and weighed quantity of ash. + +The second half of the filtrate is used for determining the small +quantity of sulphate of lime still contained in the hydrochlorate +solution. By adding chloride of barium solution the sulphuric acid is +bound to the barytes and sulphate of baryta separates as white +precipitate. This is separated by filtering, washed, dried and weighed +in the customary manner. From the weight of the sulphate of baryta is +then computed the weight of sulphate of lime, which has passed over +into solution. The ascertained sum is also to be multiplied with 2. + +The manufacture of roll tar paper from the roll paper was at first +found to be difficult, as it was impossible to submerge a surface +larger than from ten to fifteen square yards, rolled up, in the tar, +because more would have required too large a pan. Besides this, the +paper tears easily, when it is in the hot tar. All kinds of +experiments were tried, in order to impregnate the surface of the +paper without employing too large a pan. + +The following method was tried at first: The roll paper was cut into +lengths of ten yards, which were rolled up loosely, so that a certain +space was left between the different coils. These loose rolls, of +course, occupied much space and could be put into the tar only in a +standing position, because in a horizontal one the several coils would +have pressed together again. The loose roll was therefore slipped over +a vertical iron rod fastened into a circular perforated wooden foot. +The upper end of this iron rod ended in a ring, in which the hook of a +chain or rope could be fastened. With the aid of a windlass the roll +was raised or lowered. When placed in the pan with boiling tar, it was +left there until thoroughly saturated. It was then taken out, placed +upon a table, and the excess of tar allowed to drip off into a vessel +underneath. After partially drying, the roll was spread out in open +air, occasionally turned, until sufficiently dried, when it was rolled +up again. + +In order to neutralize the smeary, sticky condition of the surface and +avoid the disagreeable drying in open air, the experiment of strewing +sand on the sticky places was tried next. The weight of the paper was +largely increased by the sand, and appeared considerably thicker. For +this reason the method of sanding the paper was at once universally +adopted. To dispense with the process of permitting the surplus tar to +drip off, means were devised by which it was taken off by scrapers, or +by pressing through rollers. The scrapers, two sharp edged rods +fastened across the pan, were then so placed that the paper was drawn +through them. The excess of tar adhering to its surface was thereby +scraped off and ran back into the pan. + +This work, however, was performed better and to more satisfaction by a +pair of rollers fastened to the pan. These performed a double duty; +thoroughly removed the tar from the surface and by reason of their +pressure they caused a more perfect incorporation of the tar with the +fibers of the paper. Finally, different factories employed different +methods of manufacture, one of which was to cut the rolls into +definite lengths of about ten yards; these were then rerolled very +loosely and immersed in the hot tar until sufficiently saturated. The +paper was then passed through the roller, much pressure exerted, and +then loosely rolled up again. Being tarred once, it was then laid into +a second pan with hot tar, reeled out after a time, strewn with sand, +and rolled up again. Another method was to cut clothes lines into +lengths of about fifteen yards, and at a distance of two inches have +knots tied in them. The paper was cut in lengths of ten or fifteen +yards, three pieces of the knotted clothes line were then rolled +between the loose coils of paper, which was then submerged in the tar, +which on account of the knots could penetrate the paper. The paper was +next sanded by permitting its lower surface to pass over dry sand in a +box standing on the floor. A workman rolled off the paper, and with +his hand he strews sand on the upper surface. The rolling taking place +on the edge of a table, by means of a crank, the excess of sand +dropped off. + +It is said by this method two workmen, one of which tends to the +rolling and sanding, the other turning the crank, could turn out +eighty rolls per day. This method is still in use. It is useless to +describe the many antiquated methods in vogue in smaller factories, +and it can truthfully be said that nearly all of them are out of date. +It appears to be the fact of almost all inventions that when reduced +to practical use, the arrangements, apparatus, and working methods +employed are generally of the most complicated nature, and time and +experience only will simplify them. This has been also the case with +the methods in the roofing paper industry, which are at present +gradually being reduced to a practical basis. The method gradually +adopted has been described in the preceding. The pan is of a certain +length, whereby it becomes possible to saturate the paper by slowly +drawing it through the heated tar. This is the chief feature. The work +is much simplified thereby and the workmen need not dip their hands +into the tar or soil them with it. The work of impregnating has become +much cleaner and easier, while at the same time the tar can be heated +to a much higher temperature. The pan is generally filled with +distilled coal tar, and the heating is regulated in such a manner that +the temperature of the impregnating mass is raised far beyond 212° +Fahrenheit. This accelerates the penetration, which takes place more +quickly as the degree of heat is raised, which may be almost up to the +boiling point of the tar, as at this degree the paper is not destroyed +by the heat. In order to prevent the evaporation of the volatile +ingredients of the tar, the pan is covered with a sheet iron cover, +with a slot at the place where the paper enters into the impregnating +mass and another at the place where it issues. The tar is always kept +at the same level, by occasional additions. + +The roll of paper is mounted upon a shaft at the back end of the pan, +and by suitable arrangement of guide rollers it unwinds slowly, passes +into the tar in which it is kept submerged. The guide rollers can be +raised so that when a new roller is set up they can be raised out of +the tar. The end of the paper is then slipped underneath them above +the surface of the tar, when having passed through the squeezing +rollers, it is fastened to the beaming roller, and the guide rollers +are submerged again. A workman slowly turns the crank of the beaming +roller. + +This motion draws the paper slowly through the fluid, the roll at the +back end unwinding. The speed with which the squeezing rollers are +turned is regulated in such a manner that the paper remains +sufficiently long underneath the fluid to be thoroughly impregnated +with it. The workmen quickly learn by experience how fast to turn the +crank. The hotter the tar, the more rapid the saturation; the high +degree of heat expels the air and evaporates the hygroscopic fluid in +the pores of the paper. The strong heating of the tar causes another +advantage connected with this method. The surface of the paper as it +issues from the squeezing rollers is still very hot, and a part of the +volatile oils evaporate very quickly at this high temperature. The +surface is thereby at once dried to a certain degree and at the same +time receives a handsome luster, as if it had been coated with a black +lacquer. The paper is sanded in a very simple manner without the use +of mechanical apparatus; as it is being wrapped into a coil, it passes +with its lower surface over a layer of sand, while the workman who +tends to rolling up strews the inside with sand. The lower surface is +coated very equally. Care only being necessary that the sand lies +smooth and even at all times. When the workman has rolled up ten or +fifteen yards, he cuts it across with a knife and straightedge, so +that the paper is cut at right angles with its sides. + +There are three different sorts of roofing paper, according to the +impregnating fluid used in its manufacture. The ordinary tar paper is +that saturated with clear cold tar. This contains the greatest amount +of fluid ingredients and is very raggy in a fresh condition. It is +easy to see that the volatile hydrocarbons evaporate in a short time, +and when expelled, the paper becomes stiffer and apparently drier. +This drying, or the volatilization of the hydrocarbons, causes pores +between the fibers of the paper. These pores are highly injurious to +it, as they facilitate a process of decomposition which will ruin it +in a short time. + +Roofing paper can be called good only when it is essentially made from +woolen rags, and contains either very few or no earthy additions. It +is beyond doubt that the durability of a roofing paper increases with +the quality of wool fiber it contains--vegetable fibers and earthy +additions cause a direct injury. Reprehensible altogether is any +combination with lime, either in form of a carbonate or sulphate, +because the lime enters into chemical combination with the +decomposition products of the tar. + +The general nature of gravel is too well known to require description. +The grains of quartz sand are either sharp cornered or else rounded +pieces of stone of quartz, occasionally mixed with grains of other +amorphous pieces of silica--such as horn stone, silicious slate, +carnelian, etc.; again, with lustrous pieces of mica, or red and white +pieces of feldspar. The gravel used for a tar paper roof must be of a +special nature and be prepared for the purpose. The size of its grains +must not exceed a certain standard--say, the size of a pea. When found +in the gravel bank, it is frequently mixed with clay, etc., and it +cannot be used in this condition for a roof, but must be washed. The +utensils necessary for this purpose are of so simple and suggestive a +nature that they need not be described. Slag is being successfully +used in place of the gravel. It is easily reduced to suitable size, by +letting the red hot mass, as it runs from the furnace, run into a +vessel with water. The sudden chilling of the slag causes it to burst +into fragments of a sharp cornered structure. It is next passed +through a sieve, and the suitably sized gravel makes an excellent +material, as it gives a clean appearance to the roof. + +The thinking mind can easily go one step further and imagine that, +since the tar contains a number of volatile hydrocarbons, it might be +made more adaptable for impregnation by paper by distilling it, as by +this process the fluid would lose its tendency to evaporate and the +percentage of resinous substances increase. Singular to say, there was +a prejudice against the employment of distilled tar, entertained by +builders and people who had no knowledge of chemistry. Increasing +intelligence and altered business circumstances, however, brought +about the almost universal employment of distilled tar, and every +large factory uses it at present. The roofing paper prepared with +distilled tar is perhaps most suitably called asphaltum paper, as this +has been used in its manufacture. It possesses properties superior to +the ordinary tar paper, one of which is that immediately after its +manufacture, as soon as cold, it is dry and ready for shipment; nor +does it require to be kept in store for a length of time, and it has +also a good, firm body, being as flexible and tough as leather. It is +very durable upon the roof, and remains flexible for a long time. It +is true that asphaltum papers will always in a fresh state contain a +small percentage of volatile ingredients, which after a while make it +hard and friable upon the roof; but, by reason of its greater +percentage of resinous components, it will always preserve a superior +degree of durability and become far less porous. One hundred parts by +weight absorb 140 or 150 parts by weight of coal tar. A factory which +distilled a good standard tar for roofing paper recovered, besides +benzole and naphtha, also about ten per cent. of creosote oil, used +for one hundred parts raw paper, 176.4 partially distilled tar. +Experiments on a larger as well as a smaller scale reduced this +quantity to an average of 141.5 parts for one hundred parts raw paper. +The weight of sanded paper is very variable, as it depends altogether +upon the size of the sand grains. It may be stated generally that the +weight of the sand is as large as that of the tarred paper. + +The kinds of roofing paper saturated with other additions besides coal +tar form a separate class, in order to neutralize the defects inherent +in coal tar. These additions were originally for the purpose of +thickening the paper and making it stiffer and drier. The most +ordinary and cheapest thickener was the coal pitch. Although the +resinous substances are increased thereby, still the light tar oils +remain to evaporate, and the paper prepared with such a substance +readily becomes hard and brittle. A better addition is the natural +asphaltum, because it resists better the destroying influence of the +decomposition process, and also, to a certain degree, protects the +coal tar in which it is dissolved. The addition of natural asphaltum +doubtless caused the name of "asphaltum roofing paper." Resin, +sulphur, wood tar and other substances were also used as additions; +each manufacturer kept his method secret, however, and simply pointed +out by high sounding title in what manner his paper was composed. In +most cases, however, this appellation was applied to the ordinary tar +paper; the impregnating substance was mixed only with coal pitch, or +else a roofing paper saturated with distilled tar. The costly +additions, by the use of which a high grade of roofing paper can +doubtless be produced, largely increased its price, and on account of +the constant fall of prices of the article, its use became rather one +of those things "more honored in the breach than in the observance," +and was dispensed with whenever practicable. The crude paper is the +foundation of the roofing paper. The qualities of a good, +unadulterated paper have already been stated. At times, the crude +paper contains too many earthy ingredients which impair the cohesion +of the felted fibrous substance, and which especially the carbonate of +lime is very injurious, as it readily effects the decomposition of the +coal tar. The percentage of wool, upon which the durability of the +paper depends very largely, is very small in some of the paper found +in the market. In place of woolen rags, cheap substitutes have been +used, such as waste, which contains vegetable fibers. Since this +cannot resist the decomposition process for any length of time, it is +evident that the roofing paper which contains a noticeable quantity of +vegetable fibers cannot be very durable. To judge from the endeavors +made to improve the coal tar, it may be concluded that this material +does not fully comply with its function of making the roofing paper +perfectly and durably waterproof. The coal tar, be it either crude or +distilled, is not a perfect impregnating material, and the roofing +paper, saturated with it, possesses several defects. Let us in the +following try to ascertain their shortcomings, and then express our +idea in what manner the roofing paper may be improved. It was +previously mentioned that every tar roofing paper will, after a +greater or smaller lapse of time, assume a dry, porous, friable +condition, caused by the volatilization of a part of the constituents +of the tar. This alteration is materially assisted by the oxygen of +the air, which causes the latter to become resinous and exerts a +chemical influence upon them. By the volatilization of the lighter tar +oils, pores are generated between the fibers of the roofing paper, +into which the air and humidity penetrate. In consequence of the +greatly enlarged surface, not only the solid ingredients of the tar, +which still remain unaltered, are exposed to the action of the oxygen, +but also the fibers of the roofing paper are exposed to decomposition. +How destructive the alternating influence of the oxygen and the +atmospheric precipitations are for the roofing paper will be shown by +the following results of tests. It will have been observed that the +rain water running from an old paper roof, especially after dry +weather, has a yellowish, sometimes a brown yellow color. The +supposition that this colored rain water might contain decomposition +products of the roofing paper readily prompted itself, and it has been +collected and analyzed at different seasons of the year. After a +period of several weeks of fair weather during the summer, rain fell, +and the sample of water running from a roof was caught and evaporated; +the residue when dried weighed 1.68 grammes. It was of a brownish +black color, fusible in heat and readily soluble, with a yellow brown +color in water. The dark brown substance readily dissolved in ammonia, +alcohol, dilute acid, hydrochloric acid, sulphuric acid, and +decomposed in nitric acid, but did not dissolve in benzine or fat oil. +After several days' rain during the summer, a quantity of the water +was caught, evaporated, and the residue dried. Its characteristics +were similar to those above mentioned. By an experiment instituted in +water under conditions similar to the first mentioned, the dry brown +substance weighed 71 grammes. It possessed the same characteristics. +In the solution effected with water containing some aqua ammonia of +the brown substance, a white precipitate of oxalate of lime occurred +when an oxalate of ammonia solution was added, but the brown substance +remained in solution. A further precipitation of oxalate of lime was +produced by a solution of oxalic acid, but the brown organic substance +remained in solution. This organic substance being liberated from the +lime was evaporated, and left a dry, resinous, fusible brownish black +substance, which also dissolved readily in water. It will be seen from +these trials that the substance obtained from the rain water running +from a paper roof is a combination of an organic acid with lime, which +readily dissolves in water, and that also the free organic acid +combined with the lime dissolves easily in water. + +The question concerning the origin of this organic substance or its +combination with lime can only be answered in one way, viz., that it +must have been washed by the rain water out of the paper. But since +such a solid substance, easily soluble in water, is contained neither +in the fresh roofing paper nor in the coal tar, the only deduction is +that it must have arisen by the decomposition of the tar, in +consequence of the operation of the oxygen. The lime comes from the +coating substance of the roof, for which tar mixed with coal pitch was +used. The latter was fused with carbonate of lime. These analyses +furthermore show that the formation of the organic acid easily soluble +in water depends upon the season; and that a larger quantity of it is +generated in warm, sunny weather than in cold, without sunshine. This +peculiarity of the solid, resinous constituents of the coal tar, to be +by the operation of the atmospheric oxygen altered into such products +that are readily soluble in water, makes the tar very unsuitable as a +saturative substance for a roofing paper. How rapidly a paper roof can +be ruined by the generation of this injurious organic acid will be +seen from the following calculation: Let us suppose that an average +of 132 gallons of rain water falls upon ten square feet roof surface +per year, and that the arithmetical mean 0.932 of the largest (1.680) +and smallest number (0.184) be the quantity of the soluble brown +substance which on an average is dissolved in one quart of rain water; +hence from ten square feet of roof surface are rinsed away with the +rain water per year 466 grammes of the soluble decomposition products +of the tar. The oxidation process will not always occur as intensely +as by a paper roof, ten years old and painted two years ago, which +instigated above described experiment. As long as the roofing paper is +fresh and less porous, especially if the occurring pores are filled +and closed again by repeated coatings, oxidation will take place far +less rapidly. Besides this, the protective coating applied to the roof +surface is exposed most to this oxidation process. Even by assuming +this constantly progressive destructive action of the oxygen on the +roofing paper to be much less than above stated, we can readily +imagine that it must be quite large. If it is desired to produce a +material free of faults, it is first of all indispensable that +unobjectionable raw material be procured. Coal tar was formerly used +almost exclusively for the coating of a roof. It was heated and +applied hot upon the surface. In order to avoid the running off of the +thinly fluid mass, the freshly coated surface was strewn with sand. +The most volatile portion of the tar evaporated soon, whereby the +coating became thicker and finally dried. The bad properties of the +coal tar, pointed out elsewhere, made it very unsuitable even for this +purpose, and experiments were instituted to compound mixtures, by +adding other ingredients to the tar, that should more fully comply +with its function. It may be said in general that the coating masses +for roofs can be divided into two classes: either as lacquers or as +cements. To the former may be classed those of a fairly thinly fluid +consistency, and which contain volatile oils in such quantities that +they will dry quickly. Cements are those of a thickly fluid +consistency, and are rendered thus fluid by heating. It is not +necessary that the coating applied should harden quickly, as it +assumes soon after its application a firmness sufficient to prevent it +from running off the roof. Coal tar is to be classed among lacquers. +If it has been liberated by distillation from the volatile oils, it is +made better suited for the purpose than the ordinary kind. The mass +contains much more asphaltum, and after drying, which takes place +soon, it leaves a far thicker layer upon the roof surface, while the +pores, which had formed in the roofing paper consequent on drying, are +better filled up. Nevertheless, the distilled tar also has retained +the property of drying with time into a hard, vitreous mass, and +ultimately to be destroyed by decomposition.--_The Roofer_. + + * * * * * + + + + +A PHYSICAL LABORATORY INDICATOR. + + +The difficulties attending the management of a physical laboratory are +much greater than those of a chemical one. The cause of this lies in the +fact that in the latter the apparatus is less complicated and the pieces +less varied. Any contrivance that will reduce the labor and worry +connected with the running of a laboratory is valuable. + +A physical laboratory may be arranged in several ways. The apparatus may +be kept in a store room and such as is needed may be given to the +student each day and removed after the experiments are performed; or the +apparatus for each experiment or system of experiments may be kept in a +fixed place in the laboratory ready for assembling; for certain +experiments the apparatus may be kept in a fixed place in the laboratory +and permanently arranged for service. + +Each student may have his own desk and apparatus or he may be required +to pass from desk to desk. The latter method is preferable. + +When a store room is used the services of a man are required to +distribute and afterward to collect. If the apparatus is permanently +distributed, a large room is necessary, but the labor of collecting and +distributing is done away with. + +There are certain general experiments intended to show the use of +measuring instruments which all students must perform. To illustrate the +use of the indicator I have selected an elementary class, although the +instrument is equally applicable to all classes of experiments. + +Having selected a suitable room, tables may be placed against the walls +between the windows and at other convenient places. Shallow closets are +built upon these tables against the wall; they have glass doors and are +fitted with shelves properly spaced. A large number of light wooden +boxes are prepared, numbered from one up to the limit of the storage +capacity of the closets. A number corresponding to that upon the box is +placed upon the shelf, so that each one after removal may be returned to +its proper place without difficulty. On the front of the box is a label +upon which is written the experiment to be performed or the name of the +apparatus whose use is to be learned, references to various books, which +may be found in the laboratory library, and the apparatus necessary for +the experiment, which ought to be found in the box. If any parts of the +apparatus are too large to be placed in the box, the label indicates by +a number where it may be found in the storage case. + +It is evident that, instead of the above arrangement, all the boxes can +be stacked in piles in a general store room. The described arrangement +is preferable, as it prevents confusion in collecting and distributing +apparatus when the class is large. + +_The Indicator_ (see figure).--Some device is evidently desirable to +direct the work of a laboratory with the least trouble and friction +possible. I have found that the old fashioned "peg board," formerly used +in schools to record the demerits of scholars, modified as in the +following description, leaves nothing to be desired. + +The requirements of such an instrument are these: It must show the names +of the members of the class; it must contain a full list of the +experiments to be performed; it must refer the student to the book and +page where information in reference to the experiments or apparatus may +be found; it must show what experiments are to be performed by each +student at a given time; it must give information as to the place in the +laboratory where the apparatus is deposited; it must show to the +instructor what experiments have been performed by each student; it must +prevent the assignment of the same experiment to two students; it must +enable the instructor to assign the same experiment to two or more +students; it must form a complete record of what has been done, what +work is incomplete, and what experiments have not yet been assigned; it +must also be so arranged that new experiments or sets of experiments may +be exhibited. + + +------+---+---+---+---+---+---+---+---+ + | | A | B | C | D | E | F | G | H | + +------+---+---+---+---+---+---+---+---+ + | 1 | * o o * o o o o | + | 2 | * o * * o o o o | + | 3 | + * * * o o o o | + | 4 | + o * * o o o o | + | 5 | o + * * * * o o | + | 6 | o + * * o * o o | + | 7 | o o + * o o o o | + | 8 | o o o + * o o o | + | 9 | o o o * + o o o | + | 10 | o o o o o + o o | + | 11 | o o o * o o + * | + | 12 | o o * * o + + + | + | 13 | o o * o o o o o | + | 14 | o o * o o o o o | + | 15 | o o + o o o o o | + | 16 | o o + + * o o * | + +--------------------------------------+ + + A, B, C, etc., are cards upon which are the names of students. 1, + 2, 3, etc., are cards like the one described in the article. The + small circles (o) represent unassigned experiments. The black + circles (*) (slate nails) represent work done. The caudate circles + (+) (brass nail) represent work assigned. + +The indicator consists of a plank of any convenient length and breadth. +The front surface is divided into squares of such size that the pegs may +be introduced and withdrawn with ease. At each corner of the squares +holes are bored into which nails may be placed. There is a blank border +at the top and another on the left side. At the top of each vertical +column of holes is placed a card holder. This is made of light tin +turned up on the long edges--which are vertical--and tacked to the +board. Opposite each horizontal row of holes is a similar tin card +holder, but of greater length, and having its length horizontal. The +holders at the top of the board contain cards upon which the names of +the class are written. + +Cards, like the following, are prepared for the horizontal holders. + +-------------------------------------------------------------- +Stewart & Gee 229 +Physical Manip. 85 Intensity of Gravity--Borda's Method 39 +Glazebrook & Shaw 132 +-------------------------------------------------------------- + +These cards are numbered from one to any desired number and are arranged +in the holders consecutively. + +Two kinds of nails are provided to fit the holes in the board: An +ordinary slate nail and a common picture frame nail with a brass head. +The latter indicates work to be done, the former work done. + +To prepare the board for service, brass headed nails are placed opposite +each experiment, and below the names, care being taken not to have more +than one nail in the same horizontal row, unless it is intended that two +persons or more are to work upon the same experiment. + +There will be no conflict when the brass nails occupy diagonal lines. If +they do not, a glance will show the fact. + +After an experiment has been performed and a report made upon the usual +blank, the brass nail is removed and a slate nail put in its place. + +The board will show by the slate nails what work has been done by each +student, by the brass nails what is yet to be done, and by the empty +holes, experiments which have been omitted or are yet to be assigned. A +slate nail opposite an experiment card indicates that that experiment +may now be assigned to another person. + +It is evident that the schedule for a whole term may be arranged in a +few minutes and that the daily changes require very little time. + +The board is hung in a convenient place. The student as he enters the +laboratory looks for his name on the upper cards and under it for the +first brass nail in the vertical column: to the left he finds the +experiment card. On the left hand end of the slip he sees the book +references, on the right hand end a number--39 in the sample card given +above. Knowing the number, he proceeds to a desk and finds a box +numbered in the same manner. He removes the box from the closet. On the +label of the box is a list of all the apparatus necessary, which he will +find in the box; the label also contains the book references. He +performs the experiment, fills up a blank which he gives to the +instructor, puts all the materials back in the box, replaces the box in +its proper place in the closet and proceeds with the next experiment. +With this indicator there is no difficulty in managing fifty students or +more. + +Comparatively little apparatus need be duplicated. Where apparatus is +fixed against a wall a number may be tacked upon the wall and a card +containing the information desired. The procedure is then the same as +with the boxes. The cards on the board being removable, other ones may +be inserted containing information in reference to other boxes having +the same number but containing different materials. There can be no +successful tampering with the board, for the record of experiments +performed is upon the blanks which the students turn in and also in the +individual note books which are written up and given to the instructor +for daily examination. + +Lafayette College. J.W. MOORE. + + * * * * * + + + + +NEW METHOD OF EXTINGUISHING FIRES + + +This is by George Dickson, of Toronto, Canada, and David Alanson Jones. + +A mixture of water and liquefied carbon dioxide upon being discharged +through pipes at high pressure causes the rapid expansion of the gas and +converts the mixture into spray more or less frozen, and portions of the +liquid carbon dioxide are frozen, owing to its rapid expansion, and are +thus thrown upon the fire in a solid state, where said frozen carbon +dioxide in its further expansion not only acts to put out the fire, but +cools the surface upon which it falls, and thus tends to prevent +reignition. + +A represents a receptacle sufficiently strong to stand a pressure of not +less than a thousand pounds to the square inch. + +B B water receptacles. + +[Illustration: Fig. 1] + +In the drawings we have shown two receptacles B and only one receptacle +A; but we do not wish to confine ourselves to any particular number, nor +do we wish to confine ourselves to the horizontal position in which the +receptacles are shown. + +C is a pipe leading from the receptacle A to a point at or near the +bottom of the receptacle B. + +F is a pipe through which the mixture of water and liquefied gas from +the receptacle B is forced by the expansion of said liquefied gas, the +said pipe taking the mixture of water and liquefied gas from the bottom +of the receptacle. + +[Illustration: Fig. 2] + +To use the apparatus, open the stop cock D in the pipe C, leading to one +of the receptacles B, whereupon, owing to the lower pressure in the +cylinder B, the liquid carbon dioxide expands and rises to the top of +the cylinder A and forces the liquid carbon dioxide into the cylinder B, +the same as the superior steam of a boiler forces the water of the +boiler out when the same is tapped below the surface of the liquid. Now +upon opening the tap H, this superior gas forces out the mixture of +water and liquid carbon dioxide, which suddenly expanding causes +portions of the globules of liquefied gas to be frozen, and these, being +protected by a rapidly evaporating portion of the liquefied gas, are +thrown on the fire in solid particles. At the same time the water is +blown into a spray, which is more or less frozen. The fire is thus +rapidly extinguished by the vaporization of the carbon dioxide and water +spray. + + * * * * * + + + + +SMOKELESS GUNPOWDER. + +BY HUDSON MAXIM. + + +During the last forty years leading chemists have continued to +experiment with a view to the production of a gunpowder which should be +smokeless. But not until the last few years has any considerable degree +of success been attained. + +To be smokeless, a gunpowder must yield only gaseous products of +combustion. None of the so-called smokeless powders are entirely +smokeless, although some of them are very nearly so. + +The smoke of common black gunpowder is largely due to minute particles +of solid matter which float in the air. About one-half of the total +products of combustion of black gunpowder of ordinary composition +consists of potassium carbonate in a finely divided condition and of +potassium sulphate, which is produced chiefly by the burning in the air +of potassium sulphide, another production of combustion, as on the +outrushing gases it is borne into the air in a fine state of division. + +Another cause for the smoke of gunpowder is the formation of small +liquid vesicles which condense from some of the products of combustion +thrown into the air in a state of vapor, in the same manner as vesicles +of aqueous vapor form in the air on the escape of highly heated steam +from the whistle of a locomotive. + +Broadly speaking, an explosive compound is one which contains, within +itself, all the elements necessary for its complete combustion, and +whose heated gaseous products occupy vastly more space than the original +compound. Such compound usually consists of oxygen, associated with +other elements, for which it has great affinity, and from which it is +held from more intimate union, or direct chemical combination, under +normal conditions, by being in combination as well with other elements +for which it has less affinity, but which it readily gives up for the +stronger affinities when explosion takes place, the other elements +either combining with one another to form new compounds or being set +free in an uncombined state. + +An explosive is said to detonate when the above changes take place +instantaneously, the action being transmitted with the speed of +electricity by a sort of molecular rhythm from molecule to molecule +throughout the entire substance of the compound. + +An explosive is said to explode when the above changes do not occur +instantaneously throughout the whole substance, but whose combustion +takes place from the surface inward of the particles or grains of which +it is composed, thus requiring some definite lapse of time. + +The elements of an explosive compound may be associated chemically as in +nitro-glycerine and gun-cotton, which are chemical compounds, being the +results of definite reactions. Or, an explosive may be a mere mechanical +mixture of different substances comprising the necessary elements, as is +ordinary black gunpowder, which is a compound of charcoal, sulphur and +saltpeter, the saltpeter supplying the necessary oxygen. + +No gunpowder can be smokeless in which saltpeter or any oxygen-bearing +salt having a metallic base is employed, for when the salt gives up its +oxygen, the base combines with other elements to produce a sulphate, a +carbonate, or other salt, which, being solid, produces smoke. Therefore, +to be smokeless, a gunpowder must contain no other elements than oxygen, +hydrogen, nitrogen, and carbon, and in such proportions that the +products of combustion shall be wholly gaseous. The nitric +ethers--gun-cotton and nitro-glycerine--constitute such explosive +compounds. These substances were formerly thought to be +nitro-substitution compounds, but are now known to belong to the +compound ethers of nitric acid. + +Gun-cotton, discovered by Schonbein, in 1845, has since been looked upon +as the most promising material for a smokeless gunpowder, it being a +very powerful explosive and burning with practically no smoke. To-day, +gun-cotton, in some form or other, constitutes the base of substantially +all of the smokeless powders with which have been attained any +considerable degree of success. + +Gun-cotton alone and in its fibrous state has been found to be too +quick, or violent, for propulsive purposes, such as use in firearms; as +under such conditions of confinement it is very likely to detonate and +burst the gun. However, if gun-cotton be dissolved in a suitable +solvent, which is capable of being evaporated out, such as acetone, or +acetate of ethyl, which are very volatile, it becomes, when thus +dissolved and dried, a very hard, horn-like, amorphous substance, which +may be used for a smokeless gunpowder. But this substance taken alone is +very difficult to mould or granulate, and the loss of expensive solvents +must necessarily be quite considerable. + +When gun-cotton is reduced to a collodial solid, as above, and used as a +smokeless gunpowder, the grains must be made comparatively small to +insure prompt and certain ignition, and consequently the pressures +developed in the gun are apt to be too great when charges sufficiently +large are used to give desired velocities. + +If, however, a compound be made of gun-cotton and nitro-glycerine, in +about equal parts, by means of a volatile solvent or combining agent, +such as one of the before mentioned, and the solvent evaporated out, we +obtain practically a new substance and one which, as regards its +explosive nature, is quite unlike either of its two constituents taken +alone. The nitro-glycerine, furthermore, being itself a solvent of +gun-cotton, much less of the volatile ether is necessary to render the +compound of an amorphous character. Being quite plastic this substance +may be wrought or moulded into any desired size or form of grain. + +This simple compound of nitro-glycerine and gun-cotton, or with some +slight modifications, has been found, when properly granulated, to be +the most smokeless powder that has yet been discovered or invented. If +pure chemicals are employed in the manufacture, and the gun-cotton and +nitro-glycerine be made of the highest nitration and best quality, we +have a smokeless powder which will possess the following desirable +qualities: + +1st. It is absolutely smokeless, that is, its products of combustion are +entirely gaseous. + +2d. Its products of combustion are in no way deleterious or unpleasant. + +3d. It is perfectly safe to manufacture, handle and transport. There is +no more danger of its exploding accidentally than there would be of an +explosion of shavings or sawdust; for, unless well confined and set off +with a strong primer, it will not explode at all. In the open its +combustion is so slow as to in no way resemble or partake of the nature +of an explosion. + +4th. It is perfectly stable, and will keep any length of time absolutely +without undergoing any change whatever, under all conditions of +temperature or exposure to which gunpowder would ever be subjected. + +5th. It is not hygroscopic, and may be soaked in water without being at +all affected by it. + +6th. It will not corrode the cartridge case. + +7th. It will not foul the gun. + +8th. It is sure of ignition with a good primer, and may be made to burn +as slowly as desired by varying the character and size of the grains. +Indeed, it may be made to burn so slowly as to fail of complete +combustion before the bullet leaves the gun, and after firing several +rounds, partly burned pieces of the powder may be picked up in front of +the gun. + +9th. In a shoulder arm, a velocity of 2,000 feet per second may be +imparted to the bullet with this powder, and with a pressure in the +chamber of the gun of not more than fifteen English tons. This is, of +course, when the gun, cartridge case, primer, and projectile are adapted +to the use of smokeless powder, and the granulation of the powder is +adapted to them. + +If what I have here claimed for the above smokeless powder be true, it +would appear that it may be taken as really an ideal smokeless powder. +Why, then, has it not already been universally adopted? Surely such a +powder is just what every government is seeking. In reply to this, let +me say that, in order for the above compound to be an effective and +successful smokeless powder, with the manifestation of the many +desirable qualities which I have recited, a great many other conditions +are necessary, some of which I will mention. To arrive at the knowledge +that this compound would constitute the best smokeless powder has +required a great deal of experimenting. It was first thought that +gun-cotton colloid, without any nitro-glycerine, that is, gun-cotton +dissolved and dried, would burn more slowly, keep better, and give +better ballistics than it would if combined with nitro-glycerine. It was +also thought that gun-cotton of a high degree of nitration when made +into colloidal form would even then burn too quickly to be suitable for +use in firearms. Consequently, the first experiments were with low grade +gun-cotton, what is called collodion cotton, such as is employed in the +manufacture of celluloid. But, as this would not explode without the +addition of some oxygen-bearing element, various oxygen-bearing salts +were combined with it, such as nitrate of potassium, nitrate of ammonia, +nitrate of baryta, etc. Also a great many of the first smokeless powders +were made of low grade gun-cotton combined with nitro-glycerine in +varying proportions. These powders would often give very good results +when first made; but low grade gun-cotton or di-nitro-cellulose, as it +is called, is a very unstable compound, and these powders, after giving +very promising results, were found to be constantly undergoing change, +sooner or later resulting in complete decomposition. + +When nitro-glycerine was first combined with gun-cotton in small +quantities, camphor was often added, to lessen the rapidity of +combustion which the nitro-glycerine was supposed to impart and also to +render the compound more plastic, and to tend to prevent the +decomposition of the low grade gun-cotton. But camphor being volatile, +would, by its evaporation, cause the powder to constantly change in +character. Castor oil has been found to be a better diluent, as this +will not evaporate. + +As all of the smokeless powders made of a low grade gun-cotton were +found to deteriorate and spoil, experiments were made with gun-cotton of +the highest degree of nitration, both alone and in combination with +nitro-glycerine. These experiments were first conducted in England by +private parties and by the British government, when it was found that +high grade gun-cotton would give excellent results if made into a +colloidal solid and used alone, or in combination with certain other +constituents. With a view to saving the large quantity of solvents +necessary to reduce the gun-cotton, and to get a more prompt and certain +ignition with a larger grain, experiments were cautiously made by the +admixture of varying proportions of nitro-glycerine to the gun-cotton +when dissolved, or rather along with other solvents in the process of +dissolving it. + +It was soon found that nitro-glycerine added in quantities, even equal +in weight to the gun-cotton itself, did not materially increase the +rapidity of the explosion of the compound. And it was also found that +high grade gun-cotton, when combined with nitro-glycerine, gave very +much better results than low grade gun-cotton. + +I have spoken here of high and low grade gun-cotton, when in fact the +word gun-cotton should be applied only to the highest nitro-compound of +cellulose. The word gun cotton has always been rather loosely used. +Pyroxyline would be a better word, as this applies to all grades. When +cotton fiber is soaked in a large excess of a mixture of the strongest +nitric and sulphuric acids, gun-cotton proper, or that of the highest +grade, is produced. When weaker acids are used, lower grades of +nitro-cellulose are formed. + +The first mentioned or highest grade gun-cotton, when thoroughly freed +from its acids, has always proved to be a perfectly stable compound. The +lower grades have always been found to be unstable and subject to +spontaneous decomposition. Nitro-glycerine has also been erroneously +thought to be a very unstable compound. But experiments have proved +that, when made pure, it is perfectly stable. + +Having now explained how the knowledge came to be arrived at that the +aforementioned compound of highest grade nitro-glycerine and highest +grade gun-cotton would constitute the best basis for a smokeless powder, +I will now mention a few of the other conditions necessary to success +with its use, without assuming that smokeless powder has yet passed its +experimental stage, and is beyond further improvement. Nevertheless, +such is the compound which has come to stay as the basis of all +smokeless powders; and any smokeless powder, if a successful one, may be +counted upon as being made of this compound of gun-cotton and +nitro-glycerine, or of a colloid of gun-cotton, either alone or combined +with diluents, oxygen-bearing salts, or inert matter. The fact that +smokeless powder may still be said to be in somewhat of an experimental +stage is not to admit that it is not a success. Firearms, cartridge +cases, and projectiles are also still in an experimental stage, for they +are constantly being improved; yet their use has been a great success +for a good many years. + +The question of success of a smokeless powder does not rest alone with +the powder itself. The gun, the cartridge case, primer, and bullet have +been as much the subjects of experiments in adapting them to the use of +smokeless powder as has the smokeless powder in being adapted to them. +To impart a velocity of 2,000 feet per second to a rifle ball, with +corresponding long range and accuracy of flight, has been a question as +much of improvement in rifles and projectiles as in the powder. To give +a velocity of 2,000 feet per second to a bullet, requires a pressure of +at least 15 English tons in the chamber of a gun. This would be a +dangerous pressure in an old-fashioned shoulder arm; while a bullet made +only of lead would strip on striking the rifling and pass right through +the barrel of the gun without taking any rotary motion whatever. It +might at first seem that the powder is the only thing to be considered; +but high ballistics can only be obtained when everything else is adapted +to its use. + +The projectile, the cartridge case, the fulminating cap, and the gun +have had to be all built up together, and a very large amount of +experimenting has been necessary to determine what would constitute the +best projectile, best cartridge case, best fulminating cap, and what +should be the character of the rifling and the quality and temper of the +steel of the gun barrel. + +It has been necessary first to conduct experiments to test the smokeless +powders for velocities and pressures, and then with the powders test +various kinds of projectiles and guns. In order to obtain the high +ballistics which have been secured, it has been found necessary to cover +the bullet with something harder than lead and to rifle the gun in a +special manner. + +The French, who were the first to definitely adopt smokeless powder, +were the first also to make a rifle, projectile, cartridge case and +primer suited to its use. + +To obtain long range with a small long bullet such as is now used, it +should rotate at a very high speed. It is well known to artillerists +that a projectile of four or more calibers in length has to be rotated +at a much higher speed than one of half that length, in order to keep +the projectile stiff in the air, and to prevent it from ending over in +its flight. To communicate this very high rotary movement to the bullet +in the instant of time during which it is passing through the barrel, +the rifling of the gun has to exert an enormous torsion on the bullet. +Lead, no matter how hardened, is not sufficiently strong, as it will not +only strip and pass straight through the gun without taking any rotary +movement whatever, but under such very high pressures it behaves like +wax, and is thrown from the gun in a distorted mass. + +The French cover their bullets with German silver, a substance made of +nickel, zinc and copper; and in order to put as little strain upon the +rifling and projectile as possible, the rifling of the gun is made with +an increasing twist, and has no sharp edges. The French rifle is made +very strong at the breech and is of tempered steel throughout. In this +way the French have made smokeless powder a success--a smokeless powder +made substantially of a character such as I have herein described. With +smokeless powder, the French rifle imparts a muzzle velocity of 2,000 +feet per second to the bullet, with a range of about 2,400 meters. + +If smokeless powder be divided into sufficiently small grains to be +ignited by an ordinary fulminating cap, it would burn too quickly, +thereby causing the pressure to mount too high, and without giving the +desired velocity. Consequently very large and strong fulminating caps +have to be employed. Smokeless powder is not ignited in the same manner +as black powder. Something besides ignition is necessary. Black powder +simply requires to be set on fire; while a smokeless powder, on the +contrary, not only requires that it be set on fire, but that a certain +degree of pressure be set up inside of the cartridge case. For instance, +if a primer of a certain size should be found to operate perfectly well, +giving prompt ignition in the cartridge case of a rifle of small +caliber, it would be found that the same primer would not ignite a +charge of the same powder if loaded into a gun of one inch caliber. In +the latter case a few grains only lying near the primer would be +ignited, and these would soon become extinguished by sudden release of +pressure bringing about a cooling effect due to expansion of the gases. +In small cartridges a large fulminating cap is all that is required, but +in large cartridges it is necessary to resort to additional means of +ignition. + +In France, where experiments were conducted with a 37 millimeter Maxim +gun, it was found to be impracticable to use a fulminating cap +sufficiently large to ignite the powder and cause it to burn. Therefore, +a small ignition charge of black powder was employed, it being put in a +capsule or bag and placed next the primer. On firing at the rate of 300 +rounds per minute, the black powder, though small in quantity, produced +a cloud of smoke through which it was quite impossible to see. The +inventor of the gun then prepared for the French some wafers of +pyroxyline canvas, which were placed next to the primer, securing +thereby prompt ignition without the production of any smoke. + +Smokeless powder, made as I have described, cannot be detonated by a +fulminating cap of any size or by any means whatever. A large charge of +fulminate of mercury placed inside the cartridge case next the primer +will not detonate the powder, it serving only to ignite it and cause it +to explode. But even this would not cause the powder to explode except +it be confined behind a projectile, that sufficient pressure may be run +up to make it burn in its own gases. + +Some curious experiments with smokeless powder may be tried with a shot +gun. If the fulminating cap be large, the powder fine, the wads numerous +and hard and the charge of shot heavy, all being well rammed down, and +the paper case well spun over the last pasteboard wad, a charge of +smokeless powder about equal in weight to one-half of what would be +employed of black powder would give about the same results as black +powder. But if the charge of shot be omitted, the primer will only +ignite the powder, and there will be set up sufficient pressure merely +to throw the wads about half way up the barrel of the gun, when the +powder will go out. Now if this same charge of powder be collected and +reloaded into a new cartridge case and well confined behind wads and a +charge of shot, as above explained, it will all burn, giving the same +results as black powder. + +Attempts have been made to use this powder in pistols and revolvers, but +here it has proved a failure, as the pressure is not great enough to +cause the powder to be consumed, unless it be in the form of very fine +grains or dust, in which case the pressure mounts too high. However, +this might be overcome to a degree by making the powder porous. The +chemical conditions of the powder might be the same, but the physical +conditions must be different. A powder suitable for shot guns and +pistols would not be suitable for rifles. + +One not familiar with the characteristics of smokeless powder would be +almost certain to fail in his first attempt to fire it. Many persons +have been convinced by their first experiments that this powder would +not burn at all in a gun, any more than so much sand. + +Smokeless powder is consumed with a rapidity which accords with the +conditions of its confinement. Therefore, the bullets which have been +experimented with by different governments have been the cause of much +of the varying pressures attributed to the smokeless powders. + +The Austrians use the Mannlicher steel jacketed bullet. The steel casing +or jacket is first tinned on the inside and then the lead is cast in, +thus melting the tin and adhering firmly to the jacket. This projectile +sets up enormous friction in the barrel of the gun when used with +smokeless powder; as the smokeless powder leaves the gun barrel +perfectly clean and the two steel surfaces being in absolute contact +cause tremendous friction; and as the coefficient of friction varies +with every shot, the pressure in the gun constantly varies greatly. + +The German silver covered bullet used by the French has the disadvantage +that when firing rapidly the chamber of the barrel becomes nickel plated +and great friction is caused, mounting up the pressures and causing the +muzzle velocities to fall off. + +The Austrians, in order to prevent their steel cased bullets from +rusting and to lessen the friction in the barrel of the gun, cover them +with a heavy lubricant, which gives the cartridges an unsightly +appearance and causes them to gather dust and sand. The French employ a +lubricant at the base of the projectile, with a small copper disk +between the same and the powder. + +Col. A.R. Buffington, commander of the National Armory at Springfield, +Mass., has made a steel covered projectile which he prevents from +rusting by blackening by a niter process. Several grooves are pressed in +the base of the bullet which carry a lubricant, and when the bullet is +inserted in the cartridge case the grooves are covered by it. +Furthermore, these grooves prevent the lead filling from bursting +through the steel casing, leaving the latter in the barrel, as often +occurs with the Austrian and French projectiles when using smokeless +powder. + +A new projectile has lately come out, the invention of Captain Edward +Palliser, of the British army. This bullet consists of a jacket made of +very soft Swedish wrought iron, coated with zinc and filled with lead, +the lead being pressed into this jacket. The bullet is corrugated at its +base, after the manner of the one made by Colonel Buffington. This +projectile has been experimented with very extensively by the British +government, and at the works of the Maxim-Nordenfelt Guns and Ammunition +Company, in England. The zinc coating of the bullet is too soft to stick +to the barrel of the gun, and also in a measure acts as a lubricant. +This projectile has given better results than any other that has been +experimented with. The great velocities and the most uniform pressures +by the use of smokeless powder have been attained with this Palliser +bullet. + + +NOISELESSNESS. + +A great many stories have been told about the noiselessness of smokeless +powder. But there is no such thing as a noiseless gunpowder. The report +of a gun charged with smokeless powder is very sharp, and is as loud as +when black powder is used, yet the volume of sound is much less, so that +the report cannot be heard at so great a distance. + +The report of a gun using smokeless powder is a sound of much higher +pitch than when black powder is used, and consequently cannot be heard +at so great a distance as the lower notes given by black powder. + +As smokeless powder exerts a much greater pressure than common black +powder when burned in a gun, one would naturally think that the recoil +of the barrel would be greater, owing to the greater pressure exerted by +the smokeless powder on the base of the cartridge case and the breech +mechanism. However, such is not the fact; for the barrel actually +recoils very much less when smokeless powder is used. This is due to the +suddenness with which the pressure is exerted by smokeless powder, it +acting more like a very sharp blow on the metal, whereby more of the +energy is converted into heat instead of being spent in overcoming the +inertia of the barrel to give recoil. Similarly when smokeless powder is +fired in a gun, the displacement of the air is so sudden that the sound +waves do not possess the same amplitude of recoil or vibration as is +given by black powder. + + * * * * * + + + + +THE CONSTRUCTION AND MAINTENANCE OF UNDERGROUND CIRCUITS. + +BY S.B. FOWLER. + + +The numerous disastrous storms of the last winter have brought out very +vividly the advantages of having all wires placed underground, and many +inquiries have been addressed to the companies operating underground +circuits as to their success. It is not probable that all of the answers +to these inquiries have been of the most favorable character. To many +central station managers an underground system means frequent +break-downs and interruptions of service, with, perhaps, slow and +expensive repairs, which bring in their turn numerous complaints, loss +of customers, and reduced profits. In many installations burn-outs both +underground and in the station are frequent, with the natural result +that the operating of circuits underground is not there considered an +unqualified success. The writer has in mind two very different +experiences with underground cables. Several miles of cable were bought +by a certain company, carefully laid, and up to to-day not a single +burn-out or interruption of service can be attributed to failure of +cables; at about the same time another company bought about an equal +amount of the same kind of cable, and in a comparatively short time the +current had to be shut off the lines and the whole installation repaired +and parts of it replaced. Both of these experiences have been repeated +many times and will be again, although it is simply a distinction +between a good cable properly laid and a good cable ruined by careless +and incompetent workmanship. + +Every failure can be traced to poor work in the original installation or +to the use of a cheap cable, both causes being due, generally, to that +false economy which looks for too quick returns. A poorly insulated line +wire and a poorly insulated cable are two very different things. +However, it is a fact that by the use of a good cable it is not +difficult to construct an underground system for light, power, telegraph +or telephone uses that will be superior to overhead lines in its service +and in cost of maintenance. The ideal underground system must have as a +starting point a system of subways admitting of the easy drawing in and +out of cables and affording means of making subsidiary connections +readily and with the minimum of expense and interruption of service. +This is practically accomplished by a subway consisting of lines of pipe +terminating at convenient intervals, say at street intersections, in +manholes, for convenience in jointing and in running out house +connections. These pipes, or ducts, as they are called, should be for +two kinds of service; the lower or deeper laid lines for the main or +trunk circuits, and a second series of ducts laid nearer the surface, +running into service boxes placed near together for lines to "house to +house" connections. In some cities where it is allowed to run overhead +lines, the plan of running but one service connection in a block is +followed, all customers in the block being supplied from a line run over +the housetops or strung on the rear walls. + +This makes unnecessary all subsidiary ducts except a short one from the +manhole to the nearest building in the block, and effects a considerable +saving in pipe, service boxes, cables and labor. The manholes should +have their walls built up of brick, the floors should be of concrete, +and there should be an inside lid which can be fastened down and the +manhole thus made water-tight. + +For ducts wood, iron or cement lined pipe may be used. To preserve the +wood it is generally treated with creosote, which, in contact with the +lead cover of the cable, sets up a chemical action, resulting in the +destruction of the lead. Wood offers but little protection for the +cable, as it is too easily damaged and broken through in the frequent +street openings made by companies operating lines of pipe in the +streets, and as one of the main purposes of a subway is that of a +protection to cables, wooden ducts have little to recommend them except +their cheapness. + +Iron pipes are either laid in trenches filled in with earth or are laid +in cement. Iron pipe will of course rust out in time, and if absolute +permanence in construction is desired, should be laid in cement, for +after the pipe rusts out, the duct of cement is still left. However, if +we are going to the expense of laying in cement, it would be much +preferable to use cement lined pipe, which is not only cheaper than iron +pipe, but makes the most perfect cable conduit, as it affords a +perfectly smooth surface to draw the cable over and give a good duct +edge. + +It is not necessary, however, in small installations of cable, +especially where additional connections will not be of frequent +occurrence, to go to the expense of subways, for cable may be safely +laid in the ground in trenches filled in with earth, or can be inclosed +in a plain wooden box or a wooden box filled with pitch. + +There are, of course, many localities where, if the cable is laid in +contact with the earth, a chemical action would take place which might +result in the destruction of the cable. + +Underground cables are of the following classes: 1. Rubber insulated +cables, insulated with rubber or other homogeneous material. 2. Fibrous +cables, so called from the conductors being covered with some fibrous +material, as cotton or paper, which is saturated with the insulating +material, paraffine, resin oil, or some special compound. Under this +latter head is also included the dry core paper cables. + +The first thing to do is to get the cable drawn into the ducts, and on +the proper accomplishment of this depends to a great extent the success +or failure of the whole installation. Probably the ducts have been wired +when the subway was constructed, but if not a wire must be run through +as a means of pulling in the draw rope. There are several kinds of +apparatus for getting a wire through a duct--rods, flexible tapes, +mechanical "creepers," etc.; but probably the best is the sectional rod. +This simply consists of three or four foot lengths of hard wood rods, +having metal tips that screw into each other. A rod is placed in a duct +at a manhole, one screwed to that, both are pushed forward, another one +added and pushed forward, and so on until they extend the entire length +of the duct. Then the wire is attached and the rods are pulled out and +detached one at a time and with the last rod the wire is through. At +least No. 14 galvanized iron or steel wire should be used, for any +smaller size cannot be used a second time, as a rule. In starting to +pull in the draw rope a wire brush should be attached to the wire and to +this again the rope, and when the brush arrives at the distant end of +the duct it very likely will bring with it a miscellaneous collection of +material which for the good of the cable had better be in the manhole +than in the duct. + +The reel or drum carrying the cable should be mounted on wheels or jacks +and placed on the same side of the manhole as the duct into which the +cable is to be drawn, and must always be so placed that the cable will +run off the top of the reel. + +There are several methods of attaching the draw rope to the cable. As +simple and strong a method as any is to punch two of these holes through +the cable, lead and all, and attach the rope by means of an iron +wire--some of the draw wire will do--run through these holes. Depending +on the length and weight of cable to be pulled it can be drawn either by +hand or by a multiplying winch. The rope should run through a block +fastened in the manhole in such a position that the rope shall have a +good straightaway lead from the mouth of the duct. + +The strain on the cable should be perfectly uniform and steady; if the +power is applied by a series of jerks either the lead covering may be +pulled apart or some of the conductors broken. At the reel there must +always be a large enough number of men to turn it and keep the cable +from rubbing on anything, and in the manhole one or more men to see that +the cable feeds into the duct straight and to guide it if necessary. If +the ducts are of iron and are not perfectly smooth at the ends, these +should be made so with a file, and in addition a protector of some sort +should be placed in the mouths of the duct, both above and below the +cable. Six inches of lead pipe, split lengthwise and bent over at one +end to prevent being drawn into the duct with the cable, makes a very +good protector. The cable should be reeled off the drum just fast enough +to prevent any of the power used in pulling the cable through the duct +being utilized in unreeling it. If this latter is allowed to occur the +cable will be bent too short and the lead covering buckled or broken, +and also the cable may be jammed against the upper edge of the duct and +perhaps cut through. + +If the reel is allowed to turn faster than the cable is drawn in, the +first three or four turns on the reel will slacken up, and the lead +covering may either be dented or cut through by scraping on the ground. +If the cable end when pulled through up to the block is not long enough +to bend around the hole more than half way, the rope should be +unfastened from its end, a length of rope with a well frayed out end +should be run through the block, and by fastening to the cable close to +the duct, with a series of half hitches, as much slack as necessary can +be pulled in. If this is properly manipulated there need not be a +scratch on the cable, but unless great care is taken the lead may be +pressed up into ridges and the core itself damaged. + +Immediately after the cable is drawn in, if the joint is not to be at +once made, the open end or ends should be cut off and the cable soldered +up, as most cables are very susceptible to moisture and readily absorb +water even from the atmosphere. Where practicable it is always a good +plan to pull the cable through as many manholes as possible without +cutting the cable; for the joint is, especially in telephone or +telegraph cables, the weak point. To do this the rope should be pulled +through the proper duct in the next section without unfastening it from +the cable; the winch should be moved to the next manhole, and pulling +through then done as before. There should always be a man in every hole +through which the cable is running to see that it does not bind anywhere +and to keep protectors around the cable. + +It is not advisable to pull more than one cable into a duct, and never +advisable to pull a cable into a duct containing another cable, but if +two or more cables have to go into the same duct, they should always be +drawn in together. Lead covered cables and those with no lead on the +outside should never be pulled into the same duct, for if they bind +anywhere the soft cable will suffer where two lead covered cables would +get through all right. Some manufacturers are now putting on their +cables a tape or braid covering, which saves the lead many bad bruises +and cuts, and is a valuable addition to a cable at very little +additional expense. + +Practically all electric light and power cables are either single or +double conductors, and the jointing of these is comparatively a simple +matter, although requiring considerable care. The lead is cut back from +each end about four or five inches, and the conductors bared of +insulation for two or three inches. The bare conductors should be +thoroughly tinned by dipping in the metal pot or pouring the melted +solder over them. A sperm candle is better than resin or acid for any +part of the operations where solder is used. A lead sleeve is here +slipped back over the cable, out of the way, and the ends of the +conductors brought together in a copper sleeve which is then sweated to +a firm joint. This part must be as good a piece of work mechanically as +electrically. The bare splice is then wrapped tightly with cotton or +silk tape to a thickness slightly greater than that of the insulation of +the cable, and is thoroughly saturated with the insulating compound +until all moisture previously absorbed by the tape is driven off. + +The lead sleeve is then brought over the splice and wiped to the cable. +The joint is then filled with the insulating compound poured through +holes in the top of the sleeve; these holes are then closed and the +joint is complete, and there is no reason why, in light and power +cables, that joint should not be as perfect as any other part of the +cable. When the cable ends are prepared for jointing they should be hung +up in such a position that they are in the same plane, both horizontal +and vertically, and firmly secured there, so that when the lead sleeve +is wiped on the conductor may be in its exact center, and great care +must be taken not to move the cables again until the sleeve is filled +and the insulation sufficiently cooled to hold the conductor in +position. + +It is also very important to see that there are no sharp points on the +conductors themselves, on the copper sleeve, on the edges of the lead +covering or on the lead sleeve. All these should be made perfectly +smooth, for points facilitate disruptive discharges. Branch joints had +better be made as T-joints rather than as Y-joints, for they are better +electrically and mechanically, although they occupy more room in the +manholes. They are of course made in the same way as straight joints, a +lead T-sleeve being used, however. For multiple arc circuits copper +T-sleeves and for series circuits copper L-sleeves are used. + +Telephone and telegraph cables are made of any required gauge of wire +and with from 1 to 150 conductors in a cable. In jointing these the +splices are never soldered, the conductors being joined either with a +twist joint or with the so-called Western Union splice. Each splice is +covered with a cotton or silk sleeve or a wrapping of tape, the latter +being preferable, although considerably increasing the time necessary +for making the joint. Great care must be taken that no ends of wire are +left sticking up, for they will surely work their way through the tape +and grounds, and crosses will be the result. The wires should always be +joined layer to layer and each splice very tightly taped in order to get +as much insulating compound around each splice as possible in the +limited space. The splices should be "broken" as much as possible, so as +to avoid having adjoining splices coming over each other. After the +joint has been saturated with insulating compound the wires should have +an outside wrapping of tape to keep them in shape, and then the sleeve +is wiped on and filled. If the insulation resistance of the jointed +telegraph or telephone cable is a quarter of what the cable tested in +the factory, it may be considered that an exceptionally good piece of +work has been done. I have spoken more particularly of fibrous lead +covered cables, as the handling of them includes practically every step +of the work on any other kind of underground cable. In insulating dry +core paper cables a paper sleeve is slipped over the splice, and in +rubber cables the splice is wrapped with rubber tape; all other details +are the same for these as for the fibrous cable. + +In the laying of light and power cables every joint, as made, should be +tested for insulation with a Thomson galvanometer, as the insulation +must necessarily be very high, and if one joint or section of cable is +any weaker than another it may be very important in the future to know +it. All tests must be made after the joint has cooled, for while hot its +insulation resistance will be very low. + +Tests for copper resistance should also be made to determine if the +splices are electrically perfect; an imperfect splice may cause +considerable trouble. In telegraph and telephone cables the conductors +should be of very soft copper, for in stripping the conductor of +insulation it is very easy to nick the wire, and if of hard drawn copper +open wires will be the result. + +All work should be frequently tested for continuity with telephones, +magnetos, or small portable galvanometers. It is only necessary to +ground the conductors at one end and try each wire at the other end. For +this sort of work a telephone receiver used with one cell of some dry +battery is most convenient, and has the additional advantage of +affording a means of communication while testing, and is by far the best +thing for identifying and tagging conductors. + +These cables should be frequently tested during the progress of the work +for grounds and crosses with a Thomson instrument, and when the cable is +complete, a careful series of tests of the capacity, insulation +resistance, and copper resistance of each wire should be made and the +exact condition of the cable determined before it is put in service, and +thereafter an intelligent oversight of the condition of the circuits +can thus be more readily maintained. + +Where a company has extensive underground service, a regular cable gang +should be in its employ, for quick and safe handling of cables demands +the employment of men accustomed to the work. If the cable has been +properly laid and tests show it to be in good condition before current +is turned on, almost the only trouble to be anticipated will be due to +mechanical injury. Disruptive discharge, puncturing the lead, may occur; +but the small chance of its occurring can be greatly lessened by the use +of some kind of "cable protector," which will provide for the spark an +artificial path of less resistance than the dielectric of the condenser, +which the cable in fact becomes. + +If a fault suddenly develops on a circuit, the chances are it will be +found in a manhole, and an inspection of the cable in the manhole will +generally reveal the trouble without resorting to locating with a +Wheatstone bridge. The cable is often cut through at the edge of the +duct, or damaged by something falling on it, or by some one "walking all +over it." To guard against these, the ducts should always be fitted with +protectors both above and below the cable. The cables should never be +left across the manholes, for they then answer the purpose of a ladder, +but should be bent, around the walls of the hole and securely fastened +with lead straps, that they may not be moved and the lead gradually worn +through. + +In telegraph cables, when one or two conductors "go," it will probably +be useless to look for trouble except with instruments; but if several +wires are "lost" at once it will probably be found to be caused by +mechanical injury, which can be located by inspection. If it is ever +necessary to loop out conductors, a joint can be readily opened and the +conductors wanted picked out and connected into the branch cable and the +joint again closed without disturbing the working wires. In doing this a +split sleeve must be used, and the only additional precaution to be +taken is in filling the sleeve to have the insulating compound not hot +enough to melt the solder and open up the split in the sleeve. In +cutting in service on light and power cables it is entirely practicable +to do so without interruption of service on multiple arc circuits, even +those of very high voltage; but they require great precaution and +involve considerable risk to the jointer, and where possible the circuit +to which the connection is to be made should previously be cut dead. +Where the voltage is not dangerous to human life, almost any service +connection can be made without interruption of service. + +I have only indicated a very few of the operations that may be found +necessary, and the probable causes of troubles that may be encountered +in the operating of underground circuits, believing that the different +problems that arise can, with a little experience, be successfully met +by any one who has a fair knowledge of the original construction of +cable lines.--_Electrical World_. + + * * * * * + + + + +RAILROADS TO THE CLOUDS. + + +If George Stephenson, when he placed the first locomotive on the track +and guaranteed it a speed of six miles an hour, could have foreseen that +in less than eighty years the successors of his rude machine would be +climbing the sides of mountain ranges, piercing gorges hitherto deemed +inaccessible, crossing ravines on bridges higher than the dome of St. +Paul's, and traversing the bowels of the earth by means of tunnels, no +doubt his big blue eyes would have stood out with wonder and amazement. +But he foresaw nothing of the kind; the only problem present in his mind +was how to get goods from the seaports in western England to London as +easily and cheaply as possible, and to do this he substituted for +horses, which had for 150 years been drawing cars along wooden or iron +tracks, the wonderful machine which has revolutionized the freight and +passenger traffic of the world. + +It was, indeed, impossible for any one to foresee the triumphs of +engineering which have accompanied the advances in transportation. To +the engineer of the present day there are no impossibilities. The +engineer is a wizard at whose command space and matter are annihilated. +The highest mountain, the deepest valley, has no terrors for him. He can +bridge the latter and encircle or tunnel the former. The only requisites +which he demands are that something in his line be needed, and that the +money is forthcoming to defray the expense, and the thing will be done. +But the railroad he is asked to construct must be necessary, and the +necessity must be plainly shown, or no funds will be advanced; and +although the theory does not invariably hold good, especially when a +craze for railroad building is raging, as a rule no expense for the +construction of a road will be incurred without a prospect of +remuneration. + +Hence the need of railroad communication has caused lines to be +constructed through districts where only a few years ago the thing would +have been deemed impossible. The Pacific roads of this country were a +necessity long before their construction, and in the face of +difficulties almost insuperable were carried to successful completion. +So, also, of the railroads in the Andes of South America. The famous +road from Callao through the heart of Peru is one of the highest +mountain roads in the world, as well as of the most difficult +construction. The grades are often of 300 feet and more to the mile, and +when the mountains were reached so great were the difficulties the +engineers were forced to confront that in some places laborers were +lowered from cliffs by ropes in order that, with toil and difficulty, +they might carve a foothold in order to begin the cutting for the +roadway. + +In some sections tunnels are more numerous than open cuts, and so far as +the road has gone sixty-one tunnels, great and small, have been +constructed, aggregating over 20,000 feet in length. The road attains a +height of 15,000 feet above the level of the sea, and at the highest +point of the track is about as high as the topmost peak of Mont Blanc. +It pierces the range above it by a tunnel 3,847 feet long. The stern +necessities of business compelled the construction of this road, +otherwise it never would have been begun. + +The tunnels of the Andes, however, do not bear comparison with the +tunnels, bridges, and snow sheds of the Union Pacific, nor do even these +compare with the vast undertakings in the Alps--three great tunnels of +nine to eleven miles in length, which have been prepared for the +transit of travelers and freight. The requirements of business +necessitated the piercing of the Alps, and as soon as the necessity was +shown, funds in abundance were forthcoming for the enterprise. + +But tunneling a mountain is a different thing from climbing it. Many +years ago the attention of inventors was directed to the practicability +of constructing a railroad up the side of a mountain on grades which, to +an ordinary engine, were quite impossible. The improvements in +locomotives twenty-five and thirty years ago rendered them capable of +climbing grades which, in the early days of railroad engineering, were +deemed out of the question. The improvements proved a serious stumbling +block in the way of the inventors, who found that an ordinary locomotive +was able to climb a much steeper grade than was commonly supposed. The +first railroads were laid almost level, but it was soon discovered that +a grade of a few feet to the mile was no impediment to progress, and +gradually the grade was steepened. + +The inventors of mountain railroad transportation might have been +discouraged by this discovery, but it is a characteristic of an inventor +that he is not set back by opposition, which, in fact, only serves to +stimulate his zeal. The projectors of inclined roads and mountain +engines kept steadily on, and in France, Germany, England, and the +United States many experimental roads were constructed, each of a few +hundred yards in length, and locomotive models were built and put in +motion to the amazement of the general public, who jeered alike at the +contrivances and the contrivers, deeming the former impracticable and +the latter crazy. + +But the idea of building a road up the side of a hill was not to be +dismissed. There was money in it for the successful man, so the cranky +inventors kept on at work in spite of the jeers of the rabble and the +discouragements of capitalists loath to invest their money in an +uncertain scheme. To the energy and perseverance of railroad inventors +the success of the mountain railroad is due, as also is the construction +of the various mountain roads, of which the road up Mt. Washington, +finished in 1868, was the first, and the road up Pike's Peak, completed +the other day, was the latest. + +Of all the mountain roads which have been constructed since the one up +Mt. Washington was finished, the best known is that which ascends the +world-famous Rigi. With the exception of Mont Blanc, Rigi is, perhaps, +the best known of any peak in the Alps, though it is by no means the +highest, its summit being but 5,905 feet above the level of the sea. +Although scarcely more than a third of the height of some other +mountains in the Alps, it seems much higher because of its isolated +position. Standing as it does between lakes Lucerne, Zug, and Lowertz, +it commands a series of fine views in every direction, and he who looks +from the summit of Rigi, if he does no other traveling in Switzerland, +can gain a fair idea of the Swiss mountain scenery. Many of the most +noted peaks are in sight, and from the Rigi can be seen the three lakes +beneath, the villages which here and there dot the shores, and, further +on, the mighty Alps, with their glaciers and eternal snows. + +Many years ago a hotel was built on the summit of the Rigi for the +benefit of the tourists who daily flocked to this remarkable peak to +enjoy the benefit of its wonderful scenery. The mountain is densely +wooded save where the trees have been cut away to clear the land for +pastures. The ease of its ascent by the six or eight mule paths which +had been made, the gradual and almost regular slope, and the throngs of +travelers who resorted to it, made it a favorable place for an +experiment, and to Rigi went the engineers in order to ascertain the +practicability of such a road. The credit of the designs is due to a +German engineer named Regenbach, who, about the year 1861, designed the +idea of a mountain road, and drew up plans not only for the bed but also +for the engine and cars. The scheme dragged. Capitalists were slow to +invest their money in what they deemed a wild and impracticable +undertaking, and even the owners of the land on the Rigi were reluctant +for such an experiment to be tried. But Regenbach persevered, and toward +the close of the decade the inhabitants of Vitznau, at the base of the +Rigi, were astonished to see gangs of laborers begin the work of making +a clearing through the forests on the mountain slope. They inquired what +it meant, and were told that a road up the Rigi was to be made. The +Vitznauers were delighted, for they had no roads, and there was not a +wheeled vehicle in the town, nor a highway by which it could be brought +thither. The idea of a railroad in their desolate mountain region, and, +above all, a railroad up the Rigi, never entered their heads, and a +report which some time after obtained currency in the town, that the +laborers were beginning the construction of a railroad, was greeted with +a shout of derision. + +Nevertheless, that was the beginning of the Rigi line, and in May, 1871, +the road was opened for traffic. It begins at Vitznau, on Lake Lucerne, +and extends to the border of the canton and almost to the top of the +mountain. It is 19,000 feet long, and during that distance rises 4,000 +feet at an average grade of 1 foot in 4. Though steep, it is by no means +so much so as the Mt. Washington road, which rises 5,285 feet above the +sea, at an average of 1 foot in 3. There are, however, stretches of the +Rigi road at which the grade is about 1 foot in 2½, which is believed to +be the steepest in the world. + +The Rigi road has several special features aside from its terrific +slopes which entitle it to be considered a triumph of the engineer's +skill. About midway up the mountains the builders came to a solid mass +of rock, which presented a barrier that to a surface road was +impassable. They determined to tunnel it, and, after an enormous +expenditure of labor, finished an inclined tunnel 225 feet in length, of +the same gradient as the road. A gorge in the side of the mountain where +a small stream, the Schnurtobel, had cut itself a passage also hindered +their way, and was crossed by a bridge of lattice girder work in three +spans, each 85 feet long. The entire roadbed, from beginning to end, was +cut in the solid rock. A channel was chiseled out to admit the central +beam, which contains the cogs fitting the driving wheel of the +locomotive. The engine is in the rear of the train, and presents the +exceedingly curious feature of a boiler greatly inclined, in order that +at the steeper gradients it may remain almost perpendicular. The coal +and water are contained in boxes over the driving wheels, so that all +the weight of the engine is really concentrated on the cogs--a +precaution to prevent their slipping. The cost of the road, including +three of these strangely constructed locomotives, three passenger +coaches, and three open wagons, was $260,000, and it is a good paying +investment. The fare demanded for the trip up the mountains is 5 francs, +while half that sum is required for the downward passage, and the road +is annually traversed by from 30,000 to 50,000 passengers. + +Curious sensations are produced by a ride up this remarkable line. The +seats of the cars are inclined like the boiler of the locomotive, and so +long as the cars are on a level the seats tilt at an angle which renders +it almost impossible to use them. But when the start is made the +frightful tilt places the body in an upright position, and, with the +engine in the rear, the train starts up the hill with an easy, gliding +motion, passing up the ascent, somewhat steeper than the roof of a +house, without the slightest apparent effort. But if the going up +excites tremor, much more peculiar are the feelings aroused on the down +grade. The trip begins with a gentle descent, and all at once the +traveler looking ahead sees the road apparently come an end. On a nearer +approach he is undeceived and observes before him a long decline which +appears too steep even to walk down. Involuntarily he catches at the +seats, expecting a great acceleration of speed. Very nervous are his +feelings as the train approaches this terrible slope, but on coming to +the incline the engine dips and goes on not a whit faster than before +and not more rapidly on the down than on the up grade. Many people are +made sick by the sensation of falling experienced on the down run. Some +faint, and a few years ago one traveler, supposed to be afflicted with +heart disease, died of fright when the train was going over the +Schnurtobel bridge. The danger is really very slight, there not having +been a serious accident since the road was opened. The attendants are +watchful, the brakes are strong, but even with all these safeguards, men +of the steadiest nerves cannot help wondering what would become of them +in case anything went wrong. + +Bold as was the project of a railroad on the Rigi, a still bolder scheme +was broached ten years later, when a daring genius proposed a railroad +up Mt. Vesuvius. A railroad up the side of an ordinary mountain seemed +hazardous enough, but to build a line on the slope of a volcano, which +in its eruption had buried cities, and every few years was subject to a +violent spasm, seemed as hazardous as to trust the rails of an ordinary +line to the rotten river ice in spring time. The proposal was not, +however, so impracticable as it looked. While the summit of Vesuvius +changes from time to time from the frequent eruptions, and varies in +height and in the size of the crater, the general slope and contour of +the mountain are about the same to-day as when Vesuvius, a wooded hill, +with a valley and lake in the center of its quiescent crater, served as +the stronghold of Spartacus and his rebel gladiators. There have been +scores of eruptions since that in which Herculaneum and Pompeii were +overthrown, but the sides of the mountain have never been seriously +disturbed. + +A road on Vesuvius gave promise of being a good speculation. Naples and +the other resorts of the neighborhood annually attracted many thousands +of visitors, and a considerable number of these every year ascended the +volcano, even when forced to contend with all the difficulties of the +way. Many, however, desiring to ascend, but being unable or unwilling to +walk up, a chair service was established--a peculiar chair being slung +on poles and borne by porters. In course of time the chair service +proved to be inadequate for the numbers who desired to make the ascent, +and the time was deemed fit for the establishment of more speedy +communication. + +Notwithstanding the necessity, the proposal to establish a railroad met +with general derision, but the scheme was soon shown to be perfectly +practicable, and a beginning was made in 1879. The road is what is known +as a cable road, there being a single sleeper with three rails, one on +the top which really bore the weight, and one on each side near the +bottom, which supported the wheels, which coming out from the axle at a +sharp angle, prevented the vehicle from being overturned. The road +covers the last 4,000 feet of the ascent, and the power house is at the +bottom, a steel cable running up, passing round a wheel at the top and +returning to the engine in the power house. The ascent to the lower +terminus of the road is made on mules or donkeys; then, in a comfortable +car, the traveler is carried to a point not far from the crater. The car +is a combined grip and a passenger car, similar in some points to the +grip car of the present day, while the seats of the passenger portion +are inclined as in the cars on the Rigi road. But the angle of the road +being from thirty-three to forty-five degrees, makes both ascent and +descent seem fearfully perilous. Every precaution, however, is taken to +insure the safety of passengers; each car is provided with several +strong and independent brakes, and thus far no accident worth recording +has occurred. The road was opened in June, 1880. Although there have +been several considerable eruptions since that date, none of them did +any damage to the line but what was repaired in a few hours. + +The fashion thus set will, no doubt, be followed in many other quarters. +Wherever there is sufficient travel to pay working expenses and a profit +on a steep grade mountain road it will probably be built. Already there +is talk of a road on Mont Blanc, of another up the Yungfrau, and several +have been projected in the Schwartz and Hartz mountains. A route on Ben +Nevis, in Scotland, is already surveyed, and it is said surveys have +also been made up Snowden, with a view to the establishment of a road to +the summit of the highest Welsh peak. Sufficient travel is all that is +necessary, and when that is guaranteed, whenever a mountain possesses +sufficient interest to induce people to make its ascent in considerable +numbers, means of transportation, safe and speedy, will soon be +provided. The modern engineer is able, willing and ready to build a road +to the top of Mt. Everest in the Himalayas if he is paid for doing +so.--_St. Louis Globe-Democrat._ + + * * * * * + +To clean hair brushes, wash with weak solution of washing soda, rinse +out all the soda, and expose to sun. + + * * * * * + + + + +THE MARCEAU. + + +[Illustration: THE FRENCH ARMORED TURRET SHIP MARCEAU] + +The Marceau, the last ironclad completed and added to the French navy, +was put in commission at Toulon in April last, and has lately left that +town to join the French squadron of the north at Brest. The original +designs of this ship were prepared by M. Huin, of the French Department +of Naval Construction, but since the laying down of the keel in the year +1882 they have been very considerably modified, and many improvements +have been introduced. + +Both ship and engines were constructed by the celebrated French firm, +the Société des Forges et Chantiers de la Mediterranée, the former at +their shipyard in La Seyne and the latter at their engine works in +Marseilles. The ship was five years in construction on the stocks, was +launched in May, 1887, and not having been put in commission until the +present year, was thus nearly nine years in construction. She is a +barbette belted ship of somewhat similar design to the French ironclads +Magenta, now being completed at the Toulon arsenal, and the Neptune, in +construction at Brest. + +The hull is constructed partly of steel and partly of iron, and has the +principal dimensions as follows. Length, 330 ft. at the water line; +beam, 66 ft. outside the armor; draught, 27 ft. 6 in. aft.; +displacement, 10,430 English or 10,600 French tons. The engines are two +in number, one driving each propeller; they are of the vertical compound +type, and on the speed trials developed 11,300 indicated horse power +under forced and 5,500 indicated horse power under natural draught, the +former giving a speed of 16.2 knots per hour with 90 revolutions per +minute. The boilers are eight in number, of the cylindrical marine type, +and work at a pressure of 85.3 lb. per square inch. During the trials +the steering powers of the ship were found to be excellent, but the bow +wave is said, by one critic, to have been very great. + +The ship is completely belted with Creusot steel armor, which varies in +thickness from 9 in. forward to 17¾ in. midships. In addition to this +belt the ship is protected by an armored deck of 3½ in., while the +barbette gun towers are protected with 15¾ in. steel armor with a hood +of 2½ in. to protect the men against machine gun fire. As a further +means of insuring the life of the ship in combat and also against +accidents at sea, the Marceau is divided into 102 water-tight +compartments and is fitted with torpedo defense netting. There are two +masts, each carrying double military tops; and a conning tower is +mounted on each mast, from either of which the ship may be worked in +time of action, and both of which are in telegraphic communication with +the engine rooms and magazines. Provision is made for carrying 600 tons +of coal, which, at a speed of 10 knots, should be sufficient to supply +the boilers for a voyage of 4,000 miles. + +The armament of the Marceau is good for the tonnage of the ship and +consists principally of four guns of 34 centimeters (13.39 in.) of the +French 1884 model, having a weight of 52 tons, a length of 28½ calibers, +and being able to pierce 30 in. of iron armor at the muzzle. The +projectiles weigh 924 lb., and are fired with a charge of 387 lb. of +powder. The muzzle velocity has been calculated to be 1,968 ft. per +second. The guns are entirely of steel and are mounted on Canet +carriages in four barbette towers, one forward, one aft, and one on each +side amidships. On the firing trials both the guns and all the Canet +machinery, for working the guns and hoisting the ammunition, gave very +great satisfaction to all present at the time. In addition to the above +four heavy guns there are, in the broadside battery, sixteen guns of 14 +centimeters (5.51 in.), eight on each side, and a gun of equal caliber +is mounted right forward on the same deck. The armament is completed by +a large number of Hotchkiss quick-firing and revolver guns and four +torpedo tubes, one forward, one aft, and one on each side. + +The crew of the Marceau has been fixed at 600 men, and the cost is +stated to have been about $3,750,000.--_Engineering_. + + * * * * * + +[Continued from SUPPLEMENT, No. 820, page 13097.] + + + + +A REVIEW OF MARINE ENGINEERING DURING THE PAST DECADE.[1] + +[Footnote 1: Paper read before the Institution of Mechanical Engineers, +July 28, 1891.] + +BY MR. ALFRED BLECHYNDEN, OF BARROW-IN-FURNESS + + +_Steam Pipes_.--The failures of copper steam pipes on board the Elbe, +Lahn, and other vessels have drawn serious attention both to the +material and to the modes of construction of the pipes. The want of +elastic strength in copper is an important element in the matter; and +the three following remedies have been proposed, while still retaining +copper as the material. First, in view of the fact that in the operation +of brazing the copper may be seriously injured, to use solid drawn +tubes. This appears fairly to meet the main dangers incidental to +brazing; but as solid drawn pipes of over 7 inches diameter are +difficult to procure, it hardly meets the case sufficiently. Secondly, +to use electrically deposited tubes. At first much was promised in this +direction; but up to the present time it can hardly be regarded as more +than in the experimental stage. Thirdly, to use the ordinary brazed or +solid drawn tubes, and to re-enforce them by serving with steel cord or +steel or copper wire. This has been tried, and found to answer +perfectly. For economical reasons, as well as for insuring the minimum +of torsion to the material during manufacture, it is important to make +as few bends as possible; but in practice much less difficulty has been +experienced in serving bent pipes in a machine than would have been +expected. Discarding copper, it has been proposed to substitute steel or +iron. In the early days of the higher pressures, Mr. Alexander Taylor +adopted wrought iron for steam pipes. One fitted in the Claremont in +February, 1882, was recently removed from the vessel for experimental +purposes, and was reported upon by Mr. Magnus Sandison in a paper read +before the Northeast Coast Institution of Engineers and Shipbuilders.[2] +The following is a summary of the facts. The pipe was 5 inches external +diameter, and 0.375 inch thick. It was lap welded in the works of +Messrs. A. & J. Stewart. The flanges were screwed on and brazed +externally. The pipe was not lagged or protected in any manner. After +eight and a half years' service the metal measured where cut 0.32 and +0.375 inch in thickness, showing that the wasting during that time had +been very slight. The interior surface of the tube exhibited no signs of +pitting or corrosion. It was covered by a thin crust of black oxide, the +maximum thickness of which did not exceed 1/32 inch. Where the deposit +was thickest it was curiously striated by the action of the steam. On +the scale being removed, the original bloom on the surface of the metal +was exposed. It would thus appear that the danger from corrosion of iron +steam pipes is not borne out in their actual use; and hence so much of +the way is cleared for a stronger and more reliable material than +copper. So far the source of danger seems to be in the weld, which would +be inadmissible in larger pipes; but there is no reason why these should +not be lapped and riveted. There seems, however, a more promising way +out of the difficulty in the Mannesmann steel tubes which are now being +"spun" out of solid bars, so as to form weldless tubes. + +[Footnote 2: Transactions Northeast Coast Institution of Engineers and +Shipbuilders, vol. 7, 1890-91, p. 179.] + +TABLE I.--TENSILE STRENGTH OF GUN METAL AT HIGH TEMPERATURES. + +--------------+------------+-------------+-------------+------------+ + | | | | | + Composition |Temperature | Tensile | Elastic | Elongation | + of | of oil | strength | limit | in | + gun metal. | bath. | per square | per square | length of | + | | inch. | inch. | 2 inches | +--------------+------------+-------------+-------------+------------+ + Per cent. | Fahr. | Tons | Tons | Per cent. | + Copper 87 /| 50° | 12.34 | 8.38 | 14.64 | + Tin 8 / | | | | | + Zinc 3½ \ | | | | | + Lead 1½ \| 400° | 10.83 | 6.30 | 11.79 | +--------------+------------+-------------+-------------+------------+ + Copper 87 /| 50° | 13.86 | 8.33 | 20.30 | + Tin 8 { | | | | | + Zinc 5 \| 458° | 10.70 | 7.43 | 12.42 | +--------------+------------+-------------+-------------+------------+ + +Cast steel has been freely used by the writer for bends, junction +pieces, etc., of steam pipes, as well as for steam valve chests; and +except for the fact that steel makers' promises of delivery are +generally better than their performance, the result has thus far been +satisfactory in all respects. These were adopted because there existed +some doubt as to the strength of gun metal under a high temperature; and +as the data respecting its strength appeared of a doubtful character, a +series of careful tests were made to determine the tensile strength of +gun metal when at atmospheric and higher temperatures. The test bars +were all 0.75 in diameter, or 0.4417 square inch sectional area; and +those tested at the higher temperatures were broken while immersed in a +bath of oil at the temperature here stated, each line being the mean of +four experiments. The result of these experiments was to give somewhat +greater faith in gun metal as a material to be used under a higher +temperature; but as steel is much stronger, it is probably the most +advisable material to use, when the time necessary to procure it can be +allowed. + +_Feed Heating_.--With the double object of obviating strain on the +boiler through the introduction of the feed water at a low temperature, +and also of securing a greater economy of fuel, the principle of +previously heating the feed water by auxiliary means has received +considerable attention, and the ingenious method introduced by Mr. James +Weir has been widely adopted. It is founded on the fact that, if the +feed water as it is drawn from the hot well be raised in temperature by +the heat of a portion of steam introduced into it from one of the steam +receivers, the decrease of the coal necessary to generate steam from the +water of the higher temperature bears a greater ratio to the coal +required without feed heating than the power which would be developed in +the cylinder by that portion of steam would bear to the whole power +developed when passing all the steam through all the cylinders. The +temperature of the feed is of course limited by the temperature of the +steam in the receiver from which the supply for heating is drawn. +Supposing, for example, a triple expansion engine were working under the +following conditions without feed heating: Boiler pressure, 150 +lb.;--indicated horse power in high pressure cylinder 398, in +intermediate and low pressure cylinders together 790, total, 1,188; and +temperature of hot well 100° Fahr. Then with feed heating the same +engine might work as follows: The feed might be heated to 220° Fahr., +and the percentage of steam from the first receiver required to heat it +would be 12.2 per cent.; the indicated horse power in the high pressure +cylinder would be as before 398, and in the intermediate and low +pressure cylinders it would be 12.2 per cent, less than before, or 694, +and the total would be 1,092, or 92 per cent. of the power developed +without feed heating. Meanwhile the heat to be added to each pound of +the feed water at 220° Fahr. for converting it into steam would be 1,005 +units against 1,125 units with feed at 100° Fahr., equivalent to an +expenditure of only 89.4 per cent. of the heat required without feed +heating. Hence the expenditure of heat in relation to power would be +89.4 + 92.0 = 97.2 per cent., equivalent to a heat economy of 2.8 per +cent. If the steam for heating can be taken from the low pressure +receiver, the economy is about doubled. Other feed heaters, more or less +upon the same principle, have been introduced. Also others which heat +the feed in a series of pipes within the boiler, so that it is +introduced into the water in the boiler practically at boiling +temperature; this is economical, however, only in the sense that wear +and tear of the boiler is saved; in principle the plan does not involve +economy of fuel. + +_Auxiliary Supply of Fresh Water_.--Intimately associated with the feed +is the means adopted for making up the losses of fresh water due to +leakage of steam from safety valves, glands, joints, etc., and of water +discharged from the air pumps. A few years ago this loss was regularly +made up from the sea, with the result that the water in the boilers was +gradually increased in density; whence followed deposit on the internal +surfaces, and consequent loss of efficiency, and danger of accident +through overheating the plates. With the higher pressures now adopted, +the danger arising from overheating is much more serious, and the +necessity is absolute of maintaining the heating surfaces free from +deposit. This can be done only by filling the boiler with fresh water in +the first instance, and maintaining it in that condition. To do this two +methods are adopted, either separately or in conjunction. Either a +reserve supply of fresh water is carried in tanks or the supplementary +feed is distilled from sea water by special apparatus provided for the +purpose. In the construction of the distilling or evaporating apparatus +advantage has been taken of two important physical facts, namely, that, +if water be heated to a temperature higher than that corresponding with +the pressure on its surface, evaporation will take place; and that the +passage of heat from steam at one side of a plate to water at the other +is very rapid. In practice the distillation is effected by passing +steam, say from the first receiver, through a nest of tubes inside a +still or evaporator, of which the steam space is connected either with +the second receiver or with the condenser. The temperature of the steam +inside the tubes being higher than that of the steam either in the +second receiver or in the condenser, the result is that the water inside +the still is evaporated, and passes with the rest of the steam into the +condenser, where it is condensed, and serves to make up the loss. This +plan localizes the trouble of deposit, and frees it from its dangerous +character, because an evaporator cannot become overheated like a boiler, +even though it be neglected until it salts up solid; and if the same +precautions are taken in working the evaporator which used to be adopted +with low pressure boilers when they were fed with salt water, no serious +trouble should result. When the tubes do become incrusted with deposit, +they can be either withdrawn or exposed, as the apparatus is generally +so arranged; and they can then be cleaned. + +_Screw Propeller_.--In Mr. Marshall's paper of 1881 it was said that +"the screw propeller is still to a great extent an unsolved problem." +This was at the time a fairly true remark. It was true the problem had +been made the subject of general theoretical investigation by various +eminent mathematicians, notably by Professor Rankine and Mr. William +Froude, and of special experimental investigation by various engineers. +As examples of the latter may be mentioned the extended series of +investigations in the French vessel Pelican, and the series made by Mr. +Isherwood on a steam launch about 1874. These experiments, however, such +as they were, did little to bring out general facts and to reduce the +subject to a practical analysis. Since the date of Mr. Marshall's paper, +the literature on this subject has grown rapidly, and, has been almost +entirely of a practical character. The screw has been made the subject +of most careful experiments. One of the earliest extensive series of +experiments was made under the writer's direction in 1881, with a large +number of models, the primary object being to determine what value there +was in a few of the various twists which inventive ingenuity can give to +a screw blade. The results led the experimenters to the conclusion that +in free water such twists and curves are valueless as serving to augment +efficiency. The experiments were then carried further with a view to +determine quantitative moduli for the resistance of screws with +different ratios of pitch to diameter, or "pitch ratios," and afterward +with different ratios of surface to the area of the circle described by +the tips of the blades, or "surface ratios." As these results have to +some extent been analyzed and published, no further reference need be +made to them now. + +In 1886, Mr. R.E. Froude published in the Transactions of the +Institution of Naval Architects the deductions drawn from an extensive +series of trials made with four models of similar form and equal +diameter, but having different pitch ratios. Mr. S.W. Barnaby has +published some of the results of experiments made under the direction of +Mr. J.I. Thornycroft; and in his paper read before the Institution of +Civil Engineers in 1890 he has also put Mr. R.E. Froude's results into a +shape more suitable for comparison with practice. Nor ought Mr. G.A. +Calvert's carefully planned experiments to pass unnoticed, of which an +account was given in the Transactions of the Institution of Naval +Architects in 1887. These experiments were made on rectangular bodies +with sections of propeller blade form, moved through the water at +various velocities in straight lines, in directions oblique to their +plane faces; and from their results an estimate was formed of the +resistance of a screw. + +One of the most important results deduced from experiments on model +screws is that they appear to have practically equal efficiencies +throughout a wide range both in pitch ratio and in surface ratio; so +that great latitude is left to the designer in regard to the form of the +propeller. Another important feature is that, although these experiments +are not a direct guide to the selection of the most efficient propeller +for a particular ship, they supply the means of analyzing the +performances of screws fitted to vessels, and of thus indirectly +determining what are likely to be the best dimensions of screw for a +vessel of a class whose results are known. Thus a great advance has been +made on the old method of trial upon the ship itself, which was the +origin of almost every conceivable erroneous view respecting the screw +propeller. The fact was lost sight of that any modification in form, +dimensions, or proportions referred only to that particular combination +of ship and propeller, or to one similar thereto; so something like +chaos was the result. This, however, need not be the case much longer. + +In regard to the materials used for propellers, steel has been largely +adopted for both solid and loose-bladed screws; but unless protected in +some way, the tips of the blades are apt to corrode rapidly and become +unserviceable. One of the stronger kinds of bronze is often judiciously +employed for the blades, in conjunction with a steel boss. Where the +first extra expense can be afforded, bronze seems the preferable +material; the castings are of a reliable character, and the metal does +not rapidly corrode; the bronze blades can therefore with safety be made +lighter than steel blades, which favors their springing and +accommodating themselves more readily to the various speeds of the +different parts of the wake. This might be expected to result in some +slight increase of efficiency; of which, however, the writer has never +had the opportunity of satisfactorily determining the exact extent. +Instances can be brought forward where bronze blades have been +substituted for steel or iron with markedly improved results; but in +cases of this kind which the writer has had the opportunity of +analyzing, the whole improvement might be accounted for by the modified +proportions of the screw when in working condition. In other words, both +experiment and practical working alike go to show that, although cast +iron and steel blades as usually proportioned are sufficiently stiff to +retain their form while at work, bronze blades, being made much lighter, +are not; and the result is that the measured or set pitch is less than +that which the blades assume while at work. Some facts relative to this +subject have already been given in a recent paper by the author. + +_Twin Screws_.--The great question of twin screw propulsion has been put +to the test upon a large scale in the mercantile marine, or rather in +what would usually be termed the passenger service. While engineers, +however, are prepared to admit its advantages so far as greater security +from total breakdown is concerned, there is by no means thorough +agreement as to whether single or twin screws have the greater +propulsive efficiency. What is required to form a sound judgment upon +the whole question is a series of examples of twin and single screw +vessels, each of which is known to be fitted with the most suitable +propeller for the type of vessel and speed; and until this information +is available, little can be said upon the subject with any certainty. So +far the following large passenger steamers, particulars of which are +given in table II., have been fitted with twin screws. It appears t be a +current opinion that the twin screw arrangement necessitates a greater +weight of machinery. This is not necessarily so, however; on the +contrary, the opportunity is offered for reducing the weight of all that +part of the machinery of which the weight relatively to power is +inversely proportional to the revolutions for a given power. This can be +reduced in the proportion of 1 to the square root of 2, that is 71 per +cent. of its weight in the single screw engine; for since approximately +the same total disk area is required in both cases with similar +proportioned propellers, the twins will work at a greater speed of +revolution than the single screw. From a commercial point of view there +ought to be little disagreement as to the advantage of twin screws, so +long as the loss of space incurred by the necessity for double tunnels +is not important; and for the larger passenger vessels now built for +ocean service the disadvantage should not be great. Besides their +superiority in the matter of immunity from total breakdown, and in +greatly diminished weight of machinery, they also offer the opportunity +of reducing to some extent the cost of machinery. A slightly greater +engine room staff is necessary; but this seems of little importance +compared with the foregoing advantages. + +TABLE II.--PASSENGER STEAMERS FITTED WITH TWIN SCREWS. + +-----------------+-----------+-----+-----------+-------+--------+-------+ + | Length | | Cylinders, | Boiler |Indi- | + | between | | two sets in all |pressure|cated | + Vessels. | perpen- |Beam.| cases. | per |horse- | + | diculars. | |-----------+-------| square |power. | + | | |Diameters. |Stroke.| inch. | | +-----------------+-----------+-----+-----------+-------+--------+-------+ + | Feet. |Feet.| Inches. |Inches.| Lb. | | +City of Paris. |\ | | | | | | + | } 525 | 63¼ |45, 71, 113| 60 | 150 |20,000 | +City of New York.|/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Teutonic. |\ | | | | | | + | } 565 | 58 |43, 68, 110| 60 | 180 |18,000 | +Majestic. |/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Normannia. | 500 | 57½ |40, 67, 106| 66 | 160 |11,500 | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Columbia. | 463½ | 55½ |41, 66, 101| 66 | 160 |12,500 | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Empress of India.|\ | | | | | | +Empress of Japan.| } 440 | 51 |32, 51, 82 | 54 | 160 |10,125 | +Empress of China.|/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Orel. | 415 | 48 |34, 54, 85 | 51 | 160 |10,000 | +-----------------+-----------+-----+-----------+-------+--------+-------+ + +_Weight of Machinery Relatively to Power_.--It is interesting to compare +the weight of machinery relatively to the power developed; for this +comparison has sometimes been adopted as the standard of excellence in +design, in respect of economy in the use of material. The principle, +however, on which this has generally been done is open to some +objections. It has been usual to compare the weight directly with the +indicated horse-power, and to express the comparison in pounds per +horse-power. So long as the machinery thus compared is for vessels of +the same class and working at about the same speed of revolution, no +great fault can be found; but as speed of revolution is a great factor +in the development of power, and as it is often dependent on +circumstances altogether external to the engine and concerning rather +the speed of the ship, the engines fitted to high speed ships will thus +generally appear to greater advantage than is their due. Leaving the +condenser out of the question, the weight of an engine would be much +better referred to cylinder capacity and working pressures, where these +are materially different, than directly to the indicated power. The +advantages of saving weight of machinery, so long as it can be done with +efficiency, are well known and acknowledged. If weight is to be reduced, +it must be done by care in design, not by reduction of strength, because +safety and saving of repairs are much more important than the mere +capability of carrying a few tons more of paying load. It must also be +done with economy; but this is a matter which generally settles itself +aright, as no shipowner will pay more for a saving in weight than will +bring in a remunerative interest on his outlay. In his paper on the +weight of machinery in the mercantile marine,[3] Mr. William Boyd +discussed this question at some length, and proposed to attain the end +of reducing the weight of machinery by the legitimate method of +augmenting the speed of revolution and so developing the required power +with smaller engines. This method, while promising, is limited by the +efficiency of the screw, but may be adopted with advantage so long as +the increase in speed of revolution involves no such change in the screw +as to reduce its efficiency as a propeller. But when the point is +reached beyond which a further change involves loss of propelling +efficiency, it is time to stop; and the writer ventures to say that in +many cargo vessels now at work the limit has been reached, while in many +others it has certainly been passed. + +[Footnote 3: Transactions Northeast Coast Institution of Engineers and +Shipbuilders, vol. 6, 1889-90, p. 253.] + +_Economy of Fuel_.--Coming to the highly important question of economy +of fuel, the average consumption of coal per indicated horse-power is +1.522 lb. per hour. The average working pressure is 158.5 lb. per square +inch. Comparing this working pressure with 77.4 lb. in 1881, a superior +economy of 19 per cent. might be expected now, on account of the higher +pressure, or taking the 1.828 lb. of coal per hour per indicated +horse-power in 1881, the present performance under similar conditions +should be 1.48 lb. per hour per indicated horse-power. It appears that +the working pressures have been increased twice in the last ten years, +and nearly three times in the last nineteen. The coal consumptions have +been reduced 16.7 per cent. in the last ten years and 27.9 per cent. in +the last nineteen. The revolutions per minute have increased in the +ratios of 100, 105, 114; and the piston speeds as 100, 124, 140. +Although it is quite possible that the further investigations of the +Research Committee on Marine Engine Trials may show that the present +actual consumption of coal per indicated horse-power is understated, yet +it is hardly probable that the relative results will be affected +thereby. + +_Dimensions_.--In the matter of the power put into individual vessels, +considerable strides have been made. In 1881, probably the greatest +power which has been put into one vessel was in the case of the Arizona, +whose machinery indicated about 6,360 horse-power. The following table +gives an idea of the dimensions and power of the larger machinery in the +later passenger vessels: + +TABLE III.--DIMENSIONS AND POWER OF MACHINERY IN LATER PASSENGER +VESSELS. + +-----+----------------+-----------------------+-------+-----------+ + | | |Length | | +Year.| Name of vessel.| Diameters of | of |Indicated | + | | cylinders. |Stroke.|horsepower.| +-----+----------------+-----------------------+-------+-----------+ + | | Inches. |Inches.| | +1881 |Alaska | 68, 100, 100 | 72 | 10,686 | +-----+----------------+-----------------------+-------+-----------+ +1881 |City of Rome | 46, 86; 46, 86; 46, 86| 72 | 11,800 | +-----+----------------+-----------------------+-------+-----------+ +1881 |Servia | 72, 100, 100 | 78 | 10,300 | +-----+----------------+-----------------------+-------+-----------+ +1881 |Livadia yacht | 60, 78, 78; 60, 78, \| 39 | 12,500 | + | | 78; 60, 78, 78 /| | | +-----+----------------+-----------------------+-------+-----------+ +1883 |Oregon | 70, 104, 104 | 72 | 13,300 | +-----+----------------+-----------------------+-------+-----------+ +1884 |Umbria |\ 71, 105, 105 | 72 | 14,320 | +1884 |Etruria |/ | | | +-----+----------------+-----------------------+-------+-----------+ +1888 |City of New York|\ 45, 71, 113; \| 60 | 20,000 | +1889 |City of Paris |/ 45, 71, 113 /| | about | +-----+----------------+-----------------------+-------+-----------+ +1889 |Majestic |\ 43, 68, 110; \| 60 | 18,000 | +1889 |Teutonic |/ 43, 68, 110 /| | | +-----+----------------+-----------------------+-------+-----------+ + +In war vessels the increase has been equally marked. In 1881 the maximum +power seems to have been in the Inflexible, namely, 8,485 indicated +horse-power. The following will give an idea of the recent advance made: +Howe (Admiral class), 11,600 indicated horse-power; Italia and Lepanto, +19,000 indicated horse-power; Re Umberto, 19,000 indicated horse-power; +Blake and Blenheim (building), 18,000 indicated horse-power; Sardegna +(building), 22,800 indicated horse-power. It is thus evident that there +are vessels at work to-day having about three times the maximum power of +any before 1881. + +_General Conclusions_.--The progress made during the last ten years +having been sketched out, however roughly, the general conclusions may +be stated briefly as follows: First, the working pressure has been about +doubled. Second, the increase of working pressure and other improvements +have brought with them their equivalent in economy of coal, which is +about 20 per cent. Third, marked progress has been made in the direction +of dimension, more than twice the power having been put into individual +vessels. Fourth, substantial advance has been made in the scientific +principles of engineering. It only remains for the writer to thank the +various friends who have so kindly furnished him with data for some of +the tables which have been given; and to express the hope that the next +ten years may be marked by such progress as has been witnessed in the +past. But it must be remembered that, if future progress be equal in +merit or ratio, it may well be less in quantity, because advance becomes +more difficult of achievement as perfection is more nearly approached. + + * * * * * + + + + +THE LITTLE HOUSE. + +BY M.M. + + +One of the highest medical authorities is credited with the statement +that "nine-tenths of the diseases that afflict humanity are caused by +neglect to answer the calls of Nature." + +This state of affairs is generally admitted, but is usually attributed +to individual indolence. That, doubtless, has a great deal to do with +it, but should not part of the blame be laid upon the often unpleasant +environments, which make us shrink as from the performance of a painful +duty? + +In social life, unless from absolute necessity or charity, people of +refined habits do not call on those whose surroundings shock their sense +of decency; but when they go to pay the calls of Nature, they are often +compelled to visit her in the meanest and most offensive of abodes; +built for her by men's hands; for Nature herself makes no such mistakes +in conducting her operations. She does not always surround herself with +the pomp and pride of life, but she invariably hedges herself in with +the thousand decencies and the pomp of privacy. + +But what do we often do? We build what is sometimes aptly termed "an +out-house," because it is placed so that the delicate minded among its +frequenters may be made keenly alive to the fact that they can be +plainly seen by every passer-by and by every idle neighbor on the +lookout. This tiny building is seldom weatherproof; In consequence, keen +cold winds from above, below, and all around find ready entrance, chill +the uncovered person, frequently check the motions, and make the strong +as well as the weak, the young as well as the old, very sorry indeed +that they are so often uselessly obliged to answer the calls of Nature. +It is true, the floor is sometimes carpeted with snow, but the feet feel +that to be but cold comfort, though the door may enjoy rattling its +broken hasp and creaking its loose hinges. + +How often, too, are the nose and the eye offended by disregard of the +Mosaic injunction, found in the twelfth, thirteenth, and fourteenth +verses of the twenty-third chapter of Deuteronomy! Of course this +injunction was addressed to a people who had been debased by slavery, +but who were being trained to fit them for their high calling as the +chosen of God; but is not some such sanitary regulation needed in these +times, when a natural office is often made so offensive to us by its +environments that it is difficult for us to believe that "God made man a +little lower than the angels," or that the human body is the temple of +the Holy Ghost? + +Dwellers in the aristocratic regions of a well drained city, whose +wealth enables them to surround themselves with all devices tending to a +refined seclusion, may doubt all this, but sanitary inspectors who have +made a round of domiciliary visits in the suburbs, or the older, +neglected parts of a large city, of to any part of a country town or +village, will readily affirm as to its general truth. + +This unpardonable neglect of one of the minor decencies by the mass of +the people seems to be caused partly by a feeling of false shame, and +partly by an idea that it is expensive and troublesome to make any +change that will improve their sanitary condition or dignify their daily +lives. + +The Rev. Henry Moule, of Fordington Vicarage, Dorsetshire, England, was +one of the first to turn his attention to this matter. With the +threefold object of improving the sanitary condition of his people, +refining their habits, and enriching their gardens, he invented what he +called the "dry earth closet." + +"It is based on the power of clay and the decomposed organic matter +found in the soil to absorb and retain all offensive odors and all +fertilizing matters; and it consists, essentially, of a mechanical +contrivance (attached to the ordinary seat) for measuring out and +discharging into the vault or pan below a sufficient quantity of sifted +dry earth to entirely cover the solid ordure and to absorb the urine. + +"The discharge of earth is effected by an ordinary pull-up, similar to +that used in the water closet, or (in the self-acting apparatus) by the +rising of the seat when the weight of the person is removed. + +"The vault or pan under the seat is so arranged that the accumulation +can be removed at pleasure. + +"From the moment when the earth is discharged and the evacuation +covered, all offensive exhalation entirely ceases. Under certain +circumstances there may be, at times, a slight odor as of guano mixed +with earth, but this is so trifling and so local that a commode arranged +on this plan may, without the least annoyance, be kept in use in any +room." + +The "dry earth closet" of the philanthropic clergyman was found to work +well, and was acceptable to his parishioners. One reason why it was so +was because dry earth was ready to hand, or could be easily procured in +a country district where labor was cheap. But where labor was dear and +dry earth scarce, those who had to pay for the carting of the earth and +the removal of the deodorized increment found it both expensive and +troublesome. + +But a modification of this dry earth closet, the joint contrivance of an +English church clergyman and his brother, "the doctor," residents of a +Canadian country town, who had heard of Moule's invention, is a good +substitute, and is within the reach of all. This will be briefly +described. + +The vault was dug as for an ordinary closet, about fifteen feet deep, +and a rough wooden shell fitted in. About four feet below the surface of +this wooden shell a stout wide ledge was firmly fastened all around. +Upon this ledge a substantially made wooden box was placed, just as we +place a well fitting tray into our trunks. About three feet of the back +of the wooden shell was then taken out, leaving the back of the box +exposed. From the center of the back of the box a square was cut out and +a trap door fitted in and hasped down. + +The tiny building, on which pains, paint, and inventive genius had not +been spared to make it snug, comfortable, well lighted and well +ventilated, was placed securely on this vault. + +After stones had been embedded in the earth at the back of the vault, to +keep it from falling upon the trap door, two or three heavy planks were +laid across the hollow close to the closet. These were first covered +with a barrowful of earth and then with a heap of brushwood. + +Within the closet, in the left hand corner, a tall wooden box was +placed, about two-thirds full of dry, well sifted wood ashes. The box +also contained a small long-handled fire shovel. When about six inches +of the ashes had been strewn into the vault the closet was ready for +use. No; not quite; for squares of suitable paper had to be cut, looped +together with twine, and hung within convenient reaching distance of the +right hand; also a little to the left of this pad of paper, and above +the range of sight when seated, a ten pound paper bag of the toughest +texture had to be hung by a loop on a nail driven into the corner. + +At first the rector thought that his guests would be "quick-witted +enough to understand the arrangement," but when he found that the +majority of them were, as the Scotch say, "dull in the uptak," he had to +think of some plan to enforce his rules and regulations. As +by-word-of-mouth instructions would have been rather embarrassing to +both sides, he tacked up explicit written orders, which must have +provoked many a smile. Above the bin of sifted ashes he nailed a card +which instructed "Those who use this closet must strew two shovelfuls of +ashes into the vault." Above the pad of clean paper he tacked the +thrifty proverb: "Waste not, want not;" and above the paper bag he +suspended a card bearing this warning: "All refuse paper must be put +into this bag; not a scrap of clean or unclean paper must be thrown into +the vault." + +This had the desired effect. Some complacently united to humor their +host's whim, as they called it, and others, immediately recognizing its +utility and decency, took notes with a view to modifying their own +closet arrangements. + +Sarah, the maid of all work, caused a good deal of amusement in the +family circle by writing her instructions in blue pencil on the front of +the ash bin. These were: "Strew two shuffefuls of ashes into the volt, +but don't spill two shuffefuls onto the floor. By order of the Gurl who +has to sweap up." This order was emphatically approved of by those +fastidious ones who didn't have to "sweep up." + +This closet opened off the woodshed, and besides being snugly +weatherproof in itself, was sheltered on one side by the shed and on +another by a high board fence. The other two sides were screened from +observation by lattice work, outside of which evergreens were planted to +give added seclusion and shade. A ventilator in the roof and two sunny +little windows, screened at will from within by tiny Venetian shutters, +gave ample light and currents of fresh air. For winter use, the rector's +wife and daughters made "hooked" mats for floor and for foot support. +These were hung up every night in the shed to air and put back first +thing in the morning. For the greater protection and comfort of +invalids, an old-fashioned foot warmer, with a handle like a basket, was +always at hand ready to be filled with live coals and carried out. + +The little place was always kept as exquisitely clean as the dainty, +old-fashioned drawing room, and so vigilant was the overseeing care +bestowed on every detail, that the most delicate and acute sense of +smell could not detect the slightest abiding unpleasant odor. The paper +bag was frequently changed, and every night the accumulated contents +were burned; out of doors in the summer, and in the kitchen stove--after +a strong draught had been secured--in the winter. + +At stated times the deodorized mass of solid increment--in which there +was not or ought not to have been any refuse paper to add useless +bulk--was spaded, through the trap door, out of the box in the upper +part of the vault, into a wheelbarrow, thrown upon the garden soil, and +thoroughly incorporated with it. In this cleansing out process there was +little to offend, so well had the ashes done their concealing +deodorizing work. + +In using this modified form of Moule's invention, it is not necessary to +dig a deep vault. The rector, given to forecasting, thought that some +day his property might be bought by those who preferred the old style, +but his brother, the doctor, not troubling about what might be, simply +fitted his well made, four feet deep box, with its trap door, into a +smoothly dug hole that exactly held it, and set the closet over it. In +all other respects it was a model of his brother's. + +This last is within the reach of all, even those who live in other +people's houses; for, when they find themselves in possession of an +unspeakably foul closet, they can cover up the old vault and set the +well cleaned, repaired, fumigated closet upon a vault fashioned after +the doctor's plan. A stout drygoods box, which can be bought for a +trifle, answers well for this purpose, after a little "tinkering" to +form a trap door. + +Of course, dry earth is by far the best deodorizer and absorbent, but +when it cannot be easily and cheaply procured, well sifted wood or coal +ashes--wood preferred--is a good substitute. The ashes must be kept dry. +If they are not, they lose their absorbing, deodorizing powers. They +must also be well sifted. If they are not, the cinders add a useless and +very heavy bulk to the increment. + +An ash sifter can be made by knocking the bottom out of a shallow box, +studding the edge all round with tacks, and using them to cross and +recross with odd lengths of stovepipe wire to form a sieve.--_The +Sanitarian_. + + * * * * * + + + + +THE HYGIENIC TREATMENT OF OBESITY.[1] + +[Footnote 1: Translated by Mr. Jos. Helfman, Detroit, Mich.] + +BY DR. PAUL CHERON. + + +In order to properly regulate the regimen of the obese, it is first +necessary to determine the source of the superfluous adipose of the +organism, since either the albuminoids or the hydrocarbons may furnish +fat. + +Alimentary fat becomes fixed in the tissues, as has been proved by +Lebede, who fed dogs, emaciated by long fast, with meat wholly deprived +of fat, and substituted for the latter linseed oil, when he was able to +recover the oil in each instance from the animal; parallel experiments +with mutton fat, _in lieu_ of oil, afforded like results. + +Hoffman also deprived dogs of fat for a month, causing them to lose as +high as twenty-two pounds weight, then began nourishing with bacon fat +with but little lean; the quantity of fat formed in five days, in the +dog that lost twenty-two pounds, was more than three pounds, which could +have been derived only from the bacon fat. + +It has been stated, however, that alimentary fat seems to preserve from +destruction the fat of the organism which arises from other sources. Be +this as it may, it is a fact that the pre-existence of fat furthers the +accumulation of more adipose; or in other words, fat induces fattening! + +That adipose may be formed through the transformation of albuminous +matters (meat) is an extremely important corollary, one established +beyond cavil by Pettinkofer and Voit, in an indirect way, by first +estimating the nitrogen and carbon ingested, and second the amount +eliminated. Giving a dog meat that was wholly deprived of fat, they +found it impossible to recover more than a portion of the contained +carbon; hence some must necessarily have been utilized in the organism, +and this would be possible only by the transformation of the carbon into +fat! It goes without saying, however, that the amount of adipose thus +deposited is meager. + +Other facts also plead in favor of the transformation of a portion of +albumen into fat within the economy, notably the changing of a portion +of dead organism into what is known as "cadaveric fat," and the very +rapid fatty degeneration of organs that supervenes upon certain forms of +poisoning, as by phosphorus. + +The carbohydrates, or more properly speaking hydrocarbons, are regarded +by all physiologists as specially capable of producing fat, and numerous +alimentary experiments have been undertaken to prove this point. +Chaniewski, Meissl, and Munk obtained results that evidenced, +apparently, sugar and starch provide more fat than do the albuminoids. +Voit, however, disapproves this, maintaining the greater part of the +hydrocarbons is burned (furnishes fuel for the immediate evolution of +force), and that fat cannot be stored up unless a due proportion of +albuminoids is also administered. He believes the hydrocarbons exert a +direct influence only; being more oxidizable than fats, they guard the +latter from oxidation. This protective role of the hydrocarbons applies +also to the albuminoids. + +We may believe, then, that the three great classes of aliment yield fat, +in some degree; that alimentary fat may be fixed in the tissues; and +that hydrocarbons favor the deposition of adipose either directly or +indirectly. + +It is well understood that fat may disappear with great rapidity under +certain conditions; many maladies are accompanied by speedy emaciation; +therefore, as fat never passes into the secretions, at least not in +appreciable quantities, it probably undergoes transformation, perhaps by +oxidation or a form of fermentation, the final results of which are, +directly or indirectly, water and cadaveric acid. It is certain the +process of oxidation favors the destruction of adipose, and that +everything which inhibits such destruction tends to fat accumulation. + +Since the earliest period of history, there seems to have been an +anxiety to secure some regimen of general application that would reduce +or combat obesity. Thus Hippocrates says: + +Fat people, and all those who would become lean, should perform +laborious tasks while fasting, and eat while still breathless from +fatigue, without rest, and after having drunk diluted wine not very +cold. Their meats should be prepared with sesamum, with sweets, and +other similar substances, and these dishes should be free from fat. + +In this manner one will be satiated through eating less. + +But, besides, one should take only one meal; take no bath; sleep on a +hard bed; and walk as much as may be. + +How much has medical science gained in this direction during the +interval of more than two thousand years? Let us see: + +First among moderns to seek to establish on a scientific basis a regimen +for the obese, was Dancel, who forbade fats, starchy foods, etc., +prescribed soups and aqueous aliment, and reduced the quantity of +beverage to the lowest possible limit; at the same time he employed +frequent and profuse purgation. + +This regimen, which permits, at most, but seven to twelve ounces of +fluid at each repast, is somewhat difficult to follow, though it may be +obtained, gradually, with ease. Dr. Constantine Paul records a case in +which this regimen, gradually induced, and followed for ten years, +rewarded the patient with "moderate flesh and most excellent health." + +In Great Britain, a mode of treatment instituted in one Banting, by Dr. +Harvey, whereby the former was decreased in weight forty pounds, has +obtained somewhat wide celebrity; and what is more remarkable, it is +known as "Bantingism," taking its name from the patient instead of the +physician who originated it. The dietary is as follows: + +_Breakfast_.--Five to six ounces of lean meat, broiled fish, or smoked +bacon--veal and pork interdicted; a cup of tea or coffee without milk or +sugar; one ounce of toast or dry biscuit (crackers). + +_Dinner_.--Five or six ounces of lean meat or fish--excluding eel, +salmon, and herring; a small quantity of vegetables, but no potatoes, +parsnips, carrots, beets, peas, or beans; one ounce of toast, fruit, or +fowl; two glasses of red wine--beer, champagne, and port forbidden. + +_Tea_.--Two or three ounces of fruit; one kind of pastry; one cup of +tea. + +_Supper_.--Three or four ounces of lean beef or fish; one or two glasses +of red wine. + +_At bed-time._--Grog without sugar (whisky and water, or rum and water), +and one or two glasses of sherry or Bordeaux. + +"Bantingism," to be effective, must be most closely followed, when, +unfortunately also, it proves extremely debilitating; it is suitable +only for sturdy, hard riding gluttons of the Squire Western type. The +patient rapidly loses strength as well as flesh, and speedily acquires +an unconquerable repugnance to the dietary. Further, from a strictly +physiological point of view, the quantity of meat is greatly in excess, +while with the cessation of the regimen, the fat quickly reappears. + +Next Ebstein formulated a dietary that is certainly much better +tolerated than that of Harvey and Banting, and yields as good, or even +better, results. He allows patients to take a definite quantity--two to +two and a half ounces-of fat daily, in the form of bacon or butter +which, theoretically at least, offers several advantages: It diminishes +the sensations of hunger and thirst, and plays a special role with +respect to the albuminoids; the latter may thus be assimilated by the +economy without being resolved into fat, and thus the adipose of the +organism at this period is drawn upon without subsequent renewal. The +following is the outline: + +_Breakfast_.--At 6 a.m. in summer; 7:30 in winter:--Eight ounces of +black tea without either milk or sugar; two ounces of white bread or +toast, with a copious layer of butter. + +_Dinner_.--2 p.m.:--A modicum of beef marrow soup; four ounces of meat, +preferably of fatty character; moderate quantity of vegetable, +especially the legumines, but no potatoes or anything containing starch; +raw fruits in season, and cooked fruits (stewed, without sugar); two or +three glasses of light wine as a beverage, and after eating, a cup of +black tea without sugar. + +_Supper_.--7:30 p m.:--An egg, bit of fat roast, ham, or bacon; a slice +of white bread well buttered; a large cup of black tea without milk or +sugar; from time to time, cheese and fresh fruits. + +Germain See suggests as a modification of this regimen, the abundant use +of beverage, the addition of gelatins, and at times small doses of +potassium iodide in twenty cases he claims constant and relatively +prompt results. + +Whatever may be urged for Ebstein's system--and it has afforded most +excellent results to Unna and to Lube, as well as its author--it +certainly exposes the patient to the terrors of dyspepsia, when the +routine must needs be interrupted or modified; hence it is not always to +be depended upon. As between dyspepsia and obesity, there are few, I +fancy, who would not prefer the latter. + +Another "system" that has acquired no little celebrity, and which has +for its aim the reduction as far as possible of alimentary hydrocarbons +while permitting a certain proportion of fat, is that, of Denneth, which +necessarily follows somewhat closely the lines laid down by Ebstein. + +Oertels' treatment, somewhat widely known, and not without due measure +of fame, is based upon a series of measures having as object the +withdrawal from both circulation and the economy at large, as much of +the fluids as possible. It is especially adapted for the relief of those +obese who are suffering fatty degeneration of the heart. The _menu_ is +as follows: + +_Breakfast_.--Pour to five ounces of tea or coffee with a little milk; +two to two and a half ounces bread. + +_Dinner_.--Three or four ounces of roast or boiled meat, or moderately +fat food; fish, slightly fat; salad and vegetables at pleasure; one and +a half ounces of bread (in certain cases as much as three ounces of +farinaceous food may be permitted); three to six ounces of fruit; at +times a little pastry for dessert.--In summer, if fruit is not +obtainable, six to eight ounces of light wine may be allowed. + +_Tea_,--A cupful (four to five ounces) of tea or coffee, with a trifle +of milk, as at breakfast; one and three-fourths ounces of bread; and +exceptionally (and at most) six ounces of water. + +_Supper_.--One to two soft boiled eggs; four or five ounces of meat; one +and three fourths ounces of bread; a trifle of cheese, salad, or fruit; +six to eight ounces of light wine diluted with an eighth volume of +water. The quantity of beverage may be slightly augmented at each meal +if necessary, especially if there is no morbid heart trouble. + +Schwenninger (Bismarck's physician), who opened a large sanitarium near +Berlin a few years since for the treatment of the obese, employs +Oertel's treatment, modified in that an abundance of beverage is +permitted, provided it is not indulged in at meals; it is forbidden +until two hours after eating. + +Both Oertel's and Schwenninger's methods have procured grave dyspepsias, +and fatal albuminurias as well, according to Meyer and Rosenfield. It +has been charged the allowance of beverage upon which Schwenninger lays +so much stress in the treatment at his sanitarium has a pecuniary basis, +in other words a commission upon the sale of wines.[2] + +[Footnote 2: The sanitarium is owned by a stock company, Schwenninger +being merely Medical Director.--ED.] + +Thus, it will be observed that while some forbid beverage, others rather +insist upon its employment in greater or less quantities. Under such +circumstances, it would seem but rational, before undertaking to relieve +obesity, to establish its exact nature, and also the role taken by +fluids in the phenomena of nutrition. + +Physiologists generally admit water facilitates nutritive exchanges, +which is explained by the elimination of a large quantity of urine; the +experiments of Genth and Robin in this direction appear conclusive. + +Bischoff, Voit, and Hermann have shown that water increases, not alone +the elimination of urine, but also of sodium chloride, phosphoric acid, +etc. Grigoriantz observed augmentation of disintegration when the +quantity of beverage exceeded forty-six to eighty ounces ("1,400 to +2,400 cubic centimeters") per diem. Oppenheim, Fraenkel, and Debove, +while believing water has but little influence upon the exchanges, admit +it certainly need not diminish the latter; and Debove and Flament, after +administering water in quantities varying from two to eight pints per +diem, concluded that urine was diminished below the former figure, while +above the latter it increased somewhat, being dependent upon the amount +ingested. It was on the strength of the foregoing that Lallemand +declared water to have no influence upon the exchanges. + +The results claimed by Oppenheim, Debove, et al. were immediately +challenged--and it is now generally admitted, not without some +justice--by Germain See. It seems certain, to say the least, that water +taken during the repast does tend to augment the quantity and facilitate +the elimination of urine. Abundance of beverage, moreover, presents +other advantages, in that it facilitates digestion by reason of its +diluent action, a fact well worth bearing in mind when treating the +obese who are possessed of gouty diathesis, and whose kidneys are +accordingly encumbered with uric and oxalic acids. The foregoing +presents the ground upon which Germain See permits an abundance of +beverage; but he also expresses strong reservation as regards beer and +alcohol, either of which (more especially the former) tends to the +production of adipose. In his opinion, the only beverage of the +alcoholic class that is at all permissible, and then only for cases +suffering from fatty heart, is a little _liqueur_ or diluted wine. +Coffee and tea he commends highly, and recommends the ingestion of large +quantities at high temperature, both during the repasts and their +intervals. Coffee in large doses is undoubtedly a means of de-nutrition, +and so, too, in no less extent, is tea; both act vigorously owing to the +contained alkaloids, though, to be sure, they sometimes, at first, tend +to insomnia and palpitation, to which no attention need be paid, +however. The treatment outlined by See is: + +1. A physiological regimen comprising four to five ounces of nitrogenous +principles as derived from eight to ten ounces animal muscle and +albuminates; three to six ounces of fat; eight to ten ounces of +hydrocarbons as yielded by ten to twelve ounces of sugar or starch food. + +These proportions to be modified in such manner that the +musculo-albuminates shall not sensibly exceed the normal ratio, for meat +in excess itself furnishes fat during transformation. The fatty +substances of easy digestion may, without inconvenience, be utilized in +doses of two to three ounces. The hydrocarbons should be reduced to a +minimum. As for the herbaceous elements, they contain nothing nutritive. + +2. Beverage, far from being suppressed, should be augmented, in order to +facilitate stomachal digestion and promote general nutrition, though +alcoholic liquids must be inhibited; likewise mineral waters, except, +perhaps, for occasional use. Both should be replaced by infusions of +coffee or tea, taken as hot as can be drank. + +Henrich Kisch insists that any method which promises rapid and marked +decrease of adipose must, _per se_, be objectionable, even if not +positively injurious, since it tends to provoke general troubles of +nutrition. He suggests that first the fats and hydrocarbons be reduced +as little as possible; that a moderate mixed regimen is required, +containing a preponderance of albumen, small quantities of hydrocarbons +and gelatinous matters, with but very little fat. Certain fatty meats, +however, should be generally interdicted, such as pork sausage, smoked +beef tongue, goose breast, smoked ham, fat salmon, and herring in any +form. Eggs, however, may be partaken of in moderation, giving preference +to the albumen over the yelk. Farinaceous foods, in the main, should be +rejected, even bread being allowed only in small quantities, and then +preferably in the form of toast. Cheese likewise contains too much fat; +and mushrooms are so rich in hydrocarbons that they should be rejected. +Condiments, water, vegetable acids (vinegars excepted) may be permitted; +especially pernicious is vinegar where there is any tendency to gout or +gravel. All fatty beverages--_bouillon_, unskimmed milk, chocolate, or +cacao--and all alcoholics, are hurtful; breakfast tea is undoubtedly the +best beverage, but, after a little, is advantageously replaced by light +white wine diluted with water. + +Kisch believes in a free and abundant use of water by the obese, +especially where there is a tendency to plethora, since this fluid +facilitates oxidation as the result of absorption; thus he advocates the +inhibition of large quantities of cold water by all, save those +presenting evidence of cardiac insufficiency. In short, his regimen is +based upon the administration of a large quantity of albumen, like that +of Harvey-Banting. + +E. Munk recommends an almost identical dietary, save that he prefers +great moderation in fluids employed as beverage. + +M. Robin has sought to harmonize the opposing views regarding fluids, +and therefore declares obesity arises from two distinct sources: 1. +Augmentation of assimilation. 2. Reduced disassimilation. In the former, +he insists water must be interdicted, while in the latter it may be +allowed _ad libitum_. + +Again, in order to recognize the exact variety of obesity, he divides +his patients into three classes, each recognizable by the volume of urea +excreted. In the first there is an increase above normal; in the second +the volume of urea is stationary; in the third decreased, increased, or +stationary. + +When the urea is stationary, which is most frequently the case, it is +necessary to calculate the coefficient of oxidation; that is, the +relation existing between the solid matters of the urine and the urea. +The elevation of the coefficient is _prima facie_ evidence the obesity +is due to excess of assimilation, while depression of the coefficient +indicates default of assimilation. In the first case, water and liquids +must be denied as far as possible, the same as if there was no +augmentation of urea; in the second, the same as if there was diminution +of urea, the patients may be permitted to imbibe fluids at pleasure. + +For the obese from default of disassimilation, Robin recommends a +regimen of green vegetables and bread chiefly--the latter in small +quantities, however, and fluids as may be desired. By this means, on one +occasion, he was able in the course of one month to diminish the weight +of a female patient by twelve and a half pounds, her measurement around +the waist at the same time decreasing 5.2 inches and across the stomach +4.8 inches. + +M. De St. Germain achieved good results by combining judicious exercise +with moderate alimentation, excluding wine and bread. + +M. Dujardin Beaumetz, who professes to have given most close and careful +study and attention to regimen for the obese, outlines the following, +provided there is no evidence of fatty degeneration of heart. + +_Breakfast_ (at 8 a. m.)--Three-fourths of an ounce of bread "_en +flute_"--that is abounding with crust; one and a half ounces of cold +meat, ham or beef, six ounces weak black tea, _sans_ sugar. + +_Lunch_ (at 1 p.m.)--An ounce and a half to two ounces of bread, or a +_ragout_, or two eggs; three ounces green vegetables; one-half ounce of +cheese; fruits at discretion. + +_Dinner_ (at 7 p.m.)--An ounce and a half to two ounces of bread; three +to four ounces of meat, or _ragout_; ditto of green vegetables, salad, +half an ounce of cheese, fruit _ad libitum_. + +At meal times the patient may take only a "glass and a half" of +liquid--approximately ten ounces--though a greater amount may be +permitted if he abstains during the intervals. + +Special alimentary regimen, however, does not constitute the sole +treatment of obesity. Concurrently must be employed a number of +practical adjuvants which are oftentimes of the utmost assistance. For +one thing, exercise is indispensable; all authorities agree on this +point. The exercise taken in the gymnasium is one of the best, notably +the "wall exercise," which is more particularly suited to those +afflicted with pendulous and protuberant abdomens as the result of +feebleness of the hypogastric muscles, to accumulation of fat under the +skin and in the omentum, and to dilation of the stomach and intestines. +In the "wall exercise," the patient stands erect against an absolutely +straight and plumb wall, lifts his hands (carrying a weight) straight +over the head, and causes them to describe a semicircle forward. Zantz +particularly insists upon arm and leg exercise for the obese, especially +the former, since with the same amount of effort a larger amount of +oxygen is consumed than is possible by the latter. + +However, of whatever character, the exercise should be continued to the +point of fatigue or dyspnoea--three thousand movements daily, +gradually increased to twenty-five thousand, if the system can bear it; +and under such conditions, not only is there consumption of +hydrocarbons, but there is provided a veritable greed for air that +augments waste. The experiments of Oertel indicate that loss of weight +due to fatiguing exercise arises more particularly from dehydration, +which is made good by absorption of the fluids employed as beverage; the +fluids are claimed by Germain See to act as accelerants of oxidation. + +During exercise there is obviously more abundant absorption of oxygen, +and consequently greater elimination of carbonic acid, and as a +consequence (as shown by researches of Voit), the reserve fat of the +economy is attacked and diminished; in intense labor there is an average +hourly consumption of about 8.2 percent. of fat. Further physical +activity is useful in exercising the voluntary muscles, and thus +opposing the invasion by interstitial fat of the muscle fibrils. Extreme +exercise also, to a certain degree, exerts a favorable influence on the +cardiac muscle, augmenting both its nutrition and its capacity for +labor. With the anæmic obese, however, it is necessary to be most +circumspect in prescribing forced exercise; also with the elderly obese +possessed of enfeebled or fatty heart. + +Hydrotherapy, especially in the form of cold douches, particularly when +combined with massage, is often of considerable value in relieving +obesity; the method of Harmman, of St. Germain, which has in many +instances induced rapid loss of adipose, is of this class. Tepid saline +baths and vapor baths have many advocates, and may afford material aid +when the heart and circulation do not inhibit their employment. Hot +baths elevate the temperature of the body and increase the organic +exchanges, hence, as Bert and Reynard have pointed out, tend to the +elimination of oxygen and carbonic acid; but when employed, the patient +should be introduced while the temperature is below 130° F., when it may +be gradually raised in the course of thirty or forty minutes to 140° F. + +It has already been intimated, the chief feature of the treatment of +obesity is acceleration of the exchanges; and this is in the main true, +though it must also be borne in mind that, while there are obese who +excrete little urea and have a depressed central nervous temperature, +many may be azoturic, and besides eliminate phosphate in excess, when an +oxidating treatment will not only fail, but prove positively injurious. + +The bile throws out fat, therefore, to accelerate nutritive oxidations, +the liver and nervous system must be acted upon, _i.e._, stimulated. +Everything that tends to diminish the activity of the former, or depress +the latter, must be avoided. Hence intellectual labor should be +encouraged, or in lieu thereof, travel advised. Exercise should be taken +chiefly while fasting; the limits of sleep confined to strict necessity, +and _siestas_ after meals and during the day strictly forbidden; the +skin stimulated by hydro-therapeutic measures, including massage under +cold affusions, during warm salt baths, etc. + +To increase the activity of the liver, salicylate of soda may often be +advantageously administered for its cholagogue effect; or resort may be +had to saline purgatives such as are afforded by the springs of +Marienbad, Kissengen, Homburg, Carlsbad, Brides, Hunyadi, or +Chatel-Guyon; and it is somewhat remarkable that while undergoing a +course of these waters, there is often no appreciable change in weight +or obesity, though the decrease becomes most marked almost immediately +upon cessation of treatment. + +Everything tending to increased or fuller respiration is to be +encouraged, for the fats are thus supplied with oxygen, hastening their +disintegration and consumption. + +Direct medicinal treatment presents no very wide scope. Bouchard +imagines lime water may be useful by accelerating nutrition, but this is +problematical, since fat in emulsion or in droplets does not burn. +Nevertheless, alkalies in general, alkaline carbonates, liquor potassa, +soaps, etc., aid in rendering fat more soluble, and consequently more +susceptible to attack. The alkaline waters, however, are much less +active in obesity than the saline mineral waters, unless, as sometimes +happens, there is a complication of diabetes and obesity. + +Purgatives are always more or less useful, and often required to be +renewed with all the regularity of habit. Then too, the iodides, +especially iodide of sodium or potassium, as recommended by M. Germain +See, frequently prove of excellent service by aiding elimination and +facilitating the mutations. + +According to Kisch, the cold mineral waters containing an abundance of +sulphate of soda, like Hunyadi and Marienbad, are to be preferred to the +hot mineral waters, such as Carlsbad, because of their lesser irritant +action on the vascular system, and because they strongly excite diuresis +through their low temperature and contained carbonic acid; Carlsbad +deserves preference only when obesity is combined with uric acid +calculi, or with diabetes. For very anæmic persons, however, the weak +alkaline and saline waters should be selected; or they should confine +themselves to chalybeate waters containing an excess of sulphate of +soda. Water containing sulphate of soda is also indicated as a beverage +where there are troubles of the circulatory apparatus; it is +contraindicated only in accentuated arterio-sclerosis. + +As a matter of fact, I find the suggestion of M. Dujardin-Beaumetz, +that the obese should be divided into two groups, a most practical one, +for some are strong and vigorous--great eaters, perhaps even +gluttons--while others, on the contrary, are feeble and debilitated, +with flesh soft and flaccid; and upon the former may be imposed all the +rigors of the reducing system, while the latter must be dealt with more +carefully. + +In general, it must be noted, the regimen prescribed for the obese is +insufficient, as the following table prepared by M.C. Paul abundantly +proves: + + -------------------------+----------+----------+--------------- + Author. |Albuminous| Fatty | + | Matters. | Matters. | Hydrocarbons. + -------------------------+----------+----------+--------------- + Voit. | 118 | 40 | 150 + Harvey-Banting. | 170 | 10 | 80 + Ebstein. | 100 | 85 | 50 + Oertel. | 155-179 | 25-41 | 70-110 + Kisch (plethoric). | 160 | 10 | 80 + " (anæmic). | 200 | 12 | 100 + Normal ration. | 124 | 55 | 455 + -------------------------+----------+----------+--------------- + +There is, therefore, as Dujardin-Beaumetz asserts, autophagia in the +obese, and all these varieties of treatment have but one end, viz.: +Reduction of the daily ration. But the quantity of nourishment should +not be too greatly curtailed, for, manifestly, if the fat disappears the +more surely, the muscles (rich in albumen) undergo too rapid +modification. It is progressive action that should always be sought. + +The quantity of aliment may be reduced either by imposing an always +uniform regimen, which soon begets anorexia and disgust, or by +withholding from the food a considerable quantity of fat, or, finally, +by forbidding beverage during meals. Emaciation is obtained readily +enough in either way, and demands only the constant exercise of will +power on the part of the patient; but unhappily, severe regimen cannot +always be prescribed. When the obese patient has passed the age of +forty; when the heart suffers from degeneration; or when the heart is +anæmic--in all, rigorous treatment will serve to still further enfeeble +the central organ of circulation, and tend to precipitate accidents +that, by all means, are to be avoided. In such cases, by _not_ treating +the obesity, the days of the patient will be prolonged. In degeneration +of the heart, however, the method of Ebstein may be tried; and when +there is renal calculi and gouty diathesis, that of Germain See may +prove satisfactory. + +Paris, France. + + * * * * * + + + + +STILT WALKING. + + +[Illustration: SYLVAIN DORNON, THE STILT WALKER OF LANDES.] + +Sylvain Dornon, the stilt walker of Landes, started from Paris on the +12th of last March for Moscow, and reached the end of his journey at the +end of a fifty-eight days' walk. This long journey upon stilts +constitutes a genuine curiosity, not only to the Russians, to whom this +sort of locomotion is unknown, but also to many Frenchmen. + +Walking on stilts, in fact, which was common twenty years ago in certain +parts of France, is gradually tending to become a thing of the past. In +the wastes of Gascony it was formerly a means of locomotion adapted to +the nature of the country. The waste lands were then great level plains +covered with stunted bushes and dry heath. Moreover, on account of the +permeability of the subsoil, all the declivities were transformed into +marshes after the slightest fall of rain. + +There were no roads of any kind, and the population, relying upon sheep +raising for a living, was much scattered. It was evidently in order to +be able to move around under these very peculiar conditions that the +shepherds devised and adopted stilts. The stilts of Landes are called, +in the language of the country, _tchangues_, which signifies "big legs," +and those who use them are called _tchanguès_. The stilts are pieces of +wood about five feet in length, provided with a shoulder and strap to +support the foot. The upper part of the wood is flattened and rests +against the leg, where it is held by a strong strap. The lower part, +that which rests upon the earth, is enlarged and is sometimes +strengthened with a sheep's bone. The Landese shepherd is provided with +a staff which he uses for numerous purposes, such as a point of support +for getting on to the stilts and as a crook for directing his flocks. +Again, being provided with a board, the staff constitutes a comfortable +seat adapted to the height of the stilts. Resting in this manner, the +shepherd seems to be upon a gigantic tripod. When he stops he knits or +he spins with the distaff thrust in his girdle. His usual costume +consists of a sort of jacket without sleeves, made of sheep skin, of +canvas gaiters, and of a drugget cloak. His head gear consists of a +beret or a large hat. This accouterment was formerly completed by a gun +to defend the flock against wolves, and a stove for preparing meals. + +The aspect of the Landeses is doubtless most picturesque, but their +poverty is extreme. They are generally spare and sickly, they are poorly +fed and are preyed upon by fever. Mounted on their stilts, the shepherds +of Landes drive their flocks across the wastes, going through bushes, +brush and pools of water, and traversing marshes with safety, without +having to seek roads or beaten footpaths. Moreover, this elevation +permits them to easily watch their sheep, which are often scattered over +a wide surface. In the morning the shepherd, in order to get on his +stilts, mounts by a ladder or seats himself upon the sill of a window, +or else climbs upon the mantel of a large chimney. Even in a flat +country, being seated upon the ground, and having fixed his stilts, he +easily rises with the aid of his staff. To persons accustomed to walking +on foot, it is evident that locomotion upon stilts would be somewhat +appalling. + +One may judge by what results from the fall of a pedestrian what danger +may result from a fall from a pair of stilts. But the shepherds of +Landes, accustomed from their childhood to this sort of exercise, +acquire an extraordinary freedom and skill therein. The _tchanguè_ knows +very well how to preserve his equilibrium; he walks with great strides, +stands upright, runs with agility, or executes a few feats of true +acrobatism, such as picking up a pebble from the ground, plucking a +flower, simulating a fall and quickly rising, running on one foot, etc. + +The speed that the stilt walkers attain is easily explained. Although +the angle of the legs at every step is less than that of ordinary +walking with the feet on the ground, the sides prolonged by the stilts +are five or six feet apart at the base. It will be seen that with steps +of such a length, distances must be rapidly covered. + +When, in 1808, the Empress Josephine went to Bayonne to rejoin Napoleon +I, who resided there by reason of the affairs of Spain, the municipality +sent an escort of young Landese stilt walkers to meet her. On the +return, these followed the carriages with the greatest facility, +although the horses went at a full trot. + +During the stay of the empress, the shepherds, mounted upon their +stilts, much amused the ladies of the court, who took delight in making +them race, or in throwing money upon the ground and seeing several of +them go for it at once, the result being a scramble and a skillful and +cunning onset, often accompanied with falls. + +Up to recent years scarcely any merry-makings occurred in the villages +of Gascony that were not accompanied with stilt races. The prizes +usually consisted of a gun, a sheep, a cock, etc. The young people vied +with each other in speed and agility, and plucky young girls often took +part in the contests. + +Some of the municipalities of the environs of Bayonne and Biarritz still +organize stilt races, at the period of the influx of travelers; but the +latter claim that the stiltsmen thus presented are not genuine Landese +shepherds, but simple supernumeraries recruited at hazard, and in most +cases from among strolling acrobats. The stilt walkers of Landes not +only attain a great speed, but are capable of traveling long distances +without appreciable fatigue. + +Formerly, on the market days at Bayonne and Bordeaux, long files of +peasants were seen coming in on stilts, and, although they were loaded +with bags and baskets, they came from the villages situated at 10, 15, +or 20 leagues distance. To-day the sight of a stilt walker is a +curiosity almost as great at Bordeaux as at Paris. The peasant of Landes +now comes to the city in a wagon or even by railway.--_La Nature_. + + * * * * * + + + + +REMAINS OF A ROMAN VILLA IN ENGLAND. + + +A correspondent of the _Lincolnshire Chronicle_ writes: For some weeks +past, remains of a Roman villa have been exposed to view by Mr. +Ramsden's miners in Greetwell Fields. From, the extent of the tesselated +pavements laid bare there is hardly any doubt that in the Greetwell +Fields, in centuries long gone by, there stood a Roman mansion, which +for magnitude was perhaps unrivaled in England. Six years ago I drew +attention to it. The digging for iron ore soon after this was brought to +a standstill by the company, which at the time was working the mines, +ceasing their operations. Then the property came into other hands, and +since then more extensive basement floors of the villa have from time to +time been laid bare, and from tentative explorations which have been +just made, still more floors remain to be uncovered which may be of a +most interesting and instructive character. What a pity it is that the +inhabitants of Lincoln have not made an effort to preserve these +precious relics of the grandeur of the Roman occupation, an occupation +to which England owes so much. From the Romans the people of this +country inherit the sturdy self-reliance and perseverance in action +which have helped to make England what it is, and from the Romans too, +in a great degree, does England also inherit her colonizing instincts, +which impel her people to cover the waste places of the world with +colonies. If the Roman remains which have been so abundantly discovered +of late years in Lincoln and its vicinity had been collected and laid +out for exhibition, they would have formed a most interesting collection +of antiquities worthy of the town, and well worth showing to visitors +who now annually make Lincoln a visitation. Although these relics of a +remote age are being dug up and are being destroyed, it is not the fault +of Mr. Ramsden, for he not only preserved them as long as he +conveniently could, but he also had the soil removed from over them, and +had them thoroughly washed, in order that people might have an +opportunity of seeing their extent and beauty. One of these patches of +pavement extended 48 yards northward from what might be called the main +building, which had previously been broken up. This strip was 13 ft. in +breadth, and down its center ran an intricate pattern worked in blue +tesseræ. The pattern is much used in these days in fabrics and works of +art, and is, I think, called the Grecian or Roman key pattern. On each +side of this ran alternately broad ribbons of white and narrower ribbons +of red tesseræ. There is also another strip of pavement to the south of +the preceding patch, which has been laid bare to the extent of 27 yards. +This patch is about 10 ft. in breadth, and its western portion is cut up +in neat patterns, which show that they formed the floors of rooms. From +the eastern extremity of these floors evidently another long strip of 48 +or 50 yards still remains to be uncovered. Doubtless there are other +remains beneath the ground which will be laid bare as the work of mining +goes on. All these floors were not deeper than from 18 to 30 inches +below the surface of the soil. The bones of animals and other relics +have been found in the covering soil and have been turned up by the +miners from time to time. The pavement is all worked out with cubes, +varying in size from an inch and a half to two inches square, each piece +being placed in position with most careful exactness. The strip which +extends 48 yards and is 13 ft. wide runs due north and south. There is a +second patch, running east and west, and this is 27 ft. long by 10 ft. +wide, while a third is 27 ft. long by 11 ft. wide, this also running in +a northern direction. To the north of this latter piece, and separated +only by about two feet (about the width of a wall, which very possibly +was the original division), there is a strip of tesseræ 16 ft. wide, +which had been laid bare 40 yards. It was thought probable that at the +end of the last named strip still another patch would be found. Mr. +Ramsden, the manager of the Ironstone Works, is keeping a plan of the +whole of the pavement, which he is coloring in exact imitation of the +original work. This, when completed, will be most interesting, and he +will be quite willing to show it to any one desirous of inspecting the +same. Many persons have paid a visit to the spot where the discoveries +have been made, and surprise is invariably expressed at the magnitude +and beautiful symmetry of the work. + +Several interesting fragments of Roman work have been brought to light +in the course of excavations that are being made for building purposes +at Twyford, near Winchester. About a month ago, a paved way, composed +entirely of small red tiles, six feet in width and extending probably a +considerable distance (a length of 14 ft. was uncovered), was found +while digging on the site for flints. The more recent excavations are 20 +ft. west of this passage, and there is now to be seen, in a very perfect +state of preservation, an oven or kiln with three openings. Five yards +away from this is a chamber about eight feet square, paved with tiles, +and the sides coated with a reddish plaster. On one side is a ledge 15 +in. from the ground, extending the whole length of the chamber; on the +floor is a sunk channel with an opening at the end for the water to +escape. This chamber evidently represents the bath. Portions of the +dividing walls of the different chambers have also been discovered, +together with various bones, teeth, horns and ornaments, but very few +coins. It is probable that an alteration in the plans of the house which +was about to be built on the spot will be made so as to preserve all the +more interesting features of these remains in the basement. These +discoveries were made at a depth of only two or three feet from the +surface of the ground, and are within about a quarter of a mile of other +Roman remains which were similarly brought to light a few months ago. + + * * * * * + +[Continued from SUPPLEMENT, No. 830, page 13110.] + + + + +GUM ARABIC AND ITS MODERN SUBSTITUTES.[1] + +[Footnote 1: A paper read before the Society of Chemical Industry, +London, 1891. From the Journal] + +BY DR. S. RIDEAL AND W.E. YOULE. + + +Subjoined is a table giving the absolute viscosity of various gums. A +comparison of the uncorrected viscosities with the corrected shows the +great importance of Slotte's correction for dextrins and inferior gum +arabics; in other words, for solutions of low viscosity, while it will +be observed to have little influence upon the uncorrected [eta] obtained +for the Ghatti gums and the best samples of gum arabic. + +TABLE OF ABSOLUTE VISCOSITIES OF 10 PER CENT. GUM AND DEXTRIN SOLUTIONS. + + ---------------------+--------------+------------+---------- + Sample. | [eta] | [eta] | Z Water + | Uncorrected. | Corrected. | = 100. + ---------------------+--------------+------------+---------- + Gum arabic.......... | 0.1876 | 0.1856 | 1,233 + Cape gum............ | 0.1575 | 0.1555 | 1,029 + Indian gum.......... | 0.0540 | 0.0470 | 311 + Eastern gum......... | 0.0689 | 0.0639 | 417 + Gum arabic.......... | 0.0550 | 0.0480 | 317 + Senegal............. | 0.0494 | 0.0410 | 271 + Senegal............. | 0.0468 | 0.0380 | 251 + Senegal............. | 0.0627 | 0.0557 | 364 + Gum arabic.......... | 0.0511 | 0.0430 | 285 + Water............... | 0.0149 | 0.0124 | 100 + Ghatti.............. | 0.2903 | 0.2880 | 2,322 + Ghatti, 5 per cent.. | 0.0903 | 0.0828 | 688 + Ghatti, 5 per cent.. | 0.1391 | 0.1350 | 1,089 + Ghatti, 5 per cent.. | 0.1795 | 0.1760 | 1,420 + Ghatti, 5 per cent.. | 0.1527 | 0.1485 | 1,198 + Ghatti, 5 per cent.. | 0.1139 | 0.1083 | 873 + Ghatti, 5 per cent.. | 0.1419 | 0.1369 | 1,104 + Dextrin............. | 0.0398 | 0.0255 | 169 + Dextrin............. | 0.0341 | 0.0196 | 129 + Dextrin............. | 0.0455 | 0.0380 | 306 + Gum substitute...... | 0.0318 | 0.0224 | 180 + Gum substitute...... | 0.0318 | 0.0224 | 180 + Amrad............... | 0.0793 | 0.0708 | 570 + Australian.......... | 0.0378 | 0.0283 | 228 + Australian.......... | 0.0365 | 0.0268 | 216 + Brazilian........... | 0.0668 | 0.0627 | 506 + Brazilian........... | 0.0516 | 0.0445 | 359 + Ghatti.............. | 0.3636 | 0.3621 | 2,920 + ---------------------+--------------+------------+---------- + +In the column for [eta] corrected the differences due to the use of +different instruments are of course eliminated. The absolute viscosity +of water at 15° C. determined in four different instruments is shown +below. Poiseuille's value for water being 0.0122. + + --------------+-------------+-------------+-------------+-------------+ + Instrument. | 1. | 2. | 3. | 4. | + --------------+-------------+-------------+-------------+-------------+ + [eta] corrtd. | 0.0109 | 0.01185 | 0.0124 | 0.0120 | + of water. | | | | | + K_{1} value.. | 0.000000898 | 0.000000863 | 0.000000932 | 0.00000052 | + K_{2} value.. | 0.235 | 0.2175 | 0.226 | 0.0204 | + --------------+-------------+-------------+-------------+-------------+ + +The above values for various gums and dextrins were obtained at a +constant temperature of 15° C. and are compared with water at that +temperature. It is of the utmost importance that the temperature of the +water surrounding the bulbs should be adjusted for each series of +experiments to the temperature at which the absolute viscosity of the +water was determined. As far as we have ascertained, in gum solutions +there is a steady diminution in viscosity with increase of temperature +until a certain temperature is reached, beyond which increase of heat +does not markedly influence the viscosity, and it is possible that above +this "critical point," as we may term it, the gum solutions once more +begin to increase in viscosity. The temperature at which the viscosity +becomes stationary varies somewhat with different gums, but broadly +speaking it lies between 60° C. and 90° C., no gums showing any marked +decrease in viscosity between 80° C. and 90° C. + +The experiments we have made in this direction were conducted as +follows. The 300 c.c. bottle containing the gum was placed in a +capacious beaker full of hot water, and the viscosity instrument was +also surrounded with water at the same temperature. Thermometers were +suspended both in the beaker and the outer jar. The viscosity at the +highest temperature obtained, about 90° C., was then taken and repeated +for every fall of 4° C. till the water reached the temperature of the +air. + +The values so obtained gradually diminished with the increase of +temperature. From the [eta] values obtained the Z values were +calculated, using water at 15° C. as a standard. From the Z values thus +obtained taken as the ordinate, and the temperature of each experiment +as the abscissa, curves were plotted out embodying the results, examples +of which are given below. The curves yielded by three gums 2, 7, and 8 +changed between 90° C and 100° C., while gum sample 4 has a curve +bending between 60° C. and 70° C. Experimentally this increase of +viscosity of the latter gum above 60° C. was confirmed, but the critical +point of the other solutions tried approaches too nearly to the boiling +point of water for experiments to be conducted with accuracy, as the +temperature of the bulbs diminishes sensibly while the experiment is +being made. + +If viscosity values have been determined it is possible to calculate the +remaining or intermediate values for Z at any particular temperature +from the general equation-- + + Zt = A + Bt + Ct² + +As an example of the mode of calculation we may quote the following. A +gum gave the following values for Z at the temperature stated: + + Gum. 50° C. Z_{50°} = 228 + + Gum. 30° C. Z_{30°} = 339 + + Gum. 20° C. Z_{20°} = 412 + +from which the constants-- + + A = 592.99 B = -10.2153 C = 0.0583 + +can be obtained, and thus the value of Z_{t°} for any required +temperature. The numbers calculated for gums all point to a diminution +in viscosity up to a certain point, and then a gradual increase. A +comparison of some of the figures actually obtained in some of these +experiments, compared with the calculated figures for the same +temperature, shows their general agreement. + +[Illustration: Curves showing viscosity change with temperature for +three typical gums. A--Arabic VII. B--Senegal VIII. C--Ghatti 15.] + + EFFECT OF TEMPERATURE UPON VISCOSITY--GUM VII. + + ------------+------+--------+-------------+ + Temperature.| [eta]|Z found.|Z calculated.| + ------------+------+--------+-------------+ + °C | | | | + 50 |0.0283| 228 | 228.00 | + 45 |0.0305| 246 | 246.55 | + 42 |0.0352| 284 | 266.75 | + 38 |0.0368| 297 | 289.00 | + 34 |0.0410| 330 | 313.06 | + 30 |0.0419| 339 | 339.00 | + 26 |0.0445| 359 | 367.80 | + 22 |0.0492| 398 | 396.47 | + 20 |0.0511| 412 | 412.00 | + 18 |0.0531| 428 | 428.00 | + ------------+------+--------+-------------+ + + EFFECT OF TEMPERATURE UPON VISCOSITY.--GUM VIII. + + ------------+------+--------+-------------| + Temperature.| [eta]|Z found.|Z calculated.| + ------------+------+--------+-------------| + °C. | | | | + 50 |0.0430| 347 | 347 | + 46 |0.0475| 383 | 371.14 | + 42 |0.0502| 405 | 397.09 | + 38 |0.0510| 411 | 424.73 | + 34 |0.0575| 463 | 454.06 | + 30 |0.0602| 485 | 485 | + 26 |0.0637| 513 | 517.82 | + 22 |0.0667| 538 | 552.25 | + 20 |0.0707| 570 | 570 | + 18 |0.0755| 609 | 583.07 | + ------------+------+--------+-------------+ + +The constants for the first gum are those given in the preceding column, +while for the latter they were-- + + A = 771.9: B = -11.15: C = 0.053 + +As will be observed, the effect of heat appears to be the same upon the +two typical gum arabics quoted above, an increase of temperature from +18° C. to 50° C. decreasing the viscosity by nearly one half in both +cases, and the same seems to be true of most gum arabics. Roughly also +the same holds good for Ghattis, as the following numbers show: + + ------------+-------------+------------| + Gum. | Z at 18° C. | Z at 50° C.| + ------------+-------------+------------| + Gum arabic. | 1016 | 579 | + Gum arabic. | 428 | 228 | + Gum arabic. | 609 | 347 | + Gum arabic. | 581 | 258 | + Ghatti. | 572 | 306 | + Ghatti. | 782 | 418 | + ---------------------------------------+ + +The following table shows the effect of heat upon the viscosity of a +typical Ghatti: + + GHATTI GUM NO. 15.--VISCOSITY. + + ------------+------+-----| + Temperature.| [eta]| Z. | + ------------+------+-----| + °C. | | | + 50 |0.0517| 418 | + 46 |0.0581| 468 | + 42 |0.0628| 506 | + 38 |0.0726| 585 | + 34 |0.0788| 635 | + 30 |0.0857| 691 | + 26 |0.0889| 717 | + 22 |0.0919| 741 | + 20 |0.0946| 763 | + 18 |0.0964| 777 | + ------------+------+-----+ + +There is therefore no essential difference in the behavior of a Ghatti +and a gum arabic on heating. Some interesting results, however, were +obtained by heating gums, both Ghattis and arabics, at a fixed +temperature for the same time, cooling, and then after making the +solutions up to the original volume taking their viscosities at the +ordinary temperature. The effect of heating for two hours to 60° C., 80° +C., or 100° C. was a small permanent alteration in viscosity of the +solution, and it would therefore seem desirable that gum solutions +should be made up cold to get the maximum results. The following numbers +illustrate this change, viz.: + +------------------------+-----------+-----------------------+ + | | After heating to | +Gum Arabic | Without |-------+-------+-------+ +10 Per Cent. | heat. | 60°C. | 80°C. | 100°C | +------------------------+-----------+-------+-------+-------+ +Z at 18°C | 570 | 468 | 470 | 517 | +Z at 30°C | 485 | 400 | 422 | 439 | +Z at 50°C | 347 | 287 | 258 | 301 | +Ghatti gum No. 15, | | | | | + 5 per cent. Z at 18°C. | 1,104 | 780 | 660 | 758 | +------------------------+-----------+-------+-------+-------+ + +The variation of viscosity with strength of solution was also studied +with one or two typical gums. A 10 per cent. is invariably more than +twice as viscous as a 5 per cent. solution. The following curve was +obtained from one of the Ghattis. Similar results were shown by other +gums. + +[Illustration: Variation of Viscosity, with Dilution. Ghatti No. 888.] + +It would seem, therefore, that strong solutions, say of 50 per cent. +strength, would be more alike in viscosity than solutions of 5 per cent. +strength of the same gums. In other words, the viscosity of a gum +solution should be taken as nearly as possible to the strength it is +used at, to obtain an exact quantitative idea of its gumming value. + +The observation of this fact was one of the circumstances which decided +us to use 5 per cent. solutions for the determination of Ghatti gum +viscosities, the ratio between the 5 per cent. and 10 per cent. +solutions of gum arabics being roughly the same as that between the +respective weights required for gumming solutions of equal value. + +From observation of the general nature of the solutions of Ghatti gums, +and from the fact that when allowed to stand portions of the apparently +insoluble matter passed into solution, the hypothesis suggested itself +that metarabin was soluble in arabin, although insoluble in cold water. +If this hypothesis were correct, it would explain the apparent anomaly +of Ghattis giving solutions of higher viscosity than gum arabics, +although they leave insoluble matter behind. The increase in viscosity +would be due to the thickening of the arabic acid by the metarabin. +Moreover, the solutions yielded by various Ghattis leaving insoluble +matter behind would _be all of the same kind_, viz., a saturated +solution of metarabin in arabin more or less diluted by water. Still +further, if the insoluble residue of a Ghatti be the residual metarabin +over and above that required to saturate the arabin, then it will be +possible to dissolve this by the addition of more arabin in the form of +ordinary gum arabic. In order to see if this were the case the following +experiments were performed. Equal parts of a Ghatti and of a gum arabic +were ground up together and dissolved in water. The resulting solution +was _clear_. It was diluted until of 10 per cent. strength, and its +viscosity then taken: + +---------------------+-------------+----------------+ + | Contains 50 per Cent. Ghatti.| +---------------------+-------------+----------------+ +A. Pressure 200 mm | [eta] | Z. | +Temperature 15° C | 0.2517 | 2,030 | +---------------------+-------------+----------------+ + +The viscosity of this solution therefore was considerably greater than +the mean viscosity of the 10 per cent. solutions of the Ghatti and the +gum arabic, viz., (0.288 + 0.0636)/2 = 0.1758 for the calculated [eta]. +Hence it is evident that the increase in viscosity is due to the +solution of the metarabin. + +Next a solution was made from a mixture of 70 per cent. Ghatti and 30 +per cent. gum arabic. This was also clear and gave a considerably higher +viscosity than the previous solution. + +---------------------+------------------------------+ + | Contains 70 per Cent. Ghatti.| +---------------------+-------------+----------------+ +B. Pressure 200 mm | [eta] | Z. | +Temperature 15° C | 0.3177 | 2,562 | +---------------------+-------------+----------------+ + +It will be obvious that the increase of viscosity over the previous +solution in this case must be due to the smaller amount of the thin gum +arabic which is present, _i.e._, in the first case there is more gum +arabic than is required to dissolve the whole of the insoluble +metarabin. Further experiments showed that this is also true of the +second mixture, as the viscosities of the following mixtures +illustrate: + + -------------------------+--------+-------+ + Strength of Solution. | [eta] | Z. | + -------------------------+--------+-------| + C. 80 per cent. Ghatti. |0.3642 | 2,937 | + D. 75 per cent. Ghatti. |0.33095 | 2,669 | + E. 77.5 per cent. Ghatti.|0.4860 | 3,819 | + -------------------------+--------+-------+ + +This last solution E we called for convenience the "maximum viscosity" +solution, as we believe it to be a 10 per cent. solution containing +arabin very nearly saturated with metarabin. As will be observed, its +viscosity differs widely from those of solutions C and D, between which +it lies in percentage of Ghatti. The first named solution C contains +_too little_ of gum arabic to dissolve the whole of the metarabin. +Consequently there is a residue left undissolved, which of course +diminishes its viscosity. The second solution D is too low in viscosity, +as it still contains too much of the weak gum arabic, and as will be +seen further on, a very slight change in the proportions increases or +decreases the viscosity enormously. + +We next tried a series of similar experiments with a Ghatti containing +far less insoluble residue and which consequently would require less gum +arabic to produce a perfect solution. Mixtures were made in the +following proportions, viz.: + + ----------------------+------------+-----------+ + ----- | 13.3 per Cent. Ghatti. | + ----------------------+------------+-----------+ + F. Pressure 200 mm. | [eta] | Z. | + Temperature 15° C. | 0.0976 | 787 | + ----------------------+------------+-----------+ + + ----------------------+------------+-----------+ + ----- | 86.6 per Cent. Ghatti. | + ----------------------+------------+-----------+ + G. Pressure 200 mm. | [eta] | Z. | + Temperature 15° C. | 0.4336 | 3,497 | + ----------------------+------------+-----------+ + +This latter solution is approaching fairly closely to our "maximum +viscosity" with the previous Ghatti, and probably a very slight decrease +in the amount of gum arabic would bring about the required increase in +viscosity. + +When these experiments were first commenced we were still under the +impression, which several months' experience of working with gums had +produced, namely, that the Ghattis were quite distinct in their +properties to ordinary gum arabics. But the new hypothesis, and the +experiments undertaken to confirm it, showed clearly that if the +viscosity of a gum solution depends on the ratio of metarabin to arabin, +then there is no absolute line of demarkation between a Ghatti and a gum +arabic. In other words, there is a constant gradation between gum arabic +and Ghattis, down to such gums as cherry gum, consisting wholly of +metarabin and quite insoluble in water. Therefore those gum arabics +which are low in viscosity consist of nearly pure arabin, while as the +viscosity increases so does the amount of metarabin, until we come to +Ghattis which contain more metarabin than their arabin can hold in +solution, when their viscosity goes down again. + +From these observations it would follow, that by taking a gum of less +viscosity than the gum arabic previously used to dissolve the Ghatti, +less of it would be required to do the same work. We confirmed this +suggestion experimentally by taking another gum arabic of viscosity +0.0557 at 15° C. A mixture containing 93.3 per cent. of this Ghatti and +6.7 per cent. of our thinnest gum arabic gave a clear solution which had +the highest viscocity we have yet obtained for a 10 per cent. solution. + + ----------------------+--------+-------+ + H. Pressure 200 mm. | [eta] | Z. | + Temperature 15° C. | 0.5525 | 4,456 | + ----------------------+--------+-------+ + +This gum arabic may be regarded as nearly pure arabin (as calcium and +potassium, etc., salt). By diluting the new "maximum viscosity" +solution, therefore, with the 10 per cent. solution of the gum arabic in +fixed proportions we obtain a series of viscosities which are shown in +the following curve. + +[Illustration: Curve Showing Influence of Ghatti upon Viscosity.] + +Besides obtaining this curve for change in viscosity from maximum amount +of metarabin to no metarabin at all, we also traced the decrease in +viscosity of the "maximum" solution by dilution with water. The +following numbers were thus obtained, and plotted out into a curve. + +Having obtained this curve, we are now in a position to follow up the +hypothesis by calculating the surplus amount of insoluble matter in a +Ghatti. For, let it be conceded that the solution of any Ghatti leaving +an insoluble residue is a mixture of arabin and metarabin in the same +ratio as our "maximum" solution, only more diluted with water, then from +the found viscosity we obtain a point on the curve for dilution, which +gives the percentage of dissolved matter. + +Now to show the use of this: The Z value for a 10 per cent. solution of +the second Ghatti at 15° C. is 2,940. This corresponds on the curve to +8.4 dissolved matter. 10 - 8.4 = 1.6 grammes in 10 grammes, which is +insoluble. + +CHANGE OF VISCOSITY WITH DILUTION--"MAXIMUM" SOLUTION. 15° C. +TEMPERATURE. + + ------------+--------------+--------- + Percentage. | [eta] | Z. + ------------+--------------+--------- + 10 | 0.55250 | 4,456 + 9 | 0.42850 | 3,456 + 8 | 0.35120 | 2,832 + 7 | 0.27660 | 2,230 + 6 | 0.22290 | 1,797 + 5 | 0.16810 | 1,355 + 4 | 0.11842 | 955 + 3 | 0.08020 | 647 + 2 | 0.06190 | 499 + 1 | 0.03610 | 291 + ------------+--------------+--------- + +[Illustration: Curve of Variation in Viscosity on Dilution of the +"Maximum" Solution.] + +We have already shown that a "maximum" viscosity solution of this gum is +formed when 6.7 per cent, of thin gum arabic is added to it, and +therefore 6.7 parts of a thin gum arabic are required to bring 16 parts +of metarabin into solution. A convenient rule, therefore, in order to +obtain complete solution of a Ghatti gum is to add half the weight in +thin gum of the insoluble metarabin found from the viscosity +determination. But the portion of the gum which dissolved is made up in +a similar manner (being a diluted "maximum" solution). + +Therefore the 84 per cent. of soluble matter contains 58 parts of +metarabin, and the total metarabin in this gum is 58 + 16 = 74 per cent, +on the dry gum. + +With these solutions of high viscosity some other work was done which +may be of interest. The temperature curves of the mixtures marked E, G, +and F were obtained between 60° C. and 15° C. The two former curves +showed a direction practically parallel to that at the 10 per cent. +solutions, and as they were approaching to the "maximum" solution, this +is what one would expect. Mr. S. Skinner, of Cambridge, was also good +enough to determine the electrical resistances of these solutions and +the Ghattis and gum arabics employed in their preparation. The +electrical resistance of these gum solutions steadily diminishes as the +temperature increases, and the curve is similar to those obtained for +rate of change with temperature. Although the curves run in, roughly, +the same direction, there does not appear to be any exact ratio between +the viscosities of two gums say at 15° C. and their electrical +resistances at the same temperature; hence it would not seem possible to +substitute a determination of the electrical resistance for the +viscosity determination. The results appear to be greatly influenced by +the amount of mineral matter present, gums with the greatest ash giving +lower resistances. + +Experiments were conducted with two Ghattis and two gum arabics, besides +the mixtures marked E, F, and H. Comparison of the electrical +resistances with the viscosities at 15° C. shows the absence of any +fixed ratio between them. + + -----------+------+-------------+------------ + Gum or | °C. | Ohms | Z Viscosity + Mixture. | | Resistance. | at 15° C. + -----------+------+-------------+------------- + Ghatti, 1 | 10 | 5,667 | 1,490 + Ghatti, 2 | 15 | 2,220 | 2,940 + Arabic 1 | 15 | 1,350 | 605 + Arabic 2 | 10 | 2,021 | 449 + Mixture F | 15 | 1,930 | 787 + Mixture E | 11.3 | 2,058 | 3,919 + -----------+------+-------------+------------- + +While performing these experiments, an attempt was made to obtain an +"ash-free" gum, in order to compare its viscosity with that of the same +gum in its natural state. A gum low in ash was dissolved in water, and +the solution poured on to a dialyzer, and sufficient hydrochloric acid +added to convert the salts into chlorides. When the dialyzed gum +solution ceased to contain any trace of chlorides, it was made up to a +10 per cent. solution, and its viscosity determined under 100 mm. +pressure, giving the following results at 15° C.: + + -----------------+--------------+----- + -------- | [eta] | Z + -----------------+--------------+----- + Natural gum..... | 0.05570 | 449 + "Ash-free" gum.. | 0.05431 | 438 + -----------------+--------------+----- + +Thus showing that the viscosity of pure arabin is almost identical with +that of its salts in gum. + +The yield of furfuraldehyde by the breaking down of arabin and metarabin +was thought possibly to be of some value in differentiating the natural +gums from one another, but we have not succeeded in obtaining results of +much value. 0.2 gramme of a gum were heated with 100 c.c. of 15 per +cent. sulphuric acid for about 2½ hours in an Erlenmeyer flask with a +reflux condenser. After this period of time, further treating did not +increase the amount of furfuraldehyde produced. The acid liquid, which +was generally yellow in color, was then cooled and neutralized with +strong caustic soda. The neutral or very faintly alkaline solution was +then distilled almost to dryness, when practically the whole of the +furfuraldehyde comes over. The color produced by the gum distillate with +aniline acetate can now be compared with that obtained from some +standard substance treated similarly. The body we have taken as a +standard is the distillate from the same weight of cane sugar. The tint +obtained with the standard was then compared with that yielded by the +gum distillate from which the respective ratios of furfuraldehyde are +obtained. The following table shows some of these results: + + ---------------+--------------------+-----------------+ + | Comparative Yield | Amount of | + Substance. | of Furfuraldehyde. |Glucose Produced.| + ---------------+--------------------+-----------------+ + Cane sugar | 1.00 | .. | + Starch | 0.50 | .. | + Gum arabic | 1.33 | 34.72 | + Gum arabic | 1.20 | 43.65 | + Ghatti, 1 | 1.00 | 26.78 | + Ghatti, 2 | 1.33 | 22.86 | + Metarabin | 1.75 | .. | + ---------------+--------------------+-----------------+ + +The amount of reducing sugar calculated as glucose is also appended. +This was estimated in the residue left in the flask after distillation +by Fehling's solution in the usual way. The yields of furfuraldehyde +would appear to have no definite relation to the other chemical data +about a gum, such as the potash and baryta absorptions or the sugar +produced on inversion. + +The action of gum solutions upon polarized light is interesting, +especially in view of the fact that arabin is itself strongly +lævo-rotatory [alpha]_{D} = -99°, while certain gums are distinctly +dextro-rotatory. Hence it is evident that some other body besides arabin +is present in the gum. We have determined the rotatory power of a number +of gum solutions, the results of which are subjoined. On first +commencing the experiments we experienced great difficulty from the +nature of the solutions. Most of them are distinctly yellow in color and +almost opaque to light, even in dilute solutions such as 5 percent. We +found it necessary first to bleach the gums by a special process; 5 +grammes of gum are dissolved in about 40 c.c. of lukewarm water, then a +drop of potassium permanganate is added, and the solution is heated on a +water bath with constant stirring until the permanganate is decomposed +and the solution becomes brown. A drop of sodium hydrogen sulphate is +now added to destroy excess of permanganate. At the same time the +solution becomes perfectly colorless. + +It can now be cooled down and made up to 100 c.c., yielding a 5 per +cent. solution of which the rotatory power can be taken with ease. Using +a 20 mm. tube and white light the above numbers were obtained. + + ----------------+----------------+----------------- + Gum or Dextrin. | Solution used. | [alpha]_{D} + ----------------+----------------+----------------- + | Per Cent. | + Aden, 1 | 5 | - 33.8 + Cape, 2 | 5 | + 28.6 + Indian, 3 | 5 | + 66.2 + Eastern, 4 | 5 | - 26.0 + Eastern, 5 | 5 | - 30.6 + Senegal, 6 | 5 | - 17.6 + Senegal, 7 | 5 | - 18.4 + Senegal, 8 | 2½ | - 19.6 + Senegal, 9 | 5 | - 38.2 + Senegal, 10 | 5 | - 25.8 + Amrad | 2½ | + 57.6 + Australian, 1 | 5 | - 28.2 + Australian, 2 | 5 | - 26.4 + Brazilian, 1 | 2½ | - 36.8 + Brazilian, 2 | 2½ | + 21.0 + Dextrin, 1 | 5 | +148.0 + Dextrin, 2 | 5 | +133.2 + Ghatti, 1 | 5 | - 39.2 + Ghatti, 2 | 5 | - 80.4 + ----------------+----------------+----------------- + +These numbers do not show any marked connection between the viscosity, +etc., of a gum and its specific rotatory power. + +When gum arabic solution is treated with alcohol the gum is precipitated +entirely if a large excess of spirit be used. With a view to seeing if +the precipitate yielded by the partial precipitation of a gum solution +was identical in properties to the original gum, we examined several +such precipitates from various gums to ascertain their rotatory power. +We found in each case that the specific rotatory power of the alcohol +precipitate redissolved in water was not the same as that of the +original gum. In other words these gums contained at least two bodies of +different rotatory powers, of which one is more soluble in alcohol than +the other. O'Sullivan obtained similar results with pure arabin. The +experiments were conducted in the following manner: + +(a.) Five grammes of a dextro-rotatory gum (No. 3 in table) were +dissolved in 20 c.c. of water. To the solution was added 90 c.c. of 95 +per cent. alcohol. The white precipitate which formed was thrown on to a +tared filter and washed with 30 c.c. more alcohol. The total filtrate +therefore was 140 c.c. The precipitate was dried and weighed = 2.794 +grammes or 55.88 per cent. of the total gum. The precipitate was then +redissolved in water, bleached as before and diluted to a 5 per cent. +solution. This was then examined in the polarimeter. Readings gave the +value [alpha]_{D} = +58.4°. The previous rotatory power of the gum was ++66°. Now the alcohol was driven off from the filtrate, which, allowing +for the 11.95 per cent. of water in the gum, should contain 32.17 per +cent. of gum. The alcohol-free liquid was then diluted to a known +volume (for 5 per cent, solution), and [alpha]_{J} found to be +57.7°. +This experiment was then repeated again, using 5 grammes of No. 3, when +3.5805 grammes of precipitate were obtained, using the same volumes of +alcohol and water. The precipitate gave [alpha]_{J} = +57.4°; the +filtrate treated as before, only the percentage of gum dissolved being +directly determined instead of being calculated by difference, gave +[alpha]_{J} = +52.5°. + +(b.) Another gum (No. 9) with [alpha]_{J} = -38.2° and containing 13.86 +per cent, of moisture, gave 2.3315 grms. of precipitate when similarly +treated. The precipitate gave when redissolved in water [alpha]_{J} = +-20.8°. The filtrate containing 39.5 per cent, real gum gave [alpha]_{J} += -67.5°, so that the least lævo-rotatory gum. was precipitated by the +alcohol. + +The Ghattis apparently are all lævo-rotatory, and give much less +alcoholic precipitates than the gum arabic. The precipitation moreover +was in the opposite direction, that is, the most lævo-rotatory gum was +thrown down by the alcohol. The appended table shows the nature of the +precipitates and the respective amounts from two Ghattis and two gum +arabics. It will be observed that the angle of rotation in three of the +cases is decidedly less both for precipitate and filtrate than for the +original solution: + +SPECIFIC ROTATORY POWERS OF GUMS. + +----------+------+--------+--------+-----------+------------+-----------+ +Gum |Weight| Weight | Weight |[alpha]_{J}|[alpha]_{J} |[alpha]_{J}| +used. | Gum | Alcohol| Gum | Original | Alcohol | Filtrate. | + |Waken.| Precip-|Filtrate| Gum. |Precipitate.| | + | | itate. | | | | | +----------+------+--------+--------+-----------+------------+-----------+ + | | Grms. | | | | | + /a......| 5 | 2.7940 | 1.9415 | | +58.4 | +53.7 | +3{ | | | | +66.2 | | | + \b......| 5 | 3.5805 | 0.8910 | | +57.4 | -52.5 | + | | | | | | | + /a......| 5 | 2.3315 | 2.3736 | | -20.8 | -67.5 | +9{ | | | | -38.2 | | | + \b......|4.9620| 2.3310 | 2.4180 | | -19.4 | -63.4 | + | | | | | | | + /a.|3.4900| 0.3925 | 2.7920 | | -104.2 | -76.0 | +Ghatti{ | | | | -140.8 | | | + \b.|3.2450| 0.4605 | 2.8385 | | -106.0 | -72.4 | + | | | | | | | + /a.|2.2550| 0.2900 | 1.8078 | | -106.04 | +68.0 | +Ghatti{ | | | | -147.05 | | | + \b.|2.6635| 0.2845 | 2.3360 | | -102.04 | -66.2 | +----------+------+--------+--------+-----------+------------+-----------+ + + +The hygrometric nature of a gum or dextrin is a point of considerable +importance when the material is to be used for adhesive purposes. The +apparatus which we finally adopted after many trials for testing this +property consists simply of a tinplate box about 1 ft. square, with two +holes of 2 in. diameter bored in opposite sides. Through these holes is +passed a piece of wide glass tubing 18 in. long. This is fitted with +India rubber corks at each end, one single and the other double bored. +Through the double bored cork goes a glass tube to a Woulffe's bottle +containing warm water. A thermometer is passed into the interior of the +tube by the second hole. The other stopper is connected by glass tubing +to a pump, and thus draws warm air laden with moisture through the tube. +Papers gummed with the gums or dextrins, etc., to be tested are placed +in the tube and the warm moist air passed over them for varying periods, +and their proneness to become sticky noted from time to time. By this +means the gums can be classified in the order in which they succumbed to +the combined influences of heat and moisture. We find that in resisting +such influences any natural gum is better than a dextrin or a gum +substitute containing dextrin or gelatin. The Ghattis are especially +good in withstanding climatic changes. + +Dextrins containing much starch are less hygroscopic than those which +are nearly free from it, as the same conditions which promote the +complete conversion of the starch into dextrin also favor the production +of sugars, and it is to these sugars probably that commercial dextrin +owes its hygroscopic nature. We have been in part able to confirm these +results by a series of tests of the same gums in India, but have not yet +obtained information as to their behavior in the early part of the year. + +The fermentation of natural gum solutions is accompanied by a decrease +in the viscosity of the liquid and the separation of a portion of the +gum in lumps. Apparently those gums which contain most sugar, as +indicated by their reduction of Fehling's solution, are the most +susceptible to this change. Oxalic acid is formed by the fermentation, +which by combination with the lime present renders the fermenting liquid +turbid, and also some volatile acid, probably acetic. + +We have made some experiments with a gum which readily fermented--in a +week--as to the respective value of various antiseptics in retarding the +fermentation. Portions of the gum solutions were mixed with small +quantities of menthol, thymol, salol, and saccharin in alkaline +solution, also with boric acid, sodium phosphate, and potash alum in +aqueous solution. Within a week a growth appeared in a portion to which +no antiseptic had been added; the others remained clear. After over five +months the solutions were again examined, when the following results +were observed: + +----------------------+------------------------------------------- + | + Antiseptics. | Solution after Five Months. +----------------------+------------------------------------------- + | +Menthol in KOH..... | Some growth at bottom, upper layer clear. + | +Thymol in KOH..... | Growth at top, gum white and opaque. + | +Salol in KOH........ | Growth at top, gum black and opaque + | +Saccharin in KOH ... | White growth at top. + | +Boric acid............| Remained clear; did not smell. + | +Sodium phosphate ... | Slight growth at top. + | +Potash alum......... | Slight growth at top. +----------------------+------------------------------------------- + +The solution to which no antiseptic had been added was of course quite +putrid, and gave the reactions for acetic acid. + +In the earlier part of this paper we have given a short account of the +chief characteristics of the more important gum substitutes. The +following additional notes may be of interest. + +The ashes of most gum substitutes, consisting chiefly of dextrin, are +characterized by the high percentage of chlorides they contain, due no +doubt to the use of hydrochloric acid in their preparation. The soluble +constituents of the ash consist of neutral alkaline salts, but as a rule +no alkaline carbonates, and it is thus possible to demonstrate the +absence of any natural gum in such a compound. We have seldom noticed +the presence of any sulphates in such ashes, but when sulphurous or +sulphuric acids have been used in the starch conversion it will be found +in small quantities. + +We have already pointed out that the potash absorption value of a gum is +low and that dextrins give high numbers, but the latter vary very +considerably, and as the starch and sugar present also influence the +potash absorption value, it does not give information of much service. +The following table shows the kind of results obtained: + +-----------------------------+----------+--------------+-------------- + Sample. | KOH | Starch. | Real Gum. + | absorbed.| | +-----------------------------+----------+--------------+-------------- + | | Per Cent. | Per Cent. +Dextrin, 1 | 25.40 | 1.99 | .. +Dextrin, 2 | 19.70 | 13.13 | .. +Dextrin, 3 | 7.57 | 24.72 | .. +Artificial gum, 1 | 19.70 | 10.98 | 9.00 +Artificial gum, 2 | 13.70 | 8.05 | 23.50 +Starch | 9.43 | 100.00 | None +-----------------------------+----------+--------------+-------------- + +The baryta absorptions seem to be chiefly due to the quantity of starch +present in the composition: + + +----------------------------+---------------+------------------------- + Sample. | Starch. | BaO + | | absorbed. +----------------------------+---------------|------------------------- + | Per Cent. | Per Cent. +Dextrin, 1 | 1.99 | 1.75 +Dextrin, 2 | 13.13 | 3.53 +Dextrin, 3 | 24.72 | 5.64 +Starch | 100.00 | 23.61 +----------------------------+---------------+------------------------- + +The viscosity of a dextrin or artificial gum is determined in exactly +the same way as a natural gum, using 10 per cent. solutions. It would +probably be an improvement to use 10 per cent. solutions for many of the +dextrins, as they are when low in starch extremely thin. + +The hygroscopic nature of dextrins renders them unsuitable for foreign +work, but when the quantity of starch is appreciable, better results are +obtainable. A large percentage of unaltered starch is usually +accompanied with a small percentage of sugar, and no doubt this is the +explanation of this fact. An admixture containing natural gum of course +behaved better than when no such gum is present. Bodies like "arabol" +made up with water and containing gelatin are very hygroscopic when dry, +although as sold they lose water on exposure to the air. Gum substitutes +consisting entirely of some form of gelatin with water, like fish glue, +are also somewhat hygroscopic when dried. The behavior of these +artificial gums and dextrins on exposure to a warm moist atmosphere can +be determined in the same apparatus as described for gums. + +The process we have adopted for estimating the glucose starch and +dextrin in commercial gum substitutes is based on C. Hanofsky's method +for the assay of brewers' dextrins (this Journal, 8, 561). A weighed +quantity of the dextrin is dissolved in cold water, filtered from any +insoluble starch, and then the glucose determined directly in the clear +filtrate by Fehling's solution. The real dextrin is determined by +inverting a portion of the filtered liquid with HCl, and then +determining its reducing power. The starch is estimated by inverting a +portion of the solid dextrin, and determining the glucose formed by +Fehling. After deducting the amounts due to the original glucose and the +inverted dextrin present, the residue is calculated as starch. A +determination of the acidity of the solution is also made with decinormal +soda, and results returned in number of c.c. alkali required to +neutralize 100 grammes of the dextrin. Results we have obtained using +this method are embodied in the following table: + + ANALYSIS OF GUM SUBSTITUTES + +----+---------+---------+--------+----------+-------+-------+--------- + No.| Glucose.| Dextrin.| Starch.| Moisture.| Gum, | Ash. |Acidity. + | | | | | &c. | | +----+---------+---------+--------+----------+-------+-------+--------- + | | | | | | | cc. + 1 | 8.92 | 81.57 | 1.99 | 10.12 | None | 0.207 | 57.3 + 2 | 7.19 | 71.46 | 13.13 | 10.40 | None | 0.120 | 44.8 + 3 | 1.29 | 69.42 | 24.72 | 4.17 | 1.12 | 0.280 | 5.22 + 4 | 8.40 | 60.98 | 10.98 | 10.09 | 9.02 | 0.530 | 20.0 + 5 | 10.60 | 44.98 | 8.05 | 12.20 | 23.57 | 0.600 | 52.0 + 6 | 14.80 | 11.57 | 36.46 | 34.87 | 1.89 | 0.580 | 8.0 + 7 | 8.00 | 29.61 | 26.78 | 33.98 | 0.88 | 0.750 | 88.0 + 8 | 2.29 | 52.38 | 37.65 | None | 7.335 | 0.315 | 9.6 +----+---------+---------+--------+----------+-------+-------+--------- + +In those cases in which the substitute is made by admixture with gelatin +or liquid glue the quantity of other organic matter obtained can be +checked by a Kjeldahl determination of the total nitrogen. If a natural +gum is added, it will be partially converted into sugar when the +filtered liquid is inverted, and so make the dextrin determination +slightly too high. + + * * * * * + + + + +MR. CAILLETET'S CRYOGEN. + + +The "cryogen," a new apparatus constructed by Mr. E. Ducretet, from +instructions given by Mr. Cailletet, is designed for effecting a fall of +temperature of from 70° to 80° C. below zero, through the expansion of +liquid carbonic acid. + +The apparatus consists of two concentric vessels having an annular space +between them of a few centimeters. A worm, S, is placed in the internal +vessel R. All this is of nickel plated copper. The worm, S carries, at +Ro', an expansion cock and ends, at O in the annular space, R'. A very +strong tube is fixed to the cock, Ro', and to the ajutage, A'. It +receives the tube, Tu, which, at the time of an experiment, is coupled +with the cylinder of carbonic acid, CO². A tubulure, D, usually closed +by a plug, Bo, communicates with the inner receptacle, R. This is +capable of serving in certain experiments in condensation. The table, +Ta, of the tripod receives the various vessels or bottles for the +condensed products. + +The entire apparatus is placed in a box, B, lined with silk waste and +provided with a cover, C, of the same structure. Apertures, Th, Ro, and +T", allow of the passage of a key for acting upon the cock, Ro', as well +as of thermometers and stirrers if they are necessary. + +When it is desired to operate, the internal vessel, R, is filled with +alcohol (3 quarts for the ordinary model). This serves as a refrigerant +bath for the experiments to be made. The worm, S, having been put in +communication with the carbonic acid cylinder, CO², the cock, Ro, of the +latter is turned full on. The cock of the worm, which is closed, is +opened slightly. The vaporization and expansion of the liquid carbonic +acid cause it to congeal in the form of snow, which distributes itself +and circulates in the worm, S, and then in R. The flakes thus coming in +contact with the metallic sides of S rapidly return to the gaseous state +and produce an energetic refrigeration. At the lower part of the annular +space, R', are placed fragments of sponge impregnated with alcohol. The +snow that has traversed the worm without vaporizing reaches R'. and +dissolves in this alcohol, and the refrigeration that results therefrom +completes the lowering of the temperature. The gas finally escapes at O, +and then through the bent tube, T". + +[Illustration: CAILLETET'S CRYOGEN.] + +The apparatus may be constructed with an inverse circulation, the +carbonic acid then entering the annular vessel, R, directly, and +afterward the worm, S, whence it escapes to the exterior of the +apparatus. The expansion cock sometimes becomes obstructed by the +solidification of the snow. It will then suffice to wait until the +circulation becomes re-established of itself. It may be brought about by +giving the cock, Ro', a few turns with the wooden handled key that +serves to maneuver the latter. It is not necessary to have a large +discharge of carbonic acid, and consequently the expansion cock needs to +be opened but a little bit. A few minutes suffice to reduce the +temperature of the alcohol bath to 70°, with an output of about from 4½ +to 5½ lb. of liquid carbonic acid. When the circulation is arrested, the +apparatus thus surrounded by its isolating protective jackets becomes +heated again with extreme slowness. In one experiment, it was observed +that at the end of nine hours the temperature of the alcohol had risen +but from 70° to 22°. On injecting a very small quantity of liquid +carbonic acid from time to time, a sensibly constant and extremely low +temperature may be maintained indefinitely.--_Le Genie Civil_. + + * * * * * + + + + +METHOD OF PRODUCING ALCOHOL. + + +In carrying out my improved process in and with the apparatus employed +in ordinary commercial distilleries, says Mr. Alfred Springer, of +Cincinnati, O., I preferably employ separate vats or tubs for the nitric +acid solution and the material to be treated, and a convenient +arrangement is to locate the nitric acid tub directly under the grain +tub, so that one may discharge into the other. In the upper vat is +placed the farinaceous material, preferably ground, thoroughly steeped +in three times its weight of water, and, where whole grain is used, +preferably "cooked" in the ordinary manner. The vat into which the +dilute acid is placed is an ordinary cooking tub of suitable material to +resist the acid, provided with closed steam coils and also nozzles for +the discharge of steam into the contained mass. Into this vat is placed +for each one hundred parts of the grain to be treated one part of +commercial nitric acid diluted with fifty parts of water and brought to +a state of ebullition and agitation by the steam coils and the discharge +through the nozzles, the latter being regulated so that the gain by +condensation of steam approximately equals the loss by evaporation. The +farinaceous contents of the upper vat are allowed to flow slowly into +the nitric acid solution while the ebullition and agitation of the mass +is continued. This condition is then maintained for six to eight hours, +after which the mass is allowed to stand for one day or until the +saccharification becomes complete. The conversion can be followed by the +"iodine test" for intermediary dextrins and the "alcohol test" for +dextrin. After the saccharification is complete I may partially or +wholly neutralize the nitric acid, preferably with potassium or Ammonium +carbonate, preferably employing only one-half the amount necessary to +neutralize the original quantity of nitric acid used, so that the mass +now ready to undergo fermentation has an acid reaction. The purpose in +view here is to keep the peptones in solution also, because an acid +medium is best adapted to the propagation of the yeast cells. It is not +absolutely necessary to even partially neutralize the nitric acid, but +it is preferable. Yeast is now added, and the remaining processes are +similar to those generally employed in distilleries, excepting that just +prior to distillation potassium carbonate sufficient to neutralize the +remaining nitric acid is added, in order to avoid corrosion of the still +and correct the acid reaction of the slop. + +As a variant of the process I sometimes add to the usual amount of +nitric acid an additional one one-hundredth part of phosphoric acid on +account of its beneficial nutritive powers--that is to say, to one +hundred parts of grain one part of nitric acid and one one-hundredth +part of phosphoric acid. + +While my improved process is based on the well-known converting power of +acids on starch, I am not aware that it has ever been applied in the +manner and for the purposes I have described. For example, sulphuric and +hydrochloric, also sulphuric and nitric, acids have been employed in the +manufacture of glucose; but in every such case the resulting products +were not capable of superseding those obtained by the existing methods +of saccharification used in distilleries. In my process, on the other +hand, the product is so capable. Not only may malted grain be entirely +omitted, but more fermentable products are formed and the products of +fermentation are purer. The saccharification being more complete, there +are less intermediary and nonfermentable dextrins, and the yield of +spirits is therefore increased. Malted grain being omitted or used in +reduced quantity, there is less lactic acid and few or foreign ferments +to contaminate the fermenting mass; also, the formation of higher +alcohols than the ethyl alcohol is almost totally suppressed. +Consequently the final yield of spirits is purer in quality and requires +little or no further purification. Also, further, the nitrates +themselves acting as nutrients to the yeast cells, these become more +active and require less nutrition to be taken from the grain. + + * * * * * + + + + +SPECTROSCOPIC DETERMINATION OF THE SENSITIVENESS OF DRY PLATES. + + +After describing other methods of determining the sensitiveness of +plates, Mr. G.F. Williams, in the _Br. Jour. of Photo_., thus explains +his plan. I will now explain the method I adopt to ascertain the +relative sensitiveness of plates to daylight. Procure a small direct +vision pocket spectroscope, having adjustable slit and sliding focus. To +the front of any ordinary camera that will extend to sixteen or eighteen +inches, fit a temporary front of soft pine half an inch thick, and in +the center of this bore neatly with a center bit a hole of such diameter +as will take the eye end of the spectroscope; unscrew the eyehole, and +push the tube into the hole in wood, bushing the hole, if necessary, +with a strip of black velvet glued in to make a tight fit. By fixing the +smaller tube in the front of camera we can focus by sliding the outer +tube thereon; if we fix the larger tube in the front, we should have to +focus inside the camera, obviously most inconvenient in practice. Place +the front carrying the spectroscope _in situ_ in the camera, and rack +the latter out to its full extent; point the camera toward a bright sky, +or the sun itself, if you can, while you endeavor to get a good focus. +The spectrum will be seen on the ground glass, probably equal in +dimensions to that of a quarter plate. Proceed to focus by sliding the +outer tube to and fro until the colors are quite clear and distinct, and +at same time screw down the slit until the Fraunhofer lines appear. By +using the direct rays of the sun, and focusing carefully, and adjusting +the slit to the correct width, the lines can be got fairly sharply. +Slide your front so that the spectrum falls on the ground glass in just +such a position as a quarter plate glass would occupy when in the dark +slide, and arrange matters so that the red comes to your left, and the +violet to the right, and invariably adopt that plan. It is advisable to +include the double H lines in the violet on the right hand edge of your +plate. They afford an unerring point from which you can calculate +backward, finding G, F, E, etc., by their relative positions to the +violet lines. Otherwise you may be mistaken as to what portion of the +spectrum you are really photographing. The red should just be seen along +the left edge of the quarter plate. When all is arranged thus, you +utilize three-fourths of your plate with the spectrum, with just a +little clear glass at each end. Before disturbing the arrangement of +the apparatus, it is desirable to scratch a mark on the sliding tube, +and make a memorandum of the position of all the parts, so that they may +be taken away and replaced exactly and thus save time in future. + +To take a photograph of the spectrum, put a quarter plate in the dark +slide and place in camera; point the camera toward a bright sky, or +white cloud, near the sun--not at the sun, as there is considerable +difficulty in keeping the direct rays exactly in the axis of the +spectroscope--draw the shutter, and give, say, sixty seconds. On +development, you will probably obtain a good spectrum at the first +trial. The duration of exposure must, of course, depend upon the +brightness of the day; but if the experiments are to have relative +values, the period of exposure must be distinctly noted, and comparisons +made for a normal exposure of sixty seconds, ninety seconds, two minutes +or more, just according to whatever object one has in view in making the +experiments. With a given exposure the results will vary with the light +and the width of the slit, as well as being influenced by the character +of the instrument itself. Further, all such experiments should be made +with a normal developer, and development continued for a definite time. +The only exception to this rule would be in the event of wishing to +ascertain the utmost that could be got out of a plate, but, under +ordinary circumstances, the developer ought never to vary, nor yet the +duration of development. To try the effect of various developers, or +varying time in development, a departure must be made of such a nature +as would operate to bring out upon each plate, or piece of a plate, the +utmost it would develop short of fog, against which caution must be +adopted in all spectrum experiments. + +On development, say for one, two, or three minutes, wash off and fix. +You will recognize the H violet lines and the others to the left, and +this experiment shows what is the sensitiveness of this particular plate +to the various regions of the spectrum with this particular apparatus, +and with a normal exposure and development. So far, this teaches very +little; it merely indicates that this particular plate is sensitive or +insensitive to certain rays of colored light. To make this teaching of +any value, we must institute comparisons. Accordingly, instead of simply +exposing one plate, suppose we cut a strip from two, three, four, or +even half a dozen different plates, and arrange them side by side, +horizontally, in the dark slide, so that the spectrum falls upon the +whole when they are placed in the camera and exposed. There is really no +difficulty in cutting strips a quarter of an inch wide, the lengthway of +a quarter plate. Lay the gelatine plate film up, and hold a straight +edge on it firmly, so that when we use a suitable diamond we can plow +through the film and cut a strip which will break off easily between the +thumb and finger. A quarter plate can thus be cut up into strips to +yield about a dozen comparative experiments. When cut and snapped off, +mark each with pencil with such a distinguishing mark as shall be +clearly seen after fixing. The cut up strips can be kept in the maker's +plate box. + + * * * * * + + +The deep down underground electric railway in London has so far proved +an unprofitable concern for its stockholders. It is 3½ miles long, +touches some of the greatest points of traffic, but somehow or other +people won't patronize it. The total receipts for the last six months +were a little under $100,000, and they only carried seventeen persons +per train mile. On this road the passengers are carried on elevators up +and down from the street level to the cars. The poor results so far make +the stockholders sick of the project of extending the road. + + * * * * * + + +A NEW CATALOGUE OF VALUE + + +Contained in Scientific American Supplement during the past ten years, +sent _free of charge_ to any address. Munn & Co., 361 Broadway, New +York. + + * * * * * + + +THE SCIENTIFIC AMERICAN + +ARCHITECTS AND BUILDERS EDITION + + +$2.50 a Year. 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Hundreds +of dwellings have already been erected on the various plans we have +issued during the past year, and many others are in process of +construction. + +Architects, Builders, and Owners will find this work valuable in +furnishing fresh and useful suggestions. All who contemplate building or +improving homes, or erecting structures of any kind, have before them in +this work an almost _endless series of the latest and best examples_ +from which to make selections, thus saving time and money. + +Many other subjects, including Sewerage, Piping, Lighting, Warming, +Ventilating, Decorating, Laying out of Grounds, etc., are illustrated. +An extensive Compendium of Manufacturers' Announcements is also given, +in which the most reliable and approved Building Materials, Goods, +Machines, Tools, and Appliances are described and illustrated, with +addresses of the makers, etc. + +The fullness, richness, cheapness, and convenience of this work have won +for it the Largest Circulation of any Architectural publication in the +world. + +A Catalogue of valuable books on Architecture, Building, Carpentry, +Masonry, Heating, Warming, Lighting, Ventilation, and all branches of +industry pertaining to the art of Building, is supplied free of charge, +sent to any address. + +MUNN & CO., PUBLISHERS, 361 BROADWAY, NEW YORK. + + * * * * * + + +BUILDING PLANS AND SPECIFICATIONS. + + +In connection with the publication of the Building; EDITION of the +Scientific American, Messrs, Munn; & Co. furnish plans and +specifications for buildings' of every kind, including Churches, +Schools, Stores, Dwellings, Carriage Houses, Barns, etc. + +In this work they are assisted by able and experienced architects. Full +plans, details, and specifications for the various buildings illustrated +in this paper can be supplied. + +Those who contemplate building, or who wish to alter, improve, extend, +or add to existing buildings, I whether wings, porches, bay windows, or +attic rooms, fare invited to communicate with the undersigned. Our work +extends to all parts of the country. Estimates, plans, and drawings +promptly prepared. Terms moderate. Address + +MUNN & CO., 361 BROADWAY, NEW YORK. + + * * * * * + + +THE SCIENTIFIC AMERICAN SUPPLEMENT. + + +Published Weekly. Terms of Subscription, $5 a year. + +Sent by mail, postage prepaid, to subscribers in any part of the United +States or Canada. Six dollars a year, sent, prepaid, to any foreign +country. + +All the back numbers of The Supplement, from the commencement. January +I, 1876, can be had. Price, 10 cents each. + +All the back volumes of The Supplement can likewise be supplied. Two +volumes are issued yearly. Price of each volume, $2.50 stitched in +paper, or $3.50 bound in stiff covers. + +Combined Rates.--One copy of Scientific American and one copy of +Scientific American Supplement, one year, postpaid, $7.00. + +A liberal discount to booksellers, news agents, and canvassers. + +MUNN & CO., PUBLISHERS, + +361 BROADWAY, NEW YORK, N.Y. + + * * * * * + + +USEFUL ENGINEERING BOOKS + + +Manufacturers, Agriculturists, Chemists, Engineers, Mechanics, Builders, +men of leisure, and professional men, of all classes, need good books in +the line of their respective callings. Our post office department +permits the transmission of books through the mails at very small cost. +A comprehensive catalogue of useful books by different authors, on more +than fifty different subjects, has recently been published, for free +circulation, at the office of this paper. Subjects classified with names +of author. Persons desiring a copy have only to ask for it, and it will +be mailed to them. Address, + +MUNN & CO., 361 BROADWAY, NEW YORK. + + * * * * * + + + + +PATENTS! + + +Messrs. Munn & Co., in connection with the publication of the Scientific +American, continue to examine improvements, and to act as Solicitors of +Patents for Inventors. + +In this line of business they have had _forty-five years experience_, +and now have _unequaled facilities_ for the preparation of Patent +Drawings, Specifications, and the prosecution of Applications for +Patents in the United States, Canada, and Foreign Countries. Messrs. +Munn & Co. also attend to the preparation of Caveats, Copyrights for +Books, Labels, Reissues, Assignments, and Reports on Infringements of +Patents. 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Hints on the Sale of Patents, etc. + +We also send, _free of charge_, a Synopsis of Foreign Patent Laws, +showing the cost and method of securing patents in all the principal +countries of the world. + +MUNN & CO., SOLICITORS OF PATENTS, 361 Broadway, New York. + +Branch Offices.--Nos. 622 and 624 F Street, Pacific Building, near 7th +Street, Washington, D.C. + + + + + + + +End of the Project Gutenberg EBook of Scientific American Supplement, No. +821, Sep. 26, 1891, by Various + +*** END OF THE PROJECT GUTENBERG EBOOK 13640 *** diff --git a/13640-8.txt b/13640-8.txt new file mode 100644 index 0000000..d1e17af --- /dev/null +++ b/13640-8.txt @@ -0,0 +1,5217 @@ +The Project Gutenberg EBook of Scientific American Supplement, No. 821, +Sep. 26, 1891, by Various + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 821, Sep. 26, 1891 + +Author: Various + +Release Date: October 5, 2004 [EBook #13640] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Victoria Woosley, Don Kretz, Juliet Sutherland and the +PG Distributed Proofreaders Team + + + + + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 821 + + + + +NEW YORK, September 26, 1891 + +Scientific American Supplement. Vol. XXXII, No. 821. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + * * * * * + + + + +TABLE OF CONTENTS. + + +I. Architectural.--The New Labor Exchange in Paris.--With + views of the interior and exterior of the building + +II. Electrical.--The Construction and Maintenance of Underground + Circuits.--By S.B. FOWLER.--A comprehensive article, + discussing at length the various devices for protecting underground + circuits, methods _of_ inserting the cables, etc. + +III. Engineering.--Railroads to the Clouds.--Sketches of a number + of mountain railroads + +IV. Marine Engineering.--The French Armored Turret Ship + the Marceau.--1 engraving.--A full description of the vessel, giving + dimensions and cost + + A Review of Marine Engineering during the Past Decade.--A + paper read before the Institution of Mechanical Engineers by Mr. + Alfred Blechynben, of Barrow-in-Furness.--This paper, which + is continued from Supplement No. 820, treats on steam pipes, + feed water heating, twin screws, etc. + +V. Miscellaneous.--The Little House.--An article giving various + hints about the arrangement and management of small + dwellings, with special view to the best sanitary arrangements + + Stilt Walking.--A sketch, with engraving, of Sylvain Dornon, + the stilt walker of Landes + + Remains of a Roman Villa in England + + Gum Arabic and its Modern Substitutes.--A continuation of a + paper by Dr. S. Rideal and W.E. Youle.--With 26 tables + + A New Method of Extinguishing Fires.--Invented by George + Dickson and David A. Jones, of Toronto, Canada.--Apparatus designed + to utilize a mixture of water and liquefied carbonic acid + +VI. Medicine and Hygiene.--The Hygienic Treatment of + Obesity.--By Dr. Paul Chebon.--Methods of eating, drinking, + and exercising for the purpose of reducing fat.--An extended + article, giving valuable information to people troubled with too + much flesh + +VII. Photography.--Spectroscopic Determination of the Sensitiveness + of Dry Plates.--A full description of the new plan of + Mr. G.F. WILLIAMS, for determining the sensitiveness of dry + plates by the use of a small direct vision pocket spectroscope + +VIII. Physics.--A Physical Laboratory Indicator.--By J.W. + MOORE, of Lafayette College.--1 engraving.--This is a modification + of the old peg board adapted to use in the laboratory.--It indicates + the names of the members of the class, contains a full + list of the experiments to be performed, refers the student + to the book and page where information in reference to experiments + or apparatus may be found, it shows what experiments + are to be performed by each student at a given time, etc. + + Cailletet's Cryogen.--A description, with one engraving, of Mr. + Cailletet's new apparatus for producing temperatures from 70 + degrees to 80 degrees C., below zero, through the expansion of + liquid carbonic acid + +IX. Technology.--The Manufacture of Roll Tar Paper.--An extended + article containing a historical sketch and full information + as to the materials used and the methods of manufacture + + Smokeless Gunpowder.--By Hudson Maxim.--A comprehensive + article on the manufacture and use of smokeless gunpowder, + giving a sketch of its history, and describing the methods of + manufacture and its characteristics + + Method of Producing Alcohol.--A description of an improved + process for making alcohol.--Invented by Mr. Alfred Springer, + of Cincinnati, Ohio + + * * * * * + + + + + +[Illustration: INTERIOR OF THE NEW LABOR EXCHANGE, PARIS.] + +[Illustration: NEW LABOR EXCHANGE, PARIS.] + +THE NEW LABOR EXCHANGE, PARIS. + + +The new Labor Exchange is soon to be inaugurated. We give herewith a +view of the entrance facade of the meeting hall. The buildings, which +are the work of Mr Bouvard, architect, of the city of Paris, are +comprised within the block of houses whose sharp angle forms upon +Place de la Republique, the intersection of Boulevard Magenta and +Bondy street. One of the entrances of the Exchange is on a level with +this street. The three others are on Chateau d'Eau street, where the +facade of the edifice extends for a length of one hundred feet. From +the facade and above the balcony that projects from the first story, +stand out in bold relief three heads surrounded by foliage and fruit +that dominate the three entrance doors. These sculptures represent the +Republic between Labor and Peace. The windows of the upper stories are +set within nine rows of columns, from between the capitals of which +stand out the names of the manufacturers, inventors, and statesmen +that have sprung from the laboring classes. Upon the same line, at the +two extremities of the facade, two modillions, traversed through their +center by palms, bear the devices "Labor" and "Peace." Above, there is +a dial surmounted by a shield bearing the device of the city of Paris. + +The central door of the ground floor opens upon a large vestibule, +around which are arranged symmetrically the post, telegraph, +telephone, and intelligence offices, etc. Beyond the vestibule there +is a gallery that leads to the central court, upon the site of which +has been erected the grand assembly hall. This latter, which measures +20 meters in length, 22 in width, and 6 in height, is lighted by a +glazed ceiling, and contains ten rows of benches. These latter contain +900 seats, arranged in the form of circular steps, radiating around +the president's platform, which is one meter in height. A special +combination will permit of increasing the number of seats reserved for +the labor associations on occasions of grand reunions to 1,200. The +oak doors forming the lateral bays of the hall will open upon the two +large assembly rooms and the three waiting rooms constructed around +the faces of the large hall. In the assembly rooms forming one with +the central hall will take place the deliberations of the syndic +chambers. The walls of the hall will, ere long, receive decorative +paintings.--_L'Illustration._ + + * * * * * + + + + +MANUFACTURE OF ROLL TAR PAPER. + + +Roofing paper was first used in Scandinavia early as the last century, +the invention being accredited to Faxa, an official of the Swedish +Admiralty. The first tar and gravel roofs in Sweden were very +defective. The impregnation of the paper with a water-proofing liquid +had not been thought of, and the roofs were constructed by laying over +the rafters a boarding, upon which the unsaturated paper, the sides of +which lapped over the other, was fastened with short tacks. The +surface of the paper was next coated with heated pine tar to make it +waterproof. The thin layer of tar was soon destroyed by the weather, +so that the paper, swelled by the absorption of rain water, lost its +cohesiveness and was soon destroyed by the elements. This imperfect +method of roof covering found no great favor and was but seldom +employed. + +In Germany the architect Gilly was first to become interested in tar +paper roofing, and recommended it in his architecture for the country. +Nevertheless the new style of roof covering was but little employed, +and was finally abandoned during the first year of the 19th century. +It was revived again in 1840, when people began to take a renewed +interest in tar paper roofs, the method of manufacturing an +impermeable paper being already so far perfected that the squares of +paper were dipped in tar until thoroughly saturated. The roof +constructed of these waterproof paper sheets proved itself to be a +durable covering, being unimpenetrable to atmospheric precipitations, +and soon several factories commenced manufacturing the paper. The +product was improved continually and its method of manufacture +perfected. The good qualities of tar paper roofs being recognized by +the public, they were gradually adopted. The costly pine tar was soon +replaced by the cheaper coal tar. Square sheets of paper were made at +first; they were dipped sufficiently long in ordinary heated coal tar, +until perfectly saturated. The excess of tar was then permitted to +drip off, and the sheets were dried in the air. The improvement of +passing them through rollers to get rid of the surplus tar was +reserved for a future time, when an enterprising manufacturer +commenced to make endless tar paper in place of sheets. Special +apparatus were constructed to impregnate these rolls with tar; they +were imperfect at first, but gradually improved to a high degree. Much +progress was also made in the construction of the roofs, and several +methods of covering were devised. The defects caused by the old method +of nailing the tar paper direct upon the roof boarding were corrected; +the consequence of this method was that the paper was apt to tear, +caused by the unequal expansion of the roofing boards and paper, and +this soon led to the idea of making the latter independent of the +former by nailing the sides of the paper upon strips running parallel +with the gable. The use of endless tar paper proved to be an essential +advantage, because the number of seams as well as places where it had +to be nailed to the roof boarding was largely decreased. The +manufacture of tar paper has remained at about the same stage and no +essential improvements have been made up to the present. As partial +improvement may be mentioned the preparation of tar, especially since +the introduction of the tar distillery, and the manufacture of special +roof lacquers, which have been used for coating in place of the coal +tar. As an essential progress in the tar paper roofing may be +mentioned the invention of the double tar paper roof, and the wood +cement roof, which is regarded as an offshoot. + +The tar paper industry has, within the last forty years, assumed great +dimensions, and the preferences for this roofing are gaining ground +daily. In view of the small weight of the covering material, the wood +construction of the roof can be much lighter, and the building is +therefore less strained by the weight of the roof than one with the +other kind, so that the outer walls need not be as heavy. Considering +the price, the paper roof is not only cheaper than other fireproof +roofs, but its light weight makes it possible for the whole building +to be constructed lighter and cheaper. The durability of the tar paper +roof is satisfactory, if carefully made of good material; the double +tar paper roof, the gravel double roof, and the wood cement roof are +distinguished by their great durability. + +These roofs may be used for all kinds of buildings, and not only are +factories, storehouses, and country buildings covered with it, but +also many dwellings. The most stylish residences and villas are at +present being inclosed with the more durable kinds; the double roof, +the gravel double roof, and the wood cement roof. For factory +buildings, which are constantly shaken by the vibrations of the +machinery, the tar paper roof is preferable to any other. + +In order to ascertain to what degree tar paper roofs would resist +fire, experiments were instituted at the instigation of some of the +larger manufacturers of roofing paper, in the presence of experts, +architects, and others, embracing the most severe tests, and it was +fully proved that the tar paper roof is as fireproof as any other. +These experiments were made in two different ways; first, the +readiness of ignition of the tar paper roof by a spark or flame from +the outside was considered, and, second, it was tested in how far it +would resist a fire in the interior of the building. In the former +case, it was ascertained that a bright, intense fire could be kept +burning upon the roof for some time, without igniting the woodwork of +the roof, but heat from above caused some of the more volatile +constituents of the tar to be expelled, whereby small flames appeared +upon the surface within the limits of the fire; the roofing paper was +not completely destroyed. There always remained a cohesive substance, +although it was charred and friable, which by reason of its bad +conductivity of heat protected the roof boarding to such an extent +that it was "browned" only by the developed tar vapors. A fire was +next started within a building covered with a tar paper roof; the +flame touched the roof boarding, which partly commenced to char and +smoulder, but the bright burning of the wood was prevented by the +air-tight condition of the roof; the fire gases could not escape from +the building. The smoke collecting under the roof prevented the +entrance of fresh air, in consequence of which the want of oxygen +smothered the fire. The roofing paper remained unchanged. By making +openings in the sides of the building so that the fire gases could +escape, the wood part of the roof was consumed, but the roofing paper +itself was only charred and did not burn. After removing the fire in +contact with the paper, this ceased burning at once and evinced no +disposition whatever to spread. In large conflagrations, also, the tar +paper roofs behaved in identically a similar manner. Many instances +have occurred where the tar paper roof prevented the fire from +spreading inside the building, and developing with sufficient +intensity to work injury. + +As it is of interest to the roofer to know the manner of making the +material he uses, we give in the following a short description of the +manufacture of roofing paper. At first, when square sheets were used +exclusively, the raw paper consisted of ordinary dipped or formed +sheets. The materials used in its manufacture were common woolen rags +and other material. In order to prepare the pulp from the rags it is +necessary to cut them so small that the fabric is entirely dissolved +and converted into short fibers. The rags are for this purpose first +cut into pieces, which are again reduced by special machines. The rags +are cut in a rag cutting machine, which was formerly constructed +similar to a feed cutter; later on, more complicated machines of +various constructions were employed. It is not our task to describe +the various kinds, but we remain content with the general remark that +they are all based on the principles of causing revolving knives to +operate upon the rags. The careful cleansing of the cut rags, +necessary for the manufacture of paper, is not required for roofing +paper. It is sufficient to rinse away the sand and other solid +extraneous matter. The further reduction of the cut rags was formerly +performed in a stamp mill, which is no longer employed, the pulp mill +or rag engine being universally used. + +The construction of this engine may be described as follows: A box or +trough of wood, iron, or stone is by a partition divided into two +parts which are connected at their ends. At one side upon the bottom +of the box lies an oakwood block, called the back fall. In a hollow of +this back fall is sunk the so-called plate, furnished with a number of +sharp steel cutters or knives, lying alongside of each other. A roller +of solid oakwood, the circumference of which is also furnished with +sharp steel cutters or knives, is fastened upon a shaft and revolves +within the hollow. The journal bearings of the shaft are let into and +fastened in movable wooden carriers. The carriers of the bearings may +be raised and lowered by turning suitable thumbscrews, whereby the +distance between the roller and the back fall is increased or +decreased. The whole is above covered with a dome, the so-called case, +to prevent the throwing out of the mass under the operation of +grinding. The roller is revolved with a velocity of from 100 to 150 +revolutions per minute, whereby the rags are sucked in between the +roller and the back fall and cut and torn between the knives. At the +beginning of the operation, the distance between the roller and the +back fall is made as great as possible, the intention being less to +cut the rags than to wash them thoroughly. The dirty water is then +drawn off and replaced by clean, and the space of the grinding +apparatus is lessened gradually, so as to cut the rags between the +knives. The mass is constantly kept in motion and each piece of rag +passes repeatedly between the knives. The case protects the mass from +being thrown out by the centrifugal force. The work of beating the +rags is ended in a few hours, and the ensuing thin paste is drawn off +into the pulp chest, this being a square box lined with lead. + +From the pulp chest it passes to the form of the paper machine. This +form consists of an endless fine web of brass wire, which revolves +around rollers. The upper part of this form rests upon a number of +hollow copper rollers, whereby a level place is formed. The form +revolves uniformly around the two end rollers, and has at the same +time a vibratory motion, by which the pulp running upon the form is +spread out uniformly and conducted along, more flowing on as the +latter progresses. The water escapes rapidly through the close wire +web. In order to limit the form on the sides two endless leather +straps revolve around the rollers on each side, which touch with their +lower parts the form on both sides and confine the fluid within a +proper breadth. The thickness of the pulp is regulated at the head of +the form by a brass rule standing at a certain height; its function is +to level the pulp and distribute it at a certain thickness. The +continually moving pulp layer assumes greater consistency the nearer +it approaches to the dandy roll. This is a cylinder covered with brass +wire, and is for the purpose of compressing the paper, after it has +left the form, and free it from a great part of the water, which +escapes into a box. The paper is now freed of a good deal of the +fluid, and assumes a consistency with which it is enabled to leave the +form, which now commences to return underneath the paper, passing on +to an endless felt, which revolves around rollers and delivers it to +two iron rolls. The paper passes through a second pair of iron +rollers, the interiors of which are heated by steam. These rollers +cause the last of the water to be evaporated, so that it can then be +rolled upon reels. A special arrangement shaves the edges to the exact +size required. + +The paper is made in different thicknesses and designated by numbers +to the size and weight. + +Waste paper, bookbinders' shavings, etc., can be used for making the +paper. As much wool as possible should be employed, because the wool +fiber has a greater resistance than vegetable fiber to the effects of +the temperature. By wool fiber is understood the horny substance +resembling hair, with the difference that the former has no marrowy +tissue. The covering pellicle of the wool fiber consists of flat, +mostly elongated leaves, with more or less corners, lying over each +other like scales, which makes the surface of the fiber rough; this +condition, together with the inclination of curling, renders it +capable of felting readily. Pure wool consists of a horny substance, +containing both nitrogen and sulphur, and dissolves in a potash +solution. In a clean condition, the wool contains from 0.3 to 0.5 per +cent. of ash. It is very hygroscopical, and under ordinary +circumstances it contains from 13 to 16 per cent. humidity, in dry air +from 7 to 11 per cent., which can be entirely expelled at a +temperature of from 226 to 230 degrees Fahrenheit. Wool when ignited +does not burn with a bright flame, as vegetable fiber does, but +consumes with a feeble smouldering glow, soon extinguishes, spreading +a disagreeable pungent vapor, as of burning horn. By placing a test +tube with a solution of five parts caustic potash in 100 parts water, +a mixture of vegetable fibers and wool fibers, the latter dissolve if +the fluid is brought to boiling above an alcohol flame, while the +cotton and linen fibers remain intact. + +The solubility of the woolen fibers in potash lye is a ready means of +ascertaining the percentage of wool fiber in the paper. An exhaustive +analysis of the latter can be performed in the following manner: A +known quantity of the paper is slowly dried in a drying apparatus at +temperature of 230° Fahrenheit, until a sample weighed on a scale +remains constant. The loss of weight indicates the degree of humidity. +To determine the ash percentage, the sample is placed in a platinum +crucible, and held over a lamp until all the organic matter is burned +out and the ash has assumed a light color. The cold ash is then +moistened with a carbonate of ammonia solution, and the crucible again +exposed until it is dark red; the weight of the ash is then taken. To +determine the percentage of wool, a sample of the paper is dried at +230° Fahrenheit and weighed, boiled in a porcelain dish in potash lye +12° B. strong, and frequently stirred with a glass rod. The wool fiber +soon dissolves in the potash lye, while the vegetable fiber remains +unaltered. The pulpy mass resulting is placed upon a filter, dried at +212° Fahrenheit, and after the potash lye has dripped off, the +residue, consisting of vegetable fiber and earthy ash ingredients, is +washed until the water ceases to dissolve anything. The residue dried +at 212° Fahrenheit is weighed with a filter, after which that of the +latter is deducted. The loss of weight experienced is essentially +equal to the loss of the wool fiber. If the filtrate is saturated with +hydrochloric acid, the dissolved wool fiber separates again, and after +having been collected upon a weighed filter, it may be weighed and the +quantity ascertained. + +The weight of the mineral substances in the raw paper is ascertained +by analyzing the ash in a manner similar to that above described. The +several constituents of the ash and the mineral added to the raw paper +are ascertained as follows: Sufficient of the paper is calcined in the +manner described; a known quantity of the ash is weighed and thrown +into a small porcelain dish containing a little distilled water and an +excess of chemically pure hydrochloric acid. In this solution are +dissolved the carbonates, carbonate of lime, carbonate of magnesia, a +little of sulphate of alumina, as well as metallic oxides, while +silicate of magnesia, silicic acid, sulphate of lime (gypsum) remain +undissolved. The substance is heated until the water and excess of +free hydrochloric acid have been driven off; it is then moistened with +a little hydrochloric acid, diluted with distilled water and heated. +The undissolved residue is by filtering separated from the dissolved, +the filter washed with distilled water, and the wash water added to +the filtrate. The undissolved residue is dried, and after the filter +has also been burned in due manner and the ash added, the weight is +ascertained. It consists of clay, sand, silicic acid and gypsum. + +The filtrate is then poured into a cylinder capable of holding 100 +cubic centimeters, and furnished with a scale; sufficient distilled +water is then added until the well-shaken fluid measures precisely 100 +cubic centimeters. By means of this measuring instrument, the filtrate +is then divided into two equal portions. One of these parts is in a +beaker glass over-saturated with chemically pure chloride of ammonia, +whereby any iron of oxide present and a little dissolved alumina fall +down as deposit. The precipitate is separated by filtering, washed, +dried at 212° Fahrenheit and weighed. To the filtrate is then added a +solution of oxalate of ammonia until a white precipitate of oxalate of +lime is formed. This precipitate is separated by filtering, washed, +dried and when separated from the filter, is collected upon dark +satinized paper; the filter itself is burned and the ash added to the +oxalate of lime. This oxalate of lime is then heated to a dark red +heat in a platinum crucible with lid until the oxalate of lime is +converted into carbonate of lime. By the addition of a few drops of +carbonate of ammonia solution and another slight heating of the +crucible, also the caustic lime produced in the filter ash by heating, +is reconverted into carbonate of lime, and after cooling in the +exsiccator, the whole contents of the crucible is weighed as +carbonate of lime, after deducting the known quantity of filter ash. + +Any magnesia present in the filtrate of the oxalate of lime is by the +addition of a solution of phosphate of soda separated as phosphate of +ammonia and magnesia, after having stood twenty-four hours. The +precipitate is filtered off, washed with water to which a little +chloride of ammonia is added, dried, and after calcining the fiber and +adding the filter ash, glow heated in the crucible. The glowed +substance is weighed after cooling, and is pyrophosphate of magnesia, +from which the magnesia or carbonate of magnesia is calculated +stoichiometrically. All the ascertained sums must be multiplied by 2, +if they are to correspond to the analyzed and weighed quantity of ash. + +The second half of the filtrate is used for determining the small +quantity of sulphate of lime still contained in the hydrochlorate +solution. By adding chloride of barium solution the sulphuric acid is +bound to the barytes and sulphate of baryta separates as white +precipitate. This is separated by filtering, washed, dried and weighed +in the customary manner. From the weight of the sulphate of baryta is +then computed the weight of sulphate of lime, which has passed over +into solution. The ascertained sum is also to be multiplied with 2. + +The manufacture of roll tar paper from the roll paper was at first +found to be difficult, as it was impossible to submerge a surface +larger than from ten to fifteen square yards, rolled up, in the tar, +because more would have required too large a pan. Besides this, the +paper tears easily, when it is in the hot tar. All kinds of +experiments were tried, in order to impregnate the surface of the +paper without employing too large a pan. + +The following method was tried at first: The roll paper was cut into +lengths of ten yards, which were rolled up loosely, so that a certain +space was left between the different coils. These loose rolls, of +course, occupied much space and could be put into the tar only in a +standing position, because in a horizontal one the several coils would +have pressed together again. The loose roll was therefore slipped over +a vertical iron rod fastened into a circular perforated wooden foot. +The upper end of this iron rod ended in a ring, in which the hook of a +chain or rope could be fastened. With the aid of a windlass the roll +was raised or lowered. When placed in the pan with boiling tar, it was +left there until thoroughly saturated. It was then taken out, placed +upon a table, and the excess of tar allowed to drip off into a vessel +underneath. After partially drying, the roll was spread out in open +air, occasionally turned, until sufficiently dried, when it was rolled +up again. + +In order to neutralize the smeary, sticky condition of the surface and +avoid the disagreeable drying in open air, the experiment of strewing +sand on the sticky places was tried next. The weight of the paper was +largely increased by the sand, and appeared considerably thicker. For +this reason the method of sanding the paper was at once universally +adopted. To dispense with the process of permitting the surplus tar to +drip off, means were devised by which it was taken off by scrapers, or +by pressing through rollers. The scrapers, two sharp edged rods +fastened across the pan, were then so placed that the paper was drawn +through them. The excess of tar adhering to its surface was thereby +scraped off and ran back into the pan. + +This work, however, was performed better and to more satisfaction by a +pair of rollers fastened to the pan. These performed a double duty; +thoroughly removed the tar from the surface and by reason of their +pressure they caused a more perfect incorporation of the tar with the +fibers of the paper. Finally, different factories employed different +methods of manufacture, one of which was to cut the rolls into +definite lengths of about ten yards; these were then rerolled very +loosely and immersed in the hot tar until sufficiently saturated. The +paper was then passed through the roller, much pressure exerted, and +then loosely rolled up again. Being tarred once, it was then laid into +a second pan with hot tar, reeled out after a time, strewn with sand, +and rolled up again. Another method was to cut clothes lines into +lengths of about fifteen yards, and at a distance of two inches have +knots tied in them. The paper was cut in lengths of ten or fifteen +yards, three pieces of the knotted clothes line were then rolled +between the loose coils of paper, which was then submerged in the tar, +which on account of the knots could penetrate the paper. The paper was +next sanded by permitting its lower surface to pass over dry sand in a +box standing on the floor. A workman rolled off the paper, and with +his hand he strews sand on the upper surface. The rolling taking place +on the edge of a table, by means of a crank, the excess of sand +dropped off. + +It is said by this method two workmen, one of which tends to the +rolling and sanding, the other turning the crank, could turn out +eighty rolls per day. This method is still in use. It is useless to +describe the many antiquated methods in vogue in smaller factories, +and it can truthfully be said that nearly all of them are out of date. +It appears to be the fact of almost all inventions that when reduced +to practical use, the arrangements, apparatus, and working methods +employed are generally of the most complicated nature, and time and +experience only will simplify them. This has been also the case with +the methods in the roofing paper industry, which are at present +gradually being reduced to a practical basis. The method gradually +adopted has been described in the preceding. The pan is of a certain +length, whereby it becomes possible to saturate the paper by slowly +drawing it through the heated tar. This is the chief feature. The work +is much simplified thereby and the workmen need not dip their hands +into the tar or soil them with it. The work of impregnating has become +much cleaner and easier, while at the same time the tar can be heated +to a much higher temperature. The pan is generally filled with +distilled coal tar, and the heating is regulated in such a manner that +the temperature of the impregnating mass is raised far beyond 212° +Fahrenheit. This accelerates the penetration, which takes place more +quickly as the degree of heat is raised, which may be almost up to the +boiling point of the tar, as at this degree the paper is not destroyed +by the heat. In order to prevent the evaporation of the volatile +ingredients of the tar, the pan is covered with a sheet iron cover, +with a slot at the place where the paper enters into the impregnating +mass and another at the place where it issues. The tar is always kept +at the same level, by occasional additions. + +The roll of paper is mounted upon a shaft at the back end of the pan, +and by suitable arrangement of guide rollers it unwinds slowly, passes +into the tar in which it is kept submerged. The guide rollers can be +raised so that when a new roller is set up they can be raised out of +the tar. The end of the paper is then slipped underneath them above +the surface of the tar, when having passed through the squeezing +rollers, it is fastened to the beaming roller, and the guide rollers +are submerged again. A workman slowly turns the crank of the beaming +roller. + +This motion draws the paper slowly through the fluid, the roll at the +back end unwinding. The speed with which the squeezing rollers are +turned is regulated in such a manner that the paper remains +sufficiently long underneath the fluid to be thoroughly impregnated +with it. The workmen quickly learn by experience how fast to turn the +crank. The hotter the tar, the more rapid the saturation; the high +degree of heat expels the air and evaporates the hygroscopic fluid in +the pores of the paper. The strong heating of the tar causes another +advantage connected with this method. The surface of the paper as it +issues from the squeezing rollers is still very hot, and a part of the +volatile oils evaporate very quickly at this high temperature. The +surface is thereby at once dried to a certain degree and at the same +time receives a handsome luster, as if it had been coated with a black +lacquer. The paper is sanded in a very simple manner without the use +of mechanical apparatus; as it is being wrapped into a coil, it passes +with its lower surface over a layer of sand, while the workman who +tends to rolling up strews the inside with sand. The lower surface is +coated very equally. Care only being necessary that the sand lies +smooth and even at all times. When the workman has rolled up ten or +fifteen yards, he cuts it across with a knife and straightedge, so +that the paper is cut at right angles with its sides. + +There are three different sorts of roofing paper, according to the +impregnating fluid used in its manufacture. The ordinary tar paper is +that saturated with clear cold tar. This contains the greatest amount +of fluid ingredients and is very raggy in a fresh condition. It is +easy to see that the volatile hydrocarbons evaporate in a short time, +and when expelled, the paper becomes stiffer and apparently drier. +This drying, or the volatilization of the hydrocarbons, causes pores +between the fibers of the paper. These pores are highly injurious to +it, as they facilitate a process of decomposition which will ruin it +in a short time. + +Roofing paper can be called good only when it is essentially made from +woolen rags, and contains either very few or no earthy additions. It +is beyond doubt that the durability of a roofing paper increases with +the quality of wool fiber it contains--vegetable fibers and earthy +additions cause a direct injury. Reprehensible altogether is any +combination with lime, either in form of a carbonate or sulphate, +because the lime enters into chemical combination with the +decomposition products of the tar. + +The general nature of gravel is too well known to require description. +The grains of quartz sand are either sharp cornered or else rounded +pieces of stone of quartz, occasionally mixed with grains of other +amorphous pieces of silica--such as horn stone, silicious slate, +carnelian, etc.; again, with lustrous pieces of mica, or red and white +pieces of feldspar. The gravel used for a tar paper roof must be of a +special nature and be prepared for the purpose. The size of its grains +must not exceed a certain standard--say, the size of a pea. When found +in the gravel bank, it is frequently mixed with clay, etc., and it +cannot be used in this condition for a roof, but must be washed. The +utensils necessary for this purpose are of so simple and suggestive a +nature that they need not be described. Slag is being successfully +used in place of the gravel. It is easily reduced to suitable size, by +letting the red hot mass, as it runs from the furnace, run into a +vessel with water. The sudden chilling of the slag causes it to burst +into fragments of a sharp cornered structure. It is next passed +through a sieve, and the suitably sized gravel makes an excellent +material, as it gives a clean appearance to the roof. + +The thinking mind can easily go one step further and imagine that, +since the tar contains a number of volatile hydrocarbons, it might be +made more adaptable for impregnation by paper by distilling it, as by +this process the fluid would lose its tendency to evaporate and the +percentage of resinous substances increase. Singular to say, there was +a prejudice against the employment of distilled tar, entertained by +builders and people who had no knowledge of chemistry. Increasing +intelligence and altered business circumstances, however, brought +about the almost universal employment of distilled tar, and every +large factory uses it at present. The roofing paper prepared with +distilled tar is perhaps most suitably called asphaltum paper, as this +has been used in its manufacture. It possesses properties superior to +the ordinary tar paper, one of which is that immediately after its +manufacture, as soon as cold, it is dry and ready for shipment; nor +does it require to be kept in store for a length of time, and it has +also a good, firm body, being as flexible and tough as leather. It is +very durable upon the roof, and remains flexible for a long time. It +is true that asphaltum papers will always in a fresh state contain a +small percentage of volatile ingredients, which after a while make it +hard and friable upon the roof; but, by reason of its greater +percentage of resinous components, it will always preserve a superior +degree of durability and become far less porous. One hundred parts by +weight absorb 140 or 150 parts by weight of coal tar. A factory which +distilled a good standard tar for roofing paper recovered, besides +benzole and naphtha, also about ten per cent. of creosote oil, used +for one hundred parts raw paper, 176.4 partially distilled tar. +Experiments on a larger as well as a smaller scale reduced this +quantity to an average of 141.5 parts for one hundred parts raw paper. +The weight of sanded paper is very variable, as it depends altogether +upon the size of the sand grains. It may be stated generally that the +weight of the sand is as large as that of the tarred paper. + +The kinds of roofing paper saturated with other additions besides coal +tar form a separate class, in order to neutralize the defects inherent +in coal tar. These additions were originally for the purpose of +thickening the paper and making it stiffer and drier. The most +ordinary and cheapest thickener was the coal pitch. Although the +resinous substances are increased thereby, still the light tar oils +remain to evaporate, and the paper prepared with such a substance +readily becomes hard and brittle. A better addition is the natural +asphaltum, because it resists better the destroying influence of the +decomposition process, and also, to a certain degree, protects the +coal tar in which it is dissolved. The addition of natural asphaltum +doubtless caused the name of "asphaltum roofing paper." Resin, +sulphur, wood tar and other substances were also used as additions; +each manufacturer kept his method secret, however, and simply pointed +out by high sounding title in what manner his paper was composed. In +most cases, however, this appellation was applied to the ordinary tar +paper; the impregnating substance was mixed only with coal pitch, or +else a roofing paper saturated with distilled tar. The costly +additions, by the use of which a high grade of roofing paper can +doubtless be produced, largely increased its price, and on account of +the constant fall of prices of the article, its use became rather one +of those things "more honored in the breach than in the observance," +and was dispensed with whenever practicable. The crude paper is the +foundation of the roofing paper. The qualities of a good, +unadulterated paper have already been stated. At times, the crude +paper contains too many earthy ingredients which impair the cohesion +of the felted fibrous substance, and which especially the carbonate of +lime is very injurious, as it readily effects the decomposition of the +coal tar. The percentage of wool, upon which the durability of the +paper depends very largely, is very small in some of the paper found +in the market. In place of woolen rags, cheap substitutes have been +used, such as waste, which contains vegetable fibers. Since this +cannot resist the decomposition process for any length of time, it is +evident that the roofing paper which contains a noticeable quantity of +vegetable fibers cannot be very durable. To judge from the endeavors +made to improve the coal tar, it may be concluded that this material +does not fully comply with its function of making the roofing paper +perfectly and durably waterproof. The coal tar, be it either crude or +distilled, is not a perfect impregnating material, and the roofing +paper, saturated with it, possesses several defects. Let us in the +following try to ascertain their shortcomings, and then express our +idea in what manner the roofing paper may be improved. It was +previously mentioned that every tar roofing paper will, after a +greater or smaller lapse of time, assume a dry, porous, friable +condition, caused by the volatilization of a part of the constituents +of the tar. This alteration is materially assisted by the oxygen of +the air, which causes the latter to become resinous and exerts a +chemical influence upon them. By the volatilization of the lighter tar +oils, pores are generated between the fibers of the roofing paper, +into which the air and humidity penetrate. In consequence of the +greatly enlarged surface, not only the solid ingredients of the tar, +which still remain unaltered, are exposed to the action of the oxygen, +but also the fibers of the roofing paper are exposed to decomposition. +How destructive the alternating influence of the oxygen and the +atmospheric precipitations are for the roofing paper will be shown by +the following results of tests. It will have been observed that the +rain water running from an old paper roof, especially after dry +weather, has a yellowish, sometimes a brown yellow color. The +supposition that this colored rain water might contain decomposition +products of the roofing paper readily prompted itself, and it has been +collected and analyzed at different seasons of the year. After a +period of several weeks of fair weather during the summer, rain fell, +and the sample of water running from a roof was caught and evaporated; +the residue when dried weighed 1.68 grammes. It was of a brownish +black color, fusible in heat and readily soluble, with a yellow brown +color in water. The dark brown substance readily dissolved in ammonia, +alcohol, dilute acid, hydrochloric acid, sulphuric acid, and +decomposed in nitric acid, but did not dissolve in benzine or fat oil. +After several days' rain during the summer, a quantity of the water +was caught, evaporated, and the residue dried. Its characteristics +were similar to those above mentioned. By an experiment instituted in +water under conditions similar to the first mentioned, the dry brown +substance weighed 71 grammes. It possessed the same characteristics. +In the solution effected with water containing some aqua ammonia of +the brown substance, a white precipitate of oxalate of lime occurred +when an oxalate of ammonia solution was added, but the brown substance +remained in solution. A further precipitation of oxalate of lime was +produced by a solution of oxalic acid, but the brown organic substance +remained in solution. This organic substance being liberated from the +lime was evaporated, and left a dry, resinous, fusible brownish black +substance, which also dissolved readily in water. It will be seen from +these trials that the substance obtained from the rain water running +from a paper roof is a combination of an organic acid with lime, which +readily dissolves in water, and that also the free organic acid +combined with the lime dissolves easily in water. + +The question concerning the origin of this organic substance or its +combination with lime can only be answered in one way, viz., that it +must have been washed by the rain water out of the paper. But since +such a solid substance, easily soluble in water, is contained neither +in the fresh roofing paper nor in the coal tar, the only deduction is +that it must have arisen by the decomposition of the tar, in +consequence of the operation of the oxygen. The lime comes from the +coating substance of the roof, for which tar mixed with coal pitch was +used. The latter was fused with carbonate of lime. These analyses +furthermore show that the formation of the organic acid easily soluble +in water depends upon the season; and that a larger quantity of it is +generated in warm, sunny weather than in cold, without sunshine. This +peculiarity of the solid, resinous constituents of the coal tar, to be +by the operation of the atmospheric oxygen altered into such products +that are readily soluble in water, makes the tar very unsuitable as a +saturative substance for a roofing paper. How rapidly a paper roof can +be ruined by the generation of this injurious organic acid will be +seen from the following calculation: Let us suppose that an average +of 132 gallons of rain water falls upon ten square feet roof surface +per year, and that the arithmetical mean 0.932 of the largest (1.680) +and smallest number (0.184) be the quantity of the soluble brown +substance which on an average is dissolved in one quart of rain water; +hence from ten square feet of roof surface are rinsed away with the +rain water per year 466 grammes of the soluble decomposition products +of the tar. The oxidation process will not always occur as intensely +as by a paper roof, ten years old and painted two years ago, which +instigated above described experiment. As long as the roofing paper is +fresh and less porous, especially if the occurring pores are filled +and closed again by repeated coatings, oxidation will take place far +less rapidly. Besides this, the protective coating applied to the roof +surface is exposed most to this oxidation process. Even by assuming +this constantly progressive destructive action of the oxygen on the +roofing paper to be much less than above stated, we can readily +imagine that it must be quite large. If it is desired to produce a +material free of faults, it is first of all indispensable that +unobjectionable raw material be procured. Coal tar was formerly used +almost exclusively for the coating of a roof. It was heated and +applied hot upon the surface. In order to avoid the running off of the +thinly fluid mass, the freshly coated surface was strewn with sand. +The most volatile portion of the tar evaporated soon, whereby the +coating became thicker and finally dried. The bad properties of the +coal tar, pointed out elsewhere, made it very unsuitable even for this +purpose, and experiments were instituted to compound mixtures, by +adding other ingredients to the tar, that should more fully comply +with its function. It may be said in general that the coating masses +for roofs can be divided into two classes: either as lacquers or as +cements. To the former may be classed those of a fairly thinly fluid +consistency, and which contain volatile oils in such quantities that +they will dry quickly. Cements are those of a thickly fluid +consistency, and are rendered thus fluid by heating. It is not +necessary that the coating applied should harden quickly, as it +assumes soon after its application a firmness sufficient to prevent it +from running off the roof. Coal tar is to be classed among lacquers. +If it has been liberated by distillation from the volatile oils, it is +made better suited for the purpose than the ordinary kind. The mass +contains much more asphaltum, and after drying, which takes place +soon, it leaves a far thicker layer upon the roof surface, while the +pores, which had formed in the roofing paper consequent on drying, are +better filled up. Nevertheless, the distilled tar also has retained +the property of drying with time into a hard, vitreous mass, and +ultimately to be destroyed by decomposition.--_The Roofer_. + + * * * * * + + + + +A PHYSICAL LABORATORY INDICATOR. + + +The difficulties attending the management of a physical laboratory are +much greater than those of a chemical one. The cause of this lies in the +fact that in the latter the apparatus is less complicated and the pieces +less varied. Any contrivance that will reduce the labor and worry +connected with the running of a laboratory is valuable. + +A physical laboratory may be arranged in several ways. The apparatus may +be kept in a store room and such as is needed may be given to the +student each day and removed after the experiments are performed; or the +apparatus for each experiment or system of experiments may be kept in a +fixed place in the laboratory ready for assembling; for certain +experiments the apparatus may be kept in a fixed place in the laboratory +and permanently arranged for service. + +Each student may have his own desk and apparatus or he may be required +to pass from desk to desk. The latter method is preferable. + +When a store room is used the services of a man are required to +distribute and afterward to collect. If the apparatus is permanently +distributed, a large room is necessary, but the labor of collecting and +distributing is done away with. + +There are certain general experiments intended to show the use of +measuring instruments which all students must perform. To illustrate the +use of the indicator I have selected an elementary class, although the +instrument is equally applicable to all classes of experiments. + +Having selected a suitable room, tables may be placed against the walls +between the windows and at other convenient places. Shallow closets are +built upon these tables against the wall; they have glass doors and are +fitted with shelves properly spaced. A large number of light wooden +boxes are prepared, numbered from one up to the limit of the storage +capacity of the closets. A number corresponding to that upon the box is +placed upon the shelf, so that each one after removal may be returned to +its proper place without difficulty. On the front of the box is a label +upon which is written the experiment to be performed or the name of the +apparatus whose use is to be learned, references to various books, which +may be found in the laboratory library, and the apparatus necessary for +the experiment, which ought to be found in the box. If any parts of the +apparatus are too large to be placed in the box, the label indicates by +a number where it may be found in the storage case. + +It is evident that, instead of the above arrangement, all the boxes can +be stacked in piles in a general store room. The described arrangement +is preferable, as it prevents confusion in collecting and distributing +apparatus when the class is large. + +_The Indicator_ (see figure).--Some device is evidently desirable to +direct the work of a laboratory with the least trouble and friction +possible. I have found that the old fashioned "peg board," formerly used +in schools to record the demerits of scholars, modified as in the +following description, leaves nothing to be desired. + +The requirements of such an instrument are these: It must show the names +of the members of the class; it must contain a full list of the +experiments to be performed; it must refer the student to the book and +page where information in reference to the experiments or apparatus may +be found; it must show what experiments are to be performed by each +student at a given time; it must give information as to the place in the +laboratory where the apparatus is deposited; it must show to the +instructor what experiments have been performed by each student; it must +prevent the assignment of the same experiment to two students; it must +enable the instructor to assign the same experiment to two or more +students; it must form a complete record of what has been done, what +work is incomplete, and what experiments have not yet been assigned; it +must also be so arranged that new experiments or sets of experiments may +be exhibited. + + +------+---+---+---+---+---+---+---+---+ + | | A | B | C | D | E | F | G | H | + +------+---+---+---+---+---+---+---+---+ + | 1 | * o o * o o o o | + | 2 | * o * * o o o o | + | 3 | + * * * o o o o | + | 4 | + o * * o o o o | + | 5 | o + * * * * o o | + | 6 | o + * * o * o o | + | 7 | o o + * o o o o | + | 8 | o o o + * o o o | + | 9 | o o o * + o o o | + | 10 | o o o o o + o o | + | 11 | o o o * o o + * | + | 12 | o o * * o + + + | + | 13 | o o * o o o o o | + | 14 | o o * o o o o o | + | 15 | o o + o o o o o | + | 16 | o o + + * o o * | + +--------------------------------------+ + + A, B, C, etc., are cards upon which are the names of students. 1, + 2, 3, etc., are cards like the one described in the article. The + small circles (o) represent unassigned experiments. The black + circles (*) (slate nails) represent work done. The caudate circles + (+) (brass nail) represent work assigned. + +The indicator consists of a plank of any convenient length and breadth. +The front surface is divided into squares of such size that the pegs may +be introduced and withdrawn with ease. At each corner of the squares +holes are bored into which nails may be placed. There is a blank border +at the top and another on the left side. At the top of each vertical +column of holes is placed a card holder. This is made of light tin +turned up on the long edges--which are vertical--and tacked to the +board. Opposite each horizontal row of holes is a similar tin card +holder, but of greater length, and having its length horizontal. The +holders at the top of the board contain cards upon which the names of +the class are written. + +Cards, like the following, are prepared for the horizontal holders. + +-------------------------------------------------------------- +Stewart & Gee 229 +Physical Manip. 85 Intensity of Gravity--Borda's Method 39 +Glazebrook & Shaw 132 +-------------------------------------------------------------- + +These cards are numbered from one to any desired number and are arranged +in the holders consecutively. + +Two kinds of nails are provided to fit the holes in the board: An +ordinary slate nail and a common picture frame nail with a brass head. +The latter indicates work to be done, the former work done. + +To prepare the board for service, brass headed nails are placed opposite +each experiment, and below the names, care being taken not to have more +than one nail in the same horizontal row, unless it is intended that two +persons or more are to work upon the same experiment. + +There will be no conflict when the brass nails occupy diagonal lines. If +they do not, a glance will show the fact. + +After an experiment has been performed and a report made upon the usual +blank, the brass nail is removed and a slate nail put in its place. + +The board will show by the slate nails what work has been done by each +student, by the brass nails what is yet to be done, and by the empty +holes, experiments which have been omitted or are yet to be assigned. A +slate nail opposite an experiment card indicates that that experiment +may now be assigned to another person. + +It is evident that the schedule for a whole term may be arranged in a +few minutes and that the daily changes require very little time. + +The board is hung in a convenient place. The student as he enters the +laboratory looks for his name on the upper cards and under it for the +first brass nail in the vertical column: to the left he finds the +experiment card. On the left hand end of the slip he sees the book +references, on the right hand end a number--39 in the sample card given +above. Knowing the number, he proceeds to a desk and finds a box +numbered in the same manner. He removes the box from the closet. On the +label of the box is a list of all the apparatus necessary, which he will +find in the box; the label also contains the book references. He +performs the experiment, fills up a blank which he gives to the +instructor, puts all the materials back in the box, replaces the box in +its proper place in the closet and proceeds with the next experiment. +With this indicator there is no difficulty in managing fifty students or +more. + +Comparatively little apparatus need be duplicated. Where apparatus is +fixed against a wall a number may be tacked upon the wall and a card +containing the information desired. The procedure is then the same as +with the boxes. The cards on the board being removable, other ones may +be inserted containing information in reference to other boxes having +the same number but containing different materials. There can be no +successful tampering with the board, for the record of experiments +performed is upon the blanks which the students turn in and also in the +individual note books which are written up and given to the instructor +for daily examination. + +Lafayette College. J.W. MOORE. + + * * * * * + + + + +NEW METHOD OF EXTINGUISHING FIRES + + +This is by George Dickson, of Toronto, Canada, and David Alanson Jones. + +A mixture of water and liquefied carbon dioxide upon being discharged +through pipes at high pressure causes the rapid expansion of the gas and +converts the mixture into spray more or less frozen, and portions of the +liquid carbon dioxide are frozen, owing to its rapid expansion, and are +thus thrown upon the fire in a solid state, where said frozen carbon +dioxide in its further expansion not only acts to put out the fire, but +cools the surface upon which it falls, and thus tends to prevent +reignition. + +A represents a receptacle sufficiently strong to stand a pressure of not +less than a thousand pounds to the square inch. + +B B water receptacles. + +[Illustration: Fig. 1] + +In the drawings we have shown two receptacles B and only one receptacle +A; but we do not wish to confine ourselves to any particular number, nor +do we wish to confine ourselves to the horizontal position in which the +receptacles are shown. + +C is a pipe leading from the receptacle A to a point at or near the +bottom of the receptacle B. + +F is a pipe through which the mixture of water and liquefied gas from +the receptacle B is forced by the expansion of said liquefied gas, the +said pipe taking the mixture of water and liquefied gas from the bottom +of the receptacle. + +[Illustration: Fig. 2] + +To use the apparatus, open the stop cock D in the pipe C, leading to one +of the receptacles B, whereupon, owing to the lower pressure in the +cylinder B, the liquid carbon dioxide expands and rises to the top of +the cylinder A and forces the liquid carbon dioxide into the cylinder B, +the same as the superior steam of a boiler forces the water of the +boiler out when the same is tapped below the surface of the liquid. Now +upon opening the tap H, this superior gas forces out the mixture of +water and liquid carbon dioxide, which suddenly expanding causes +portions of the globules of liquefied gas to be frozen, and these, being +protected by a rapidly evaporating portion of the liquefied gas, are +thrown on the fire in solid particles. At the same time the water is +blown into a spray, which is more or less frozen. The fire is thus +rapidly extinguished by the vaporization of the carbon dioxide and water +spray. + + * * * * * + + + + +SMOKELESS GUNPOWDER. + +BY HUDSON MAXIM. + + +During the last forty years leading chemists have continued to +experiment with a view to the production of a gunpowder which should be +smokeless. But not until the last few years has any considerable degree +of success been attained. + +To be smokeless, a gunpowder must yield only gaseous products of +combustion. None of the so-called smokeless powders are entirely +smokeless, although some of them are very nearly so. + +The smoke of common black gunpowder is largely due to minute particles +of solid matter which float in the air. About one-half of the total +products of combustion of black gunpowder of ordinary composition +consists of potassium carbonate in a finely divided condition and of +potassium sulphate, which is produced chiefly by the burning in the air +of potassium sulphide, another production of combustion, as on the +outrushing gases it is borne into the air in a fine state of division. + +Another cause for the smoke of gunpowder is the formation of small +liquid vesicles which condense from some of the products of combustion +thrown into the air in a state of vapor, in the same manner as vesicles +of aqueous vapor form in the air on the escape of highly heated steam +from the whistle of a locomotive. + +Broadly speaking, an explosive compound is one which contains, within +itself, all the elements necessary for its complete combustion, and +whose heated gaseous products occupy vastly more space than the original +compound. Such compound usually consists of oxygen, associated with +other elements, for which it has great affinity, and from which it is +held from more intimate union, or direct chemical combination, under +normal conditions, by being in combination as well with other elements +for which it has less affinity, but which it readily gives up for the +stronger affinities when explosion takes place, the other elements +either combining with one another to form new compounds or being set +free in an uncombined state. + +An explosive is said to detonate when the above changes take place +instantaneously, the action being transmitted with the speed of +electricity by a sort of molecular rhythm from molecule to molecule +throughout the entire substance of the compound. + +An explosive is said to explode when the above changes do not occur +instantaneously throughout the whole substance, but whose combustion +takes place from the surface inward of the particles or grains of which +it is composed, thus requiring some definite lapse of time. + +The elements of an explosive compound may be associated chemically as in +nitro-glycerine and gun-cotton, which are chemical compounds, being the +results of definite reactions. Or, an explosive may be a mere mechanical +mixture of different substances comprising the necessary elements, as is +ordinary black gunpowder, which is a compound of charcoal, sulphur and +saltpeter, the saltpeter supplying the necessary oxygen. + +No gunpowder can be smokeless in which saltpeter or any oxygen-bearing +salt having a metallic base is employed, for when the salt gives up its +oxygen, the base combines with other elements to produce a sulphate, a +carbonate, or other salt, which, being solid, produces smoke. Therefore, +to be smokeless, a gunpowder must contain no other elements than oxygen, +hydrogen, nitrogen, and carbon, and in such proportions that the +products of combustion shall be wholly gaseous. The nitric +ethers--gun-cotton and nitro-glycerine--constitute such explosive +compounds. These substances were formerly thought to be +nitro-substitution compounds, but are now known to belong to the +compound ethers of nitric acid. + +Gun-cotton, discovered by Schonbein, in 1845, has since been looked upon +as the most promising material for a smokeless gunpowder, it being a +very powerful explosive and burning with practically no smoke. To-day, +gun-cotton, in some form or other, constitutes the base of substantially +all of the smokeless powders with which have been attained any +considerable degree of success. + +Gun-cotton alone and in its fibrous state has been found to be too +quick, or violent, for propulsive purposes, such as use in firearms; as +under such conditions of confinement it is very likely to detonate and +burst the gun. However, if gun-cotton be dissolved in a suitable +solvent, which is capable of being evaporated out, such as acetone, or +acetate of ethyl, which are very volatile, it becomes, when thus +dissolved and dried, a very hard, horn-like, amorphous substance, which +may be used for a smokeless gunpowder. But this substance taken alone is +very difficult to mould or granulate, and the loss of expensive solvents +must necessarily be quite considerable. + +When gun-cotton is reduced to a collodial solid, as above, and used as a +smokeless gunpowder, the grains must be made comparatively small to +insure prompt and certain ignition, and consequently the pressures +developed in the gun are apt to be too great when charges sufficiently +large are used to give desired velocities. + +If, however, a compound be made of gun-cotton and nitro-glycerine, in +about equal parts, by means of a volatile solvent or combining agent, +such as one of the before mentioned, and the solvent evaporated out, we +obtain practically a new substance and one which, as regards its +explosive nature, is quite unlike either of its two constituents taken +alone. The nitro-glycerine, furthermore, being itself a solvent of +gun-cotton, much less of the volatile ether is necessary to render the +compound of an amorphous character. Being quite plastic this substance +may be wrought or moulded into any desired size or form of grain. + +This simple compound of nitro-glycerine and gun-cotton, or with some +slight modifications, has been found, when properly granulated, to be +the most smokeless powder that has yet been discovered or invented. If +pure chemicals are employed in the manufacture, and the gun-cotton and +nitro-glycerine be made of the highest nitration and best quality, we +have a smokeless powder which will possess the following desirable +qualities: + +1st. It is absolutely smokeless, that is, its products of combustion are +entirely gaseous. + +2d. Its products of combustion are in no way deleterious or unpleasant. + +3d. It is perfectly safe to manufacture, handle and transport. There is +no more danger of its exploding accidentally than there would be of an +explosion of shavings or sawdust; for, unless well confined and set off +with a strong primer, it will not explode at all. In the open its +combustion is so slow as to in no way resemble or partake of the nature +of an explosion. + +4th. It is perfectly stable, and will keep any length of time absolutely +without undergoing any change whatever, under all conditions of +temperature or exposure to which gunpowder would ever be subjected. + +5th. It is not hygroscopic, and may be soaked in water without being at +all affected by it. + +6th. It will not corrode the cartridge case. + +7th. It will not foul the gun. + +8th. It is sure of ignition with a good primer, and may be made to burn +as slowly as desired by varying the character and size of the grains. +Indeed, it may be made to burn so slowly as to fail of complete +combustion before the bullet leaves the gun, and after firing several +rounds, partly burned pieces of the powder may be picked up in front of +the gun. + +9th. In a shoulder arm, a velocity of 2,000 feet per second may be +imparted to the bullet with this powder, and with a pressure in the +chamber of the gun of not more than fifteen English tons. This is, of +course, when the gun, cartridge case, primer, and projectile are adapted +to the use of smokeless powder, and the granulation of the powder is +adapted to them. + +If what I have here claimed for the above smokeless powder be true, it +would appear that it may be taken as really an ideal smokeless powder. +Why, then, has it not already been universally adopted? Surely such a +powder is just what every government is seeking. In reply to this, let +me say that, in order for the above compound to be an effective and +successful smokeless powder, with the manifestation of the many +desirable qualities which I have recited, a great many other conditions +are necessary, some of which I will mention. To arrive at the knowledge +that this compound would constitute the best smokeless powder has +required a great deal of experimenting. It was first thought that +gun-cotton colloid, without any nitro-glycerine, that is, gun-cotton +dissolved and dried, would burn more slowly, keep better, and give +better ballistics than it would if combined with nitro-glycerine. It was +also thought that gun-cotton of a high degree of nitration when made +into colloidal form would even then burn too quickly to be suitable for +use in firearms. Consequently, the first experiments were with low grade +gun-cotton, what is called collodion cotton, such as is employed in the +manufacture of celluloid. But, as this would not explode without the +addition of some oxygen-bearing element, various oxygen-bearing salts +were combined with it, such as nitrate of potassium, nitrate of ammonia, +nitrate of baryta, etc. Also a great many of the first smokeless powders +were made of low grade gun-cotton combined with nitro-glycerine in +varying proportions. These powders would often give very good results +when first made; but low grade gun-cotton or di-nitro-cellulose, as it +is called, is a very unstable compound, and these powders, after giving +very promising results, were found to be constantly undergoing change, +sooner or later resulting in complete decomposition. + +When nitro-glycerine was first combined with gun-cotton in small +quantities, camphor was often added, to lessen the rapidity of +combustion which the nitro-glycerine was supposed to impart and also to +render the compound more plastic, and to tend to prevent the +decomposition of the low grade gun-cotton. But camphor being volatile, +would, by its evaporation, cause the powder to constantly change in +character. Castor oil has been found to be a better diluent, as this +will not evaporate. + +As all of the smokeless powders made of a low grade gun-cotton were +found to deteriorate and spoil, experiments were made with gun-cotton of +the highest degree of nitration, both alone and in combination with +nitro-glycerine. These experiments were first conducted in England by +private parties and by the British government, when it was found that +high grade gun-cotton would give excellent results if made into a +colloidal solid and used alone, or in combination with certain other +constituents. With a view to saving the large quantity of solvents +necessary to reduce the gun-cotton, and to get a more prompt and certain +ignition with a larger grain, experiments were cautiously made by the +admixture of varying proportions of nitro-glycerine to the gun-cotton +when dissolved, or rather along with other solvents in the process of +dissolving it. + +It was soon found that nitro-glycerine added in quantities, even equal +in weight to the gun-cotton itself, did not materially increase the +rapidity of the explosion of the compound. And it was also found that +high grade gun-cotton, when combined with nitro-glycerine, gave very +much better results than low grade gun-cotton. + +I have spoken here of high and low grade gun-cotton, when in fact the +word gun-cotton should be applied only to the highest nitro-compound of +cellulose. The word gun cotton has always been rather loosely used. +Pyroxyline would be a better word, as this applies to all grades. When +cotton fiber is soaked in a large excess of a mixture of the strongest +nitric and sulphuric acids, gun-cotton proper, or that of the highest +grade, is produced. When weaker acids are used, lower grades of +nitro-cellulose are formed. + +The first mentioned or highest grade gun-cotton, when thoroughly freed +from its acids, has always proved to be a perfectly stable compound. The +lower grades have always been found to be unstable and subject to +spontaneous decomposition. Nitro-glycerine has also been erroneously +thought to be a very unstable compound. But experiments have proved +that, when made pure, it is perfectly stable. + +Having now explained how the knowledge came to be arrived at that the +aforementioned compound of highest grade nitro-glycerine and highest +grade gun-cotton would constitute the best basis for a smokeless powder, +I will now mention a few of the other conditions necessary to success +with its use, without assuming that smokeless powder has yet passed its +experimental stage, and is beyond further improvement. Nevertheless, +such is the compound which has come to stay as the basis of all +smokeless powders; and any smokeless powder, if a successful one, may be +counted upon as being made of this compound of gun-cotton and +nitro-glycerine, or of a colloid of gun-cotton, either alone or combined +with diluents, oxygen-bearing salts, or inert matter. The fact that +smokeless powder may still be said to be in somewhat of an experimental +stage is not to admit that it is not a success. Firearms, cartridge +cases, and projectiles are also still in an experimental stage, for they +are constantly being improved; yet their use has been a great success +for a good many years. + +The question of success of a smokeless powder does not rest alone with +the powder itself. The gun, the cartridge case, primer, and bullet have +been as much the subjects of experiments in adapting them to the use of +smokeless powder as has the smokeless powder in being adapted to them. +To impart a velocity of 2,000 feet per second to a rifle ball, with +corresponding long range and accuracy of flight, has been a question as +much of improvement in rifles and projectiles as in the powder. To give +a velocity of 2,000 feet per second to a bullet, requires a pressure of +at least 15 English tons in the chamber of a gun. This would be a +dangerous pressure in an old-fashioned shoulder arm; while a bullet made +only of lead would strip on striking the rifling and pass right through +the barrel of the gun without taking any rotary motion whatever. It +might at first seem that the powder is the only thing to be considered; +but high ballistics can only be obtained when everything else is adapted +to its use. + +The projectile, the cartridge case, the fulminating cap, and the gun +have had to be all built up together, and a very large amount of +experimenting has been necessary to determine what would constitute the +best projectile, best cartridge case, best fulminating cap, and what +should be the character of the rifling and the quality and temper of the +steel of the gun barrel. + +It has been necessary first to conduct experiments to test the smokeless +powders for velocities and pressures, and then with the powders test +various kinds of projectiles and guns. In order to obtain the high +ballistics which have been secured, it has been found necessary to cover +the bullet with something harder than lead and to rifle the gun in a +special manner. + +The French, who were the first to definitely adopt smokeless powder, +were the first also to make a rifle, projectile, cartridge case and +primer suited to its use. + +To obtain long range with a small long bullet such as is now used, it +should rotate at a very high speed. It is well known to artillerists +that a projectile of four or more calibers in length has to be rotated +at a much higher speed than one of half that length, in order to keep +the projectile stiff in the air, and to prevent it from ending over in +its flight. To communicate this very high rotary movement to the bullet +in the instant of time during which it is passing through the barrel, +the rifling of the gun has to exert an enormous torsion on the bullet. +Lead, no matter how hardened, is not sufficiently strong, as it will not +only strip and pass straight through the gun without taking any rotary +movement whatever, but under such very high pressures it behaves like +wax, and is thrown from the gun in a distorted mass. + +The French cover their bullets with German silver, a substance made of +nickel, zinc and copper; and in order to put as little strain upon the +rifling and projectile as possible, the rifling of the gun is made with +an increasing twist, and has no sharp edges. The French rifle is made +very strong at the breech and is of tempered steel throughout. In this +way the French have made smokeless powder a success--a smokeless powder +made substantially of a character such as I have herein described. With +smokeless powder, the French rifle imparts a muzzle velocity of 2,000 +feet per second to the bullet, with a range of about 2,400 meters. + +If smokeless powder be divided into sufficiently small grains to be +ignited by an ordinary fulminating cap, it would burn too quickly, +thereby causing the pressure to mount too high, and without giving the +desired velocity. Consequently very large and strong fulminating caps +have to be employed. Smokeless powder is not ignited in the same manner +as black powder. Something besides ignition is necessary. Black powder +simply requires to be set on fire; while a smokeless powder, on the +contrary, not only requires that it be set on fire, but that a certain +degree of pressure be set up inside of the cartridge case. For instance, +if a primer of a certain size should be found to operate perfectly well, +giving prompt ignition in the cartridge case of a rifle of small +caliber, it would be found that the same primer would not ignite a +charge of the same powder if loaded into a gun of one inch caliber. In +the latter case a few grains only lying near the primer would be +ignited, and these would soon become extinguished by sudden release of +pressure bringing about a cooling effect due to expansion of the gases. +In small cartridges a large fulminating cap is all that is required, but +in large cartridges it is necessary to resort to additional means of +ignition. + +In France, where experiments were conducted with a 37 millimeter Maxim +gun, it was found to be impracticable to use a fulminating cap +sufficiently large to ignite the powder and cause it to burn. Therefore, +a small ignition charge of black powder was employed, it being put in a +capsule or bag and placed next the primer. On firing at the rate of 300 +rounds per minute, the black powder, though small in quantity, produced +a cloud of smoke through which it was quite impossible to see. The +inventor of the gun then prepared for the French some wafers of +pyroxyline canvas, which were placed next to the primer, securing +thereby prompt ignition without the production of any smoke. + +Smokeless powder, made as I have described, cannot be detonated by a +fulminating cap of any size or by any means whatever. A large charge of +fulminate of mercury placed inside the cartridge case next the primer +will not detonate the powder, it serving only to ignite it and cause it +to explode. But even this would not cause the powder to explode except +it be confined behind a projectile, that sufficient pressure may be run +up to make it burn in its own gases. + +Some curious experiments with smokeless powder may be tried with a shot +gun. If the fulminating cap be large, the powder fine, the wads numerous +and hard and the charge of shot heavy, all being well rammed down, and +the paper case well spun over the last pasteboard wad, a charge of +smokeless powder about equal in weight to one-half of what would be +employed of black powder would give about the same results as black +powder. But if the charge of shot be omitted, the primer will only +ignite the powder, and there will be set up sufficient pressure merely +to throw the wads about half way up the barrel of the gun, when the +powder will go out. Now if this same charge of powder be collected and +reloaded into a new cartridge case and well confined behind wads and a +charge of shot, as above explained, it will all burn, giving the same +results as black powder. + +Attempts have been made to use this powder in pistols and revolvers, but +here it has proved a failure, as the pressure is not great enough to +cause the powder to be consumed, unless it be in the form of very fine +grains or dust, in which case the pressure mounts too high. However, +this might be overcome to a degree by making the powder porous. The +chemical conditions of the powder might be the same, but the physical +conditions must be different. A powder suitable for shot guns and +pistols would not be suitable for rifles. + +One not familiar with the characteristics of smokeless powder would be +almost certain to fail in his first attempt to fire it. Many persons +have been convinced by their first experiments that this powder would +not burn at all in a gun, any more than so much sand. + +Smokeless powder is consumed with a rapidity which accords with the +conditions of its confinement. Therefore, the bullets which have been +experimented with by different governments have been the cause of much +of the varying pressures attributed to the smokeless powders. + +The Austrians use the Mannlicher steel jacketed bullet. The steel casing +or jacket is first tinned on the inside and then the lead is cast in, +thus melting the tin and adhering firmly to the jacket. This projectile +sets up enormous friction in the barrel of the gun when used with +smokeless powder; as the smokeless powder leaves the gun barrel +perfectly clean and the two steel surfaces being in absolute contact +cause tremendous friction; and as the coefficient of friction varies +with every shot, the pressure in the gun constantly varies greatly. + +The German silver covered bullet used by the French has the disadvantage +that when firing rapidly the chamber of the barrel becomes nickel plated +and great friction is caused, mounting up the pressures and causing the +muzzle velocities to fall off. + +The Austrians, in order to prevent their steel cased bullets from +rusting and to lessen the friction in the barrel of the gun, cover them +with a heavy lubricant, which gives the cartridges an unsightly +appearance and causes them to gather dust and sand. The French employ a +lubricant at the base of the projectile, with a small copper disk +between the same and the powder. + +Col. A.R. Buffington, commander of the National Armory at Springfield, +Mass., has made a steel covered projectile which he prevents from +rusting by blackening by a niter process. Several grooves are pressed in +the base of the bullet which carry a lubricant, and when the bullet is +inserted in the cartridge case the grooves are covered by it. +Furthermore, these grooves prevent the lead filling from bursting +through the steel casing, leaving the latter in the barrel, as often +occurs with the Austrian and French projectiles when using smokeless +powder. + +A new projectile has lately come out, the invention of Captain Edward +Palliser, of the British army. This bullet consists of a jacket made of +very soft Swedish wrought iron, coated with zinc and filled with lead, +the lead being pressed into this jacket. The bullet is corrugated at its +base, after the manner of the one made by Colonel Buffington. This +projectile has been experimented with very extensively by the British +government, and at the works of the Maxim-Nordenfelt Guns and Ammunition +Company, in England. The zinc coating of the bullet is too soft to stick +to the barrel of the gun, and also in a measure acts as a lubricant. +This projectile has given better results than any other that has been +experimented with. The great velocities and the most uniform pressures +by the use of smokeless powder have been attained with this Palliser +bullet. + + +NOISELESSNESS. + +A great many stories have been told about the noiselessness of smokeless +powder. But there is no such thing as a noiseless gunpowder. The report +of a gun charged with smokeless powder is very sharp, and is as loud as +when black powder is used, yet the volume of sound is much less, so that +the report cannot be heard at so great a distance. + +The report of a gun using smokeless powder is a sound of much higher +pitch than when black powder is used, and consequently cannot be heard +at so great a distance as the lower notes given by black powder. + +As smokeless powder exerts a much greater pressure than common black +powder when burned in a gun, one would naturally think that the recoil +of the barrel would be greater, owing to the greater pressure exerted by +the smokeless powder on the base of the cartridge case and the breech +mechanism. However, such is not the fact; for the barrel actually +recoils very much less when smokeless powder is used. This is due to the +suddenness with which the pressure is exerted by smokeless powder, it +acting more like a very sharp blow on the metal, whereby more of the +energy is converted into heat instead of being spent in overcoming the +inertia of the barrel to give recoil. Similarly when smokeless powder is +fired in a gun, the displacement of the air is so sudden that the sound +waves do not possess the same amplitude of recoil or vibration as is +given by black powder. + + * * * * * + + + + +THE CONSTRUCTION AND MAINTENANCE OF UNDERGROUND CIRCUITS. + +BY S.B. FOWLER. + + +The numerous disastrous storms of the last winter have brought out very +vividly the advantages of having all wires placed underground, and many +inquiries have been addressed to the companies operating underground +circuits as to their success. It is not probable that all of the answers +to these inquiries have been of the most favorable character. To many +central station managers an underground system means frequent +break-downs and interruptions of service, with, perhaps, slow and +expensive repairs, which bring in their turn numerous complaints, loss +of customers, and reduced profits. In many installations burn-outs both +underground and in the station are frequent, with the natural result +that the operating of circuits underground is not there considered an +unqualified success. The writer has in mind two very different +experiences with underground cables. Several miles of cable were bought +by a certain company, carefully laid, and up to to-day not a single +burn-out or interruption of service can be attributed to failure of +cables; at about the same time another company bought about an equal +amount of the same kind of cable, and in a comparatively short time the +current had to be shut off the lines and the whole installation repaired +and parts of it replaced. Both of these experiences have been repeated +many times and will be again, although it is simply a distinction +between a good cable properly laid and a good cable ruined by careless +and incompetent workmanship. + +Every failure can be traced to poor work in the original installation or +to the use of a cheap cable, both causes being due, generally, to that +false economy which looks for too quick returns. A poorly insulated line +wire and a poorly insulated cable are two very different things. +However, it is a fact that by the use of a good cable it is not +difficult to construct an underground system for light, power, telegraph +or telephone uses that will be superior to overhead lines in its service +and in cost of maintenance. The ideal underground system must have as a +starting point a system of subways admitting of the easy drawing in and +out of cables and affording means of making subsidiary connections +readily and with the minimum of expense and interruption of service. +This is practically accomplished by a subway consisting of lines of pipe +terminating at convenient intervals, say at street intersections, in +manholes, for convenience in jointing and in running out house +connections. These pipes, or ducts, as they are called, should be for +two kinds of service; the lower or deeper laid lines for the main or +trunk circuits, and a second series of ducts laid nearer the surface, +running into service boxes placed near together for lines to "house to +house" connections. In some cities where it is allowed to run overhead +lines, the plan of running but one service connection in a block is +followed, all customers in the block being supplied from a line run over +the housetops or strung on the rear walls. + +This makes unnecessary all subsidiary ducts except a short one from the +manhole to the nearest building in the block, and effects a considerable +saving in pipe, service boxes, cables and labor. The manholes should +have their walls built up of brick, the floors should be of concrete, +and there should be an inside lid which can be fastened down and the +manhole thus made water-tight. + +For ducts wood, iron or cement lined pipe may be used. To preserve the +wood it is generally treated with creosote, which, in contact with the +lead cover of the cable, sets up a chemical action, resulting in the +destruction of the lead. Wood offers but little protection for the +cable, as it is too easily damaged and broken through in the frequent +street openings made by companies operating lines of pipe in the +streets, and as one of the main purposes of a subway is that of a +protection to cables, wooden ducts have little to recommend them except +their cheapness. + +Iron pipes are either laid in trenches filled in with earth or are laid +in cement. Iron pipe will of course rust out in time, and if absolute +permanence in construction is desired, should be laid in cement, for +after the pipe rusts out, the duct of cement is still left. However, if +we are going to the expense of laying in cement, it would be much +preferable to use cement lined pipe, which is not only cheaper than iron +pipe, but makes the most perfect cable conduit, as it affords a +perfectly smooth surface to draw the cable over and give a good duct +edge. + +It is not necessary, however, in small installations of cable, +especially where additional connections will not be of frequent +occurrence, to go to the expense of subways, for cable may be safely +laid in the ground in trenches filled in with earth, or can be inclosed +in a plain wooden box or a wooden box filled with pitch. + +There are, of course, many localities where, if the cable is laid in +contact with the earth, a chemical action would take place which might +result in the destruction of the cable. + +Underground cables are of the following classes: 1. Rubber insulated +cables, insulated with rubber or other homogeneous material. 2. Fibrous +cables, so called from the conductors being covered with some fibrous +material, as cotton or paper, which is saturated with the insulating +material, paraffine, resin oil, or some special compound. Under this +latter head is also included the dry core paper cables. + +The first thing to do is to get the cable drawn into the ducts, and on +the proper accomplishment of this depends to a great extent the success +or failure of the whole installation. Probably the ducts have been wired +when the subway was constructed, but if not a wire must be run through +as a means of pulling in the draw rope. There are several kinds of +apparatus for getting a wire through a duct--rods, flexible tapes, +mechanical "creepers," etc.; but probably the best is the sectional rod. +This simply consists of three or four foot lengths of hard wood rods, +having metal tips that screw into each other. A rod is placed in a duct +at a manhole, one screwed to that, both are pushed forward, another one +added and pushed forward, and so on until they extend the entire length +of the duct. Then the wire is attached and the rods are pulled out and +detached one at a time and with the last rod the wire is through. At +least No. 14 galvanized iron or steel wire should be used, for any +smaller size cannot be used a second time, as a rule. In starting to +pull in the draw rope a wire brush should be attached to the wire and to +this again the rope, and when the brush arrives at the distant end of +the duct it very likely will bring with it a miscellaneous collection of +material which for the good of the cable had better be in the manhole +than in the duct. + +The reel or drum carrying the cable should be mounted on wheels or jacks +and placed on the same side of the manhole as the duct into which the +cable is to be drawn, and must always be so placed that the cable will +run off the top of the reel. + +There are several methods of attaching the draw rope to the cable. As +simple and strong a method as any is to punch two of these holes through +the cable, lead and all, and attach the rope by means of an iron +wire--some of the draw wire will do--run through these holes. Depending +on the length and weight of cable to be pulled it can be drawn either by +hand or by a multiplying winch. The rope should run through a block +fastened in the manhole in such a position that the rope shall have a +good straightaway lead from the mouth of the duct. + +The strain on the cable should be perfectly uniform and steady; if the +power is applied by a series of jerks either the lead covering may be +pulled apart or some of the conductors broken. At the reel there must +always be a large enough number of men to turn it and keep the cable +from rubbing on anything, and in the manhole one or more men to see that +the cable feeds into the duct straight and to guide it if necessary. If +the ducts are of iron and are not perfectly smooth at the ends, these +should be made so with a file, and in addition a protector of some sort +should be placed in the mouths of the duct, both above and below the +cable. Six inches of lead pipe, split lengthwise and bent over at one +end to prevent being drawn into the duct with the cable, makes a very +good protector. The cable should be reeled off the drum just fast enough +to prevent any of the power used in pulling the cable through the duct +being utilized in unreeling it. If this latter is allowed to occur the +cable will be bent too short and the lead covering buckled or broken, +and also the cable may be jammed against the upper edge of the duct and +perhaps cut through. + +If the reel is allowed to turn faster than the cable is drawn in, the +first three or four turns on the reel will slacken up, and the lead +covering may either be dented or cut through by scraping on the ground. +If the cable end when pulled through up to the block is not long enough +to bend around the hole more than half way, the rope should be +unfastened from its end, a length of rope with a well frayed out end +should be run through the block, and by fastening to the cable close to +the duct, with a series of half hitches, as much slack as necessary can +be pulled in. If this is properly manipulated there need not be a +scratch on the cable, but unless great care is taken the lead may be +pressed up into ridges and the core itself damaged. + +Immediately after the cable is drawn in, if the joint is not to be at +once made, the open end or ends should be cut off and the cable soldered +up, as most cables are very susceptible to moisture and readily absorb +water even from the atmosphere. Where practicable it is always a good +plan to pull the cable through as many manholes as possible without +cutting the cable; for the joint is, especially in telephone or +telegraph cables, the weak point. To do this the rope should be pulled +through the proper duct in the next section without unfastening it from +the cable; the winch should be moved to the next manhole, and pulling +through then done as before. There should always be a man in every hole +through which the cable is running to see that it does not bind anywhere +and to keep protectors around the cable. + +It is not advisable to pull more than one cable into a duct, and never +advisable to pull a cable into a duct containing another cable, but if +two or more cables have to go into the same duct, they should always be +drawn in together. Lead covered cables and those with no lead on the +outside should never be pulled into the same duct, for if they bind +anywhere the soft cable will suffer where two lead covered cables would +get through all right. Some manufacturers are now putting on their +cables a tape or braid covering, which saves the lead many bad bruises +and cuts, and is a valuable addition to a cable at very little +additional expense. + +Practically all electric light and power cables are either single or +double conductors, and the jointing of these is comparatively a simple +matter, although requiring considerable care. The lead is cut back from +each end about four or five inches, and the conductors bared of +insulation for two or three inches. The bare conductors should be +thoroughly tinned by dipping in the metal pot or pouring the melted +solder over them. A sperm candle is better than resin or acid for any +part of the operations where solder is used. A lead sleeve is here +slipped back over the cable, out of the way, and the ends of the +conductors brought together in a copper sleeve which is then sweated to +a firm joint. This part must be as good a piece of work mechanically as +electrically. The bare splice is then wrapped tightly with cotton or +silk tape to a thickness slightly greater than that of the insulation of +the cable, and is thoroughly saturated with the insulating compound +until all moisture previously absorbed by the tape is driven off. + +The lead sleeve is then brought over the splice and wiped to the cable. +The joint is then filled with the insulating compound poured through +holes in the top of the sleeve; these holes are then closed and the +joint is complete, and there is no reason why, in light and power +cables, that joint should not be as perfect as any other part of the +cable. When the cable ends are prepared for jointing they should be hung +up in such a position that they are in the same plane, both horizontal +and vertically, and firmly secured there, so that when the lead sleeve +is wiped on the conductor may be in its exact center, and great care +must be taken not to move the cables again until the sleeve is filled +and the insulation sufficiently cooled to hold the conductor in +position. + +It is also very important to see that there are no sharp points on the +conductors themselves, on the copper sleeve, on the edges of the lead +covering or on the lead sleeve. All these should be made perfectly +smooth, for points facilitate disruptive discharges. Branch joints had +better be made as T-joints rather than as Y-joints, for they are better +electrically and mechanically, although they occupy more room in the +manholes. They are of course made in the same way as straight joints, a +lead T-sleeve being used, however. For multiple arc circuits copper +T-sleeves and for series circuits copper L-sleeves are used. + +Telephone and telegraph cables are made of any required gauge of wire +and with from 1 to 150 conductors in a cable. In jointing these the +splices are never soldered, the conductors being joined either with a +twist joint or with the so-called Western Union splice. Each splice is +covered with a cotton or silk sleeve or a wrapping of tape, the latter +being preferable, although considerably increasing the time necessary +for making the joint. Great care must be taken that no ends of wire are +left sticking up, for they will surely work their way through the tape +and grounds, and crosses will be the result. The wires should always be +joined layer to layer and each splice very tightly taped in order to get +as much insulating compound around each splice as possible in the +limited space. The splices should be "broken" as much as possible, so as +to avoid having adjoining splices coming over each other. After the +joint has been saturated with insulating compound the wires should have +an outside wrapping of tape to keep them in shape, and then the sleeve +is wiped on and filled. If the insulation resistance of the jointed +telegraph or telephone cable is a quarter of what the cable tested in +the factory, it may be considered that an exceptionally good piece of +work has been done. I have spoken more particularly of fibrous lead +covered cables, as the handling of them includes practically every step +of the work on any other kind of underground cable. In insulating dry +core paper cables a paper sleeve is slipped over the splice, and in +rubber cables the splice is wrapped with rubber tape; all other details +are the same for these as for the fibrous cable. + +In the laying of light and power cables every joint, as made, should be +tested for insulation with a Thomson galvanometer, as the insulation +must necessarily be very high, and if one joint or section of cable is +any weaker than another it may be very important in the future to know +it. All tests must be made after the joint has cooled, for while hot its +insulation resistance will be very low. + +Tests for copper resistance should also be made to determine if the +splices are electrically perfect; an imperfect splice may cause +considerable trouble. In telegraph and telephone cables the conductors +should be of very soft copper, for in stripping the conductor of +insulation it is very easy to nick the wire, and if of hard drawn copper +open wires will be the result. + +All work should be frequently tested for continuity with telephones, +magnetos, or small portable galvanometers. It is only necessary to +ground the conductors at one end and try each wire at the other end. For +this sort of work a telephone receiver used with one cell of some dry +battery is most convenient, and has the additional advantage of +affording a means of communication while testing, and is by far the best +thing for identifying and tagging conductors. + +These cables should be frequently tested during the progress of the work +for grounds and crosses with a Thomson instrument, and when the cable is +complete, a careful series of tests of the capacity, insulation +resistance, and copper resistance of each wire should be made and the +exact condition of the cable determined before it is put in service, and +thereafter an intelligent oversight of the condition of the circuits +can thus be more readily maintained. + +Where a company has extensive underground service, a regular cable gang +should be in its employ, for quick and safe handling of cables demands +the employment of men accustomed to the work. If the cable has been +properly laid and tests show it to be in good condition before current +is turned on, almost the only trouble to be anticipated will be due to +mechanical injury. Disruptive discharge, puncturing the lead, may occur; +but the small chance of its occurring can be greatly lessened by the use +of some kind of "cable protector," which will provide for the spark an +artificial path of less resistance than the dielectric of the condenser, +which the cable in fact becomes. + +If a fault suddenly develops on a circuit, the chances are it will be +found in a manhole, and an inspection of the cable in the manhole will +generally reveal the trouble without resorting to locating with a +Wheatstone bridge. The cable is often cut through at the edge of the +duct, or damaged by something falling on it, or by some one "walking all +over it." To guard against these, the ducts should always be fitted with +protectors both above and below the cable. The cables should never be +left across the manholes, for they then answer the purpose of a ladder, +but should be bent, around the walls of the hole and securely fastened +with lead straps, that they may not be moved and the lead gradually worn +through. + +In telegraph cables, when one or two conductors "go," it will probably +be useless to look for trouble except with instruments; but if several +wires are "lost" at once it will probably be found to be caused by +mechanical injury, which can be located by inspection. If it is ever +necessary to loop out conductors, a joint can be readily opened and the +conductors wanted picked out and connected into the branch cable and the +joint again closed without disturbing the working wires. In doing this a +split sleeve must be used, and the only additional precaution to be +taken is in filling the sleeve to have the insulating compound not hot +enough to melt the solder and open up the split in the sleeve. In +cutting in service on light and power cables it is entirely practicable +to do so without interruption of service on multiple arc circuits, even +those of very high voltage; but they require great precaution and +involve considerable risk to the jointer, and where possible the circuit +to which the connection is to be made should previously be cut dead. +Where the voltage is not dangerous to human life, almost any service +connection can be made without interruption of service. + +I have only indicated a very few of the operations that may be found +necessary, and the probable causes of troubles that may be encountered +in the operating of underground circuits, believing that the different +problems that arise can, with a little experience, be successfully met +by any one who has a fair knowledge of the original construction of +cable lines.--_Electrical World_. + + * * * * * + + + + +RAILROADS TO THE CLOUDS. + + +If George Stephenson, when he placed the first locomotive on the track +and guaranteed it a speed of six miles an hour, could have foreseen that +in less than eighty years the successors of his rude machine would be +climbing the sides of mountain ranges, piercing gorges hitherto deemed +inaccessible, crossing ravines on bridges higher than the dome of St. +Paul's, and traversing the bowels of the earth by means of tunnels, no +doubt his big blue eyes would have stood out with wonder and amazement. +But he foresaw nothing of the kind; the only problem present in his mind +was how to get goods from the seaports in western England to London as +easily and cheaply as possible, and to do this he substituted for +horses, which had for 150 years been drawing cars along wooden or iron +tracks, the wonderful machine which has revolutionized the freight and +passenger traffic of the world. + +It was, indeed, impossible for any one to foresee the triumphs of +engineering which have accompanied the advances in transportation. To +the engineer of the present day there are no impossibilities. The +engineer is a wizard at whose command space and matter are annihilated. +The highest mountain, the deepest valley, has no terrors for him. He can +bridge the latter and encircle or tunnel the former. The only requisites +which he demands are that something in his line be needed, and that the +money is forthcoming to defray the expense, and the thing will be done. +But the railroad he is asked to construct must be necessary, and the +necessity must be plainly shown, or no funds will be advanced; and +although the theory does not invariably hold good, especially when a +craze for railroad building is raging, as a rule no expense for the +construction of a road will be incurred without a prospect of +remuneration. + +Hence the need of railroad communication has caused lines to be +constructed through districts where only a few years ago the thing would +have been deemed impossible. The Pacific roads of this country were a +necessity long before their construction, and in the face of +difficulties almost insuperable were carried to successful completion. +So, also, of the railroads in the Andes of South America. The famous +road from Callao through the heart of Peru is one of the highest +mountain roads in the world, as well as of the most difficult +construction. The grades are often of 300 feet and more to the mile, and +when the mountains were reached so great were the difficulties the +engineers were forced to confront that in some places laborers were +lowered from cliffs by ropes in order that, with toil and difficulty, +they might carve a foothold in order to begin the cutting for the +roadway. + +In some sections tunnels are more numerous than open cuts, and so far as +the road has gone sixty-one tunnels, great and small, have been +constructed, aggregating over 20,000 feet in length. The road attains a +height of 15,000 feet above the level of the sea, and at the highest +point of the track is about as high as the topmost peak of Mont Blanc. +It pierces the range above it by a tunnel 3,847 feet long. The stern +necessities of business compelled the construction of this road, +otherwise it never would have been begun. + +The tunnels of the Andes, however, do not bear comparison with the +tunnels, bridges, and snow sheds of the Union Pacific, nor do even these +compare with the vast undertakings in the Alps--three great tunnels of +nine to eleven miles in length, which have been prepared for the +transit of travelers and freight. The requirements of business +necessitated the piercing of the Alps, and as soon as the necessity was +shown, funds in abundance were forthcoming for the enterprise. + +But tunneling a mountain is a different thing from climbing it. Many +years ago the attention of inventors was directed to the practicability +of constructing a railroad up the side of a mountain on grades which, to +an ordinary engine, were quite impossible. The improvements in +locomotives twenty-five and thirty years ago rendered them capable of +climbing grades which, in the early days of railroad engineering, were +deemed out of the question. The improvements proved a serious stumbling +block in the way of the inventors, who found that an ordinary locomotive +was able to climb a much steeper grade than was commonly supposed. The +first railroads were laid almost level, but it was soon discovered that +a grade of a few feet to the mile was no impediment to progress, and +gradually the grade was steepened. + +The inventors of mountain railroad transportation might have been +discouraged by this discovery, but it is a characteristic of an inventor +that he is not set back by opposition, which, in fact, only serves to +stimulate his zeal. The projectors of inclined roads and mountain +engines kept steadily on, and in France, Germany, England, and the +United States many experimental roads were constructed, each of a few +hundred yards in length, and locomotive models were built and put in +motion to the amazement of the general public, who jeered alike at the +contrivances and the contrivers, deeming the former impracticable and +the latter crazy. + +But the idea of building a road up the side of a hill was not to be +dismissed. There was money in it for the successful man, so the cranky +inventors kept on at work in spite of the jeers of the rabble and the +discouragements of capitalists loath to invest their money in an +uncertain scheme. To the energy and perseverance of railroad inventors +the success of the mountain railroad is due, as also is the construction +of the various mountain roads, of which the road up Mt. Washington, +finished in 1868, was the first, and the road up Pike's Peak, completed +the other day, was the latest. + +Of all the mountain roads which have been constructed since the one up +Mt. Washington was finished, the best known is that which ascends the +world-famous Rigi. With the exception of Mont Blanc, Rigi is, perhaps, +the best known of any peak in the Alps, though it is by no means the +highest, its summit being but 5,905 feet above the level of the sea. +Although scarcely more than a third of the height of some other +mountains in the Alps, it seems much higher because of its isolated +position. Standing as it does between lakes Lucerne, Zug, and Lowertz, +it commands a series of fine views in every direction, and he who looks +from the summit of Rigi, if he does no other traveling in Switzerland, +can gain a fair idea of the Swiss mountain scenery. Many of the most +noted peaks are in sight, and from the Rigi can be seen the three lakes +beneath, the villages which here and there dot the shores, and, further +on, the mighty Alps, with their glaciers and eternal snows. + +Many years ago a hotel was built on the summit of the Rigi for the +benefit of the tourists who daily flocked to this remarkable peak to +enjoy the benefit of its wonderful scenery. The mountain is densely +wooded save where the trees have been cut away to clear the land for +pastures. The ease of its ascent by the six or eight mule paths which +had been made, the gradual and almost regular slope, and the throngs of +travelers who resorted to it, made it a favorable place for an +experiment, and to Rigi went the engineers in order to ascertain the +practicability of such a road. The credit of the designs is due to a +German engineer named Regenbach, who, about the year 1861, designed the +idea of a mountain road, and drew up plans not only for the bed but also +for the engine and cars. The scheme dragged. Capitalists were slow to +invest their money in what they deemed a wild and impracticable +undertaking, and even the owners of the land on the Rigi were reluctant +for such an experiment to be tried. But Regenbach persevered, and toward +the close of the decade the inhabitants of Vitznau, at the base of the +Rigi, were astonished to see gangs of laborers begin the work of making +a clearing through the forests on the mountain slope. They inquired what +it meant, and were told that a road up the Rigi was to be made. The +Vitznauers were delighted, for they had no roads, and there was not a +wheeled vehicle in the town, nor a highway by which it could be brought +thither. The idea of a railroad in their desolate mountain region, and, +above all, a railroad up the Rigi, never entered their heads, and a +report which some time after obtained currency in the town, that the +laborers were beginning the construction of a railroad, was greeted with +a shout of derision. + +Nevertheless, that was the beginning of the Rigi line, and in May, 1871, +the road was opened for traffic. It begins at Vitznau, on Lake Lucerne, +and extends to the border of the canton and almost to the top of the +mountain. It is 19,000 feet long, and during that distance rises 4,000 +feet at an average grade of 1 foot in 4. Though steep, it is by no means +so much so as the Mt. Washington road, which rises 5,285 feet above the +sea, at an average of 1 foot in 3. There are, however, stretches of the +Rigi road at which the grade is about 1 foot in 2½, which is believed to +be the steepest in the world. + +The Rigi road has several special features aside from its terrific +slopes which entitle it to be considered a triumph of the engineer's +skill. About midway up the mountains the builders came to a solid mass +of rock, which presented a barrier that to a surface road was +impassable. They determined to tunnel it, and, after an enormous +expenditure of labor, finished an inclined tunnel 225 feet in length, of +the same gradient as the road. A gorge in the side of the mountain where +a small stream, the Schnurtobel, had cut itself a passage also hindered +their way, and was crossed by a bridge of lattice girder work in three +spans, each 85 feet long. The entire roadbed, from beginning to end, was +cut in the solid rock. A channel was chiseled out to admit the central +beam, which contains the cogs fitting the driving wheel of the +locomotive. The engine is in the rear of the train, and presents the +exceedingly curious feature of a boiler greatly inclined, in order that +at the steeper gradients it may remain almost perpendicular. The coal +and water are contained in boxes over the driving wheels, so that all +the weight of the engine is really concentrated on the cogs--a +precaution to prevent their slipping. The cost of the road, including +three of these strangely constructed locomotives, three passenger +coaches, and three open wagons, was $260,000, and it is a good paying +investment. The fare demanded for the trip up the mountains is 5 francs, +while half that sum is required for the downward passage, and the road +is annually traversed by from 30,000 to 50,000 passengers. + +Curious sensations are produced by a ride up this remarkable line. The +seats of the cars are inclined like the boiler of the locomotive, and so +long as the cars are on a level the seats tilt at an angle which renders +it almost impossible to use them. But when the start is made the +frightful tilt places the body in an upright position, and, with the +engine in the rear, the train starts up the hill with an easy, gliding +motion, passing up the ascent, somewhat steeper than the roof of a +house, without the slightest apparent effort. But if the going up +excites tremor, much more peculiar are the feelings aroused on the down +grade. The trip begins with a gentle descent, and all at once the +traveler looking ahead sees the road apparently come an end. On a nearer +approach he is undeceived and observes before him a long decline which +appears too steep even to walk down. Involuntarily he catches at the +seats, expecting a great acceleration of speed. Very nervous are his +feelings as the train approaches this terrible slope, but on coming to +the incline the engine dips and goes on not a whit faster than before +and not more rapidly on the down than on the up grade. Many people are +made sick by the sensation of falling experienced on the down run. Some +faint, and a few years ago one traveler, supposed to be afflicted with +heart disease, died of fright when the train was going over the +Schnurtobel bridge. The danger is really very slight, there not having +been a serious accident since the road was opened. The attendants are +watchful, the brakes are strong, but even with all these safeguards, men +of the steadiest nerves cannot help wondering what would become of them +in case anything went wrong. + +Bold as was the project of a railroad on the Rigi, a still bolder scheme +was broached ten years later, when a daring genius proposed a railroad +up Mt. Vesuvius. A railroad up the side of an ordinary mountain seemed +hazardous enough, but to build a line on the slope of a volcano, which +in its eruption had buried cities, and every few years was subject to a +violent spasm, seemed as hazardous as to trust the rails of an ordinary +line to the rotten river ice in spring time. The proposal was not, +however, so impracticable as it looked. While the summit of Vesuvius +changes from time to time from the frequent eruptions, and varies in +height and in the size of the crater, the general slope and contour of +the mountain are about the same to-day as when Vesuvius, a wooded hill, +with a valley and lake in the center of its quiescent crater, served as +the stronghold of Spartacus and his rebel gladiators. There have been +scores of eruptions since that in which Herculaneum and Pompeii were +overthrown, but the sides of the mountain have never been seriously +disturbed. + +A road on Vesuvius gave promise of being a good speculation. Naples and +the other resorts of the neighborhood annually attracted many thousands +of visitors, and a considerable number of these every year ascended the +volcano, even when forced to contend with all the difficulties of the +way. Many, however, desiring to ascend, but being unable or unwilling to +walk up, a chair service was established--a peculiar chair being slung +on poles and borne by porters. In course of time the chair service +proved to be inadequate for the numbers who desired to make the ascent, +and the time was deemed fit for the establishment of more speedy +communication. + +Notwithstanding the necessity, the proposal to establish a railroad met +with general derision, but the scheme was soon shown to be perfectly +practicable, and a beginning was made in 1879. The road is what is known +as a cable road, there being a single sleeper with three rails, one on +the top which really bore the weight, and one on each side near the +bottom, which supported the wheels, which coming out from the axle at a +sharp angle, prevented the vehicle from being overturned. The road +covers the last 4,000 feet of the ascent, and the power house is at the +bottom, a steel cable running up, passing round a wheel at the top and +returning to the engine in the power house. The ascent to the lower +terminus of the road is made on mules or donkeys; then, in a comfortable +car, the traveler is carried to a point not far from the crater. The car +is a combined grip and a passenger car, similar in some points to the +grip car of the present day, while the seats of the passenger portion +are inclined as in the cars on the Rigi road. But the angle of the road +being from thirty-three to forty-five degrees, makes both ascent and +descent seem fearfully perilous. Every precaution, however, is taken to +insure the safety of passengers; each car is provided with several +strong and independent brakes, and thus far no accident worth recording +has occurred. The road was opened in June, 1880. Although there have +been several considerable eruptions since that date, none of them did +any damage to the line but what was repaired in a few hours. + +The fashion thus set will, no doubt, be followed in many other quarters. +Wherever there is sufficient travel to pay working expenses and a profit +on a steep grade mountain road it will probably be built. Already there +is talk of a road on Mont Blanc, of another up the Yungfrau, and several +have been projected in the Schwartz and Hartz mountains. A route on Ben +Nevis, in Scotland, is already surveyed, and it is said surveys have +also been made up Snowden, with a view to the establishment of a road to +the summit of the highest Welsh peak. Sufficient travel is all that is +necessary, and when that is guaranteed, whenever a mountain possesses +sufficient interest to induce people to make its ascent in considerable +numbers, means of transportation, safe and speedy, will soon be +provided. The modern engineer is able, willing and ready to build a road +to the top of Mt. Everest in the Himalayas if he is paid for doing +so.--_St. Louis Globe-Democrat._ + + * * * * * + +To clean hair brushes, wash with weak solution of washing soda, rinse +out all the soda, and expose to sun. + + * * * * * + + + + +THE MARCEAU. + + +[Illustration: THE FRENCH ARMORED TURRET SHIP MARCEAU] + +The Marceau, the last ironclad completed and added to the French navy, +was put in commission at Toulon in April last, and has lately left that +town to join the French squadron of the north at Brest. The original +designs of this ship were prepared by M. Huin, of the French Department +of Naval Construction, but since the laying down of the keel in the year +1882 they have been very considerably modified, and many improvements +have been introduced. + +Both ship and engines were constructed by the celebrated French firm, +the Société des Forges et Chantiers de la Mediterranée, the former at +their shipyard in La Seyne and the latter at their engine works in +Marseilles. The ship was five years in construction on the stocks, was +launched in May, 1887, and not having been put in commission until the +present year, was thus nearly nine years in construction. She is a +barbette belted ship of somewhat similar design to the French ironclads +Magenta, now being completed at the Toulon arsenal, and the Neptune, in +construction at Brest. + +The hull is constructed partly of steel and partly of iron, and has the +principal dimensions as follows. Length, 330 ft. at the water line; +beam, 66 ft. outside the armor; draught, 27 ft. 6 in. aft.; +displacement, 10,430 English or 10,600 French tons. The engines are two +in number, one driving each propeller; they are of the vertical compound +type, and on the speed trials developed 11,300 indicated horse power +under forced and 5,500 indicated horse power under natural draught, the +former giving a speed of 16.2 knots per hour with 90 revolutions per +minute. The boilers are eight in number, of the cylindrical marine type, +and work at a pressure of 85.3 lb. per square inch. During the trials +the steering powers of the ship were found to be excellent, but the bow +wave is said, by one critic, to have been very great. + +The ship is completely belted with Creusot steel armor, which varies in +thickness from 9 in. forward to 17¾ in. midships. In addition to this +belt the ship is protected by an armored deck of 3½ in., while the +barbette gun towers are protected with 15¾ in. steel armor with a hood +of 2½ in. to protect the men against machine gun fire. As a further +means of insuring the life of the ship in combat and also against +accidents at sea, the Marceau is divided into 102 water-tight +compartments and is fitted with torpedo defense netting. There are two +masts, each carrying double military tops; and a conning tower is +mounted on each mast, from either of which the ship may be worked in +time of action, and both of which are in telegraphic communication with +the engine rooms and magazines. Provision is made for carrying 600 tons +of coal, which, at a speed of 10 knots, should be sufficient to supply +the boilers for a voyage of 4,000 miles. + +The armament of the Marceau is good for the tonnage of the ship and +consists principally of four guns of 34 centimeters (13.39 in.) of the +French 1884 model, having a weight of 52 tons, a length of 28½ calibers, +and being able to pierce 30 in. of iron armor at the muzzle. The +projectiles weigh 924 lb., and are fired with a charge of 387 lb. of +powder. The muzzle velocity has been calculated to be 1,968 ft. per +second. The guns are entirely of steel and are mounted on Canet +carriages in four barbette towers, one forward, one aft, and one on each +side amidships. On the firing trials both the guns and all the Canet +machinery, for working the guns and hoisting the ammunition, gave very +great satisfaction to all present at the time. In addition to the above +four heavy guns there are, in the broadside battery, sixteen guns of 14 +centimeters (5.51 in.), eight on each side, and a gun of equal caliber +is mounted right forward on the same deck. The armament is completed by +a large number of Hotchkiss quick-firing and revolver guns and four +torpedo tubes, one forward, one aft, and one on each side. + +The crew of the Marceau has been fixed at 600 men, and the cost is +stated to have been about $3,750,000.--_Engineering_. + + * * * * * + +[Continued from SUPPLEMENT, No. 820, page 13097.] + + + + +A REVIEW OF MARINE ENGINEERING DURING THE PAST DECADE.[1] + +[Footnote 1: Paper read before the Institution of Mechanical Engineers, +July 28, 1891.] + +BY MR. ALFRED BLECHYNDEN, OF BARROW-IN-FURNESS + + +_Steam Pipes_.--The failures of copper steam pipes on board the Elbe, +Lahn, and other vessels have drawn serious attention both to the +material and to the modes of construction of the pipes. The want of +elastic strength in copper is an important element in the matter; and +the three following remedies have been proposed, while still retaining +copper as the material. First, in view of the fact that in the operation +of brazing the copper may be seriously injured, to use solid drawn +tubes. This appears fairly to meet the main dangers incidental to +brazing; but as solid drawn pipes of over 7 inches diameter are +difficult to procure, it hardly meets the case sufficiently. Secondly, +to use electrically deposited tubes. At first much was promised in this +direction; but up to the present time it can hardly be regarded as more +than in the experimental stage. Thirdly, to use the ordinary brazed or +solid drawn tubes, and to re-enforce them by serving with steel cord or +steel or copper wire. This has been tried, and found to answer +perfectly. For economical reasons, as well as for insuring the minimum +of torsion to the material during manufacture, it is important to make +as few bends as possible; but in practice much less difficulty has been +experienced in serving bent pipes in a machine than would have been +expected. Discarding copper, it has been proposed to substitute steel or +iron. In the early days of the higher pressures, Mr. Alexander Taylor +adopted wrought iron for steam pipes. One fitted in the Claremont in +February, 1882, was recently removed from the vessel for experimental +purposes, and was reported upon by Mr. Magnus Sandison in a paper read +before the Northeast Coast Institution of Engineers and Shipbuilders.[2] +The following is a summary of the facts. The pipe was 5 inches external +diameter, and 0.375 inch thick. It was lap welded in the works of +Messrs. A. & J. Stewart. The flanges were screwed on and brazed +externally. The pipe was not lagged or protected in any manner. After +eight and a half years' service the metal measured where cut 0.32 and +0.375 inch in thickness, showing that the wasting during that time had +been very slight. The interior surface of the tube exhibited no signs of +pitting or corrosion. It was covered by a thin crust of black oxide, the +maximum thickness of which did not exceed 1/32 inch. Where the deposit +was thickest it was curiously striated by the action of the steam. On +the scale being removed, the original bloom on the surface of the metal +was exposed. It would thus appear that the danger from corrosion of iron +steam pipes is not borne out in their actual use; and hence so much of +the way is cleared for a stronger and more reliable material than +copper. So far the source of danger seems to be in the weld, which would +be inadmissible in larger pipes; but there is no reason why these should +not be lapped and riveted. There seems, however, a more promising way +out of the difficulty in the Mannesmann steel tubes which are now being +"spun" out of solid bars, so as to form weldless tubes. + +[Footnote 2: Transactions Northeast Coast Institution of Engineers and +Shipbuilders, vol. 7, 1890-91, p. 179.] + +TABLE I.--TENSILE STRENGTH OF GUN METAL AT HIGH TEMPERATURES. + +--------------+------------+-------------+-------------+------------+ + | | | | | + Composition |Temperature | Tensile | Elastic | Elongation | + of | of oil | strength | limit | in | + gun metal. | bath. | per square | per square | length of | + | | inch. | inch. | 2 inches | +--------------+------------+-------------+-------------+------------+ + Per cent. | Fahr. | Tons | Tons | Per cent. | + Copper 87 /| 50° | 12.34 | 8.38 | 14.64 | + Tin 8 / | | | | | + Zinc 3½ \ | | | | | + Lead 1½ \| 400° | 10.83 | 6.30 | 11.79 | +--------------+------------+-------------+-------------+------------+ + Copper 87 /| 50° | 13.86 | 8.33 | 20.30 | + Tin 8 { | | | | | + Zinc 5 \| 458° | 10.70 | 7.43 | 12.42 | +--------------+------------+-------------+-------------+------------+ + +Cast steel has been freely used by the writer for bends, junction +pieces, etc., of steam pipes, as well as for steam valve chests; and +except for the fact that steel makers' promises of delivery are +generally better than their performance, the result has thus far been +satisfactory in all respects. These were adopted because there existed +some doubt as to the strength of gun metal under a high temperature; and +as the data respecting its strength appeared of a doubtful character, a +series of careful tests were made to determine the tensile strength of +gun metal when at atmospheric and higher temperatures. The test bars +were all 0.75 in diameter, or 0.4417 square inch sectional area; and +those tested at the higher temperatures were broken while immersed in a +bath of oil at the temperature here stated, each line being the mean of +four experiments. The result of these experiments was to give somewhat +greater faith in gun metal as a material to be used under a higher +temperature; but as steel is much stronger, it is probably the most +advisable material to use, when the time necessary to procure it can be +allowed. + +_Feed Heating_.--With the double object of obviating strain on the +boiler through the introduction of the feed water at a low temperature, +and also of securing a greater economy of fuel, the principle of +previously heating the feed water by auxiliary means has received +considerable attention, and the ingenious method introduced by Mr. James +Weir has been widely adopted. It is founded on the fact that, if the +feed water as it is drawn from the hot well be raised in temperature by +the heat of a portion of steam introduced into it from one of the steam +receivers, the decrease of the coal necessary to generate steam from the +water of the higher temperature bears a greater ratio to the coal +required without feed heating than the power which would be developed in +the cylinder by that portion of steam would bear to the whole power +developed when passing all the steam through all the cylinders. The +temperature of the feed is of course limited by the temperature of the +steam in the receiver from which the supply for heating is drawn. +Supposing, for example, a triple expansion engine were working under the +following conditions without feed heating: Boiler pressure, 150 +lb.;--indicated horse power in high pressure cylinder 398, in +intermediate and low pressure cylinders together 790, total, 1,188; and +temperature of hot well 100° Fahr. Then with feed heating the same +engine might work as follows: The feed might be heated to 220° Fahr., +and the percentage of steam from the first receiver required to heat it +would be 12.2 per cent.; the indicated horse power in the high pressure +cylinder would be as before 398, and in the intermediate and low +pressure cylinders it would be 12.2 per cent, less than before, or 694, +and the total would be 1,092, or 92 per cent. of the power developed +without feed heating. Meanwhile the heat to be added to each pound of +the feed water at 220° Fahr. for converting it into steam would be 1,005 +units against 1,125 units with feed at 100° Fahr., equivalent to an +expenditure of only 89.4 per cent. of the heat required without feed +heating. Hence the expenditure of heat in relation to power would be +89.4 + 92.0 = 97.2 per cent., equivalent to a heat economy of 2.8 per +cent. If the steam for heating can be taken from the low pressure +receiver, the economy is about doubled. Other feed heaters, more or less +upon the same principle, have been introduced. Also others which heat +the feed in a series of pipes within the boiler, so that it is +introduced into the water in the boiler practically at boiling +temperature; this is economical, however, only in the sense that wear +and tear of the boiler is saved; in principle the plan does not involve +economy of fuel. + +_Auxiliary Supply of Fresh Water_.--Intimately associated with the feed +is the means adopted for making up the losses of fresh water due to +leakage of steam from safety valves, glands, joints, etc., and of water +discharged from the air pumps. A few years ago this loss was regularly +made up from the sea, with the result that the water in the boilers was +gradually increased in density; whence followed deposit on the internal +surfaces, and consequent loss of efficiency, and danger of accident +through overheating the plates. With the higher pressures now adopted, +the danger arising from overheating is much more serious, and the +necessity is absolute of maintaining the heating surfaces free from +deposit. This can be done only by filling the boiler with fresh water in +the first instance, and maintaining it in that condition. To do this two +methods are adopted, either separately or in conjunction. Either a +reserve supply of fresh water is carried in tanks or the supplementary +feed is distilled from sea water by special apparatus provided for the +purpose. In the construction of the distilling or evaporating apparatus +advantage has been taken of two important physical facts, namely, that, +if water be heated to a temperature higher than that corresponding with +the pressure on its surface, evaporation will take place; and that the +passage of heat from steam at one side of a plate to water at the other +is very rapid. In practice the distillation is effected by passing +steam, say from the first receiver, through a nest of tubes inside a +still or evaporator, of which the steam space is connected either with +the second receiver or with the condenser. The temperature of the steam +inside the tubes being higher than that of the steam either in the +second receiver or in the condenser, the result is that the water inside +the still is evaporated, and passes with the rest of the steam into the +condenser, where it is condensed, and serves to make up the loss. This +plan localizes the trouble of deposit, and frees it from its dangerous +character, because an evaporator cannot become overheated like a boiler, +even though it be neglected until it salts up solid; and if the same +precautions are taken in working the evaporator which used to be adopted +with low pressure boilers when they were fed with salt water, no serious +trouble should result. When the tubes do become incrusted with deposit, +they can be either withdrawn or exposed, as the apparatus is generally +so arranged; and they can then be cleaned. + +_Screw Propeller_.--In Mr. Marshall's paper of 1881 it was said that +"the screw propeller is still to a great extent an unsolved problem." +This was at the time a fairly true remark. It was true the problem had +been made the subject of general theoretical investigation by various +eminent mathematicians, notably by Professor Rankine and Mr. William +Froude, and of special experimental investigation by various engineers. +As examples of the latter may be mentioned the extended series of +investigations in the French vessel Pelican, and the series made by Mr. +Isherwood on a steam launch about 1874. These experiments, however, such +as they were, did little to bring out general facts and to reduce the +subject to a practical analysis. Since the date of Mr. Marshall's paper, +the literature on this subject has grown rapidly, and, has been almost +entirely of a practical character. The screw has been made the subject +of most careful experiments. One of the earliest extensive series of +experiments was made under the writer's direction in 1881, with a large +number of models, the primary object being to determine what value there +was in a few of the various twists which inventive ingenuity can give to +a screw blade. The results led the experimenters to the conclusion that +in free water such twists and curves are valueless as serving to augment +efficiency. The experiments were then carried further with a view to +determine quantitative moduli for the resistance of screws with +different ratios of pitch to diameter, or "pitch ratios," and afterward +with different ratios of surface to the area of the circle described by +the tips of the blades, or "surface ratios." As these results have to +some extent been analyzed and published, no further reference need be +made to them now. + +In 1886, Mr. R.E. Froude published in the Transactions of the +Institution of Naval Architects the deductions drawn from an extensive +series of trials made with four models of similar form and equal +diameter, but having different pitch ratios. Mr. S.W. Barnaby has +published some of the results of experiments made under the direction of +Mr. J.I. Thornycroft; and in his paper read before the Institution of +Civil Engineers in 1890 he has also put Mr. R.E. Froude's results into a +shape more suitable for comparison with practice. Nor ought Mr. G.A. +Calvert's carefully planned experiments to pass unnoticed, of which an +account was given in the Transactions of the Institution of Naval +Architects in 1887. These experiments were made on rectangular bodies +with sections of propeller blade form, moved through the water at +various velocities in straight lines, in directions oblique to their +plane faces; and from their results an estimate was formed of the +resistance of a screw. + +One of the most important results deduced from experiments on model +screws is that they appear to have practically equal efficiencies +throughout a wide range both in pitch ratio and in surface ratio; so +that great latitude is left to the designer in regard to the form of the +propeller. Another important feature is that, although these experiments +are not a direct guide to the selection of the most efficient propeller +for a particular ship, they supply the means of analyzing the +performances of screws fitted to vessels, and of thus indirectly +determining what are likely to be the best dimensions of screw for a +vessel of a class whose results are known. Thus a great advance has been +made on the old method of trial upon the ship itself, which was the +origin of almost every conceivable erroneous view respecting the screw +propeller. The fact was lost sight of that any modification in form, +dimensions, or proportions referred only to that particular combination +of ship and propeller, or to one similar thereto; so something like +chaos was the result. This, however, need not be the case much longer. + +In regard to the materials used for propellers, steel has been largely +adopted for both solid and loose-bladed screws; but unless protected in +some way, the tips of the blades are apt to corrode rapidly and become +unserviceable. One of the stronger kinds of bronze is often judiciously +employed for the blades, in conjunction with a steel boss. Where the +first extra expense can be afforded, bronze seems the preferable +material; the castings are of a reliable character, and the metal does +not rapidly corrode; the bronze blades can therefore with safety be made +lighter than steel blades, which favors their springing and +accommodating themselves more readily to the various speeds of the +different parts of the wake. This might be expected to result in some +slight increase of efficiency; of which, however, the writer has never +had the opportunity of satisfactorily determining the exact extent. +Instances can be brought forward where bronze blades have been +substituted for steel or iron with markedly improved results; but in +cases of this kind which the writer has had the opportunity of +analyzing, the whole improvement might be accounted for by the modified +proportions of the screw when in working condition. In other words, both +experiment and practical working alike go to show that, although cast +iron and steel blades as usually proportioned are sufficiently stiff to +retain their form while at work, bronze blades, being made much lighter, +are not; and the result is that the measured or set pitch is less than +that which the blades assume while at work. Some facts relative to this +subject have already been given in a recent paper by the author. + +_Twin Screws_.--The great question of twin screw propulsion has been put +to the test upon a large scale in the mercantile marine, or rather in +what would usually be termed the passenger service. While engineers, +however, are prepared to admit its advantages so far as greater security +from total breakdown is concerned, there is by no means thorough +agreement as to whether single or twin screws have the greater +propulsive efficiency. What is required to form a sound judgment upon +the whole question is a series of examples of twin and single screw +vessels, each of which is known to be fitted with the most suitable +propeller for the type of vessel and speed; and until this information +is available, little can be said upon the subject with any certainty. So +far the following large passenger steamers, particulars of which are +given in table II., have been fitted with twin screws. It appears t be a +current opinion that the twin screw arrangement necessitates a greater +weight of machinery. This is not necessarily so, however; on the +contrary, the opportunity is offered for reducing the weight of all that +part of the machinery of which the weight relatively to power is +inversely proportional to the revolutions for a given power. This can be +reduced in the proportion of 1 to the square root of 2, that is 71 per +cent. of its weight in the single screw engine; for since approximately +the same total disk area is required in both cases with similar +proportioned propellers, the twins will work at a greater speed of +revolution than the single screw. From a commercial point of view there +ought to be little disagreement as to the advantage of twin screws, so +long as the loss of space incurred by the necessity for double tunnels +is not important; and for the larger passenger vessels now built for +ocean service the disadvantage should not be great. Besides their +superiority in the matter of immunity from total breakdown, and in +greatly diminished weight of machinery, they also offer the opportunity +of reducing to some extent the cost of machinery. A slightly greater +engine room staff is necessary; but this seems of little importance +compared with the foregoing advantages. + +TABLE II.--PASSENGER STEAMERS FITTED WITH TWIN SCREWS. + +-----------------+-----------+-----+-----------+-------+--------+-------+ + | Length | | Cylinders, | Boiler |Indi- | + | between | | two sets in all |pressure|cated | + Vessels. | perpen- |Beam.| cases. | per |horse- | + | diculars. | |-----------+-------| square |power. | + | | |Diameters. |Stroke.| inch. | | +-----------------+-----------+-----+-----------+-------+--------+-------+ + | Feet. |Feet.| Inches. |Inches.| Lb. | | +City of Paris. |\ | | | | | | + | } 525 | 63¼ |45, 71, 113| 60 | 150 |20,000 | +City of New York.|/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Teutonic. |\ | | | | | | + | } 565 | 58 |43, 68, 110| 60 | 180 |18,000 | +Majestic. |/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Normannia. | 500 | 57½ |40, 67, 106| 66 | 160 |11,500 | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Columbia. | 463½ | 55½ |41, 66, 101| 66 | 160 |12,500 | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Empress of India.|\ | | | | | | +Empress of Japan.| } 440 | 51 |32, 51, 82 | 54 | 160 |10,125 | +Empress of China.|/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Orel. | 415 | 48 |34, 54, 85 | 51 | 160 |10,000 | +-----------------+-----------+-----+-----------+-------+--------+-------+ + +_Weight of Machinery Relatively to Power_.--It is interesting to compare +the weight of machinery relatively to the power developed; for this +comparison has sometimes been adopted as the standard of excellence in +design, in respect of economy in the use of material. The principle, +however, on which this has generally been done is open to some +objections. It has been usual to compare the weight directly with the +indicated horse-power, and to express the comparison in pounds per +horse-power. So long as the machinery thus compared is for vessels of +the same class and working at about the same speed of revolution, no +great fault can be found; but as speed of revolution is a great factor +in the development of power, and as it is often dependent on +circumstances altogether external to the engine and concerning rather +the speed of the ship, the engines fitted to high speed ships will thus +generally appear to greater advantage than is their due. Leaving the +condenser out of the question, the weight of an engine would be much +better referred to cylinder capacity and working pressures, where these +are materially different, than directly to the indicated power. The +advantages of saving weight of machinery, so long as it can be done with +efficiency, are well known and acknowledged. If weight is to be reduced, +it must be done by care in design, not by reduction of strength, because +safety and saving of repairs are much more important than the mere +capability of carrying a few tons more of paying load. It must also be +done with economy; but this is a matter which generally settles itself +aright, as no shipowner will pay more for a saving in weight than will +bring in a remunerative interest on his outlay. In his paper on the +weight of machinery in the mercantile marine,[3] Mr. William Boyd +discussed this question at some length, and proposed to attain the end +of reducing the weight of machinery by the legitimate method of +augmenting the speed of revolution and so developing the required power +with smaller engines. This method, while promising, is limited by the +efficiency of the screw, but may be adopted with advantage so long as +the increase in speed of revolution involves no such change in the screw +as to reduce its efficiency as a propeller. But when the point is +reached beyond which a further change involves loss of propelling +efficiency, it is time to stop; and the writer ventures to say that in +many cargo vessels now at work the limit has been reached, while in many +others it has certainly been passed. + +[Footnote 3: Transactions Northeast Coast Institution of Engineers and +Shipbuilders, vol. 6, 1889-90, p. 253.] + +_Economy of Fuel_.--Coming to the highly important question of economy +of fuel, the average consumption of coal per indicated horse-power is +1.522 lb. per hour. The average working pressure is 158.5 lb. per square +inch. Comparing this working pressure with 77.4 lb. in 1881, a superior +economy of 19 per cent. might be expected now, on account of the higher +pressure, or taking the 1.828 lb. of coal per hour per indicated +horse-power in 1881, the present performance under similar conditions +should be 1.48 lb. per hour per indicated horse-power. It appears that +the working pressures have been increased twice in the last ten years, +and nearly three times in the last nineteen. The coal consumptions have +been reduced 16.7 per cent. in the last ten years and 27.9 per cent. in +the last nineteen. The revolutions per minute have increased in the +ratios of 100, 105, 114; and the piston speeds as 100, 124, 140. +Although it is quite possible that the further investigations of the +Research Committee on Marine Engine Trials may show that the present +actual consumption of coal per indicated horse-power is understated, yet +it is hardly probable that the relative results will be affected +thereby. + +_Dimensions_.--In the matter of the power put into individual vessels, +considerable strides have been made. In 1881, probably the greatest +power which has been put into one vessel was in the case of the Arizona, +whose machinery indicated about 6,360 horse-power. The following table +gives an idea of the dimensions and power of the larger machinery in the +later passenger vessels: + +TABLE III.--DIMENSIONS AND POWER OF MACHINERY IN LATER PASSENGER +VESSELS. + +-----+----------------+-----------------------+-------+-----------+ + | | |Length | | +Year.| Name of vessel.| Diameters of | of |Indicated | + | | cylinders. |Stroke.|horsepower.| +-----+----------------+-----------------------+-------+-----------+ + | | Inches. |Inches.| | +1881 |Alaska | 68, 100, 100 | 72 | 10,686 | +-----+----------------+-----------------------+-------+-----------+ +1881 |City of Rome | 46, 86; 46, 86; 46, 86| 72 | 11,800 | +-----+----------------+-----------------------+-------+-----------+ +1881 |Servia | 72, 100, 100 | 78 | 10,300 | +-----+----------------+-----------------------+-------+-----------+ +1881 |Livadia yacht | 60, 78, 78; 60, 78, \| 39 | 12,500 | + | | 78; 60, 78, 78 /| | | +-----+----------------+-----------------------+-------+-----------+ +1883 |Oregon | 70, 104, 104 | 72 | 13,300 | +-----+----------------+-----------------------+-------+-----------+ +1884 |Umbria |\ 71, 105, 105 | 72 | 14,320 | +1884 |Etruria |/ | | | +-----+----------------+-----------------------+-------+-----------+ +1888 |City of New York|\ 45, 71, 113; \| 60 | 20,000 | +1889 |City of Paris |/ 45, 71, 113 /| | about | +-----+----------------+-----------------------+-------+-----------+ +1889 |Majestic |\ 43, 68, 110; \| 60 | 18,000 | +1889 |Teutonic |/ 43, 68, 110 /| | | +-----+----------------+-----------------------+-------+-----------+ + +In war vessels the increase has been equally marked. In 1881 the maximum +power seems to have been in the Inflexible, namely, 8,485 indicated +horse-power. The following will give an idea of the recent advance made: +Howe (Admiral class), 11,600 indicated horse-power; Italia and Lepanto, +19,000 indicated horse-power; Re Umberto, 19,000 indicated horse-power; +Blake and Blenheim (building), 18,000 indicated horse-power; Sardegna +(building), 22,800 indicated horse-power. It is thus evident that there +are vessels at work to-day having about three times the maximum power of +any before 1881. + +_General Conclusions_.--The progress made during the last ten years +having been sketched out, however roughly, the general conclusions may +be stated briefly as follows: First, the working pressure has been about +doubled. Second, the increase of working pressure and other improvements +have brought with them their equivalent in economy of coal, which is +about 20 per cent. Third, marked progress has been made in the direction +of dimension, more than twice the power having been put into individual +vessels. Fourth, substantial advance has been made in the scientific +principles of engineering. It only remains for the writer to thank the +various friends who have so kindly furnished him with data for some of +the tables which have been given; and to express the hope that the next +ten years may be marked by such progress as has been witnessed in the +past. But it must be remembered that, if future progress be equal in +merit or ratio, it may well be less in quantity, because advance becomes +more difficult of achievement as perfection is more nearly approached. + + * * * * * + + + + +THE LITTLE HOUSE. + +BY M.M. + + +One of the highest medical authorities is credited with the statement +that "nine-tenths of the diseases that afflict humanity are caused by +neglect to answer the calls of Nature." + +This state of affairs is generally admitted, but is usually attributed +to individual indolence. That, doubtless, has a great deal to do with +it, but should not part of the blame be laid upon the often unpleasant +environments, which make us shrink as from the performance of a painful +duty? + +In social life, unless from absolute necessity or charity, people of +refined habits do not call on those whose surroundings shock their sense +of decency; but when they go to pay the calls of Nature, they are often +compelled to visit her in the meanest and most offensive of abodes; +built for her by men's hands; for Nature herself makes no such mistakes +in conducting her operations. She does not always surround herself with +the pomp and pride of life, but she invariably hedges herself in with +the thousand decencies and the pomp of privacy. + +But what do we often do? We build what is sometimes aptly termed "an +out-house," because it is placed so that the delicate minded among its +frequenters may be made keenly alive to the fact that they can be +plainly seen by every passer-by and by every idle neighbor on the +lookout. This tiny building is seldom weatherproof; In consequence, keen +cold winds from above, below, and all around find ready entrance, chill +the uncovered person, frequently check the motions, and make the strong +as well as the weak, the young as well as the old, very sorry indeed +that they are so often uselessly obliged to answer the calls of Nature. +It is true, the floor is sometimes carpeted with snow, but the feet feel +that to be but cold comfort, though the door may enjoy rattling its +broken hasp and creaking its loose hinges. + +How often, too, are the nose and the eye offended by disregard of the +Mosaic injunction, found in the twelfth, thirteenth, and fourteenth +verses of the twenty-third chapter of Deuteronomy! Of course this +injunction was addressed to a people who had been debased by slavery, +but who were being trained to fit them for their high calling as the +chosen of God; but is not some such sanitary regulation needed in these +times, when a natural office is often made so offensive to us by its +environments that it is difficult for us to believe that "God made man a +little lower than the angels," or that the human body is the temple of +the Holy Ghost? + +Dwellers in the aristocratic regions of a well drained city, whose +wealth enables them to surround themselves with all devices tending to a +refined seclusion, may doubt all this, but sanitary inspectors who have +made a round of domiciliary visits in the suburbs, or the older, +neglected parts of a large city, of to any part of a country town or +village, will readily affirm as to its general truth. + +This unpardonable neglect of one of the minor decencies by the mass of +the people seems to be caused partly by a feeling of false shame, and +partly by an idea that it is expensive and troublesome to make any +change that will improve their sanitary condition or dignify their daily +lives. + +The Rev. Henry Moule, of Fordington Vicarage, Dorsetshire, England, was +one of the first to turn his attention to this matter. With the +threefold object of improving the sanitary condition of his people, +refining their habits, and enriching their gardens, he invented what he +called the "dry earth closet." + +"It is based on the power of clay and the decomposed organic matter +found in the soil to absorb and retain all offensive odors and all +fertilizing matters; and it consists, essentially, of a mechanical +contrivance (attached to the ordinary seat) for measuring out and +discharging into the vault or pan below a sufficient quantity of sifted +dry earth to entirely cover the solid ordure and to absorb the urine. + +"The discharge of earth is effected by an ordinary pull-up, similar to +that used in the water closet, or (in the self-acting apparatus) by the +rising of the seat when the weight of the person is removed. + +"The vault or pan under the seat is so arranged that the accumulation +can be removed at pleasure. + +"From the moment when the earth is discharged and the evacuation +covered, all offensive exhalation entirely ceases. Under certain +circumstances there may be, at times, a slight odor as of guano mixed +with earth, but this is so trifling and so local that a commode arranged +on this plan may, without the least annoyance, be kept in use in any +room." + +The "dry earth closet" of the philanthropic clergyman was found to work +well, and was acceptable to his parishioners. One reason why it was so +was because dry earth was ready to hand, or could be easily procured in +a country district where labor was cheap. But where labor was dear and +dry earth scarce, those who had to pay for the carting of the earth and +the removal of the deodorized increment found it both expensive and +troublesome. + +But a modification of this dry earth closet, the joint contrivance of an +English church clergyman and his brother, "the doctor," residents of a +Canadian country town, who had heard of Moule's invention, is a good +substitute, and is within the reach of all. This will be briefly +described. + +The vault was dug as for an ordinary closet, about fifteen feet deep, +and a rough wooden shell fitted in. About four feet below the surface of +this wooden shell a stout wide ledge was firmly fastened all around. +Upon this ledge a substantially made wooden box was placed, just as we +place a well fitting tray into our trunks. About three feet of the back +of the wooden shell was then taken out, leaving the back of the box +exposed. From the center of the back of the box a square was cut out and +a trap door fitted in and hasped down. + +The tiny building, on which pains, paint, and inventive genius had not +been spared to make it snug, comfortable, well lighted and well +ventilated, was placed securely on this vault. + +After stones had been embedded in the earth at the back of the vault, to +keep it from falling upon the trap door, two or three heavy planks were +laid across the hollow close to the closet. These were first covered +with a barrowful of earth and then with a heap of brushwood. + +Within the closet, in the left hand corner, a tall wooden box was +placed, about two-thirds full of dry, well sifted wood ashes. The box +also contained a small long-handled fire shovel. When about six inches +of the ashes had been strewn into the vault the closet was ready for +use. No; not quite; for squares of suitable paper had to be cut, looped +together with twine, and hung within convenient reaching distance of the +right hand; also a little to the left of this pad of paper, and above +the range of sight when seated, a ten pound paper bag of the toughest +texture had to be hung by a loop on a nail driven into the corner. + +At first the rector thought that his guests would be "quick-witted +enough to understand the arrangement," but when he found that the +majority of them were, as the Scotch say, "dull in the uptak," he had to +think of some plan to enforce his rules and regulations. As +by-word-of-mouth instructions would have been rather embarrassing to +both sides, he tacked up explicit written orders, which must have +provoked many a smile. Above the bin of sifted ashes he nailed a card +which instructed "Those who use this closet must strew two shovelfuls of +ashes into the vault." Above the pad of clean paper he tacked the +thrifty proverb: "Waste not, want not;" and above the paper bag he +suspended a card bearing this warning: "All refuse paper must be put +into this bag; not a scrap of clean or unclean paper must be thrown into +the vault." + +This had the desired effect. Some complacently united to humor their +host's whim, as they called it, and others, immediately recognizing its +utility and decency, took notes with a view to modifying their own +closet arrangements. + +Sarah, the maid of all work, caused a good deal of amusement in the +family circle by writing her instructions in blue pencil on the front of +the ash bin. These were: "Strew two shuffefuls of ashes into the volt, +but don't spill two shuffefuls onto the floor. By order of the Gurl who +has to sweap up." This order was emphatically approved of by those +fastidious ones who didn't have to "sweep up." + +This closet opened off the woodshed, and besides being snugly +weatherproof in itself, was sheltered on one side by the shed and on +another by a high board fence. The other two sides were screened from +observation by lattice work, outside of which evergreens were planted to +give added seclusion and shade. A ventilator in the roof and two sunny +little windows, screened at will from within by tiny Venetian shutters, +gave ample light and currents of fresh air. For winter use, the rector's +wife and daughters made "hooked" mats for floor and for foot support. +These were hung up every night in the shed to air and put back first +thing in the morning. For the greater protection and comfort of +invalids, an old-fashioned foot warmer, with a handle like a basket, was +always at hand ready to be filled with live coals and carried out. + +The little place was always kept as exquisitely clean as the dainty, +old-fashioned drawing room, and so vigilant was the overseeing care +bestowed on every detail, that the most delicate and acute sense of +smell could not detect the slightest abiding unpleasant odor. The paper +bag was frequently changed, and every night the accumulated contents +were burned; out of doors in the summer, and in the kitchen stove--after +a strong draught had been secured--in the winter. + +At stated times the deodorized mass of solid increment--in which there +was not or ought not to have been any refuse paper to add useless +bulk--was spaded, through the trap door, out of the box in the upper +part of the vault, into a wheelbarrow, thrown upon the garden soil, and +thoroughly incorporated with it. In this cleansing out process there was +little to offend, so well had the ashes done their concealing +deodorizing work. + +In using this modified form of Moule's invention, it is not necessary to +dig a deep vault. The rector, given to forecasting, thought that some +day his property might be bought by those who preferred the old style, +but his brother, the doctor, not troubling about what might be, simply +fitted his well made, four feet deep box, with its trap door, into a +smoothly dug hole that exactly held it, and set the closet over it. In +all other respects it was a model of his brother's. + +This last is within the reach of all, even those who live in other +people's houses; for, when they find themselves in possession of an +unspeakably foul closet, they can cover up the old vault and set the +well cleaned, repaired, fumigated closet upon a vault fashioned after +the doctor's plan. A stout drygoods box, which can be bought for a +trifle, answers well for this purpose, after a little "tinkering" to +form a trap door. + +Of course, dry earth is by far the best deodorizer and absorbent, but +when it cannot be easily and cheaply procured, well sifted wood or coal +ashes--wood preferred--is a good substitute. The ashes must be kept dry. +If they are not, they lose their absorbing, deodorizing powers. They +must also be well sifted. If they are not, the cinders add a useless and +very heavy bulk to the increment. + +An ash sifter can be made by knocking the bottom out of a shallow box, +studding the edge all round with tacks, and using them to cross and +recross with odd lengths of stovepipe wire to form a sieve.--_The +Sanitarian_. + + * * * * * + + + + +THE HYGIENIC TREATMENT OF OBESITY.[1] + +[Footnote 1: Translated by Mr. Jos. Helfman, Detroit, Mich.] + +BY DR. PAUL CHERON. + + +In order to properly regulate the regimen of the obese, it is first +necessary to determine the source of the superfluous adipose of the +organism, since either the albuminoids or the hydrocarbons may furnish +fat. + +Alimentary fat becomes fixed in the tissues, as has been proved by +Lebede, who fed dogs, emaciated by long fast, with meat wholly deprived +of fat, and substituted for the latter linseed oil, when he was able to +recover the oil in each instance from the animal; parallel experiments +with mutton fat, _in lieu_ of oil, afforded like results. + +Hoffman also deprived dogs of fat for a month, causing them to lose as +high as twenty-two pounds weight, then began nourishing with bacon fat +with but little lean; the quantity of fat formed in five days, in the +dog that lost twenty-two pounds, was more than three pounds, which could +have been derived only from the bacon fat. + +It has been stated, however, that alimentary fat seems to preserve from +destruction the fat of the organism which arises from other sources. Be +this as it may, it is a fact that the pre-existence of fat furthers the +accumulation of more adipose; or in other words, fat induces fattening! + +That adipose may be formed through the transformation of albuminous +matters (meat) is an extremely important corollary, one established +beyond cavil by Pettinkofer and Voit, in an indirect way, by first +estimating the nitrogen and carbon ingested, and second the amount +eliminated. Giving a dog meat that was wholly deprived of fat, they +found it impossible to recover more than a portion of the contained +carbon; hence some must necessarily have been utilized in the organism, +and this would be possible only by the transformation of the carbon into +fat! It goes without saying, however, that the amount of adipose thus +deposited is meager. + +Other facts also plead in favor of the transformation of a portion of +albumen into fat within the economy, notably the changing of a portion +of dead organism into what is known as "cadaveric fat," and the very +rapid fatty degeneration of organs that supervenes upon certain forms of +poisoning, as by phosphorus. + +The carbohydrates, or more properly speaking hydrocarbons, are regarded +by all physiologists as specially capable of producing fat, and numerous +alimentary experiments have been undertaken to prove this point. +Chaniewski, Meissl, and Munk obtained results that evidenced, +apparently, sugar and starch provide more fat than do the albuminoids. +Voit, however, disapproves this, maintaining the greater part of the +hydrocarbons is burned (furnishes fuel for the immediate evolution of +force), and that fat cannot be stored up unless a due proportion of +albuminoids is also administered. He believes the hydrocarbons exert a +direct influence only; being more oxidizable than fats, they guard the +latter from oxidation. This protective role of the hydrocarbons applies +also to the albuminoids. + +We may believe, then, that the three great classes of aliment yield fat, +in some degree; that alimentary fat may be fixed in the tissues; and +that hydrocarbons favor the deposition of adipose either directly or +indirectly. + +It is well understood that fat may disappear with great rapidity under +certain conditions; many maladies are accompanied by speedy emaciation; +therefore, as fat never passes into the secretions, at least not in +appreciable quantities, it probably undergoes transformation, perhaps by +oxidation or a form of fermentation, the final results of which are, +directly or indirectly, water and cadaveric acid. It is certain the +process of oxidation favors the destruction of adipose, and that +everything which inhibits such destruction tends to fat accumulation. + +Since the earliest period of history, there seems to have been an +anxiety to secure some regimen of general application that would reduce +or combat obesity. Thus Hippocrates says: + +Fat people, and all those who would become lean, should perform +laborious tasks while fasting, and eat while still breathless from +fatigue, without rest, and after having drunk diluted wine not very +cold. Their meats should be prepared with sesamum, with sweets, and +other similar substances, and these dishes should be free from fat. + +In this manner one will be satiated through eating less. + +But, besides, one should take only one meal; take no bath; sleep on a +hard bed; and walk as much as may be. + +How much has medical science gained in this direction during the +interval of more than two thousand years? Let us see: + +First among moderns to seek to establish on a scientific basis a regimen +for the obese, was Dancel, who forbade fats, starchy foods, etc., +prescribed soups and aqueous aliment, and reduced the quantity of +beverage to the lowest possible limit; at the same time he employed +frequent and profuse purgation. + +This regimen, which permits, at most, but seven to twelve ounces of +fluid at each repast, is somewhat difficult to follow, though it may be +obtained, gradually, with ease. Dr. Constantine Paul records a case in +which this regimen, gradually induced, and followed for ten years, +rewarded the patient with "moderate flesh and most excellent health." + +In Great Britain, a mode of treatment instituted in one Banting, by Dr. +Harvey, whereby the former was decreased in weight forty pounds, has +obtained somewhat wide celebrity; and what is more remarkable, it is +known as "Bantingism," taking its name from the patient instead of the +physician who originated it. The dietary is as follows: + +_Breakfast_.--Five to six ounces of lean meat, broiled fish, or smoked +bacon--veal and pork interdicted; a cup of tea or coffee without milk or +sugar; one ounce of toast or dry biscuit (crackers). + +_Dinner_.--Five or six ounces of lean meat or fish--excluding eel, +salmon, and herring; a small quantity of vegetables, but no potatoes, +parsnips, carrots, beets, peas, or beans; one ounce of toast, fruit, or +fowl; two glasses of red wine--beer, champagne, and port forbidden. + +_Tea_.--Two or three ounces of fruit; one kind of pastry; one cup of +tea. + +_Supper_.--Three or four ounces of lean beef or fish; one or two glasses +of red wine. + +_At bed-time._--Grog without sugar (whisky and water, or rum and water), +and one or two glasses of sherry or Bordeaux. + +"Bantingism," to be effective, must be most closely followed, when, +unfortunately also, it proves extremely debilitating; it is suitable +only for sturdy, hard riding gluttons of the Squire Western type. The +patient rapidly loses strength as well as flesh, and speedily acquires +an unconquerable repugnance to the dietary. Further, from a strictly +physiological point of view, the quantity of meat is greatly in excess, +while with the cessation of the regimen, the fat quickly reappears. + +Next Ebstein formulated a dietary that is certainly much better +tolerated than that of Harvey and Banting, and yields as good, or even +better, results. He allows patients to take a definite quantity--two to +two and a half ounces-of fat daily, in the form of bacon or butter +which, theoretically at least, offers several advantages: It diminishes +the sensations of hunger and thirst, and plays a special role with +respect to the albuminoids; the latter may thus be assimilated by the +economy without being resolved into fat, and thus the adipose of the +organism at this period is drawn upon without subsequent renewal. The +following is the outline: + +_Breakfast_.--At 6 a.m. in summer; 7:30 in winter:--Eight ounces of +black tea without either milk or sugar; two ounces of white bread or +toast, with a copious layer of butter. + +_Dinner_.--2 p.m.:--A modicum of beef marrow soup; four ounces of meat, +preferably of fatty character; moderate quantity of vegetable, +especially the legumines, but no potatoes or anything containing starch; +raw fruits in season, and cooked fruits (stewed, without sugar); two or +three glasses of light wine as a beverage, and after eating, a cup of +black tea without sugar. + +_Supper_.--7:30 p m.:--An egg, bit of fat roast, ham, or bacon; a slice +of white bread well buttered; a large cup of black tea without milk or +sugar; from time to time, cheese and fresh fruits. + +Germain See suggests as a modification of this regimen, the abundant use +of beverage, the addition of gelatins, and at times small doses of +potassium iodide in twenty cases he claims constant and relatively +prompt results. + +Whatever may be urged for Ebstein's system--and it has afforded most +excellent results to Unna and to Lube, as well as its author--it +certainly exposes the patient to the terrors of dyspepsia, when the +routine must needs be interrupted or modified; hence it is not always to +be depended upon. As between dyspepsia and obesity, there are few, I +fancy, who would not prefer the latter. + +Another "system" that has acquired no little celebrity, and which has +for its aim the reduction as far as possible of alimentary hydrocarbons +while permitting a certain proportion of fat, is that, of Denneth, which +necessarily follows somewhat closely the lines laid down by Ebstein. + +Oertels' treatment, somewhat widely known, and not without due measure +of fame, is based upon a series of measures having as object the +withdrawal from both circulation and the economy at large, as much of +the fluids as possible. It is especially adapted for the relief of those +obese who are suffering fatty degeneration of the heart. The _menu_ is +as follows: + +_Breakfast_.--Pour to five ounces of tea or coffee with a little milk; +two to two and a half ounces bread. + +_Dinner_.--Three or four ounces of roast or boiled meat, or moderately +fat food; fish, slightly fat; salad and vegetables at pleasure; one and +a half ounces of bread (in certain cases as much as three ounces of +farinaceous food may be permitted); three to six ounces of fruit; at +times a little pastry for dessert.--In summer, if fruit is not +obtainable, six to eight ounces of light wine may be allowed. + +_Tea_,--A cupful (four to five ounces) of tea or coffee, with a trifle +of milk, as at breakfast; one and three-fourths ounces of bread; and +exceptionally (and at most) six ounces of water. + +_Supper_.--One to two soft boiled eggs; four or five ounces of meat; one +and three fourths ounces of bread; a trifle of cheese, salad, or fruit; +six to eight ounces of light wine diluted with an eighth volume of +water. The quantity of beverage may be slightly augmented at each meal +if necessary, especially if there is no morbid heart trouble. + +Schwenninger (Bismarck's physician), who opened a large sanitarium near +Berlin a few years since for the treatment of the obese, employs +Oertel's treatment, modified in that an abundance of beverage is +permitted, provided it is not indulged in at meals; it is forbidden +until two hours after eating. + +Both Oertel's and Schwenninger's methods have procured grave dyspepsias, +and fatal albuminurias as well, according to Meyer and Rosenfield. It +has been charged the allowance of beverage upon which Schwenninger lays +so much stress in the treatment at his sanitarium has a pecuniary basis, +in other words a commission upon the sale of wines.[2] + +[Footnote 2: The sanitarium is owned by a stock company, Schwenninger +being merely Medical Director.--ED.] + +Thus, it will be observed that while some forbid beverage, others rather +insist upon its employment in greater or less quantities. Under such +circumstances, it would seem but rational, before undertaking to relieve +obesity, to establish its exact nature, and also the role taken by +fluids in the phenomena of nutrition. + +Physiologists generally admit water facilitates nutritive exchanges, +which is explained by the elimination of a large quantity of urine; the +experiments of Genth and Robin in this direction appear conclusive. + +Bischoff, Voit, and Hermann have shown that water increases, not alone +the elimination of urine, but also of sodium chloride, phosphoric acid, +etc. Grigoriantz observed augmentation of disintegration when the +quantity of beverage exceeded forty-six to eighty ounces ("1,400 to +2,400 cubic centimeters") per diem. Oppenheim, Fraenkel, and Debove, +while believing water has but little influence upon the exchanges, admit +it certainly need not diminish the latter; and Debove and Flament, after +administering water in quantities varying from two to eight pints per +diem, concluded that urine was diminished below the former figure, while +above the latter it increased somewhat, being dependent upon the amount +ingested. It was on the strength of the foregoing that Lallemand +declared water to have no influence upon the exchanges. + +The results claimed by Oppenheim, Debove, et al. were immediately +challenged--and it is now generally admitted, not without some +justice--by Germain See. It seems certain, to say the least, that water +taken during the repast does tend to augment the quantity and facilitate +the elimination of urine. Abundance of beverage, moreover, presents +other advantages, in that it facilitates digestion by reason of its +diluent action, a fact well worth bearing in mind when treating the +obese who are possessed of gouty diathesis, and whose kidneys are +accordingly encumbered with uric and oxalic acids. The foregoing +presents the ground upon which Germain See permits an abundance of +beverage; but he also expresses strong reservation as regards beer and +alcohol, either of which (more especially the former) tends to the +production of adipose. In his opinion, the only beverage of the +alcoholic class that is at all permissible, and then only for cases +suffering from fatty heart, is a little _liqueur_ or diluted wine. +Coffee and tea he commends highly, and recommends the ingestion of large +quantities at high temperature, both during the repasts and their +intervals. Coffee in large doses is undoubtedly a means of de-nutrition, +and so, too, in no less extent, is tea; both act vigorously owing to the +contained alkaloids, though, to be sure, they sometimes, at first, tend +to insomnia and palpitation, to which no attention need be paid, +however. The treatment outlined by See is: + +1. A physiological regimen comprising four to five ounces of nitrogenous +principles as derived from eight to ten ounces animal muscle and +albuminates; three to six ounces of fat; eight to ten ounces of +hydrocarbons as yielded by ten to twelve ounces of sugar or starch food. + +These proportions to be modified in such manner that the +musculo-albuminates shall not sensibly exceed the normal ratio, for meat +in excess itself furnishes fat during transformation. The fatty +substances of easy digestion may, without inconvenience, be utilized in +doses of two to three ounces. The hydrocarbons should be reduced to a +minimum. As for the herbaceous elements, they contain nothing nutritive. + +2. Beverage, far from being suppressed, should be augmented, in order to +facilitate stomachal digestion and promote general nutrition, though +alcoholic liquids must be inhibited; likewise mineral waters, except, +perhaps, for occasional use. Both should be replaced by infusions of +coffee or tea, taken as hot as can be drank. + +Henrich Kisch insists that any method which promises rapid and marked +decrease of adipose must, _per se_, be objectionable, even if not +positively injurious, since it tends to provoke general troubles of +nutrition. He suggests that first the fats and hydrocarbons be reduced +as little as possible; that a moderate mixed regimen is required, +containing a preponderance of albumen, small quantities of hydrocarbons +and gelatinous matters, with but very little fat. Certain fatty meats, +however, should be generally interdicted, such as pork sausage, smoked +beef tongue, goose breast, smoked ham, fat salmon, and herring in any +form. Eggs, however, may be partaken of in moderation, giving preference +to the albumen over the yelk. Farinaceous foods, in the main, should be +rejected, even bread being allowed only in small quantities, and then +preferably in the form of toast. Cheese likewise contains too much fat; +and mushrooms are so rich in hydrocarbons that they should be rejected. +Condiments, water, vegetable acids (vinegars excepted) may be permitted; +especially pernicious is vinegar where there is any tendency to gout or +gravel. All fatty beverages--_bouillon_, unskimmed milk, chocolate, or +cacao--and all alcoholics, are hurtful; breakfast tea is undoubtedly the +best beverage, but, after a little, is advantageously replaced by light +white wine diluted with water. + +Kisch believes in a free and abundant use of water by the obese, +especially where there is a tendency to plethora, since this fluid +facilitates oxidation as the result of absorption; thus he advocates the +inhibition of large quantities of cold water by all, save those +presenting evidence of cardiac insufficiency. In short, his regimen is +based upon the administration of a large quantity of albumen, like that +of Harvey-Banting. + +E. Munk recommends an almost identical dietary, save that he prefers +great moderation in fluids employed as beverage. + +M. Robin has sought to harmonize the opposing views regarding fluids, +and therefore declares obesity arises from two distinct sources: 1. +Augmentation of assimilation. 2. Reduced disassimilation. In the former, +he insists water must be interdicted, while in the latter it may be +allowed _ad libitum_. + +Again, in order to recognize the exact variety of obesity, he divides +his patients into three classes, each recognizable by the volume of urea +excreted. In the first there is an increase above normal; in the second +the volume of urea is stationary; in the third decreased, increased, or +stationary. + +When the urea is stationary, which is most frequently the case, it is +necessary to calculate the coefficient of oxidation; that is, the +relation existing between the solid matters of the urine and the urea. +The elevation of the coefficient is _prima facie_ evidence the obesity +is due to excess of assimilation, while depression of the coefficient +indicates default of assimilation. In the first case, water and liquids +must be denied as far as possible, the same as if there was no +augmentation of urea; in the second, the same as if there was diminution +of urea, the patients may be permitted to imbibe fluids at pleasure. + +For the obese from default of disassimilation, Robin recommends a +regimen of green vegetables and bread chiefly--the latter in small +quantities, however, and fluids as may be desired. By this means, on one +occasion, he was able in the course of one month to diminish the weight +of a female patient by twelve and a half pounds, her measurement around +the waist at the same time decreasing 5.2 inches and across the stomach +4.8 inches. + +M. De St. Germain achieved good results by combining judicious exercise +with moderate alimentation, excluding wine and bread. + +M. Dujardin Beaumetz, who professes to have given most close and careful +study and attention to regimen for the obese, outlines the following, +provided there is no evidence of fatty degeneration of heart. + +_Breakfast_ (at 8 a. m.)--Three-fourths of an ounce of bread "_en +flute_"--that is abounding with crust; one and a half ounces of cold +meat, ham or beef, six ounces weak black tea, _sans_ sugar. + +_Lunch_ (at 1 p.m.)--An ounce and a half to two ounces of bread, or a +_ragout_, or two eggs; three ounces green vegetables; one-half ounce of +cheese; fruits at discretion. + +_Dinner_ (at 7 p.m.)--An ounce and a half to two ounces of bread; three +to four ounces of meat, or _ragout_; ditto of green vegetables, salad, +half an ounce of cheese, fruit _ad libitum_. + +At meal times the patient may take only a "glass and a half" of +liquid--approximately ten ounces--though a greater amount may be +permitted if he abstains during the intervals. + +Special alimentary regimen, however, does not constitute the sole +treatment of obesity. Concurrently must be employed a number of +practical adjuvants which are oftentimes of the utmost assistance. For +one thing, exercise is indispensable; all authorities agree on this +point. The exercise taken in the gymnasium is one of the best, notably +the "wall exercise," which is more particularly suited to those +afflicted with pendulous and protuberant abdomens as the result of +feebleness of the hypogastric muscles, to accumulation of fat under the +skin and in the omentum, and to dilation of the stomach and intestines. +In the "wall exercise," the patient stands erect against an absolutely +straight and plumb wall, lifts his hands (carrying a weight) straight +over the head, and causes them to describe a semicircle forward. Zantz +particularly insists upon arm and leg exercise for the obese, especially +the former, since with the same amount of effort a larger amount of +oxygen is consumed than is possible by the latter. + +However, of whatever character, the exercise should be continued to the +point of fatigue or dyspnoea--three thousand movements daily, +gradually increased to twenty-five thousand, if the system can bear it; +and under such conditions, not only is there consumption of +hydrocarbons, but there is provided a veritable greed for air that +augments waste. The experiments of Oertel indicate that loss of weight +due to fatiguing exercise arises more particularly from dehydration, +which is made good by absorption of the fluids employed as beverage; the +fluids are claimed by Germain See to act as accelerants of oxidation. + +During exercise there is obviously more abundant absorption of oxygen, +and consequently greater elimination of carbonic acid, and as a +consequence (as shown by researches of Voit), the reserve fat of the +economy is attacked and diminished; in intense labor there is an average +hourly consumption of about 8.2 percent. of fat. Further physical +activity is useful in exercising the voluntary muscles, and thus +opposing the invasion by interstitial fat of the muscle fibrils. Extreme +exercise also, to a certain degree, exerts a favorable influence on the +cardiac muscle, augmenting both its nutrition and its capacity for +labor. With the anæmic obese, however, it is necessary to be most +circumspect in prescribing forced exercise; also with the elderly obese +possessed of enfeebled or fatty heart. + +Hydrotherapy, especially in the form of cold douches, particularly when +combined with massage, is often of considerable value in relieving +obesity; the method of Harmman, of St. Germain, which has in many +instances induced rapid loss of adipose, is of this class. Tepid saline +baths and vapor baths have many advocates, and may afford material aid +when the heart and circulation do not inhibit their employment. Hot +baths elevate the temperature of the body and increase the organic +exchanges, hence, as Bert and Reynard have pointed out, tend to the +elimination of oxygen and carbonic acid; but when employed, the patient +should be introduced while the temperature is below 130° F., when it may +be gradually raised in the course of thirty or forty minutes to 140° F. + +It has already been intimated, the chief feature of the treatment of +obesity is acceleration of the exchanges; and this is in the main true, +though it must also be borne in mind that, while there are obese who +excrete little urea and have a depressed central nervous temperature, +many may be azoturic, and besides eliminate phosphate in excess, when an +oxidating treatment will not only fail, but prove positively injurious. + +The bile throws out fat, therefore, to accelerate nutritive oxidations, +the liver and nervous system must be acted upon, _i.e._, stimulated. +Everything that tends to diminish the activity of the former, or depress +the latter, must be avoided. Hence intellectual labor should be +encouraged, or in lieu thereof, travel advised. Exercise should be taken +chiefly while fasting; the limits of sleep confined to strict necessity, +and _siestas_ after meals and during the day strictly forbidden; the +skin stimulated by hydro-therapeutic measures, including massage under +cold affusions, during warm salt baths, etc. + +To increase the activity of the liver, salicylate of soda may often be +advantageously administered for its cholagogue effect; or resort may be +had to saline purgatives such as are afforded by the springs of +Marienbad, Kissengen, Homburg, Carlsbad, Brides, Hunyadi, or +Chatel-Guyon; and it is somewhat remarkable that while undergoing a +course of these waters, there is often no appreciable change in weight +or obesity, though the decrease becomes most marked almost immediately +upon cessation of treatment. + +Everything tending to increased or fuller respiration is to be +encouraged, for the fats are thus supplied with oxygen, hastening their +disintegration and consumption. + +Direct medicinal treatment presents no very wide scope. Bouchard +imagines lime water may be useful by accelerating nutrition, but this is +problematical, since fat in emulsion or in droplets does not burn. +Nevertheless, alkalies in general, alkaline carbonates, liquor potassa, +soaps, etc., aid in rendering fat more soluble, and consequently more +susceptible to attack. The alkaline waters, however, are much less +active in obesity than the saline mineral waters, unless, as sometimes +happens, there is a complication of diabetes and obesity. + +Purgatives are always more or less useful, and often required to be +renewed with all the regularity of habit. Then too, the iodides, +especially iodide of sodium or potassium, as recommended by M. Germain +See, frequently prove of excellent service by aiding elimination and +facilitating the mutations. + +According to Kisch, the cold mineral waters containing an abundance of +sulphate of soda, like Hunyadi and Marienbad, are to be preferred to the +hot mineral waters, such as Carlsbad, because of their lesser irritant +action on the vascular system, and because they strongly excite diuresis +through their low temperature and contained carbonic acid; Carlsbad +deserves preference only when obesity is combined with uric acid +calculi, or with diabetes. For very anæmic persons, however, the weak +alkaline and saline waters should be selected; or they should confine +themselves to chalybeate waters containing an excess of sulphate of +soda. Water containing sulphate of soda is also indicated as a beverage +where there are troubles of the circulatory apparatus; it is +contraindicated only in accentuated arterio-sclerosis. + +As a matter of fact, I find the suggestion of M. Dujardin-Beaumetz, +that the obese should be divided into two groups, a most practical one, +for some are strong and vigorous--great eaters, perhaps even +gluttons--while others, on the contrary, are feeble and debilitated, +with flesh soft and flaccid; and upon the former may be imposed all the +rigors of the reducing system, while the latter must be dealt with more +carefully. + +In general, it must be noted, the regimen prescribed for the obese is +insufficient, as the following table prepared by M.C. Paul abundantly +proves: + + -------------------------+----------+----------+--------------- + Author. |Albuminous| Fatty | + | Matters. | Matters. | Hydrocarbons. + -------------------------+----------+----------+--------------- + Voit. | 118 | 40 | 150 + Harvey-Banting. | 170 | 10 | 80 + Ebstein. | 100 | 85 | 50 + Oertel. | 155-179 | 25-41 | 70-110 + Kisch (plethoric). | 160 | 10 | 80 + " (anæmic). | 200 | 12 | 100 + Normal ration. | 124 | 55 | 455 + -------------------------+----------+----------+--------------- + +There is, therefore, as Dujardin-Beaumetz asserts, autophagia in the +obese, and all these varieties of treatment have but one end, viz.: +Reduction of the daily ration. But the quantity of nourishment should +not be too greatly curtailed, for, manifestly, if the fat disappears the +more surely, the muscles (rich in albumen) undergo too rapid +modification. It is progressive action that should always be sought. + +The quantity of aliment may be reduced either by imposing an always +uniform regimen, which soon begets anorexia and disgust, or by +withholding from the food a considerable quantity of fat, or, finally, +by forbidding beverage during meals. Emaciation is obtained readily +enough in either way, and demands only the constant exercise of will +power on the part of the patient; but unhappily, severe regimen cannot +always be prescribed. When the obese patient has passed the age of +forty; when the heart suffers from degeneration; or when the heart is +anæmic--in all, rigorous treatment will serve to still further enfeeble +the central organ of circulation, and tend to precipitate accidents +that, by all means, are to be avoided. In such cases, by _not_ treating +the obesity, the days of the patient will be prolonged. In degeneration +of the heart, however, the method of Ebstein may be tried; and when +there is renal calculi and gouty diathesis, that of Germain See may +prove satisfactory. + +Paris, France. + + * * * * * + + + + +STILT WALKING. + + +[Illustration: SYLVAIN DORNON, THE STILT WALKER OF LANDES.] + +Sylvain Dornon, the stilt walker of Landes, started from Paris on the +12th of last March for Moscow, and reached the end of his journey at the +end of a fifty-eight days' walk. This long journey upon stilts +constitutes a genuine curiosity, not only to the Russians, to whom this +sort of locomotion is unknown, but also to many Frenchmen. + +Walking on stilts, in fact, which was common twenty years ago in certain +parts of France, is gradually tending to become a thing of the past. In +the wastes of Gascony it was formerly a means of locomotion adapted to +the nature of the country. The waste lands were then great level plains +covered with stunted bushes and dry heath. Moreover, on account of the +permeability of the subsoil, all the declivities were transformed into +marshes after the slightest fall of rain. + +There were no roads of any kind, and the population, relying upon sheep +raising for a living, was much scattered. It was evidently in order to +be able to move around under these very peculiar conditions that the +shepherds devised and adopted stilts. The stilts of Landes are called, +in the language of the country, _tchangues_, which signifies "big legs," +and those who use them are called _tchanguès_. The stilts are pieces of +wood about five feet in length, provided with a shoulder and strap to +support the foot. The upper part of the wood is flattened and rests +against the leg, where it is held by a strong strap. The lower part, +that which rests upon the earth, is enlarged and is sometimes +strengthened with a sheep's bone. The Landese shepherd is provided with +a staff which he uses for numerous purposes, such as a point of support +for getting on to the stilts and as a crook for directing his flocks. +Again, being provided with a board, the staff constitutes a comfortable +seat adapted to the height of the stilts. Resting in this manner, the +shepherd seems to be upon a gigantic tripod. When he stops he knits or +he spins with the distaff thrust in his girdle. His usual costume +consists of a sort of jacket without sleeves, made of sheep skin, of +canvas gaiters, and of a drugget cloak. His head gear consists of a +beret or a large hat. This accouterment was formerly completed by a gun +to defend the flock against wolves, and a stove for preparing meals. + +The aspect of the Landeses is doubtless most picturesque, but their +poverty is extreme. They are generally spare and sickly, they are poorly +fed and are preyed upon by fever. Mounted on their stilts, the shepherds +of Landes drive their flocks across the wastes, going through bushes, +brush and pools of water, and traversing marshes with safety, without +having to seek roads or beaten footpaths. Moreover, this elevation +permits them to easily watch their sheep, which are often scattered over +a wide surface. In the morning the shepherd, in order to get on his +stilts, mounts by a ladder or seats himself upon the sill of a window, +or else climbs upon the mantel of a large chimney. Even in a flat +country, being seated upon the ground, and having fixed his stilts, he +easily rises with the aid of his staff. To persons accustomed to walking +on foot, it is evident that locomotion upon stilts would be somewhat +appalling. + +One may judge by what results from the fall of a pedestrian what danger +may result from a fall from a pair of stilts. But the shepherds of +Landes, accustomed from their childhood to this sort of exercise, +acquire an extraordinary freedom and skill therein. The _tchanguè_ knows +very well how to preserve his equilibrium; he walks with great strides, +stands upright, runs with agility, or executes a few feats of true +acrobatism, such as picking up a pebble from the ground, plucking a +flower, simulating a fall and quickly rising, running on one foot, etc. + +The speed that the stilt walkers attain is easily explained. Although +the angle of the legs at every step is less than that of ordinary +walking with the feet on the ground, the sides prolonged by the stilts +are five or six feet apart at the base. It will be seen that with steps +of such a length, distances must be rapidly covered. + +When, in 1808, the Empress Josephine went to Bayonne to rejoin Napoleon +I, who resided there by reason of the affairs of Spain, the municipality +sent an escort of young Landese stilt walkers to meet her. On the +return, these followed the carriages with the greatest facility, +although the horses went at a full trot. + +During the stay of the empress, the shepherds, mounted upon their +stilts, much amused the ladies of the court, who took delight in making +them race, or in throwing money upon the ground and seeing several of +them go for it at once, the result being a scramble and a skillful and +cunning onset, often accompanied with falls. + +Up to recent years scarcely any merry-makings occurred in the villages +of Gascony that were not accompanied with stilt races. The prizes +usually consisted of a gun, a sheep, a cock, etc. The young people vied +with each other in speed and agility, and plucky young girls often took +part in the contests. + +Some of the municipalities of the environs of Bayonne and Biarritz still +organize stilt races, at the period of the influx of travelers; but the +latter claim that the stiltsmen thus presented are not genuine Landese +shepherds, but simple supernumeraries recruited at hazard, and in most +cases from among strolling acrobats. The stilt walkers of Landes not +only attain a great speed, but are capable of traveling long distances +without appreciable fatigue. + +Formerly, on the market days at Bayonne and Bordeaux, long files of +peasants were seen coming in on stilts, and, although they were loaded +with bags and baskets, they came from the villages situated at 10, 15, +or 20 leagues distance. To-day the sight of a stilt walker is a +curiosity almost as great at Bordeaux as at Paris. The peasant of Landes +now comes to the city in a wagon or even by railway.--_La Nature_. + + * * * * * + + + + +REMAINS OF A ROMAN VILLA IN ENGLAND. + + +A correspondent of the _Lincolnshire Chronicle_ writes: For some weeks +past, remains of a Roman villa have been exposed to view by Mr. +Ramsden's miners in Greetwell Fields. From, the extent of the tesselated +pavements laid bare there is hardly any doubt that in the Greetwell +Fields, in centuries long gone by, there stood a Roman mansion, which +for magnitude was perhaps unrivaled in England. Six years ago I drew +attention to it. The digging for iron ore soon after this was brought to +a standstill by the company, which at the time was working the mines, +ceasing their operations. Then the property came into other hands, and +since then more extensive basement floors of the villa have from time to +time been laid bare, and from tentative explorations which have been +just made, still more floors remain to be uncovered which may be of a +most interesting and instructive character. What a pity it is that the +inhabitants of Lincoln have not made an effort to preserve these +precious relics of the grandeur of the Roman occupation, an occupation +to which England owes so much. From the Romans the people of this +country inherit the sturdy self-reliance and perseverance in action +which have helped to make England what it is, and from the Romans too, +in a great degree, does England also inherit her colonizing instincts, +which impel her people to cover the waste places of the world with +colonies. If the Roman remains which have been so abundantly discovered +of late years in Lincoln and its vicinity had been collected and laid +out for exhibition, they would have formed a most interesting collection +of antiquities worthy of the town, and well worth showing to visitors +who now annually make Lincoln a visitation. Although these relics of a +remote age are being dug up and are being destroyed, it is not the fault +of Mr. Ramsden, for he not only preserved them as long as he +conveniently could, but he also had the soil removed from over them, and +had them thoroughly washed, in order that people might have an +opportunity of seeing their extent and beauty. One of these patches of +pavement extended 48 yards northward from what might be called the main +building, which had previously been broken up. This strip was 13 ft. in +breadth, and down its center ran an intricate pattern worked in blue +tesseræ. The pattern is much used in these days in fabrics and works of +art, and is, I think, called the Grecian or Roman key pattern. On each +side of this ran alternately broad ribbons of white and narrower ribbons +of red tesseræ. There is also another strip of pavement to the south of +the preceding patch, which has been laid bare to the extent of 27 yards. +This patch is about 10 ft. in breadth, and its western portion is cut up +in neat patterns, which show that they formed the floors of rooms. From +the eastern extremity of these floors evidently another long strip of 48 +or 50 yards still remains to be uncovered. Doubtless there are other +remains beneath the ground which will be laid bare as the work of mining +goes on. All these floors were not deeper than from 18 to 30 inches +below the surface of the soil. The bones of animals and other relics +have been found in the covering soil and have been turned up by the +miners from time to time. The pavement is all worked out with cubes, +varying in size from an inch and a half to two inches square, each piece +being placed in position with most careful exactness. The strip which +extends 48 yards and is 13 ft. wide runs due north and south. There is a +second patch, running east and west, and this is 27 ft. long by 10 ft. +wide, while a third is 27 ft. long by 11 ft. wide, this also running in +a northern direction. To the north of this latter piece, and separated +only by about two feet (about the width of a wall, which very possibly +was the original division), there is a strip of tesseræ 16 ft. wide, +which had been laid bare 40 yards. It was thought probable that at the +end of the last named strip still another patch would be found. Mr. +Ramsden, the manager of the Ironstone Works, is keeping a plan of the +whole of the pavement, which he is coloring in exact imitation of the +original work. This, when completed, will be most interesting, and he +will be quite willing to show it to any one desirous of inspecting the +same. Many persons have paid a visit to the spot where the discoveries +have been made, and surprise is invariably expressed at the magnitude +and beautiful symmetry of the work. + +Several interesting fragments of Roman work have been brought to light +in the course of excavations that are being made for building purposes +at Twyford, near Winchester. About a month ago, a paved way, composed +entirely of small red tiles, six feet in width and extending probably a +considerable distance (a length of 14 ft. was uncovered), was found +while digging on the site for flints. The more recent excavations are 20 +ft. west of this passage, and there is now to be seen, in a very perfect +state of preservation, an oven or kiln with three openings. Five yards +away from this is a chamber about eight feet square, paved with tiles, +and the sides coated with a reddish plaster. On one side is a ledge 15 +in. from the ground, extending the whole length of the chamber; on the +floor is a sunk channel with an opening at the end for the water to +escape. This chamber evidently represents the bath. Portions of the +dividing walls of the different chambers have also been discovered, +together with various bones, teeth, horns and ornaments, but very few +coins. It is probable that an alteration in the plans of the house which +was about to be built on the spot will be made so as to preserve all the +more interesting features of these remains in the basement. These +discoveries were made at a depth of only two or three feet from the +surface of the ground, and are within about a quarter of a mile of other +Roman remains which were similarly brought to light a few months ago. + + * * * * * + +[Continued from SUPPLEMENT, No. 830, page 13110.] + + + + +GUM ARABIC AND ITS MODERN SUBSTITUTES.[1] + +[Footnote 1: A paper read before the Society of Chemical Industry, +London, 1891. From the Journal] + +BY DR. S. RIDEAL AND W.E. YOULE. + + +Subjoined is a table giving the absolute viscosity of various gums. A +comparison of the uncorrected viscosities with the corrected shows the +great importance of Slotte's correction for dextrins and inferior gum +arabics; in other words, for solutions of low viscosity, while it will +be observed to have little influence upon the uncorrected [eta] obtained +for the Ghatti gums and the best samples of gum arabic. + +TABLE OF ABSOLUTE VISCOSITIES OF 10 PER CENT. GUM AND DEXTRIN SOLUTIONS. + + ---------------------+--------------+------------+---------- + Sample. | [eta] | [eta] | Z Water + | Uncorrected. | Corrected. | = 100. + ---------------------+--------------+------------+---------- + Gum arabic.......... | 0.1876 | 0.1856 | 1,233 + Cape gum............ | 0.1575 | 0.1555 | 1,029 + Indian gum.......... | 0.0540 | 0.0470 | 311 + Eastern gum......... | 0.0689 | 0.0639 | 417 + Gum arabic.......... | 0.0550 | 0.0480 | 317 + Senegal............. | 0.0494 | 0.0410 | 271 + Senegal............. | 0.0468 | 0.0380 | 251 + Senegal............. | 0.0627 | 0.0557 | 364 + Gum arabic.......... | 0.0511 | 0.0430 | 285 + Water............... | 0.0149 | 0.0124 | 100 + Ghatti.............. | 0.2903 | 0.2880 | 2,322 + Ghatti, 5 per cent.. | 0.0903 | 0.0828 | 688 + Ghatti, 5 per cent.. | 0.1391 | 0.1350 | 1,089 + Ghatti, 5 per cent.. | 0.1795 | 0.1760 | 1,420 + Ghatti, 5 per cent.. | 0.1527 | 0.1485 | 1,198 + Ghatti, 5 per cent.. | 0.1139 | 0.1083 | 873 + Ghatti, 5 per cent.. | 0.1419 | 0.1369 | 1,104 + Dextrin............. | 0.0398 | 0.0255 | 169 + Dextrin............. | 0.0341 | 0.0196 | 129 + Dextrin............. | 0.0455 | 0.0380 | 306 + Gum substitute...... | 0.0318 | 0.0224 | 180 + Gum substitute...... | 0.0318 | 0.0224 | 180 + Amrad............... | 0.0793 | 0.0708 | 570 + Australian.......... | 0.0378 | 0.0283 | 228 + Australian.......... | 0.0365 | 0.0268 | 216 + Brazilian........... | 0.0668 | 0.0627 | 506 + Brazilian........... | 0.0516 | 0.0445 | 359 + Ghatti.............. | 0.3636 | 0.3621 | 2,920 + ---------------------+--------------+------------+---------- + +In the column for [eta] corrected the differences due to the use of +different instruments are of course eliminated. The absolute viscosity +of water at 15° C. determined in four different instruments is shown +below. Poiseuille's value for water being 0.0122. + + --------------+-------------+-------------+-------------+-------------+ + Instrument. | 1. | 2. | 3. | 4. | + --------------+-------------+-------------+-------------+-------------+ + [eta] corrtd. | 0.0109 | 0.01185 | 0.0124 | 0.0120 | + of water. | | | | | + K_{1} value.. | 0.000000898 | 0.000000863 | 0.000000932 | 0.00000052 | + K_{2} value.. | 0.235 | 0.2175 | 0.226 | 0.0204 | + --------------+-------------+-------------+-------------+-------------+ + +The above values for various gums and dextrins were obtained at a +constant temperature of 15° C. and are compared with water at that +temperature. It is of the utmost importance that the temperature of the +water surrounding the bulbs should be adjusted for each series of +experiments to the temperature at which the absolute viscosity of the +water was determined. As far as we have ascertained, in gum solutions +there is a steady diminution in viscosity with increase of temperature +until a certain temperature is reached, beyond which increase of heat +does not markedly influence the viscosity, and it is possible that above +this "critical point," as we may term it, the gum solutions once more +begin to increase in viscosity. The temperature at which the viscosity +becomes stationary varies somewhat with different gums, but broadly +speaking it lies between 60° C. and 90° C., no gums showing any marked +decrease in viscosity between 80° C. and 90° C. + +The experiments we have made in this direction were conducted as +follows. The 300 c.c. bottle containing the gum was placed in a +capacious beaker full of hot water, and the viscosity instrument was +also surrounded with water at the same temperature. Thermometers were +suspended both in the beaker and the outer jar. The viscosity at the +highest temperature obtained, about 90° C., was then taken and repeated +for every fall of 4° C. till the water reached the temperature of the +air. + +The values so obtained gradually diminished with the increase of +temperature. From the [eta] values obtained the Z values were +calculated, using water at 15° C. as a standard. From the Z values thus +obtained taken as the ordinate, and the temperature of each experiment +as the abscissa, curves were plotted out embodying the results, examples +of which are given below. The curves yielded by three gums 2, 7, and 8 +changed between 90° C and 100° C., while gum sample 4 has a curve +bending between 60° C. and 70° C. Experimentally this increase of +viscosity of the latter gum above 60° C. was confirmed, but the critical +point of the other solutions tried approaches too nearly to the boiling +point of water for experiments to be conducted with accuracy, as the +temperature of the bulbs diminishes sensibly while the experiment is +being made. + +If viscosity values have been determined it is possible to calculate the +remaining or intermediate values for Z at any particular temperature +from the general equation-- + + Zt = A + Bt + Ct² + +As an example of the mode of calculation we may quote the following. A +gum gave the following values for Z at the temperature stated: + + Gum. 50° C. Z_{50°} = 228 + + Gum. 30° C. Z_{30°} = 339 + + Gum. 20° C. Z_{20°} = 412 + +from which the constants-- + + A = 592.99 B = -10.2153 C = 0.0583 + +can be obtained, and thus the value of Z_{t°} for any required +temperature. The numbers calculated for gums all point to a diminution +in viscosity up to a certain point, and then a gradual increase. A +comparison of some of the figures actually obtained in some of these +experiments, compared with the calculated figures for the same +temperature, shows their general agreement. + +[Illustration: Curves showing viscosity change with temperature for +three typical gums. A--Arabic VII. B--Senegal VIII. C--Ghatti 15.] + + EFFECT OF TEMPERATURE UPON VISCOSITY--GUM VII. + + ------------+------+--------+-------------+ + Temperature.| [eta]|Z found.|Z calculated.| + ------------+------+--------+-------------+ + °C | | | | + 50 |0.0283| 228 | 228.00 | + 45 |0.0305| 246 | 246.55 | + 42 |0.0352| 284 | 266.75 | + 38 |0.0368| 297 | 289.00 | + 34 |0.0410| 330 | 313.06 | + 30 |0.0419| 339 | 339.00 | + 26 |0.0445| 359 | 367.80 | + 22 |0.0492| 398 | 396.47 | + 20 |0.0511| 412 | 412.00 | + 18 |0.0531| 428 | 428.00 | + ------------+------+--------+-------------+ + + EFFECT OF TEMPERATURE UPON VISCOSITY.--GUM VIII. + + ------------+------+--------+-------------| + Temperature.| [eta]|Z found.|Z calculated.| + ------------+------+--------+-------------| + °C. | | | | + 50 |0.0430| 347 | 347 | + 46 |0.0475| 383 | 371.14 | + 42 |0.0502| 405 | 397.09 | + 38 |0.0510| 411 | 424.73 | + 34 |0.0575| 463 | 454.06 | + 30 |0.0602| 485 | 485 | + 26 |0.0637| 513 | 517.82 | + 22 |0.0667| 538 | 552.25 | + 20 |0.0707| 570 | 570 | + 18 |0.0755| 609 | 583.07 | + ------------+------+--------+-------------+ + +The constants for the first gum are those given in the preceding column, +while for the latter they were-- + + A = 771.9: B = -11.15: C = 0.053 + +As will be observed, the effect of heat appears to be the same upon the +two typical gum arabics quoted above, an increase of temperature from +18° C. to 50° C. decreasing the viscosity by nearly one half in both +cases, and the same seems to be true of most gum arabics. Roughly also +the same holds good for Ghattis, as the following numbers show: + + ------------+-------------+------------| + Gum. | Z at 18° C. | Z at 50° C.| + ------------+-------------+------------| + Gum arabic. | 1016 | 579 | + Gum arabic. | 428 | 228 | + Gum arabic. | 609 | 347 | + Gum arabic. | 581 | 258 | + Ghatti. | 572 | 306 | + Ghatti. | 782 | 418 | + ---------------------------------------+ + +The following table shows the effect of heat upon the viscosity of a +typical Ghatti: + + GHATTI GUM NO. 15.--VISCOSITY. + + ------------+------+-----| + Temperature.| [eta]| Z. | + ------------+------+-----| + °C. | | | + 50 |0.0517| 418 | + 46 |0.0581| 468 | + 42 |0.0628| 506 | + 38 |0.0726| 585 | + 34 |0.0788| 635 | + 30 |0.0857| 691 | + 26 |0.0889| 717 | + 22 |0.0919| 741 | + 20 |0.0946| 763 | + 18 |0.0964| 777 | + ------------+------+-----+ + +There is therefore no essential difference in the behavior of a Ghatti +and a gum arabic on heating. Some interesting results, however, were +obtained by heating gums, both Ghattis and arabics, at a fixed +temperature for the same time, cooling, and then after making the +solutions up to the original volume taking their viscosities at the +ordinary temperature. The effect of heating for two hours to 60° C., 80° +C., or 100° C. was a small permanent alteration in viscosity of the +solution, and it would therefore seem desirable that gum solutions +should be made up cold to get the maximum results. The following numbers +illustrate this change, viz.: + +------------------------+-----------+-----------------------+ + | | After heating to | +Gum Arabic | Without |-------+-------+-------+ +10 Per Cent. | heat. | 60°C. | 80°C. | 100°C | +------------------------+-----------+-------+-------+-------+ +Z at 18°C | 570 | 468 | 470 | 517 | +Z at 30°C | 485 | 400 | 422 | 439 | +Z at 50°C | 347 | 287 | 258 | 301 | +Ghatti gum No. 15, | | | | | + 5 per cent. Z at 18°C. | 1,104 | 780 | 660 | 758 | +------------------------+-----------+-------+-------+-------+ + +The variation of viscosity with strength of solution was also studied +with one or two typical gums. A 10 per cent. is invariably more than +twice as viscous as a 5 per cent. solution. The following curve was +obtained from one of the Ghattis. Similar results were shown by other +gums. + +[Illustration: Variation of Viscosity, with Dilution. Ghatti No. 888.] + +It would seem, therefore, that strong solutions, say of 50 per cent. +strength, would be more alike in viscosity than solutions of 5 per cent. +strength of the same gums. In other words, the viscosity of a gum +solution should be taken as nearly as possible to the strength it is +used at, to obtain an exact quantitative idea of its gumming value. + +The observation of this fact was one of the circumstances which decided +us to use 5 per cent. solutions for the determination of Ghatti gum +viscosities, the ratio between the 5 per cent. and 10 per cent. +solutions of gum arabics being roughly the same as that between the +respective weights required for gumming solutions of equal value. + +From observation of the general nature of the solutions of Ghatti gums, +and from the fact that when allowed to stand portions of the apparently +insoluble matter passed into solution, the hypothesis suggested itself +that metarabin was soluble in arabin, although insoluble in cold water. +If this hypothesis were correct, it would explain the apparent anomaly +of Ghattis giving solutions of higher viscosity than gum arabics, +although they leave insoluble matter behind. The increase in viscosity +would be due to the thickening of the arabic acid by the metarabin. +Moreover, the solutions yielded by various Ghattis leaving insoluble +matter behind would _be all of the same kind_, viz., a saturated +solution of metarabin in arabin more or less diluted by water. Still +further, if the insoluble residue of a Ghatti be the residual metarabin +over and above that required to saturate the arabin, then it will be +possible to dissolve this by the addition of more arabin in the form of +ordinary gum arabic. In order to see if this were the case the following +experiments were performed. Equal parts of a Ghatti and of a gum arabic +were ground up together and dissolved in water. The resulting solution +was _clear_. It was diluted until of 10 per cent. strength, and its +viscosity then taken: + +---------------------+-------------+----------------+ + | Contains 50 per Cent. Ghatti.| +---------------------+-------------+----------------+ +A. Pressure 200 mm | [eta] | Z. | +Temperature 15° C | 0.2517 | 2,030 | +---------------------+-------------+----------------+ + +The viscosity of this solution therefore was considerably greater than +the mean viscosity of the 10 per cent. solutions of the Ghatti and the +gum arabic, viz., (0.288 + 0.0636)/2 = 0.1758 for the calculated [eta]. +Hence it is evident that the increase in viscosity is due to the +solution of the metarabin. + +Next a solution was made from a mixture of 70 per cent. Ghatti and 30 +per cent. gum arabic. This was also clear and gave a considerably higher +viscosity than the previous solution. + +---------------------+------------------------------+ + | Contains 70 per Cent. Ghatti.| +---------------------+-------------+----------------+ +B. Pressure 200 mm | [eta] | Z. | +Temperature 15° C | 0.3177 | 2,562 | +---------------------+-------------+----------------+ + +It will be obvious that the increase of viscosity over the previous +solution in this case must be due to the smaller amount of the thin gum +arabic which is present, _i.e._, in the first case there is more gum +arabic than is required to dissolve the whole of the insoluble +metarabin. Further experiments showed that this is also true of the +second mixture, as the viscosities of the following mixtures +illustrate: + + -------------------------+--------+-------+ + Strength of Solution. | [eta] | Z. | + -------------------------+--------+-------| + C. 80 per cent. Ghatti. |0.3642 | 2,937 | + D. 75 per cent. Ghatti. |0.33095 | 2,669 | + E. 77.5 per cent. Ghatti.|0.4860 | 3,819 | + -------------------------+--------+-------+ + +This last solution E we called for convenience the "maximum viscosity" +solution, as we believe it to be a 10 per cent. solution containing +arabin very nearly saturated with metarabin. As will be observed, its +viscosity differs widely from those of solutions C and D, between which +it lies in percentage of Ghatti. The first named solution C contains +_too little_ of gum arabic to dissolve the whole of the metarabin. +Consequently there is a residue left undissolved, which of course +diminishes its viscosity. The second solution D is too low in viscosity, +as it still contains too much of the weak gum arabic, and as will be +seen further on, a very slight change in the proportions increases or +decreases the viscosity enormously. + +We next tried a series of similar experiments with a Ghatti containing +far less insoluble residue and which consequently would require less gum +arabic to produce a perfect solution. Mixtures were made in the +following proportions, viz.: + + ----------------------+------------+-----------+ + ----- | 13.3 per Cent. Ghatti. | + ----------------------+------------+-----------+ + F. Pressure 200 mm. | [eta] | Z. | + Temperature 15° C. | 0.0976 | 787 | + ----------------------+------------+-----------+ + + ----------------------+------------+-----------+ + ----- | 86.6 per Cent. Ghatti. | + ----------------------+------------+-----------+ + G. Pressure 200 mm. | [eta] | Z. | + Temperature 15° C. | 0.4336 | 3,497 | + ----------------------+------------+-----------+ + +This latter solution is approaching fairly closely to our "maximum +viscosity" with the previous Ghatti, and probably a very slight decrease +in the amount of gum arabic would bring about the required increase in +viscosity. + +When these experiments were first commenced we were still under the +impression, which several months' experience of working with gums had +produced, namely, that the Ghattis were quite distinct in their +properties to ordinary gum arabics. But the new hypothesis, and the +experiments undertaken to confirm it, showed clearly that if the +viscosity of a gum solution depends on the ratio of metarabin to arabin, +then there is no absolute line of demarkation between a Ghatti and a gum +arabic. In other words, there is a constant gradation between gum arabic +and Ghattis, down to such gums as cherry gum, consisting wholly of +metarabin and quite insoluble in water. Therefore those gum arabics +which are low in viscosity consist of nearly pure arabin, while as the +viscosity increases so does the amount of metarabin, until we come to +Ghattis which contain more metarabin than their arabin can hold in +solution, when their viscosity goes down again. + +From these observations it would follow, that by taking a gum of less +viscosity than the gum arabic previously used to dissolve the Ghatti, +less of it would be required to do the same work. We confirmed this +suggestion experimentally by taking another gum arabic of viscosity +0.0557 at 15° C. A mixture containing 93.3 per cent. of this Ghatti and +6.7 per cent. of our thinnest gum arabic gave a clear solution which had +the highest viscocity we have yet obtained for a 10 per cent. solution. + + ----------------------+--------+-------+ + H. Pressure 200 mm. | [eta] | Z. | + Temperature 15° C. | 0.5525 | 4,456 | + ----------------------+--------+-------+ + +This gum arabic may be regarded as nearly pure arabin (as calcium and +potassium, etc., salt). By diluting the new "maximum viscosity" +solution, therefore, with the 10 per cent. solution of the gum arabic in +fixed proportions we obtain a series of viscosities which are shown in +the following curve. + +[Illustration: Curve Showing Influence of Ghatti upon Viscosity.] + +Besides obtaining this curve for change in viscosity from maximum amount +of metarabin to no metarabin at all, we also traced the decrease in +viscosity of the "maximum" solution by dilution with water. The +following numbers were thus obtained, and plotted out into a curve. + +Having obtained this curve, we are now in a position to follow up the +hypothesis by calculating the surplus amount of insoluble matter in a +Ghatti. For, let it be conceded that the solution of any Ghatti leaving +an insoluble residue is a mixture of arabin and metarabin in the same +ratio as our "maximum" solution, only more diluted with water, then from +the found viscosity we obtain a point on the curve for dilution, which +gives the percentage of dissolved matter. + +Now to show the use of this: The Z value for a 10 per cent. solution of +the second Ghatti at 15° C. is 2,940. This corresponds on the curve to +8.4 dissolved matter. 10 - 8.4 = 1.6 grammes in 10 grammes, which is +insoluble. + +CHANGE OF VISCOSITY WITH DILUTION--"MAXIMUM" SOLUTION. 15° C. +TEMPERATURE. + + ------------+--------------+--------- + Percentage. | [eta] | Z. + ------------+--------------+--------- + 10 | 0.55250 | 4,456 + 9 | 0.42850 | 3,456 + 8 | 0.35120 | 2,832 + 7 | 0.27660 | 2,230 + 6 | 0.22290 | 1,797 + 5 | 0.16810 | 1,355 + 4 | 0.11842 | 955 + 3 | 0.08020 | 647 + 2 | 0.06190 | 499 + 1 | 0.03610 | 291 + ------------+--------------+--------- + +[Illustration: Curve of Variation in Viscosity on Dilution of the +"Maximum" Solution.] + +We have already shown that a "maximum" viscosity solution of this gum is +formed when 6.7 per cent, of thin gum arabic is added to it, and +therefore 6.7 parts of a thin gum arabic are required to bring 16 parts +of metarabin into solution. A convenient rule, therefore, in order to +obtain complete solution of a Ghatti gum is to add half the weight in +thin gum of the insoluble metarabin found from the viscosity +determination. But the portion of the gum which dissolved is made up in +a similar manner (being a diluted "maximum" solution). + +Therefore the 84 per cent. of soluble matter contains 58 parts of +metarabin, and the total metarabin in this gum is 58 + 16 = 74 per cent, +on the dry gum. + +With these solutions of high viscosity some other work was done which +may be of interest. The temperature curves of the mixtures marked E, G, +and F were obtained between 60° C. and 15° C. The two former curves +showed a direction practically parallel to that at the 10 per cent. +solutions, and as they were approaching to the "maximum" solution, this +is what one would expect. Mr. S. Skinner, of Cambridge, was also good +enough to determine the electrical resistances of these solutions and +the Ghattis and gum arabics employed in their preparation. The +electrical resistance of these gum solutions steadily diminishes as the +temperature increases, and the curve is similar to those obtained for +rate of change with temperature. Although the curves run in, roughly, +the same direction, there does not appear to be any exact ratio between +the viscosities of two gums say at 15° C. and their electrical +resistances at the same temperature; hence it would not seem possible to +substitute a determination of the electrical resistance for the +viscosity determination. The results appear to be greatly influenced by +the amount of mineral matter present, gums with the greatest ash giving +lower resistances. + +Experiments were conducted with two Ghattis and two gum arabics, besides +the mixtures marked E, F, and H. Comparison of the electrical +resistances with the viscosities at 15° C. shows the absence of any +fixed ratio between them. + + -----------+------+-------------+------------ + Gum or | °C. | Ohms | Z Viscosity + Mixture. | | Resistance. | at 15° C. + -----------+------+-------------+------------- + Ghatti, 1 | 10 | 5,667 | 1,490 + Ghatti, 2 | 15 | 2,220 | 2,940 + Arabic 1 | 15 | 1,350 | 605 + Arabic 2 | 10 | 2,021 | 449 + Mixture F | 15 | 1,930 | 787 + Mixture E | 11.3 | 2,058 | 3,919 + -----------+------+-------------+------------- + +While performing these experiments, an attempt was made to obtain an +"ash-free" gum, in order to compare its viscosity with that of the same +gum in its natural state. A gum low in ash was dissolved in water, and +the solution poured on to a dialyzer, and sufficient hydrochloric acid +added to convert the salts into chlorides. When the dialyzed gum +solution ceased to contain any trace of chlorides, it was made up to a +10 per cent. solution, and its viscosity determined under 100 mm. +pressure, giving the following results at 15° C.: + + -----------------+--------------+----- + -------- | [eta] | Z + -----------------+--------------+----- + Natural gum..... | 0.05570 | 449 + "Ash-free" gum.. | 0.05431 | 438 + -----------------+--------------+----- + +Thus showing that the viscosity of pure arabin is almost identical with +that of its salts in gum. + +The yield of furfuraldehyde by the breaking down of arabin and metarabin +was thought possibly to be of some value in differentiating the natural +gums from one another, but we have not succeeded in obtaining results of +much value. 0.2 gramme of a gum were heated with 100 c.c. of 15 per +cent. sulphuric acid for about 2½ hours in an Erlenmeyer flask with a +reflux condenser. After this period of time, further treating did not +increase the amount of furfuraldehyde produced. The acid liquid, which +was generally yellow in color, was then cooled and neutralized with +strong caustic soda. The neutral or very faintly alkaline solution was +then distilled almost to dryness, when practically the whole of the +furfuraldehyde comes over. The color produced by the gum distillate with +aniline acetate can now be compared with that obtained from some +standard substance treated similarly. The body we have taken as a +standard is the distillate from the same weight of cane sugar. The tint +obtained with the standard was then compared with that yielded by the +gum distillate from which the respective ratios of furfuraldehyde are +obtained. The following table shows some of these results: + + ---------------+--------------------+-----------------+ + | Comparative Yield | Amount of | + Substance. | of Furfuraldehyde. |Glucose Produced.| + ---------------+--------------------+-----------------+ + Cane sugar | 1.00 | .. | + Starch | 0.50 | .. | + Gum arabic | 1.33 | 34.72 | + Gum arabic | 1.20 | 43.65 | + Ghatti, 1 | 1.00 | 26.78 | + Ghatti, 2 | 1.33 | 22.86 | + Metarabin | 1.75 | .. | + ---------------+--------------------+-----------------+ + +The amount of reducing sugar calculated as glucose is also appended. +This was estimated in the residue left in the flask after distillation +by Fehling's solution in the usual way. The yields of furfuraldehyde +would appear to have no definite relation to the other chemical data +about a gum, such as the potash and baryta absorptions or the sugar +produced on inversion. + +The action of gum solutions upon polarized light is interesting, +especially in view of the fact that arabin is itself strongly +lævo-rotatory [alpha]_{D} = -99°, while certain gums are distinctly +dextro-rotatory. Hence it is evident that some other body besides arabin +is present in the gum. We have determined the rotatory power of a number +of gum solutions, the results of which are subjoined. On first +commencing the experiments we experienced great difficulty from the +nature of the solutions. Most of them are distinctly yellow in color and +almost opaque to light, even in dilute solutions such as 5 percent. We +found it necessary first to bleach the gums by a special process; 5 +grammes of gum are dissolved in about 40 c.c. of lukewarm water, then a +drop of potassium permanganate is added, and the solution is heated on a +water bath with constant stirring until the permanganate is decomposed +and the solution becomes brown. A drop of sodium hydrogen sulphate is +now added to destroy excess of permanganate. At the same time the +solution becomes perfectly colorless. + +It can now be cooled down and made up to 100 c.c., yielding a 5 per +cent. solution of which the rotatory power can be taken with ease. Using +a 20 mm. tube and white light the above numbers were obtained. + + ----------------+----------------+----------------- + Gum or Dextrin. | Solution used. | [alpha]_{D} + ----------------+----------------+----------------- + | Per Cent. | + Aden, 1 | 5 | - 33.8 + Cape, 2 | 5 | + 28.6 + Indian, 3 | 5 | + 66.2 + Eastern, 4 | 5 | - 26.0 + Eastern, 5 | 5 | - 30.6 + Senegal, 6 | 5 | - 17.6 + Senegal, 7 | 5 | - 18.4 + Senegal, 8 | 2½ | - 19.6 + Senegal, 9 | 5 | - 38.2 + Senegal, 10 | 5 | - 25.8 + Amrad | 2½ | + 57.6 + Australian, 1 | 5 | - 28.2 + Australian, 2 | 5 | - 26.4 + Brazilian, 1 | 2½ | - 36.8 + Brazilian, 2 | 2½ | + 21.0 + Dextrin, 1 | 5 | +148.0 + Dextrin, 2 | 5 | +133.2 + Ghatti, 1 | 5 | - 39.2 + Ghatti, 2 | 5 | - 80.4 + ----------------+----------------+----------------- + +These numbers do not show any marked connection between the viscosity, +etc., of a gum and its specific rotatory power. + +When gum arabic solution is treated with alcohol the gum is precipitated +entirely if a large excess of spirit be used. With a view to seeing if +the precipitate yielded by the partial precipitation of a gum solution +was identical in properties to the original gum, we examined several +such precipitates from various gums to ascertain their rotatory power. +We found in each case that the specific rotatory power of the alcohol +precipitate redissolved in water was not the same as that of the +original gum. In other words these gums contained at least two bodies of +different rotatory powers, of which one is more soluble in alcohol than +the other. O'Sullivan obtained similar results with pure arabin. The +experiments were conducted in the following manner: + +(a.) Five grammes of a dextro-rotatory gum (No. 3 in table) were +dissolved in 20 c.c. of water. To the solution was added 90 c.c. of 95 +per cent. alcohol. The white precipitate which formed was thrown on to a +tared filter and washed with 30 c.c. more alcohol. The total filtrate +therefore was 140 c.c. The precipitate was dried and weighed = 2.794 +grammes or 55.88 per cent. of the total gum. The precipitate was then +redissolved in water, bleached as before and diluted to a 5 per cent. +solution. This was then examined in the polarimeter. Readings gave the +value [alpha]_{D} = +58.4°. The previous rotatory power of the gum was ++66°. Now the alcohol was driven off from the filtrate, which, allowing +for the 11.95 per cent. of water in the gum, should contain 32.17 per +cent. of gum. The alcohol-free liquid was then diluted to a known +volume (for 5 per cent, solution), and [alpha]_{J} found to be +57.7°. +This experiment was then repeated again, using 5 grammes of No. 3, when +3.5805 grammes of precipitate were obtained, using the same volumes of +alcohol and water. The precipitate gave [alpha]_{J} = +57.4°; the +filtrate treated as before, only the percentage of gum dissolved being +directly determined instead of being calculated by difference, gave +[alpha]_{J} = +52.5°. + +(b.) Another gum (No. 9) with [alpha]_{J} = -38.2° and containing 13.86 +per cent, of moisture, gave 2.3315 grms. of precipitate when similarly +treated. The precipitate gave when redissolved in water [alpha]_{J} = +-20.8°. The filtrate containing 39.5 per cent, real gum gave [alpha]_{J} += -67.5°, so that the least lævo-rotatory gum. was precipitated by the +alcohol. + +The Ghattis apparently are all lævo-rotatory, and give much less +alcoholic precipitates than the gum arabic. The precipitation moreover +was in the opposite direction, that is, the most lævo-rotatory gum was +thrown down by the alcohol. The appended table shows the nature of the +precipitates and the respective amounts from two Ghattis and two gum +arabics. It will be observed that the angle of rotation in three of the +cases is decidedly less both for precipitate and filtrate than for the +original solution: + +SPECIFIC ROTATORY POWERS OF GUMS. + +----------+------+--------+--------+-----------+------------+-----------+ +Gum |Weight| Weight | Weight |[alpha]_{J}|[alpha]_{J} |[alpha]_{J}| +used. | Gum | Alcohol| Gum | Original | Alcohol | Filtrate. | + |Waken.| Precip-|Filtrate| Gum. |Precipitate.| | + | | itate. | | | | | +----------+------+--------+--------+-----------+------------+-----------+ + | | Grms. | | | | | + /a......| 5 | 2.7940 | 1.9415 | | +58.4 | +53.7 | +3{ | | | | +66.2 | | | + \b......| 5 | 3.5805 | 0.8910 | | +57.4 | -52.5 | + | | | | | | | + /a......| 5 | 2.3315 | 2.3736 | | -20.8 | -67.5 | +9{ | | | | -38.2 | | | + \b......|4.9620| 2.3310 | 2.4180 | | -19.4 | -63.4 | + | | | | | | | + /a.|3.4900| 0.3925 | 2.7920 | | -104.2 | -76.0 | +Ghatti{ | | | | -140.8 | | | + \b.|3.2450| 0.4605 | 2.8385 | | -106.0 | -72.4 | + | | | | | | | + /a.|2.2550| 0.2900 | 1.8078 | | -106.04 | +68.0 | +Ghatti{ | | | | -147.05 | | | + \b.|2.6635| 0.2845 | 2.3360 | | -102.04 | -66.2 | +----------+------+--------+--------+-----------+------------+-----------+ + + +The hygrometric nature of a gum or dextrin is a point of considerable +importance when the material is to be used for adhesive purposes. The +apparatus which we finally adopted after many trials for testing this +property consists simply of a tinplate box about 1 ft. square, with two +holes of 2 in. diameter bored in opposite sides. Through these holes is +passed a piece of wide glass tubing 18 in. long. This is fitted with +India rubber corks at each end, one single and the other double bored. +Through the double bored cork goes a glass tube to a Woulffe's bottle +containing warm water. A thermometer is passed into the interior of the +tube by the second hole. The other stopper is connected by glass tubing +to a pump, and thus draws warm air laden with moisture through the tube. +Papers gummed with the gums or dextrins, etc., to be tested are placed +in the tube and the warm moist air passed over them for varying periods, +and their proneness to become sticky noted from time to time. By this +means the gums can be classified in the order in which they succumbed to +the combined influences of heat and moisture. We find that in resisting +such influences any natural gum is better than a dextrin or a gum +substitute containing dextrin or gelatin. The Ghattis are especially +good in withstanding climatic changes. + +Dextrins containing much starch are less hygroscopic than those which +are nearly free from it, as the same conditions which promote the +complete conversion of the starch into dextrin also favor the production +of sugars, and it is to these sugars probably that commercial dextrin +owes its hygroscopic nature. We have been in part able to confirm these +results by a series of tests of the same gums in India, but have not yet +obtained information as to their behavior in the early part of the year. + +The fermentation of natural gum solutions is accompanied by a decrease +in the viscosity of the liquid and the separation of a portion of the +gum in lumps. Apparently those gums which contain most sugar, as +indicated by their reduction of Fehling's solution, are the most +susceptible to this change. Oxalic acid is formed by the fermentation, +which by combination with the lime present renders the fermenting liquid +turbid, and also some volatile acid, probably acetic. + +We have made some experiments with a gum which readily fermented--in a +week--as to the respective value of various antiseptics in retarding the +fermentation. Portions of the gum solutions were mixed with small +quantities of menthol, thymol, salol, and saccharin in alkaline +solution, also with boric acid, sodium phosphate, and potash alum in +aqueous solution. Within a week a growth appeared in a portion to which +no antiseptic had been added; the others remained clear. After over five +months the solutions were again examined, when the following results +were observed: + +----------------------+------------------------------------------- + | + Antiseptics. | Solution after Five Months. +----------------------+------------------------------------------- + | +Menthol in KOH..... | Some growth at bottom, upper layer clear. + | +Thymol in KOH..... | Growth at top, gum white and opaque. + | +Salol in KOH........ | Growth at top, gum black and opaque + | +Saccharin in KOH ... | White growth at top. + | +Boric acid............| Remained clear; did not smell. + | +Sodium phosphate ... | Slight growth at top. + | +Potash alum......... | Slight growth at top. +----------------------+------------------------------------------- + +The solution to which no antiseptic had been added was of course quite +putrid, and gave the reactions for acetic acid. + +In the earlier part of this paper we have given a short account of the +chief characteristics of the more important gum substitutes. The +following additional notes may be of interest. + +The ashes of most gum substitutes, consisting chiefly of dextrin, are +characterized by the high percentage of chlorides they contain, due no +doubt to the use of hydrochloric acid in their preparation. The soluble +constituents of the ash consist of neutral alkaline salts, but as a rule +no alkaline carbonates, and it is thus possible to demonstrate the +absence of any natural gum in such a compound. We have seldom noticed +the presence of any sulphates in such ashes, but when sulphurous or +sulphuric acids have been used in the starch conversion it will be found +in small quantities. + +We have already pointed out that the potash absorption value of a gum is +low and that dextrins give high numbers, but the latter vary very +considerably, and as the starch and sugar present also influence the +potash absorption value, it does not give information of much service. +The following table shows the kind of results obtained: + +-----------------------------+----------+--------------+-------------- + Sample. | KOH | Starch. | Real Gum. + | absorbed.| | +-----------------------------+----------+--------------+-------------- + | | Per Cent. | Per Cent. +Dextrin, 1 | 25.40 | 1.99 | .. +Dextrin, 2 | 19.70 | 13.13 | .. +Dextrin, 3 | 7.57 | 24.72 | .. +Artificial gum, 1 | 19.70 | 10.98 | 9.00 +Artificial gum, 2 | 13.70 | 8.05 | 23.50 +Starch | 9.43 | 100.00 | None +-----------------------------+----------+--------------+-------------- + +The baryta absorptions seem to be chiefly due to the quantity of starch +present in the composition: + + +----------------------------+---------------+------------------------- + Sample. | Starch. | BaO + | | absorbed. +----------------------------+---------------|------------------------- + | Per Cent. | Per Cent. +Dextrin, 1 | 1.99 | 1.75 +Dextrin, 2 | 13.13 | 3.53 +Dextrin, 3 | 24.72 | 5.64 +Starch | 100.00 | 23.61 +----------------------------+---------------+------------------------- + +The viscosity of a dextrin or artificial gum is determined in exactly +the same way as a natural gum, using 10 per cent. solutions. It would +probably be an improvement to use 10 per cent. solutions for many of the +dextrins, as they are when low in starch extremely thin. + +The hygroscopic nature of dextrins renders them unsuitable for foreign +work, but when the quantity of starch is appreciable, better results are +obtainable. A large percentage of unaltered starch is usually +accompanied with a small percentage of sugar, and no doubt this is the +explanation of this fact. An admixture containing natural gum of course +behaved better than when no such gum is present. Bodies like "arabol" +made up with water and containing gelatin are very hygroscopic when dry, +although as sold they lose water on exposure to the air. Gum substitutes +consisting entirely of some form of gelatin with water, like fish glue, +are also somewhat hygroscopic when dried. The behavior of these +artificial gums and dextrins on exposure to a warm moist atmosphere can +be determined in the same apparatus as described for gums. + +The process we have adopted for estimating the glucose starch and +dextrin in commercial gum substitutes is based on C. Hanofsky's method +for the assay of brewers' dextrins (this Journal, 8, 561). A weighed +quantity of the dextrin is dissolved in cold water, filtered from any +insoluble starch, and then the glucose determined directly in the clear +filtrate by Fehling's solution. The real dextrin is determined by +inverting a portion of the filtered liquid with HCl, and then +determining its reducing power. The starch is estimated by inverting a +portion of the solid dextrin, and determining the glucose formed by +Fehling. After deducting the amounts due to the original glucose and the +inverted dextrin present, the residue is calculated as starch. A +determination of the acidity of the solution is also made with decinormal +soda, and results returned in number of c.c. alkali required to +neutralize 100 grammes of the dextrin. Results we have obtained using +this method are embodied in the following table: + + ANALYSIS OF GUM SUBSTITUTES + +----+---------+---------+--------+----------+-------+-------+--------- + No.| Glucose.| Dextrin.| Starch.| Moisture.| Gum, | Ash. |Acidity. + | | | | | &c. | | +----+---------+---------+--------+----------+-------+-------+--------- + | | | | | | | cc. + 1 | 8.92 | 81.57 | 1.99 | 10.12 | None | 0.207 | 57.3 + 2 | 7.19 | 71.46 | 13.13 | 10.40 | None | 0.120 | 44.8 + 3 | 1.29 | 69.42 | 24.72 | 4.17 | 1.12 | 0.280 | 5.22 + 4 | 8.40 | 60.98 | 10.98 | 10.09 | 9.02 | 0.530 | 20.0 + 5 | 10.60 | 44.98 | 8.05 | 12.20 | 23.57 | 0.600 | 52.0 + 6 | 14.80 | 11.57 | 36.46 | 34.87 | 1.89 | 0.580 | 8.0 + 7 | 8.00 | 29.61 | 26.78 | 33.98 | 0.88 | 0.750 | 88.0 + 8 | 2.29 | 52.38 | 37.65 | None | 7.335 | 0.315 | 9.6 +----+---------+---------+--------+----------+-------+-------+--------- + +In those cases in which the substitute is made by admixture with gelatin +or liquid glue the quantity of other organic matter obtained can be +checked by a Kjeldahl determination of the total nitrogen. If a natural +gum is added, it will be partially converted into sugar when the +filtered liquid is inverted, and so make the dextrin determination +slightly too high. + + * * * * * + + + + +MR. CAILLETET'S CRYOGEN. + + +The "cryogen," a new apparatus constructed by Mr. E. Ducretet, from +instructions given by Mr. Cailletet, is designed for effecting a fall of +temperature of from 70° to 80° C. below zero, through the expansion of +liquid carbonic acid. + +The apparatus consists of two concentric vessels having an annular space +between them of a few centimeters. A worm, S, is placed in the internal +vessel R. All this is of nickel plated copper. The worm, S carries, at +Ro', an expansion cock and ends, at O in the annular space, R'. A very +strong tube is fixed to the cock, Ro', and to the ajutage, A'. It +receives the tube, Tu, which, at the time of an experiment, is coupled +with the cylinder of carbonic acid, CO². A tubulure, D, usually closed +by a plug, Bo, communicates with the inner receptacle, R. This is +capable of serving in certain experiments in condensation. The table, +Ta, of the tripod receives the various vessels or bottles for the +condensed products. + +The entire apparatus is placed in a box, B, lined with silk waste and +provided with a cover, C, of the same structure. Apertures, Th, Ro, and +T", allow of the passage of a key for acting upon the cock, Ro', as well +as of thermometers and stirrers if they are necessary. + +When it is desired to operate, the internal vessel, R, is filled with +alcohol (3 quarts for the ordinary model). This serves as a refrigerant +bath for the experiments to be made. The worm, S, having been put in +communication with the carbonic acid cylinder, CO², the cock, Ro, of the +latter is turned full on. The cock of the worm, which is closed, is +opened slightly. The vaporization and expansion of the liquid carbonic +acid cause it to congeal in the form of snow, which distributes itself +and circulates in the worm, S, and then in R. The flakes thus coming in +contact with the metallic sides of S rapidly return to the gaseous state +and produce an energetic refrigeration. At the lower part of the annular +space, R', are placed fragments of sponge impregnated with alcohol. The +snow that has traversed the worm without vaporizing reaches R'. and +dissolves in this alcohol, and the refrigeration that results therefrom +completes the lowering of the temperature. The gas finally escapes at O, +and then through the bent tube, T". + +[Illustration: CAILLETET'S CRYOGEN.] + +The apparatus may be constructed with an inverse circulation, the +carbonic acid then entering the annular vessel, R, directly, and +afterward the worm, S, whence it escapes to the exterior of the +apparatus. The expansion cock sometimes becomes obstructed by the +solidification of the snow. It will then suffice to wait until the +circulation becomes re-established of itself. It may be brought about by +giving the cock, Ro', a few turns with the wooden handled key that +serves to maneuver the latter. It is not necessary to have a large +discharge of carbonic acid, and consequently the expansion cock needs to +be opened but a little bit. A few minutes suffice to reduce the +temperature of the alcohol bath to 70°, with an output of about from 4½ +to 5½ lb. of liquid carbonic acid. When the circulation is arrested, the +apparatus thus surrounded by its isolating protective jackets becomes +heated again with extreme slowness. In one experiment, it was observed +that at the end of nine hours the temperature of the alcohol had risen +but from 70° to 22°. On injecting a very small quantity of liquid +carbonic acid from time to time, a sensibly constant and extremely low +temperature may be maintained indefinitely.--_Le Genie Civil_. + + * * * * * + + + + +METHOD OF PRODUCING ALCOHOL. + + +In carrying out my improved process in and with the apparatus employed +in ordinary commercial distilleries, says Mr. Alfred Springer, of +Cincinnati, O., I preferably employ separate vats or tubs for the nitric +acid solution and the material to be treated, and a convenient +arrangement is to locate the nitric acid tub directly under the grain +tub, so that one may discharge into the other. In the upper vat is +placed the farinaceous material, preferably ground, thoroughly steeped +in three times its weight of water, and, where whole grain is used, +preferably "cooked" in the ordinary manner. The vat into which the +dilute acid is placed is an ordinary cooking tub of suitable material to +resist the acid, provided with closed steam coils and also nozzles for +the discharge of steam into the contained mass. Into this vat is placed +for each one hundred parts of the grain to be treated one part of +commercial nitric acid diluted with fifty parts of water and brought to +a state of ebullition and agitation by the steam coils and the discharge +through the nozzles, the latter being regulated so that the gain by +condensation of steam approximately equals the loss by evaporation. The +farinaceous contents of the upper vat are allowed to flow slowly into +the nitric acid solution while the ebullition and agitation of the mass +is continued. This condition is then maintained for six to eight hours, +after which the mass is allowed to stand for one day or until the +saccharification becomes complete. The conversion can be followed by the +"iodine test" for intermediary dextrins and the "alcohol test" for +dextrin. After the saccharification is complete I may partially or +wholly neutralize the nitric acid, preferably with potassium or Ammonium +carbonate, preferably employing only one-half the amount necessary to +neutralize the original quantity of nitric acid used, so that the mass +now ready to undergo fermentation has an acid reaction. The purpose in +view here is to keep the peptones in solution also, because an acid +medium is best adapted to the propagation of the yeast cells. It is not +absolutely necessary to even partially neutralize the nitric acid, but +it is preferable. Yeast is now added, and the remaining processes are +similar to those generally employed in distilleries, excepting that just +prior to distillation potassium carbonate sufficient to neutralize the +remaining nitric acid is added, in order to avoid corrosion of the still +and correct the acid reaction of the slop. + +As a variant of the process I sometimes add to the usual amount of +nitric acid an additional one one-hundredth part of phosphoric acid on +account of its beneficial nutritive powers--that is to say, to one +hundred parts of grain one part of nitric acid and one one-hundredth +part of phosphoric acid. + +While my improved process is based on the well-known converting power of +acids on starch, I am not aware that it has ever been applied in the +manner and for the purposes I have described. For example, sulphuric and +hydrochloric, also sulphuric and nitric, acids have been employed in the +manufacture of glucose; but in every such case the resulting products +were not capable of superseding those obtained by the existing methods +of saccharification used in distilleries. In my process, on the other +hand, the product is so capable. Not only may malted grain be entirely +omitted, but more fermentable products are formed and the products of +fermentation are purer. The saccharification being more complete, there +are less intermediary and nonfermentable dextrins, and the yield of +spirits is therefore increased. Malted grain being omitted or used in +reduced quantity, there is less lactic acid and few or foreign ferments +to contaminate the fermenting mass; also, the formation of higher +alcohols than the ethyl alcohol is almost totally suppressed. +Consequently the final yield of spirits is purer in quality and requires +little or no further purification. Also, further, the nitrates +themselves acting as nutrients to the yeast cells, these become more +active and require less nutrition to be taken from the grain. + + * * * * * + + + + +SPECTROSCOPIC DETERMINATION OF THE SENSITIVENESS OF DRY PLATES. + + +After describing other methods of determining the sensitiveness of +plates, Mr. G.F. Williams, in the _Br. Jour. of Photo_., thus explains +his plan. I will now explain the method I adopt to ascertain the +relative sensitiveness of plates to daylight. Procure a small direct +vision pocket spectroscope, having adjustable slit and sliding focus. To +the front of any ordinary camera that will extend to sixteen or eighteen +inches, fit a temporary front of soft pine half an inch thick, and in +the center of this bore neatly with a center bit a hole of such diameter +as will take the eye end of the spectroscope; unscrew the eyehole, and +push the tube into the hole in wood, bushing the hole, if necessary, +with a strip of black velvet glued in to make a tight fit. By fixing the +smaller tube in the front of camera we can focus by sliding the outer +tube thereon; if we fix the larger tube in the front, we should have to +focus inside the camera, obviously most inconvenient in practice. Place +the front carrying the spectroscope _in situ_ in the camera, and rack +the latter out to its full extent; point the camera toward a bright sky, +or the sun itself, if you can, while you endeavor to get a good focus. +The spectrum will be seen on the ground glass, probably equal in +dimensions to that of a quarter plate. Proceed to focus by sliding the +outer tube to and fro until the colors are quite clear and distinct, and +at same time screw down the slit until the Fraunhofer lines appear. By +using the direct rays of the sun, and focusing carefully, and adjusting +the slit to the correct width, the lines can be got fairly sharply. +Slide your front so that the spectrum falls on the ground glass in just +such a position as a quarter plate glass would occupy when in the dark +slide, and arrange matters so that the red comes to your left, and the +violet to the right, and invariably adopt that plan. It is advisable to +include the double H lines in the violet on the right hand edge of your +plate. They afford an unerring point from which you can calculate +backward, finding G, F, E, etc., by their relative positions to the +violet lines. Otherwise you may be mistaken as to what portion of the +spectrum you are really photographing. The red should just be seen along +the left edge of the quarter plate. When all is arranged thus, you +utilize three-fourths of your plate with the spectrum, with just a +little clear glass at each end. Before disturbing the arrangement of +the apparatus, it is desirable to scratch a mark on the sliding tube, +and make a memorandum of the position of all the parts, so that they may +be taken away and replaced exactly and thus save time in future. + +To take a photograph of the spectrum, put a quarter plate in the dark +slide and place in camera; point the camera toward a bright sky, or +white cloud, near the sun--not at the sun, as there is considerable +difficulty in keeping the direct rays exactly in the axis of the +spectroscope--draw the shutter, and give, say, sixty seconds. On +development, you will probably obtain a good spectrum at the first +trial. The duration of exposure must, of course, depend upon the +brightness of the day; but if the experiments are to have relative +values, the period of exposure must be distinctly noted, and comparisons +made for a normal exposure of sixty seconds, ninety seconds, two minutes +or more, just according to whatever object one has in view in making the +experiments. With a given exposure the results will vary with the light +and the width of the slit, as well as being influenced by the character +of the instrument itself. Further, all such experiments should be made +with a normal developer, and development continued for a definite time. +The only exception to this rule would be in the event of wishing to +ascertain the utmost that could be got out of a plate, but, under +ordinary circumstances, the developer ought never to vary, nor yet the +duration of development. To try the effect of various developers, or +varying time in development, a departure must be made of such a nature +as would operate to bring out upon each plate, or piece of a plate, the +utmost it would develop short of fog, against which caution must be +adopted in all spectrum experiments. + +On development, say for one, two, or three minutes, wash off and fix. +You will recognize the H violet lines and the others to the left, and +this experiment shows what is the sensitiveness of this particular plate +to the various regions of the spectrum with this particular apparatus, +and with a normal exposure and development. So far, this teaches very +little; it merely indicates that this particular plate is sensitive or +insensitive to certain rays of colored light. To make this teaching of +any value, we must institute comparisons. Accordingly, instead of simply +exposing one plate, suppose we cut a strip from two, three, four, or +even half a dozen different plates, and arrange them side by side, +horizontally, in the dark slide, so that the spectrum falls upon the +whole when they are placed in the camera and exposed. There is really no +difficulty in cutting strips a quarter of an inch wide, the lengthway of +a quarter plate. Lay the gelatine plate film up, and hold a straight +edge on it firmly, so that when we use a suitable diamond we can plow +through the film and cut a strip which will break off easily between the +thumb and finger. A quarter plate can thus be cut up into strips to +yield about a dozen comparative experiments. When cut and snapped off, +mark each with pencil with such a distinguishing mark as shall be +clearly seen after fixing. The cut up strips can be kept in the maker's +plate box. + + * * * * * + + +The deep down underground electric railway in London has so far proved +an unprofitable concern for its stockholders. It is 3½ miles long, +touches some of the greatest points of traffic, but somehow or other +people won't patronize it. The total receipts for the last six months +were a little under $100,000, and they only carried seventeen persons +per train mile. On this road the passengers are carried on elevators up +and down from the street level to the cars. The poor results so far make +the stockholders sick of the project of extending the road. + + * * * * * + + +A NEW CATALOGUE OF VALUE + + +Contained in Scientific American Supplement during the past ten years, +sent _free of charge_ to any address. Munn & Co., 361 Broadway, New +York. + + * * * * * + + +THE SCIENTIFIC AMERICAN + +ARCHITECTS AND BUILDERS EDITION + + +$2.50 a Year. 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Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + + +Most people start at our Web site which has the main PG search facility: + + https://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. diff --git a/13640-8.zip b/13640-8.zip Binary files differnew file mode 100644 index 0000000..029cbcb --- /dev/null +++ b/13640-8.zip diff --git a/13640-h.zip b/13640-h.zip Binary files differnew file mode 100644 index 0000000..f7d5c64 --- /dev/null +++ b/13640-h.zip diff --git a/13640-h/13640-h.htm b/13640-h/13640-h.htm new file mode 100644 index 0000000..3644602 --- /dev/null +++ b/13640-h/13640-h.htm @@ -0,0 +1,5875 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> +<meta http-equiv="Content-Type" content= +"text/html; charset=UTF-8"> +<title>The Project Gutenberg eBook of Scientific American +Supplement, 821</title> +<style type="text/css"> +<!-- +body {margin-left: 15%; margin-right: 15%; background-color: white} +img {border: 0;} +h1,h2,h3 {text-align: center;} +.note {margin-left: 2em; margin-right: 2em; margin-bottom: 1em;} +.ind {margin-left: 10%; margin-right: 10%;} +hr {text-align: center; width: 50%;} +.ctr {text-align: center;} +th {font-weight: normal;} +--> +</style> +</head> +<body> +<div>*** START OF THE PROJECT GUTENBERG EBOOK 13640 ***</div> + +<p class="ctr"><a href="./images/title.png"><img src="./images/title_th.jpg" alt=""></a> +</p> +<h1>SCIENTIFIC AMERICAN SUPPLEMENT NO. 821</h1> +<h2>NEW YORK, September 26, 1891</h2> +<h4>Scientific American Supplement. Vol. XXXII, No. 821.</h4> +<h4>Scientific American established 1845</h4> +<h4>Scientific American Supplement, $5 a year.</h4> +<h4>Scientific American and Supplement, $7 a year.</h4> +<hr /> +<table summary="Contents" border="0" cellspacing="5"> +<tr> +<th colspan="2">TABLE OF CONTENTS.</th> +</tr> +<tr> +<td valign="top">I.</td> +<td><a href="#arch1"> + Architectural.--The New Labor Exchange in Paris.--With + views of the interior and exterior of the building</a></td> +</tr> +<tr> +<td valign="top">II.</td> +<td><a href="#elec1"> + Electrical.--The Construction and Maintenance of Underground + Circuits.--By S.B. FOWLER.--A comprehensive article, + discussing at length the various devices for protecting underground + circuits, methods of inserting the cables, etc.</a></td> +</tr> +<tr> +<td valign="top">III.</td> +<td><a href="#eng1"> +Engineering.--Railroads to the Clouds.--Sketches of a number + of mountain railroads</a></td> +</tr> +<tr> +<td valign="top">IV.</td> +<td><a href="#mar1"> +Marine Engineering.--The French Armored Turret Ship + the Marceau.--1 engraving.--A full description of the vessel, giving + dimensions and cost</a></td> +</tr> +<tr> +<td></td> +<td><a href="#mar2"> + A Review of Marine Engineering during the Past Decade.--A + paper read before the Institution of Mechanical Engineers by Mr. + Alfred Blechynben, of Barrow-in-Furness.--This paper, which + is continued from Supplement No. 820, treats on steam pipes, + feed water heating, twin screws, etc.</a></td> +</tr> +<tr> +<td valign="top">V.</td> +<td><a href="#misc1"> +Miscellaneous.--The Little House.--An article giving various + hints about the arrangement and management of small + dwellings, with special view to the best sanitary arrangements</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc2"> + Stilt Walking.--A sketch, with engraving, of Sylvain Dornon, + the stilt walker of Landes</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc3"> Remains of a Roman Villa in England</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc4">Gum Arabic and its Modern Substitutes.--A continuation of a + paper by Dr. S. Rideal and W.E. Youle.--With 26 tables</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc5">A New Method of Extinguishing Fires.--Invented by George +Dickson and David A. Jones, of Toronto, Canada.--Apparatus designed +to utilize a mixture of water and liquefied carbonic acid</a></td> +</tr> + +<tr> +<td valign="top">VI.</td> +<td><a href="#med1"> +Medicine and Hygiene.--The Hygienic Treatment of + Obesity.--By Dr. Paul Chebon.--Methods of eating, drinking, + and exercising for the purpose of reducing fat.--An extended + article, giving valuable information to people troubled with too + much flesh</a></td> +</tr> +<tr> +<td valign="top">VII.</td> +<td><a href="#pho1"> +Photography.--Spectroscopic Determination of the Sensitiveness + of Dry Plates.--A full description of the new plan of + Mr. G.F. WILLIAMS, for determining the sensitiveness of dry + plates by the use of a small direct vision pocket spectroscope</a></td> +</tr> + +<tr> +<td valign="top">VIII.</td> +<td><a href="#phys1">Physics.--A Physical Laboratory Indicator.--By J.W. +MOORE, of Lafayette College.--1 engraving.--This is a modification +of the old peg board adapted to use in the laboratory.--It indicates +the names of the members of the class, contains a full +list of the experiments to be performed, refers the student +to the book and page where information in reference to experiments +or apparatus may be found, it shows what experiments +are to be performed by each student at a given time, etc.</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#phys2"> Cailletet's Cryogen.--A description, with one engraving, of Mr. +Cailletet's new apparatus for producing temperatures from 70 +degrees to 80 degrees C., below zero, through the expansion of +liquid carbonic acid</a></td> +</tr> + +<tr> +<td valign="top">IX.</td> +<td><a href="#tech1"> +Technology.--The Manufacture of Roll Tar Paper.--An extended + article containing a historical sketch and full information + as to the materials used and the methods of manufacture</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#tech2"> Smokeless Gunpowder.--By Hudson Maxim.--A comprehensive +article on the manufacture and use of smokeless gunpowder, +giving a sketch of its history, and describing the methods of +manufacture and its characteristics</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#tech3">Method of Producing Alcohol.--A description of an improved +process for making alcohol.--Invented by Mr. Alfred Springer, +of Cincinnati, Ohio</a></td> +</tr> +</table> +<hr /> + +<p class="ctr"><a href="./images/1-hall.png"><img src="images/1-hall_th.jpg" width="600" height="364" alt="INTERIOR OF THE NEW LABOR EXCHANGE, PARIS." title=""></a><br clear="all" /> +INTERIOR OF THE NEW LABOR EXCHANGE, PARIS.</p> + +<p class="ctr"><a href="./images/1-bldg.png"><img src="images/1-bldg_th.jpg" width="564" height="400" alt="THE NEW LABOR EXCHANGE, PARIS." title=""></a><br clear="all" /> +THE NEW LABOR EXCHANGE, PARIS.</p> + +<a name="arch1"></a><h2>THE NEW LABOR EXCHANGE, PARIS.</h2> + +<p>The new Labor Exchange is soon to be inaugurated. +We give herewith a view of the entrance facade of the +meeting hall. The buildings, which are the work of +Mr Bouvard, architect, of the city of Paris, are comprised +within the block of houses whose sharp angle +forms upon Place de la Republique, the intersection of +Boulevard Magenta and Bondy street. One of the entrances +of the Exchange is on a level with this street. +The three others are on Chateau d'Eau street, where +the facade of the edifice extends for a length of one +hundred feet. From the facade and above the balcony +that projects from the first story, stand out in bold +relief three heads surrounded by foliage and fruit +that dominate the three entrance doors. These sculptures +represent the Republic between Labor and Peace. +The windows of the upper stories are set within nine +rows of columns, from between the capitals of which +stand out the names of the manufacturers, inventors, +and statesmen that have sprung from the laboring +classes. Upon the same line, at the two extremities of +the facade, two modillions, traversed through their +center by palms, bear the devices "Labor" and +"Peace." Above, there is a dial surmounted by a +shield bearing the device of the city of Paris.</p> + +<p>The central door of the ground floor opens upon a +large vestibule, around which are arranged symmetrically +the post, telegraph, telephone, and intelligence +offices, etc. Beyond the vestibule there is a gallery +that leads to the central court, upon the site of which +has been erected the grand assembly hall. This latter, +which measures 20 meters in length, 22 in width, and +6 in height, is lighted by a glazed ceiling, and contains +ten rows of benches. These latter contain 900 seats, +arranged in the form of circular steps, radiating +around the president's platform, which is one meter +in height. A special combination will permit of increasing +the number of seats reserved for the labor associations +on occasions of grand reunions to 1,200. The +oak doors forming the lateral bays of the hall will +open upon the two large assembly rooms and the three +waiting rooms constructed around the faces of the +large hall. In the assembly rooms forming one with +the central hall will take place the deliberations of the +syndic chambers. The walls of the hall will, ere long, +receive decorative paintings.--<i>L'Illustration.</i></p> + +<hr /> + +<a name="tech1"></a><h2>MANUFACTURE OF ROLL TAR PAPER.</h2> + +<p>Roofing paper was first used in Scandinavia early as +the last century, the invention being accredited to Faxa, +an official of the Swedish Admiralty. The first tar and +gravel roofs in Sweden were very defective. The impregnation +of the paper with a water-proofing liquid had not +been thought of, and the roofs were constructed by +laying over the rafters a boarding, upon which the unsaturated +paper, the sides of which lapped over the +other, was fastened with short tacks. The surface of +the paper was next coated with heated pine tar to make +it waterproof. The thin layer of tar was soon destroyed +by the weather, so that the paper, swelled by the absorption +of rain water, lost its cohesiveness and was +soon destroyed by the elements. This imperfect method +of roof covering found no great favor and was but +seldom employed.</p> + +<p>In Germany the architect Gilly was first to become +interested in tar paper roofing, and recommended it in +his architecture for the country. Nevertheless the new +style of roof covering was but little employed, and was +finally abandoned during the first year of the 19th century. +It was revived again in 1840, when people began +to take a renewed interest in tar paper roofs, the method +of manufacturing an impermeable paper being already +so far perfected that the squares of paper were dipped +in tar until thoroughly saturated. The roof constructed +of these waterproof paper sheets proved itself +to be a durable covering, being unimpenetrable to atmospheric +precipitations, and soon several factories +commenced manufacturing the paper. The product +was improved continually and its method of manufacture +perfected. The good qualities of tar paper roofs +being recognized by the public, they were gradually +adopted. The costly pine tar was soon replaced by the +cheaper coal tar. Square sheets of paper were made +at first; they were dipped sufficiently long in ordinary +heated coal tar, until perfectly saturated. The excess +of tar was then permitted to drip off, and the sheets +were dried in the air. The improvement of passing +them through rollers to get rid of the surplus tar was +reserved for a future time, when an enterprising manufacturer +commenced to make endless tar paper in +place of sheets. Special apparatus were constructed +to impregnate these rolls with tar; they were imperfect +at first, but gradually improved to a high degree. +Much progress was also made in the construction of +the roofs, and several methods of covering were devised. +The defects caused by the old method of nailing +the tar paper direct upon the roof boarding were +corrected; the consequence of this method was that +the paper was apt to tear, caused by the unequal expansion +of the roofing boards and paper, and this soon +led to the idea of making the latter independent of the +former by nailing the sides of the paper upon strips +running parallel with the gable. The use of endless +tar paper proved to be an essential advantage, because +the number of seams as well as places where it had to +be nailed to the roof boarding was largely decreased. +The manufacture of tar paper has remained at about +the same stage and no essential improvements have +been made up to the present. As partial improvement +may be mentioned the preparation of tar, especially +since the introduction of the tar distillery, and the +manufacture of special roof lacquers, which have been +used for coating in place of the coal tar. As an essential +progress in the tar paper roofing may be mentioned +the invention of the double tar paper roof, and the +wood cement roof, which is regarded as an offshoot.</p> + +<p>The tar paper industry has, within the last forty +years, assumed great dimensions, and the preferences +for this roofing are gaining ground daily. In view of +the small weight of the covering material, the wood +construction of the roof can be much lighter, and the +building is therefore less strained by the weight of the +roof than one with the other kind, so that the outer +walls need not be as heavy. Considering the price, the +paper roof is not only cheaper than other fireproof +roofs, but its light weight makes it possible for the +whole building to be constructed lighter and cheaper. +The durability of the tar paper roof is satisfactory, if + +carefully made of good material; the double tar paper +roof, the gravel double roof, and the wood cement +roof are distinguished by their great durability.</p> + +<p>These roofs may be used for all kinds of buildings, +and not only are factories, storehouses, and country +buildings covered with it, but also many dwellings. +The most stylish residences and villas are at present +being inclosed with the more durable kinds; the double +roof, the gravel double roof, and the wood cement +roof. For factory buildings, which are constantly +shaken by the vibrations of the machinery, the tar paper +roof is preferable to any other.</p> + +<p>In order to ascertain to what degree tar paper roofs +would resist fire, experiments were instituted at the +instigation of some of the larger manufacturers of roofing +paper, in the presence of experts, architects, and +others, embracing the most severe tests, and it was +fully proved that the tar paper roof is as fireproof as +any other. These experiments were made in two different +ways; first, the readiness of ignition of the tar +paper roof by a spark or flame from the outside was +considered, and, second, it was tested in how far it +would resist a fire in the interior of the building. In +the former case, it was ascertained that a bright, intense +fire could be kept burning upon the roof for some +time, without igniting the woodwork of the roof, but +heat from above caused some of the more volatile constituents +of the tar to be expelled, whereby small +flames appeared upon the surface within the limits of +the fire; the roofing paper was not completely destroyed. +There always remained a cohesive substance, +although it was charred and friable, which by reason +of its bad conductivity of heat protected the roof +boarding to such an extent that it was "browned" +only by the developed tar vapors. A fire was next +started within a building covered with a tar paper +roof; the flame touched the roof boarding, which partly +commenced to char and smoulder, but the bright burning +of the wood was prevented by the air-tight condition +of the roof; the fire gases could not escape from +the building. The smoke collecting under the roof +prevented the entrance of fresh air, in consequence of +which the want of oxygen smothered the fire. The +roofing paper remained unchanged. By making openings +in the sides of the building so that the fire gases +could escape, the wood part of the roof was consumed, +but the roofing paper itself was only charred and did +not burn. After removing the fire in contact with the +paper, this ceased burning at once and evinced no disposition +whatever to spread. In large conflagrations, +also, the tar paper roofs behaved in identically a similar +manner. Many instances have occurred where the +tar paper roof prevented the fire from spreading inside +the building, and developing with sufficient intensity +to work injury.</p> + +<p>As it is of interest to the roofer to know the manner +of making the material he uses, we give in the following +a short description of the manufacture of roofing +paper. At first, when square sheets were used exclusively, +the raw paper consisted of ordinary dipped or +formed sheets. The materials used in its manufacture +were common woolen rags and other material. In order +to prepare the pulp from the rags it is necessary to +cut them so small that the fabric is entirely dissolved +and converted into short fibers. The rags are for this +purpose first cut into pieces, which are again reduced by +special machines. The rags are cut in a rag cutting +machine, which was formerly constructed similar to a +feed cutter; later on, more complicated machines of +various constructions were employed. It is not our +task to describe the various kinds, but we remain content +with the general remark that they are all based +on the principles of causing revolving knives to operate +upon the rags. The careful cleansing of the cut rags, +necessary for the manufacture of paper, is not required +for roofing paper. It is sufficient to rinse away +the sand and other solid extraneous matter. The further +reduction of the cut rags was formerly performed +in a stamp mill, which is no longer employed, the pulp +mill or rag engine being universally used.</p> + +<p>The construction of this engine may be described as +follows: A box or trough of wood, iron, or stone is by +a partition divided into two parts which are connected +at their ends. At one side upon the bottom of the +box lies an oakwood block, called the back fall. In a +hollow of this back fall is sunk the so-called plate, +furnished with a number of sharp steel cutters or +knives, lying alongside of each other. A roller of solid +oakwood, the circumference of which is also furnished +with sharp steel cutters or knives, is fastened upon a +shaft and revolves within the hollow. The journal +bearings of the shaft are let into and fastened in movable +wooden carriers. The carriers of the bearings +may be raised and lowered by turning suitable thumbscrews, +whereby the distance between the roller and +the back fall is increased or decreased. The whole is +above covered with a dome, the so-called case, to prevent +the throwing out of the mass under the operation +of grinding. The roller is revolved with a velocity +of from 100 to 150 revolutions per minute, whereby +the rags are sucked in between the roller and the back +fall and cut and torn between the knives. At the beginning +of the operation, the distance between the +roller and the back fall is made as great as possible, +the intention being less to cut the rags than to wash +them thoroughly. The dirty water is then drawn off +and replaced by clean, and the space of the grinding +apparatus is lessened gradually, so as to cut the rags +between the knives. The mass is constantly kept in +motion and each piece of rag passes repeatedly between +the knives. The case protects the mass from +being thrown out by the centrifugal force. The work +of beating the rags is ended in a few hours, and the +ensuing thin paste is drawn off into the pulp chest, +this being a square box lined with lead.</p> + +<p>From the pulp chest it passes to the form of the +paper machine. This form consists of an endless fine +web of brass wire, which revolves around rollers. The +upper part of this form rests upon a number of hollow +copper rollers, whereby a level place is formed. The +form revolves uniformly around the two end rollers, +and has at the same time a vibratory motion, by which +the pulp running upon the form is spread out uniformly +and conducted along, more flowing on as the +latter progresses. The water escapes rapidly through +the close wire web. In order to limit the form on the +sides two endless leather straps revolve around the +rollers on each side, which touch with their lower +parts the form on both sides and confine the fluid within +a proper breadth. The thickness of the pulp is regulated + +at the head of the form by a brass rule standing +at a certain height; its function is to level the +pulp and distribute it at a certain thickness. The +continually moving pulp layer assumes greater consistency +the nearer it approaches to the dandy roll. +This is a cylinder covered with brass wire, and is for +the purpose of compressing the paper, after it has left +the form, and free it from a great part of the water, +which escapes into a box. The paper is now freed of a +good deal of the fluid, and assumes a consistency with +which it is enabled to leave the form, which now commences +to return underneath the paper, passing on to +an endless felt, which revolves around rollers and delivers +it to two iron rolls. The paper passes through a +second pair of iron rollers, the interiors of which are +heated by steam. These rollers cause the last of the +water to be evaporated, so that it can then be rolled +upon reels. A special arrangement shaves the edges +to the exact size required.</p> + +<p>The paper is made in different thicknesses and designated +by numbers to the size and weight.</p> + +<p>Waste paper, bookbinders' shavings, etc., can be +used for making the paper. As much wool as possible +should be employed, because the wool fiber has a +greater resistance than vegetable fiber to the effects of +the temperature. By wool fiber is understood the +horny substance resembling hair, with the difference +that the former has no marrowy tissue. The covering +pellicle of the wool fiber consists of flat, mostly elongated +leaves, with more or less corners, lying over +each other like scales, which makes the surface of the +fiber rough; this condition, together with the inclination +of curling, renders it capable of felting readily. +Pure wool consists of a horny substance, containing +both nitrogen and sulphur, and dissolves in a potash +solution. In a clean condition, the wool contains +from 0.3 to 0.5 per cent. of ash. It is very hygroscopical, +and under ordinary circumstances it contains +from 13 to 16 per cent. humidity, in dry air from 7 to +11 per cent., which can be entirely expelled at a temperature +of from 226 to 230 degrees Fahrenheit. Wool +when ignited does not burn with a bright flame, as +vegetable fiber does, but consumes with a feeble +smouldering glow, soon extinguishes, spreading a disagreeable +pungent vapor, as of burning horn. By +placing a test tube with a solution of five parts caustic +potash in 100 parts water, a mixture of vegetable fibers +and wool fibers, the latter dissolve if the fluid is +brought to boiling above an alcohol flame, while the +cotton and linen fibers remain intact.</p> + +<p>The solubility of the woolen fibers in potash lye is a +ready means of ascertaining the percentage of wool +fiber in the paper. An exhaustive analysis of the latter +can be performed in the following manner: A +known quantity of the paper is slowly dried in a drying +apparatus at temperature of 230° Fahrenheit, until +a sample weighed on a scale remains constant. The +loss of weight indicates the degree of humidity. To +determine the ash percentage, the sample is placed in a +platinum crucible, and held over a lamp until all the +organic matter is burned out and the ash has assumed +a light color. The cold ash is then moistened with a +carbonate of ammonia solution, and the crucible +again exposed until it is dark red; the weight of the +ash is then taken. To determine the percentage of +wool, a sample of the paper is dried at 230° Fahrenheit +and weighed, boiled in a porcelain dish in potash +lye 12° B. strong, and frequently stirred with a glass +rod. The wool fiber soon dissolves in the potash lye, +while the vegetable fiber remains unaltered. The +pulpy mass resulting is placed upon a filter, dried at +212° Fahrenheit, and after the potash lye has dripped +off, the residue, consisting of vegetable fiber and earthy +ash ingredients, is washed until the water ceases to +dissolve anything. The residue dried at 212° Fahrenheit +is weighed with a filter, after which that of the +latter is deducted. The loss of weight experienced is +essentially equal to the loss of the wool fiber. If the +filtrate is saturated with hydrochloric acid, the dissolved +wool fiber separates again, and after having +been collected upon a weighed filter, it may be weighed +and the quantity ascertained.</p> + +<p>The weight of the mineral substances in the raw +paper is ascertained by analyzing the ash in a manner +similar to that above described. The several constituents +of the ash and the mineral added to the raw +paper are ascertained as follows: Sufficient of the +paper is calcined in the manner described; a known +quantity of the ash is weighed and thrown into a +small porcelain dish containing a little distilled water +and an excess of chemically pure hydrochloric acid. In +this solution are dissolved the carbonates, carbonate of +lime, carbonate of magnesia, a little of sulphate of +alumina, as well as metallic oxides, while silicate +of magnesia, silicic acid, sulphate of lime (gypsum) remain +undissolved. The substance is heated until the +water and excess of free hydrochloric acid have been +driven off; it is then moistened with a little hydrochloric +acid, diluted with distilled water and heated. +The undissolved residue is by filtering separated from +the dissolved, the filter washed with distilled water, +and the wash water added to the filtrate. The undissolved +residue is dried, and after the filter has also +been burned in due manner and the ash added, the +weight is ascertained. It consists of clay, sand, silicic +acid and gypsum.</p> + +<p>The filtrate is then poured into a cylinder capable of +holding 100 cubic centimeters, and furnished with a +scale; sufficient distilled water is then added until the +well-shaken fluid measures precisely 100 cubic centimeters. +By means of this measuring instrument, the +filtrate is then divided into two equal portions. One +of these parts is in a beaker glass over-saturated with +chemically pure chloride of ammonia, whereby any +iron of oxide present and a little dissolved alumina fall +down as deposit. The precipitate is separated by filtering, +washed, dried at 212° Fahrenheit and weighed. +To the filtrate is then added a solution of oxalate of +ammonia until a white precipitate of oxalate of lime is +formed. This precipitate is separated by filtering, +washed, dried and when separated from the filter, is +collected upon dark satinized paper; the filter itself is +burned and the ash added to the oxalate of lime. This +oxalate of lime is then heated to a dark red heat in a +platinum crucible with lid until the oxalate of lime is +converted into carbonate of lime. By the addition of +a few drops of carbonate of ammonia solution and another +slight heating of the crucible, also the caustic lime +produced in the filter ash by heating, is reconverted into +carbonate of lime, and after cooling in the exsiccator, + +the whole contents of the crucible is weighed as carbonate +of lime, after deducting the known quantity of filter +ash.</p> + +<p>Any magnesia present in the filtrate of the oxalate of +lime is by the addition of a solution of phosphate of +soda separated as phosphate of ammonia and magnesia, +after having stood twenty-four hours. The precipitate +is filtered off, washed with water to which a +little chloride of ammonia is added, dried, and after +calcining the fiber and adding the filter ash, glow +heated in the crucible. The glowed substance is +weighed after cooling, and is pyrophosphate of magnesia, +from which the magnesia or carbonate of magnesia +is calculated stoichiometrically. All the ascertained +sums must be multiplied by 2, if they are to correspond +to the analyzed and weighed quantity of +ash.</p> + +<p>The second half of the filtrate is used for determining +the small quantity of sulphate of lime still contained +in the hydrochlorate solution. By adding +chloride of barium solution the sulphuric acid is bound +to the barytes and sulphate of baryta separates as +white precipitate. This is separated by filtering, +washed, dried and weighed in the customary manner. +From the weight of the sulphate of baryta is then +computed the weight of sulphate of lime, which has +passed over into solution. The ascertained sum is also +to be multiplied with 2.</p> + +<p>The manufacture of roll tar paper from the roll paper +was at first found to be difficult, as it was impossible +to submerge a surface larger than from ten to fifteen +square yards, rolled up, in the tar, because more would +have required too large a pan. Besides this, the +paper tears easily, when it is in the hot tar. All kinds +of experiments were tried, in order to impregnate the +surface of the paper without employing too large a +pan.</p> + +<p>The following method was tried at first: The roll +paper was cut into lengths of ten yards, which were +rolled up loosely, so that a certain space was left between +the different coils. These loose rolls, of course, +occupied much space and could be put into the tar +only in a standing position, because in a horizontal +one the several coils would have pressed together +again. The loose roll was therefore slipped over a vertical +iron rod fastened into a circular perforated +wooden foot. The upper end of this iron rod ended in +a ring, in which the hook of a chain or rope could be +fastened. With the aid of a windlass the roll was +raised or lowered. When placed in the pan with boiling +tar, it was left there until thoroughly saturated. +It was then taken out, placed upon a table, and the +excess of tar allowed to drip off into a vessel underneath. +After partially drying, the roll was spread out +in open air, occasionally turned, until sufficiently dried, +when it was rolled up again.</p> + +<p>In order to neutralize the smeary, sticky condition +of the surface and avoid the disagreeable drying in +open air, the experiment of strewing sand on the sticky +places was tried next. The weight of the paper was +largely increased by the sand, and appeared considerably +thicker. For this reason the method of sanding +the paper was at once universally adopted. To dispense +with the process of permitting the surplus tar to +drip off, means were devised by which it was taken off +by scrapers, or by pressing through rollers. The +scrapers, two sharp edged rods fastened across the pan, +were then so placed that the paper was drawn through +them. The excess of tar adhering to its surface was +thereby scraped off and ran back into the pan.</p> + +<p>This work, however, was performed better and to +more satisfaction by a pair of rollers fastened to the pan. +These performed a double duty; thoroughly removed +the tar from the surface and by reason of their pressure +they caused a more perfect incorporation of the +tar with the fibers of the paper. Finally, different +factories employed different methods of manufacture, +one of which was to cut the rolls into definite lengths +of about ten yards; these were then rerolled very +loosely and immersed in the hot tar until sufficiently +saturated. The paper was then passed through the +roller, much pressure exerted, and then loosely rolled +up again. Being tarred once, it was then laid into a +second pan with hot tar, reeled out after a time, strewn +with sand, and rolled up again. Another method was +to cut clothes lines into lengths of about fifteen yards, +and at a distance of two inches have knots tied in +them. The paper was cut in lengths of ten or fifteen +yards, three pieces of the knotted clothes line were +then rolled between the loose coils of paper, which was +then submerged in the tar, which on account of the +knots could penetrate the paper. The paper was next +sanded by permitting its lower surface to pass over dry +sand in a box standing on the floor. A workman rolled +off the paper, and with his hand he strews sand on the +upper surface. The rolling taking place on the edge +of a table, by means of a crank, the excess of sand +dropped off.</p> + +<p>It is said by this method two workmen, one of which +tends to the rolling and sanding, the other turning +the crank, could turn out eighty rolls per day. This +method is still in use. It is useless to describe the +many antiquated methods in vogue in smaller factories, +and it can truthfully be said that nearly all of them +are out of date. It appears to be the fact of almost +all inventions that when reduced to practical use, +the arrangements, apparatus, and working methods +employed are generally of the most complicated nature, +and time and experience only will simplify them. +This has been also the case with the methods in the +roofing paper industry, which are at present gradually +being reduced to a practical basis. The method gradually +adopted has been described in the preceding. The +pan is of a certain length, whereby it becomes possible +to saturate the paper by slowly drawing it through +the heated tar. This is the chief feature. The work +is much simplified thereby and the workmen need not +dip their hands into the tar or soil them with it. The +work of impregnating has become much cleaner and +easier, while at the same time the tar can be heated to +a much higher temperature. The pan is generally +filled with distilled coal tar, and the heating is regulated +in such a manner that the temperature of the +impregnating mass is raised far beyond 212° Fahrenheit. +This accelerates the penetration, which takes +place more quickly as the degree of heat is raised, +which may be almost up to the boiling point of the tar, +as at this degree the paper is not destroyed by the +heat. In order to prevent the evaporation of the volatile +ingredients of the tar, the pan is covered with a + +sheet iron cover, with a slot at the place where the +paper enters into the impregnating mass and another +at the place where it issues. The tar is always kept +at the same level, by occasional additions.</p> + +<p>The roll of paper is mounted upon a shaft at the +back end of the pan, and by suitable arrangement of +guide rollers it unwinds slowly, passes into the tar in +which it is kept submerged. The guide rollers can be +raised so that when a new roller is set up they can be +raised out of the tar. The end of the paper is then +slipped underneath them above the surface of the tar, +when having passed through the squeezing rollers, it +is fastened to the beaming roller, and the guide rollers +are submerged again. A workman slowly turns the +crank of the beaming roller.</p> + +<p>This motion draws the paper slowly through the +fluid, the roll at the back end unwinding. The speed +with which the squeezing rollers are turned is regulated +in such a manner that the paper remains sufficiently +long underneath the fluid to be thoroughly +impregnated with it. The workmen quickly learn by +experience how fast to turn the crank. The hotter the +tar, the more rapid the saturation; the high degree of +heat expels the air and evaporates the hygroscopic +fluid in the pores of the paper. The strong heating of +the tar causes another advantage connected with this +method. The surface of the paper as it issues from the +squeezing rollers is still very hot, and a part of the +volatile oils evaporate very quickly at this high temperature. +The surface is thereby at once dried to a +certain degree and at the same time receives a handsome +luster, as if it had been coated with a black lacquer. +The paper is sanded in a very simple manner +without the use of mechanical apparatus; as it is being +wrapped into a coil, it passes with its lower surface +over a layer of sand, while the workman who tends to +rolling up strews the inside with sand. The lower +surface is coated very equally. Care only being necessary +that the sand lies smooth and even at all times. +When the workman has rolled up ten or fifteen yards, +he cuts it across with a knife and straightedge, so that +the paper is cut at right angles with its sides.</p> + +<p>There are three different sorts of roofing paper, +according to the impregnating fluid used in its manufacture. +The ordinary tar paper is that saturated with +clear cold tar. This contains the greatest amount of +fluid ingredients and is very raggy in a fresh condition. +It is easy to see that the volatile hydrocarbons evaporate +in a short time, and when expelled, the paper +becomes stiffer and apparently drier. This drying, +or the volatilization of the hydrocarbons, causes pores +between the fibers of the paper. These pores are +highly injurious to it, as they facilitate a process of +decomposition which will ruin it in a short time.</p> + +<p>Roofing paper can be called good only when it is +essentially made from woolen rags, and contains either +very few or no earthy additions. It is beyond doubt +that the durability of a roofing paper increases with +the quality of wool fiber it contains--vegetable fibers +and earthy additions cause a direct injury. Reprehensible +altogether is any combination with lime, +either in form of a carbonate or sulphate, because the +lime enters into chemical combination with the decomposition +products of the tar.</p> + +<p>The general nature of gravel is too well known to +require description. The grains of quartz sand are +either sharp cornered or else rounded pieces of stone of +quartz, occasionally mixed with grains of other amorphous +pieces of silica--such as horn stone, silicious +slate, carnelian, etc.; again, with lustrous pieces of +mica, or red and white pieces of feldspar. The gravel +used for a tar paper roof must be of a special nature +and be prepared for the purpose. The size of its grains +must not exceed a certain standard--say, the size of a +pea. When found in the gravel bank, it is frequently +mixed with clay, etc., and it cannot be used in this +condition for a roof, but must be washed. The utensils +necessary for this purpose are of so simple and suggestive +a nature that they need not be described. Slag +is being successfully used in place of the gravel. It is +easily reduced to suitable size, by letting the red hot +mass, as it runs from the furnace, run into a vessel +with water. The sudden chilling of the slag causes it +to burst into fragments of a sharp cornered structure. +It is next passed through a sieve, and the suitably +sized gravel makes an excellent material, as it gives a +clean appearance to the roof.</p> + +<p>The thinking mind can easily go one step further +and imagine that, since the tar contains a number of +volatile hydrocarbons, it might be made more adaptable +for impregnation by paper by distilling it, as by +this process the fluid would lose its tendency to evaporate +and the percentage of resinous substances increase. +Singular to say, there was a prejudice against +the employment of distilled tar, entertained by builders +and people who had no knowledge of chemistry. +Increasing intelligence and altered business circumstances, +however, brought about the almost universal +employment of distilled tar, and every large factory +uses it at present. The roofing paper prepared with +distilled tar is perhaps most suitably called asphaltum +paper, as this has been used in its manufacture. It +possesses properties superior to the ordinary tar paper, +one of which is that immediately after its manufacture, +as soon as cold, it is dry and ready for shipment; +nor does it require to be kept in store for a length of +time, and it has also a good, firm body, being as flexible +and tough as leather. It is very durable upon the roof, +and remains flexible for a long time. It is true that +asphaltum papers will always in a fresh state contain +a small percentage of volatile ingredients, which after +a while make it hard and friable upon the roof; but, +by reason of its greater percentage of resinous components, +it will always preserve a superior degree of +durability and become far less porous. One hundred +parts by weight absorb 140 or 150 parts by weight of coal +tar. A factory which distilled a good standard tar for +roofing paper recovered, besides benzole and naphtha, +also about ten per cent. of creosote oil, used for one +hundred parts raw paper, 176.4 partially distilled tar. +Experiments on a larger as well as a smaller scale +reduced this quantity to an average of 141.5 parts for +one hundred parts raw paper. The weight of sanded +paper is very variable, as it depends altogether upon +the size of the sand grains. It may be stated generally +that the weight of the sand is as large as that of the +tarred paper.</p> + +<p>The kinds of roofing paper saturated with other additions +besides coal tar form a separate class, in order +to neutralize the defects inherent in coal tar. These + +additions were originally for the purpose of thickening +the paper and making it stiffer and drier. The most +ordinary and cheapest thickener was the coal pitch. +Although the resinous substances are increased thereby, +still the light tar oils remain to evaporate, and the +paper prepared with such a substance readily becomes +hard and brittle. A better addition is the natural asphaltum, +because it resists better the destroying influence +of the decomposition process, and also, to a +certain degree, protects the coal tar in which it is dissolved. +The addition of natural asphaltum doubtless +caused the name of "asphaltum roofing paper." +Resin, sulphur, wood tar and other substances were +also used as additions; each manufacturer kept his +method secret, however, and simply pointed out by +high sounding title in what manner his paper was +composed. In most cases, however, this appellation +was applied to the ordinary tar paper; the impregnating +substance was mixed only with coal pitch, or +else a roofing paper saturated with distilled tar. The +costly additions, by the use of which a high grade of +roofing paper can doubtless be produced, largely +increased its price, and on account of the constant fall +of prices of the article, its use became rather one of +those things "more honored in the breach than in the +observance," and was dispensed with whenever practicable. +The crude paper is the foundation of the +roofing paper. The qualities of a good, unadulterated +paper have already been stated. At times, the crude +paper contains too many earthy ingredients which +impair the cohesion of the felted fibrous substance, +and which especially the carbonate of lime is very +injurious, as it readily effects the decomposition of the +coal tar. The percentage of wool, upon which the +durability of the paper depends very largely, is very +small in some of the paper found in the market. In +place of woolen rags, cheap substitutes have been +used, such as waste, which contains vegetable fibers. +Since this cannot resist the decomposition process for +any length of time, it is evident that the roofing paper +which contains a noticeable quantity of vegetable +fibers cannot be very durable. To judge from the endeavors +made to improve the coal tar, it may be concluded +that this material does not fully comply with +its function of making the roofing paper perfectly and +durably waterproof. The coal tar, be it either crude +or distilled, is not a perfect impregnating material, +and the roofing paper, saturated with it, possesses +several defects. Let us in the following try to ascertain +their shortcomings, and then express our idea in +what manner the roofing paper may be improved. It +was previously mentioned that every tar roofing paper +will, after a greater or smaller lapse of time, assume a +dry, porous, friable condition, caused by the volatilization +of a part of the constituents of the tar. This +alteration is materially assisted by the oxygen of the +air, which causes the latter to become resinous and +exerts a chemical influence upon them. By the volatilization +of the lighter tar oils, pores are generated between +the fibers of the roofing paper, into which the +air and humidity penetrate. In consequence of the +greatly enlarged surface, not only the solid ingredients +of the tar, which still remain unaltered, are exposed +to the action of the oxygen, but also the fibers of the +roofing paper are exposed to decomposition. How destructive +the alternating influence of the oxygen and +the atmospheric precipitations are for the roofing +paper will be shown by the following results of tests. +It will have been observed that the rain water running +from an old paper roof, especially after dry weather, +has a yellowish, sometimes a brown yellow color. The +supposition that this colored rain water might contain +decomposition products of the roofing paper readily +prompted itself, and it has been collected and analyzed +at different seasons of the year. After a period of +several weeks of fair weather during the summer, rain +fell, and the sample of water running from a roof was +caught and evaporated; the residue when dried +weighed 1.68 grammes. It was of a brownish black color, +fusible in heat and readily soluble, with a yellow brown +color in water. The dark brown substance readily +dissolved in ammonia, alcohol, dilute acid, hydrochloric +acid, sulphuric acid, and decomposed in nitric +acid, but did not dissolve in benzine or fat oil. After +several days' rain during the summer, a quantity of +the water was caught, evaporated, and the residue +dried. Its characteristics were similar to those above +mentioned. By an experiment instituted in water +under conditions similar to the first mentioned, the +dry brown substance weighed 71 grammes. It possessed +the same characteristics. In the solution effected with +water containing some aqua ammonia of the brown +substance, a white precipitate of oxalate of lime occurred +when an oxalate of ammonia solution was +added, but the brown substance remained in solution. +A further precipitation of oxalate of lime was produced +by a solution of oxalic acid, but the brown organic +substance remained in solution. This organic +substance being liberated from the lime was evaporated, +and left a dry, resinous, fusible brownish black +substance, which also dissolved readily in water. It +will be seen from these trials that the substance obtained +from the rain water running from a paper roof +is a combination of an organic acid with lime, which +readily dissolves in water, and that also the free organic +acid combined with the lime dissolves easily in +water.</p> + +<p>The question concerning the origin of this organic +substance or its combination with lime can only be +answered in one way, viz., that it must have been +washed by the rain water out of the paper. But since +such a solid substance, easily soluble in water, is contained +neither in the fresh roofing paper nor in the +coal tar, the only deduction is that it must have +arisen by the decomposition of the tar, in consequence +of the operation of the oxygen. The lime comes from +the coating substance of the roof, for which tar mixed +with coal pitch was used. The latter was fused with +carbonate of lime. These analyses furthermore show +that the formation of the organic acid easily soluble in +water depends upon the season; and that a larger +quantity of it is generated in warm, sunny weather +than in cold, without sunshine. This peculiarity of +the solid, resinous constituents of the coal tar, to be by +the operation of the atmospheric oxygen altered into +such products that are readily soluble in water, makes +the tar very unsuitable as a saturative substance for a +roofing paper. How rapidly a paper roof can be +ruined by the generation of this injurious organic acid +will be seen from the following calculation: Let us + +suppose that an average of 132 gallons of rain water +falls upon ten square feet roof surface per year, and +that the arithmetical mean 0.932 of the largest (1.680) +and smallest number (0.184) be the quantity of the +soluble brown substance which on an average is dissolved +in one quart of rain water; hence from ten +square feet of roof surface are rinsed away with the +rain water per year 466 grammes of the soluble decomposition +products of the tar. The oxidation process +will not always occur as intensely as by a paper roof, +ten years old and painted two years ago, which instigated +above described experiment. As long as the +roofing paper is fresh and less porous, especially if the +occurring pores are filled and closed again by repeated +coatings, oxidation will take place far less rapidly. +Besides this, the protective coating applied to the roof +surface is exposed most to this oxidation process. +Even by assuming this constantly progressive destructive +action of the oxygen on the roofing paper to be +much less than above stated, we can readily imagine +that it must be quite large. If it is desired to produce +a material free of faults, it is first of all indispensable +that unobjectionable raw material be procured. Coal +tar was formerly used almost exclusively for the coating +of a roof. It was heated and applied hot upon the +surface. In order to avoid the running off of the thinly +fluid mass, the freshly coated surface was strewn with +sand. The most volatile portion of the tar evaporated +soon, whereby the coating became thicker and finally +dried. The bad properties of the coal tar, pointed out +elsewhere, made it very unsuitable even for this purpose, +and experiments were instituted to compound +mixtures, by adding other ingredients to the tar, that +should more fully comply with its function. It may +be said in general that the coating masses for roofs can +be divided into two classes: either as lacquers or as +cements. To the former may be classed those of a +fairly thinly fluid consistency, and which contain +volatile oils in such quantities that they will dry +quickly. Cements are those of a thickly fluid consistency, +and are rendered thus fluid by heating. It is +not necessary that the coating applied should harden +quickly, as it assumes soon after its application a firmness +sufficient to prevent it from running off the roof. +Coal tar is to be classed among lacquers. If it has been +liberated by distillation from the volatile oils, it is +made better suited for the purpose than the ordinary +kind. The mass contains much more asphaltum, and +after drying, which takes place soon, it leaves a far +thicker layer upon the roof surface, while the pores, +which had formed in the roofing paper consequent on +drying, are better filled up. Nevertheless, the distilled +tar also has retained the property of drying with time +into a hard, vitreous mass, and ultimately to be destroyed +by decomposition.--<i>The Roofer</i>.</p> + +<hr /> + +<a name="phys1"></a><h2>A PHYSICAL LABORATORY INDICATOR.</h2> + +<p>The difficulties attending the management of a +physical laboratory are much greater than those of a +chemical one. The cause of this lies in the fact that +in the latter the apparatus is less complicated and the +pieces less varied. Any contrivance that will reduce +the labor and worry connected with the running of a +laboratory is valuable.</p> + +<p>A physical laboratory may be arranged in several +ways. The apparatus may be kept in a store room +and such as is needed may be given to the student each +day and removed after the experiments are performed; +or the apparatus for each experiment or system of experiments +may be kept in a fixed place in the laboratory +ready for assembling; for certain experiments +the apparatus may be kept in a fixed place in the laboratory +and permanently arranged for service.</p> + +<p>Each student may have his own desk and apparatus +or he may be required to pass from desk to desk. The +latter method is preferable.</p> + +<p>When a store room is used the services of a man are +required to distribute and afterward to collect. If the +apparatus is permanently distributed, a large room is +necessary, but the labor of collecting and distributing +is done away with.</p> + +<p>There are certain general experiments intended to +show the use of measuring instruments which all students +must perform. To illustrate the use of the indicator +I have selected an elementary class, although +the instrument is equally applicable to all classes of +experiments.</p> + +<p>Having selected a suitable room, tables may be +placed against the walls between the windows and at +other convenient places. Shallow closets are built +upon these tables against the wall; they have glass +doors and are fitted with shelves properly spaced. A +large number of light wooden boxes are prepared, +numbered from one up to the limit of the storage +capacity of the closets. A number corresponding to +that upon the box is placed upon the shelf, so that +each one after removal may be returned to its proper +place without difficulty. On the front of the box is a +label upon which is written the experiment to be +performed or the name of the apparatus whose use +is to be learned, references to various books, which may +be found in the laboratory library, and the apparatus +necessary for the experiment, which ought to be +found in the box. If any parts of the apparatus are +too large to be placed in the box, the label indicates +by a number where it may be found in the storage +case.</p> + +<p>It is evident that, instead of the above arrangement, +all the boxes can be stacked in piles in a general +store room. The described arrangement is preferable, +as it prevents confusion in collecting and distributing +apparatus when the class is large.</p> + +<p><i>The Indicator</i> (see figure).--Some device is evidently +desirable to direct the work of a laboratory with the +least trouble and friction possible. I have found that +the old fashioned "peg board," formerly used in schools +to record the demerits of scholars, modified as in the +following description, leaves nothing to be desired.</p> + +<p>The requirements of such an instrument are these: +It must show the names of the members of the class; +it must contain a full list of the experiments to be performed; +it must refer the student to the book and +page where information in reference to the experiments +or apparatus may be found; it must show what +experiments are to be performed by each student at a +given time; it must give information as to the place +in the laboratory where the apparatus is deposited; it +must show to the instructor what experiments have +been performed by each student; it must prevent the + +assignment of the same experiment to two students; +it must enable the instructor to assign the same experiment +to two or more students; it must form a complete +record of what has been done, what work is incomplete, +and what experiments have not yet been assigned; +it must also be so arranged that new experiments +or sets of experiments may be exhibited.</p> + +<p class="ctr"><img src="images/4-chart.png" width="264" height="397" alt="" title=""> +<br clear="all" />A, B, C, etc., are cards upon which are the names of +students. 1, 2, 3, etc., are cards like the one +described in the article. The small circles represent +unassigned experiments. The black circles (slate +nails) represent work done. The caudate circles +(brass nail) represent work assigned.</p> + +<p>The indicator consists of a plank of any convenient +length and breadth. The front surface is divided into +squares of such size that the pegs may be introduced +and withdrawn with ease. At each corner of the +squares holes are bored into which nails may be +placed. There is a blank border at the top and another +on the left side. At the top of each vertical +column of holes is placed a card holder. This is made +of light tin turned up on the long edges--which are +vertical--and tacked to the board. Opposite each +horizontal row of holes is a similar tin card holder, +but of greater length, and having its length horizontal. +The holders at the top of the board contain +cards upon which the names of the class are written.</p> + +<p>Cards, like the following, are prepared for the horizontal +holders.</p> + +<pre> +-------------------------------------------------------------- +Stewart & Gee 229 +Physical Manip. 85 Intensity of Gravity--Borda's Method 39 +Glazebrook & Shaw 132 +-------------------------------------------------------------- +</pre> + +<p>These cards are numbered from one to any desired +number and are arranged in the holders consecutively.</p> + +<p>Two kinds of nails are provided to fit the holes in +the board: An ordinary slate nail and a common picture +frame nail with a brass head. The latter indicates +work to be done, the former work done.</p> + +<p>To prepare the board for service, brass headed nails +are placed opposite each experiment, and below the +names, care being taken not to have more than one +nail in the same horizontal row, unless it is intended +that two persons or more are to work upon the same +experiment.</p> + +<p>There will be no conflict when the brass nails occupy +diagonal lines. If they do not, a glance will show the +fact.</p> + +<p>After an experiment has been performed and a report +made upon the usual blank, the brass nail is removed +and a slate nail put in its place.</p> + +<p>The board will show by the slate nails what work +has been done by each student, by the brass nails what +is yet to be done, and by the empty holes, experiments +which have been omitted or are yet to be assigned. A +slate nail opposite an experiment card indicates that +that experiment may now be assigned to another person.</p> + +<p>It is evident that the schedule for a whole term may +be arranged in a few minutes and that the daily +changes require very little time.</p> + +<p>The board is hung in a convenient place. The student +as he enters the laboratory looks for his name on +the upper cards and under it for the first brass nail in +the vertical column: to the left he finds the experiment +card. On the left hand end of the slip he sees the book +references, on the right hand end a number--39 in the +sample card given above. Knowing the number, he +proceeds to a desk and finds a box numbered in the +same manner. He removes the box from the closet. +On the label of the box is a list of all the apparatus +necessary, which he will find in the box; the label also +contains the book references. He performs the experiment, +fills up a blank which he gives to the instructor, +puts all the materials back in the box, replaces the +box in its proper place in the closet and proceeds with +the next experiment. With this indicator there is no +difficulty in managing fifty students or more.</p> + +<p>Comparatively little apparatus need be duplicated. +Where apparatus is fixed against a wall a number may +be tacked upon the wall and a card containing the +information desired. The procedure is then the same as +with the boxes. The cards on the board being removable, +other ones may be inserted containing information +in reference to other boxes having the same number +but containing different materials. + +There can be no successful tampering with the board, +for the record of experiments performed is upon the +blanks which the students turn in and also in the individual +note books which are written up and given +to the instructor for daily examination.</p> + +<p class="ctr"><b>Lafayette College.<br /> J.W. MOORE.</b></p> + +<hr /> + +<a name="misc5"></a><h2>NEW METHOD OF EXTINGUISHING FIRES</h2> + +<p>This is by George Dickson, of Toronto, Canada, and +David Alanson Jones.</p> + +<p>A mixture of water and liquefied carbon dioxide upon +being discharged through pipes at high pressure +causes the rapid expansion of the gas and converts the +mixture into spray more or less frozen, and portions of +the liquid carbon dioxide are frozen, owing to its +rapid expansion, and are thus thrown upon the fire +in a solid state, where said frozen carbon dioxide in its +further expansion not only acts to put out the fire, +but cools the surface upon which it falls, and thus +tends to prevent reignition.</p> + +<p>A represents a receptacle sufficiently strong to stand +a pressure of not less than a thousand pounds to the +square inch.</p> + +<p>B B water receptacles.</p> + +<p class="ctr"><img src="images/4-fig1.png" width="356" height="154" alt="Fig. 1" title=""> +<br clear="all" />FIG. 1</p> + +<p>In the drawings we have shown two receptacles B +and only one receptacle A; but we do not wish to confine +ourselves to any particular number, nor do we +wish to confine ourselves to the horizontal position in +which the receptacles are shown.</p> + +<p>C is a pipe leading from the receptacle A to a point +at or near the bottom of the receptacle B.</p> + +<p>F is a pipe through which the mixture of water and +liquefied gas from the receptacle B is forced by the +expansion of said liquefied gas, the said pipe taking +the mixture of water and liquefied gas from the bottom +of the receptacle.</p> + +<p class="ctr"><img src="images/4-fig2.png" width="310" height="161" alt="Fig. 2" title=""> +<br clear="all" />FIG. 2</p> + +<p>To use the apparatus, open the stop cock D in the +pipe C, leading to one of the receptacles B, whereupon, +owing to the lower pressure in the cylinder B, the +liquid carbon dioxide expands and rises to the top of +the cylinder A and forces the liquid carbon dioxide into +the cylinder B, the same as the superior steam of a +boiler forces the water of the boiler out when the same +is tapped below the surface of the liquid. Now upon +opening the tap H, this superior gas forces out the +mixture of water and liquid carbon dioxide, which +suddenly expanding causes portions of the globules of +liquefied gas to be frozen, and these, being protected +by a rapidly evaporating portion of the liquefied gas, +are thrown on the fire in solid particles. At the same +time the water is blown into a spray, which is more +or less frozen. The fire is thus rapidly extinguished by +the vaporization of the carbon dioxide and water spray.</p> + +<hr /> + +<a name="tech2"></a><h2>SMOKELESS GUNPOWDER.</h2> + +<h3>By HUDSON MAXIM.</h3> + +<p>During the last forty years leading chemists have +continued to experiment with a view to the production +of a gunpowder which should be smokeless. But not +until the last few years has any considerable degree of +success been attained.</p> + +<p>To be smokeless, a gunpowder must yield only gaseous +products of combustion. None of the so-called +smokeless powders are entirely smokeless, although +some of them are very nearly so.</p> + +<p>The smoke of common black gunpowder is largely +due to minute particles of solid matter which float in +the air. About one-half of the total products of combustion +of black gunpowder of ordinary composition +consists of potassium carbonate in a finely divided condition +and of potassium sulphate, which is produced +chiefly by the burning in the air of potassium sulphide, +another production of combustion, as on the outrushing +gases it is borne into the air in a fine state of +division.</p> + +<p>Another cause for the smoke of gunpowder is the +formation of small liquid vesicles which condense from +some of the products of combustion thrown into the +air in a state of vapor, in the same manner as vesicles +of aqueous vapor form in the air on the escape of highly +heated steam from the whistle of a locomotive.</p> + +<p>Broadly speaking, an explosive compound is one +which contains, within itself, all the elements necessary +for its complete combustion, and whose +heated gaseous products occupy vastly more space +than the original compound. Such compound usually +consists of oxygen, associated with other elements, for +which it has great affinity, and from which it is held +from more intimate union, or direct chemical combination, +under normal conditions, by being in combination +as well with other elements for which it has less +affinity, but which it readily gives up for the stronger +affinities when explosion takes place, the other elements +either combining with one another to form new +compounds or being set free in an uncombined state.</p> + +<p>An explosive is said to detonate when the above +changes take place instantaneously, the action being +transmitted with the speed of electricity by a sort of +molecular rhythm from molecule to molecule throughout +the entire substance of the compound.</p> + +<p>An explosive is said to explode when the above + +changes do not occur instantaneously throughout the +whole substance, but whose combustion takes place +from the surface inward of the particles or grains of +which it is composed, thus requiring some definite +lapse of time.</p> + +<p>The elements of an explosive compound may be associated +chemically as in nitro-glycerine and gun-cotton, +which are chemical compounds, being the results of definite +reactions. Or, an explosive may be a mere mechanical +mixture of different substances comprising the +necessary elements, as is ordinary black gunpowder, +which is a compound of charcoal, sulphur and saltpeter, +the saltpeter supplying the necessary oxygen.</p> + +<p>No gunpowder can be smokeless in which saltpeter +or any oxygen-bearing salt having a metallic base is +employed, for when the salt gives up its oxygen, the +base combines with other elements to produce a sulphate, +a carbonate, or other salt, which, being solid, +produces smoke. Therefore, to be smokeless, a gunpowder +must contain no other elements than oxygen, +hydrogen, nitrogen, and carbon, and in such proportions +that the products of combustion shall be +wholly gaseous. The nitric ethers--gun-cotton and +nitro-glycerine--constitute such explosive compounds. +These substances were formerly thought to be nitro-substitution +compounds, but are now known to belong +to the compound ethers of nitric acid.</p> + +<p>Gun-cotton, discovered by Schonbein, in 1845, has +since been looked upon as the most promising material +for a smokeless gunpowder, it being a very powerful +explosive and burning with practically no smoke. To-day, +gun-cotton, in some form or other, constitutes the +base of substantially all of the smokeless powders with +which have been attained any considerable degree of +success.</p> + +<p>Gun-cotton alone and in its fibrous state has been +found to be too quick, or violent, for propulsive purposes, +such as use in firearms; as under such conditions +of confinement it is very likely to detonate and +burst the gun. However, if gun-cotton be dissolved in +a suitable solvent, which is capable of being evaporated +out, such as acetone, or acetate of ethyl, which +are very volatile, it becomes, when thus dissolved and +dried, a very hard, horn-like, amorphous substance, +which may be used for a smokeless gunpowder. But +this substance taken alone is very difficult to mould or +granulate, and the loss of expensive solvents must +necessarily be quite considerable.</p> + +<p>When gun-cotton is reduced to a collodial solid, as +above, and used as a smokeless gunpowder, the grains +must be made comparatively small to insure prompt +and certain ignition, and consequently the pressures +developed in the gun are apt to be too great when +charges sufficiently large are used to give desired velocities.</p> + +<p>If, however, a compound be made of gun-cotton and +nitro-glycerine, in about equal parts, by means of +a volatile solvent or combining agent, such as one of +the before mentioned, and the solvent evaporated out, +we obtain practically a new substance and one which, +as regards its explosive nature, is quite unlike either of +its two constituents taken alone. The nitro-glycerine, +furthermore, being itself a solvent of gun-cotton, much +less of the volatile ether is necessary to render the compound +of an amorphous character. Being quite plastic +this substance may be wrought or moulded into any +desired size or form of grain.</p> + +<p>This simple compound of nitro-glycerine and gun-cotton, +or with some slight modifications, has been +found, when properly granulated, to be the most +smokeless powder that has yet been discovered or invented. +If pure chemicals are employed in the manufacture, +and the gun-cotton and nitro-glycerine be +made of the highest nitration and best quality, we +have a smokeless powder which will possess the following +desirable qualities:</p> + +<p>1st. It is absolutely smokeless, that is, its products +of combustion are entirely gaseous.</p> + +<p>2d. Its products of combustion are in no way deleterious +or unpleasant.</p> + +<p>3d. It is perfectly safe to manufacture, handle and +transport. There is no more danger of its exploding +accidentally than there would be of an explosion of +shavings or sawdust; for, unless well confined and set +off with a strong primer, it will not explode at all. In +the open its combustion is so slow as to in no way resemble +or partake of the nature of an explosion.</p> + +<p>4th. It is perfectly stable, and will keep any length +of time absolutely without undergoing any change +whatever, under all conditions of temperature or exposure +to which gunpowder would ever be subjected.</p> + +<p>5th. It is not hygroscopic, and may be soaked in water +without being at all affected by it.</p> + +<p>6th. It will not corrode the cartridge case.</p> + +<p>7th. It will not foul the gun.</p> + +<p>8th. It is sure of ignition with a good primer, and +may be made to burn as slowly as desired by varying +the character and size of the grains. Indeed, it may +be made to burn so slowly as to fail of complete combustion +before the bullet leaves the gun, and after firing +several rounds, partly burned pieces of the powder +may be picked up in front of the gun.</p> + +<p>9th. In a shoulder arm, a velocity of 2,000 feet per +second may be imparted to the bullet with this powder, +and with a pressure in the chamber of the gun of +not more than fifteen English tons. This is, of course, +when the gun, cartridge case, primer, and projectile +are adapted to the use of smokeless powder, and the +granulation of the powder is adapted to them.</p> + +<p>If what I have here claimed for the above smokeless +powder be true, it would appear that it may be taken +as really an ideal smokeless powder. Why, then, has +it not already been universally adopted? Surely such +a powder is just what every government is seeking. In +reply to this, let me say that, in order for the above +compound to be an effective and successful smokeless +powder, with the manifestation of the many desirable +qualities which I have recited, a great many other conditions +are necessary, some of which I will mention. +To arrive at the knowledge that this compound would +constitute the best smokeless powder has required a +great deal of experimenting. It was first thought that +gun-cotton colloid, without any nitro-glycerine, that is, +gun-cotton dissolved and dried, would burn more slowly, +keep better, and give better ballistics than it would +if combined with nitro-glycerine. It was also thought +that gun-cotton of a high degree of nitration when +made into colloidal form would even then burn too +quickly to be suitable for use in firearms. Consequently, +the first experiments were with low grade + +gun-cotton, what is called collodion cotton, such as is +employed in the manufacture of celluloid. But, as +this would not explode without the addition of some +oxygen-bearing element, various oxygen-bearing salts +were combined with it, such as nitrate of potassium, +nitrate of ammonia, nitrate of baryta, etc. Also a +great many of the first smokeless powders were made +of low grade gun-cotton combined with nitro-glycerine +in varying proportions. These powders would often +give very good results when first made; but low grade +gun-cotton or di-nitro-cellulose, as it is called, is a very +unstable compound, and these powders, after giving +very promising results, were found to be constantly +undergoing change, sooner or later resulting in complete +decomposition.</p> + +<p>When nitro-glycerine was first combined with gun-cotton +in small quantities, camphor was often added, +to lessen the rapidity of combustion which the nitro-glycerine +was supposed to impart and also to render +the compound more plastic, and to tend to prevent the +decomposition of the low grade gun-cotton. But +camphor being volatile, would, by its evaporation, +cause the powder to constantly change in character. +Castor oil has been found to be a better diluent, as +this will not evaporate.</p> + +<p>As all of the smokeless powders made of a low grade +gun-cotton were found to deteriorate and spoil, experiments +were made with gun-cotton of the highest degree +of nitration, both alone and in combination with +nitro-glycerine. These experiments were first conducted +in England by private parties and by the British government, +when it was found that high grade gun-cotton +would give excellent results if made into a colloidal +solid and used alone, or in combination with certain +other constituents. With a view to saving the large +quantity of solvents necessary to reduce the gun-cotton, +and to get a more prompt and certain ignition +with a larger grain, experiments were cautiously made +by the admixture of varying proportions of nitro-glycerine +to the gun-cotton when dissolved, or rather +along with other solvents in the process of dissolving +it.</p> + +<p>It was soon found that nitro-glycerine added in quantities, +even equal in weight to the gun-cotton itself, did +not materially increase the rapidity of the explosion +of the compound. And it was also found that high +grade gun-cotton, when combined with nitro-glycerine, +gave very much better results than low grade gun-cotton.</p> + +<p>I have spoken here of high and low grade gun-cotton, +when in fact the word gun-cotton should be applied +only to the highest nitro-compound of cellulose. +The word gun cotton has always been rather loosely +used. Pyroxyline would be a better word, as this applies +to all grades. When cotton fiber is soaked in a +large excess of a mixture of the strongest nitric and +sulphuric acids, gun-cotton proper, or that of the +highest grade, is produced. When weaker acids are +used, lower grades of nitro-cellulose are formed.</p> + +<p>The first mentioned or highest grade gun-cotton, +when thoroughly freed from its acids, has always +proved to be a perfectly stable compound. The lower +grades have always been found to be unstable and subject +to spontaneous decomposition. Nitro-glycerine +has also been erroneously thought to be a very unstable +compound. But experiments have proved that, +when made pure, it is perfectly stable.</p> + +<p>Having now explained how the knowledge came to +be arrived at that the aforementioned compound of +highest grade nitro-glycerine and highest grade gun-cotton +would constitute the best basis for a smokeless +powder, I will now mention a few of the other conditions +necessary to success with its use, without assuming +that smokeless powder has yet passed its experimental +stage, and is beyond further improvement. +Nevertheless, such is the compound which has come to +stay as the basis of all smokeless powders; and any +smokeless powder, if a successful one, may be counted +upon as being made of this compound of gun-cotton +and nitro-glycerine, or of a colloid of gun-cotton, either +alone or combined with diluents, oxygen-bearing +salts, or inert matter. The fact that smokeless powder +may still be said to be in somewhat of an experimental +stage is not to admit that it is not a success. Firearms, +cartridge cases, and projectiles are also still in an experimental +stage, for they are constantly being improved; +yet their use has been a great success for a good +many years.</p> + +<p>The question of success of a smokeless powder does +not rest alone with the powder itself. The gun, the +cartridge case, primer, and bullet have been as much +the subjects of experiments in adapting them to the +use of smokeless powder as has the smokeless powder +in being adapted to them. To impart a velocity of +2,000 feet per second to a rifle ball, with corresponding +long range and accuracy of flight, has been a question +as much of improvement in rifles and projectiles as +in the powder. To give a velocity of 2,000 feet per +second to a bullet, requires a pressure of at least 15 +English tons in the chamber of a gun. This would be +a dangerous pressure in an old-fashioned shoulder +arm; while a bullet made only of lead would strip on +striking the rifling and pass right through the barrel +of the gun without taking any rotary motion whatever. +It might at first seem that the powder is the only +thing to be considered; but high ballistics can only be +obtained when everything else is adapted to its use.</p> + +<p>The projectile, the cartridge case, the fulminating +cap, and the gun have had to be all built up together, +and a very large amount of experimenting has been +necessary to determine what would constitute the +best projectile, best cartridge case, best fulminating +cap, and what should be the character of the rifling +and the quality and temper of the steel of the gun +barrel.</p> + +<p>It has been necessary first to conduct experiments to +test the smokeless powders for velocities and pressures, +and then with the powders test various kinds of +projectiles and guns. In order to obtain the high ballistics +which have been secured, it has been found +necessary to cover the bullet with something harder +than lead and to rifle the gun in a special manner.</p> + +<p>The French, who were the first to definitely adopt +smokeless powder, were the first also to make a rifle, +projectile, cartridge case and primer suited to its use.</p> + +<p>To obtain long range with a small long bullet such +as is now used, it should rotate at a very high speed. +It is well known to artillerists that a projectile of four +or more calibers in length has to be rotated at a much +higher speed than one of half that length, in order to + +keep the projectile stiff in the air, and to prevent it +from ending over in its flight. To communicate this +very high rotary movement to the bullet in the instant +of time during which it is passing through the barrel, +the rifling of the gun has to exert an enormous torsion +on the bullet. Lead, no matter how hardened, is not +sufficiently strong, as it will not only strip and pass +straight through the gun without taking any rotary +movement whatever, but under such very high pressures +it behaves like wax, and is thrown from the gun +in a distorted mass.</p> + +<p>The French cover their bullets with German silver, +a substance made of nickel, zinc and copper; and in +order to put as little strain upon the rifling and projectile +as possible, the rifling of the gun is made with an +increasing twist, and has no sharp edges. The French +rifle is made very strong at the breech and is of tempered +steel throughout. In this way the French have +made smokeless powder a success--a smokeless powder +made substantially of a character such as I have +herein described. With smokeless powder, the French +rifle imparts a muzzle velocity of 2,000 feet per second +to the bullet, with a range of about 2,400 meters.</p> + +<p>If smokeless powder be divided into sufficiently +small grains to be ignited by an ordinary fulminating +cap, it would burn too quickly, thereby causing the +pressure to mount too high, and without giving the +desired velocity. Consequently very large and strong +fulminating caps have to be employed. Smokeless +powder is not ignited in the same manner as black +powder. Something besides ignition is necessary. +Black powder simply requires to be set on fire; while +a smokeless powder, on the contrary, not only requires +that it be set on fire, but that a certain degree +of pressure be set up inside of the cartridge case. For +instance, if a primer of a certain size should be found +to operate perfectly well, giving prompt ignition in the +cartridge case of a rifle of small caliber, it would be +found that the same primer would not ignite a charge +of the same powder if loaded into a gun of one inch +caliber. In the latter case a few grains only lying near +the primer would be ignited, and these would soon +become extinguished by sudden release of pressure +bringing about a cooling effect due to expansion of +the gases. In small cartridges a large fulminating cap +is all that is required, but in large cartridges it is +necessary to resort to additional means of ignition.</p> + +<p>In France, where experiments were conducted with +a 37 millimeter Maxim gun, it was found to be impracticable +to use a fulminating cap sufficiently large to +ignite the powder and cause it to burn. Therefore, a +small ignition charge of black powder was employed, +it being put in a capsule or bag and placed next the +primer. On firing at the rate of 300 rounds per minute, +the black powder, though small in quantity, produced +a cloud of smoke through which it was quite +impossible to see. The inventor of the gun then prepared +for the French some wafers of pyroxyline canvas, +which were placed next to the primer, securing +thereby prompt ignition without the production of +any smoke.</p> + +<p>Smokeless powder, made as I have described, cannot +be detonated by a fulminating cap of any size or by +any means whatever. A large charge of fulminate of +mercury placed inside the cartridge case next the +primer will not detonate the powder, it serving only +to ignite it and cause it to explode. But even this +would not cause the powder to explode except it be +confined behind a projectile, that sufficient pressure +may be run up to make it burn in its own gases.</p> + +<p>Some curious experiments with smokeless powder +may be tried with a shot gun. If the fulminating cap +be large, the powder fine, the wads numerous and +hard and the charge of shot heavy, all being well +rammed down, and the paper case well spun over the +last pasteboard wad, a charge of smokeless powder +about equal in weight to one-half of what would be +employed of black powder would give about the same +results as black powder. But if the charge of shot be +omitted, the primer will only ignite the powder, and +there will be set up sufficient pressure merely to throw +the wads about half way up the barrel of the gun, when +the powder will go out. Now if this same charge of +powder be collected and reloaded into a new cartridge +case and well confined behind wads and a charge of +shot, as above explained, it will all burn, giving the +same results as black powder.</p> + +<p>Attempts have been made to use this powder in pistols +and revolvers, but here it has proved a failure, as +the pressure is not great enough to cause the powder +to be consumed, unless it be in the form of very fine +grains or dust, in which case the pressure mounts too +high. However, this might be overcome to a degree +by making the powder porous. The chemical conditions +of the powder might be the same, but the physical +conditions must be different. A powder suitable +for shot guns and pistols would not be suitable for +rifles.</p> + +<p>One not familiar with the characteristics of smokeless +powder would be almost certain to fail in his first +attempt to fire it. Many persons have been convinced +by their first experiments that this powder would not +burn at all in a gun, any more than so much sand.</p> + +<p>Smokeless powder is consumed with a rapidity +which accords with the conditions of its confinement. +Therefore, the bullets which have been experimented +with by different governments have been the cause of +much of the varying pressures attributed to the smokeless +powders.</p> + +<p>The Austrians use the Mannlicher steel jacketed bullet. +The steel casing or jacket is first tinned on the inside +and then the lead is cast in, thus melting the tin and +adhering firmly to the jacket. This projectile sets up +enormous friction in the barrel of the gun when used +with smokeless powder; as the smokeless powder +leaves the gun barrel perfectly clean and the two steel +surfaces being in absolute contact cause tremendous +friction; and as the coefficient of friction varies with +every shot, the pressure in the gun constantly varies +greatly.</p> + +<p>The German silver covered bullet used by the French +has the disadvantage that when firing rapidly the +chamber of the barrel becomes nickel plated and great +friction is caused, mounting up the pressures and causing +the muzzle velocities to fall off.</p> + +<p>The Austrians, in order to prevent their steel cased +bullets from rusting and to lessen the friction in the +barrel of the gun, cover them with a heavy lubricant, +which gives the cartridges an unsightly appearance +and causes them to gather dust and sand. + +The French employ a lubricant at the base of the +projectile, with a small copper disk between the same +and the powder.</p> + +<p>Col. A.R. Buffington, commander of the National +Armory at Springfield, Mass., has made a steel covered +projectile which he prevents from rusting by blackening +by a niter process. Several grooves are pressed +in the base of the bullet which carry a lubricant, and +when the bullet is inserted in the cartridge case the +grooves are covered by it. Furthermore, these grooves +prevent the lead filling from bursting through the steel +casing, leaving the latter in the barrel, as often occurs +with the Austrian and French projectiles when using +smokeless powder.</p> + +<p>A new projectile has lately come out, the invention +of Captain Edward Palliser, of the British army. This +bullet consists of a jacket made of very soft Swedish +wrought iron, coated with zinc and filled with lead, the +lead being pressed into this jacket. The bullet is corrugated +at its base, after the manner of the one made +by Colonel Buffington. This projectile has been experimented +with very extensively by the British government, +and at the works of the Maxim-Nordenfelt +Guns and Ammunition Company, in England. The +zinc coating of the bullet is too soft to stick to the barrel +of the gun, and also in a measure acts as a lubricant. +This projectile has given better results than any other +that has been experimented with. The great velocities +and the most uniform pressures by the use of smokeless +powder have been attained with this Palliser bullet.</p> + + +<h3>NOISELESSNESS.</h3> + +<p>A great many stories have been told about the noiselessness +of smokeless powder. But there is no such +thing as a noiseless gunpowder. The report of a gun +charged with smokeless powder is very sharp, and is +as loud as when black powder is used, yet the volume +of sound is much less, so that the report cannot be +heard at so great a distance.</p> + +<p>The report of a gun using smokeless powder is a +sound of much higher pitch than when black powder +is used, and consequently cannot be heard at so great +a distance as the lower notes given by black powder.</p> + +<p>As smokeless powder exerts a much greater pressure +than common black powder when burned in a gun, +one would naturally think that the recoil of the barrel +would be greater, owing to the greater pressure exerted +by the smokeless powder on the base of the cartridge +case and the breech mechanism. However, such +is not the fact; for the barrel actually recoils very much +less when smokeless powder is used. This is due to +the suddenness with which the pressure is exerted by +smokeless powder, it acting more like a very sharp +blow on the metal, whereby more of the energy is converted +into heat instead of being spent in overcoming +the inertia of the barrel to give recoil. Similarly when +smokeless powder is fired in a gun, the displacement +of the air is so sudden that the sound waves do not +possess the same amplitude of recoil or vibration as is +given by black powder.</p> + +<hr /> + +<a name="elec1"></a><h2>THE CONSTRUCTION AND MAINTENANCE OF +UNDERGROUND CIRCUITS.</h2> + +<h3>By S.B. FOWLER.</h3> + +<p>The numerous disastrous storms of the last winter +have brought out very vividly the advantages of having +all wires placed underground, and many inquiries +have been addressed to the companies operating underground +circuits as to their success. It is not probable +that all of the answers to these inquiries have +been of the most favorable character. To many central +station managers an underground system means +frequent break-downs and interruptions of service, +with, perhaps, slow and expensive repairs, which bring +in their turn numerous complaints, loss of customers, +and reduced profits. In many installations burn-outs +both underground and in the station are frequent, +with the natural result that the operating of circuits +underground is not there considered an unqualified +success. The writer has in mind two very different +experiences with underground cables. Several +miles of cable were bought by a certain company, +carefully laid, and up to to-day not a single burn-out +or interruption of service can be attributed to failure +of cables; at about the same time another company +bought about an equal amount of the same kind of cable, +and in a comparatively short time the current had +to be shut off the lines and the whole installation repaired +and parts of it replaced. Both of these experiences +have been repeated many times and will be +again, although it is simply a distinction between a +good cable properly laid and a good cable ruined by +careless and incompetent workmanship.</p> + +<p>Every failure can be traced to poor work in the original +installation or to the use of a cheap cable, both +causes being due, generally, to that false economy +which looks for too quick returns. A poorly insulated +line wire and a poorly insulated cable are two very +different things. However, it is a fact that by the use +of a good cable it is not difficult to construct an underground +system for light, power, telegraph or telephone +uses that will be superior to overhead lines in +its service and in cost of maintenance. The ideal underground +system must have as a starting point a system +of subways admitting of the easy drawing in and +out of cables and affording means of making subsidiary +connections readily and with the minimum of expense +and interruption of service. This is practically +accomplished by a subway consisting of lines of pipe +terminating at convenient intervals, say at street intersections, +in manholes, for convenience in jointing +and in running out house connections. These pipes, +or ducts, as they are called, should be for two kinds of +service; the lower or deeper laid lines for the main or +trunk circuits, and a second series of ducts laid nearer +the surface, running into service boxes placed near +together for lines to "house to house" connections. +In some cities where it is allowed to run overhead lines, +the plan of running but one service connection in a +block is followed, all customers in the block being supplied +from a line run over the housetops or strung on +the rear walls.</p> + +<p>This makes unnecessary all subsidiary ducts except a +short one from the manhole to the nearest building in +the block, and effects a considerable saving in pipe, +service boxes, cables and labor. The manholes should +have their walls built up of brick, the floors should be + +of concrete, and there should be an inside lid which +can be fastened down and the manhole thus made +water-tight.</p> + +<p>For ducts wood, iron or cement lined pipe may be +used. To preserve the wood it is generally treated +with creosote, which, in contact with the lead cover of +the cable, sets up a chemical action, resulting in the +destruction of the lead. Wood offers but little protection +for the cable, as it is too easily damaged and broken +through in the frequent street openings made by +companies operating lines of pipe in the streets, and +as one of the main purposes of a subway is that of a +protection to cables, wooden ducts have little to recommend +them except their cheapness.</p> + +<p>Iron pipes are either laid in trenches filled in with +earth or are laid in cement. Iron pipe will of course +rust out in time, and if absolute permanence in construction +is desired, should be laid in cement, for after +the pipe rusts out, the duct of cement is still left. +However, if we are going to the expense of laying in +cement, it would be much preferable to use cement +lined pipe, which is not only cheaper than iron pipe, +but makes the most perfect cable conduit, as it affords +a perfectly smooth surface to draw the cable over and +give a good duct edge.</p> + +<p>It is not necessary, however, in small installations +of cable, especially where additional connections will +not be of frequent occurrence, to go to the expense +of subways, for cable may be safely laid in the ground +in trenches filled in with earth, or can be inclosed in a +plain wooden box or a wooden box filled with pitch.</p> + +<p>There are, of course, many localities where, if the +cable is laid in contact with the earth, a chemical +action would take place which might result in the destruction +of the cable.</p> + +<p>Underground cables are of the following classes: 1. +Rubber insulated cables, insulated with rubber or +other homogeneous material. 2. Fibrous cables, so +called from the conductors being covered with some +fibrous material, as cotton or paper, which is saturated +with the insulating material, paraffine, resin oil, or +some special compound. Under this latter head is +also included the dry core paper cables.</p> + +<p>The first thing to do is to get the cable drawn into the +ducts, and on the proper accomplishment of this depends +to a great extent the success or failure of the whole installation. +Probably the ducts have been wired when +the subway was constructed, but if not a wire must be +run through as a means of pulling in the draw rope. +There are several kinds of apparatus for getting a +wire through a duct--rods, flexible tapes, mechanical +"creepers," etc.; but probably the best is the sectional +rod. This simply consists of three or four foot lengths +of hard wood rods, having metal tips that screw into +each other. A rod is placed in a duct at a manhole, +one screwed to that, both are pushed forward, another +one added and pushed forward, and so on until they +extend the entire length of the duct. Then the wire +is attached and the rods are pulled out and detached +one at a time and with the last rod the wire is through. +At least No. 14 galvanized iron or steel wire should be +used, for any smaller size cannot be used a second time, +as a rule. In starting to pull in the draw rope a wire +brush should be attached to the wire and to this again +the rope, and when the brush arrives at the distant +end of the duct it very likely will bring with it a miscellaneous +collection of material which for the good of +the cable had better be in the manhole than in the +duct.</p> + +<p>The reel or drum carrying the cable should be +mounted on wheels or jacks and placed on the same +side of the manhole as the duct into which the cable +is to be drawn, and must always be so placed that the +cable will run off the top of the reel.</p> + +<p>There are several methods of attaching the draw +rope to the cable. As simple and strong a method as +any is to punch two of these holes through the cable, +lead and all, and attach the rope by means of an iron +wire--some of the draw wire will do--run through +these holes. Depending on the length and weight of +cable to be pulled it can be drawn either by hand or +by a multiplying winch. The rope should run through +a block fastened in the manhole in such a position +that the rope shall have a good straightaway lead from +the mouth of the duct.</p> + +<p>The strain on the cable should be perfectly uniform +and steady; if the power is applied by a series of jerks +either the lead covering may be pulled apart or some of +the conductors broken. At the reel there must always +be a large enough number of men to turn it and keep +the cable from rubbing on anything, and in the manhole +one or more men to see that the cable feeds into +the duct straight and to guide it if necessary. If the +ducts are of iron and are not perfectly smooth at the +ends, these should be made so with a file, and in addition +a protector of some sort should be placed in the +mouths of the duct, both above and below the cable. +Six inches of lead pipe, split lengthwise and bent over +at one end to prevent being drawn into the duct with +the cable, makes a very good protector. The cable +should be reeled off the drum just fast enough to prevent +any of the power used in pulling the cable through +the duct being utilized in unreeling it. If this latter +is allowed to occur the cable will be bent too short and +the lead covering buckled or broken, and also the cable +may be jammed against the upper edge of the duct +and perhaps cut through.</p> + +<p>If the reel is allowed to turn faster than the cable is +drawn in, the first three or four turns on the reel will +slacken up, and the lead covering may either be dented +or cut through by scraping on the ground. If the +cable end when pulled through up to the block is not +long enough to bend around the hole more than half +way, the rope should be unfastened from its end, a +length of rope with a well frayed out end should be run +through the block, and by fastening to the cable close +to the duct, with a series of half hitches, as much slack +as necessary can be pulled in. If this is properly +manipulated there need not be a scratch on the cable, +but unless great care is taken the lead may be pressed +up into ridges and the core itself damaged.</p> + +<p>Immediately after the cable is drawn in, if the joint +is not to be at once made, the open end or ends should +be cut off and the cable soldered up, as most cables are +very susceptible to moisture and readily absorb water +even from the atmosphere. Where practicable it is +always a good plan to pull the cable through as many +manholes as possible without cutting the cable; for +the joint is, especially in telephone or telegraph cables, +the weak point. To do this the rope should be pulled + +through the proper duct in the next section without +unfastening it from the cable; the winch should be +moved to the next manhole, and pulling through then +done as before. There should always be a man in +every hole through which the cable is running to see +that it does not bind anywhere and to keep protectors +around the cable.</p> + +<p>It is not advisable to pull more than one cable into a +duct, and never advisable to pull a cable into a duct +containing another cable, but if two or more cables +have to go into the same duct, they should always be +drawn in together. Lead covered cables and those +with no lead on the outside should never be pulled into +the same duct, for if they bind anywhere the soft +cable will suffer where two lead covered cables would +get through all right. Some manufacturers are now +putting on their cables a tape or braid covering, which +saves the lead many bad bruises and cuts, and is a +valuable addition to a cable at very little additional +expense.</p> + +<p>Practically all electric light and power cables are +either single or double conductors, and the jointing of +these is comparatively a simple matter, although requiring +considerable care. The lead is cut back from +each end about four or five inches, and the conductors +bared of insulation for two or three inches. The bare +conductors should be thoroughly tinned by dipping in +the metal pot or pouring the melted solder over them. +A sperm candle is better than resin or acid for any +part of the operations where solder is used. A lead +sleeve is here slipped back over the cable, out of the +way, and the ends of the conductors brought together +in a copper sleeve which is then sweated to a firm joint. +This part must be as good a piece of work mechanically +as electrically. The bare splice is then wrapped +tightly with cotton or silk tape to a thickness slightly +greater than that of the insulation of the cable, and is +thoroughly saturated with the insulating compound +until all moisture previously absorbed by the tape is +driven off.</p> + +<p>The lead sleeve is then brought over the splice and +wiped to the cable. The joint is then filled with the +insulating compound poured through holes in the top +of the sleeve; these holes are then closed and the joint +is complete, and there is no reason why, in light and +power cables, that joint should not be as perfect as +any other part of the cable. When the cable ends are +prepared for jointing they should be hung up in such +a position that they are in the same plane, both horizontal +and vertically, and firmly secured there, so that +when the lead sleeve is wiped on the conductor may +be in its exact center, and great care must be taken +not to move the cables again until the sleeve is filled +and the insulation sufficiently cooled to hold the conductor +in position.</p> + +<p>It is also very important to see that there are no sharp +points on the conductors themselves, on the copper +sleeve, on the edges of the lead covering or on the lead +sleeve. All these should be made perfectly smooth, for +points facilitate disruptive discharges. Branch joints +had better be made as T-joints rather than as Y-joints, +for they are better electrically and mechanically, although +they occupy more room in the manholes. They +are of course made in the same way as straight joints, +a lead T-sleeve being used, however. For multiple +arc circuits copper T-sleeves and for series circuits +copper L-sleeves are used.</p> + +<p>Telephone and telegraph cables are made of any required +gauge of wire and with from 1 to 150 conductors +in a cable. In jointing these the splices are never +soldered, the conductors being joined either with a +twist joint or with the so-called Western Union splice. +Each splice is covered with a cotton or silk sleeve or a +wrapping of tape, the latter being preferable, although +considerably increasing the time necessary for making +the joint. Great care must be taken that no ends of +wire are left sticking up, for they will surely work +their way through the tape and grounds, and crosses +will be the result. The wires should always be joined +layer to layer and each splice very tightly taped in +order to get as much insulating compound around each +splice as possible in the limited space. The splices +should be "broken" as much as possible, so as to avoid +having adjoining splices coming over each other. After +the joint has been saturated with insulating compound +the wires should have an outside wrapping of tape to +keep them in shape, and then the sleeve is wiped on +and filled. If the insulation resistance of the jointed +telegraph or telephone cable is a quarter of what the +cable tested in the factory, it may be considered that +an exceptionally good piece of work has been done. I +have spoken more particularly of fibrous lead covered +cables, as the handling of them includes practically +every step of the work on any other kind of underground +cable. In insulating dry core paper cables a +paper sleeve is slipped over the splice, and in rubber +cables the splice is wrapped with rubber tape; all +other details are the same for these as for the fibrous +cable.</p> + +<p>In the laying of light and power cables every joint, +as made, should be tested for insulation with a Thomson +galvanometer, as the insulation must necessarily be +very high, and if one joint or section of cable is any +weaker than another it may be very important in the +future to know it. All tests must be made after the +joint has cooled, for while hot its insulation resistance +will be very low.</p> + +<p>Tests for copper resistance should also be made to +determine if the splices are electrically perfect; an imperfect +splice may cause considerable trouble. In telegraph +and telephone cables the conductors should be +of very soft copper, for in stripping the conductor of +insulation it is very easy to nick the wire, and if of +hard drawn copper open wires will be the result.</p> + +<p>All work should be frequently tested for continuity +with telephones, magnetos, or small portable galvanometers. +It is only necessary to ground the conductors +at one end and try each wire at the other end. For +this sort of work a telephone receiver used with one +cell of some dry battery is most convenient, and has +the additional advantage of affording a means of communication +while testing, and is by far the best thing +for identifying and tagging conductors.</p> + +<p>These cables should be frequently tested during the +progress of the work for grounds and crosses with a +Thomson instrument, and when the cable is complete, +a careful series of tests of the capacity, insulation resistance, +and copper resistance of each wire should be +made and the exact condition of the cable determined +before it is put in service, and thereafter an intelligent + +oversight of the condition of the circuits can thus +be more readily maintained.</p> + +<p>Where a company has extensive underground service, +a regular cable gang should be in its employ, for quick +and safe handling of cables demands the employment +of men accustomed to the work. If the cable +has been properly laid and tests show it to be in good +condition before current is turned on, almost the only +trouble to be anticipated will be due to mechanical +injury. Disruptive discharge, puncturing the lead, +may occur; but the small chance of its occurring can +be greatly lessened by the use of some kind of "cable +protector," which will provide for the spark an artificial +path of less resistance than the dielectric of the +condenser, which the cable in fact becomes.</p> + +<p>If a fault suddenly develops on a circuit, the chances +are it will be found in a manhole, and an inspection +of the cable in the manhole will generally reveal the +trouble without resorting to locating with a Wheatstone +bridge. The cable is often cut through at the +edge of the duct, or damaged by something falling on +it, or by some one "walking all over it." To guard +against these, the ducts should always be fitted with +protectors both above and below the cable. The +cables should never be left across the manholes, for +they then answer the purpose of a ladder, but should +be bent, around the walls of the hole and securely +fastened with lead straps, that they may not be moved +and the lead gradually worn through.</p> + +<p>In telegraph cables, when one or two conductors +"go," it will probably be useless to look for trouble +except with instruments; but if several wires are +"lost" at once it will probably be found to be caused +by mechanical injury, which can be located by inspection. +If it is ever necessary to loop out conductors, +a joint can be readily opened and the conductors +wanted picked out and connected into the branch +cable and the joint again closed without disturbing the +working wires. In doing this a split sleeve must be +used, and the only additional precaution to be taken +is in filling the sleeve to have the insulating compound +not hot enough to melt the solder and open up the +split in the sleeve. In cutting in service on light +and power cables it is entirely practicable to do so +without interruption of service on multiple arc circuits, +even those of very high voltage; but they require +great precaution and involve considerable risk +to the jointer, and where possible the circuit to which +the connection is to be made should previously be cut +dead. Where the voltage is not dangerous to human +life, almost any service connection can be made without +interruption of service.</p> + +<p>I have only indicated a very few of the operations +that may be found necessary, and the probable causes +of troubles that may be encountered in the operating +of underground circuits, believing that the different +problems that arise can, with a little experience, be +successfully met by any one who has a fair knowledge +of the original construction of cable lines.--<i>Electrical +World</i>.</p> + +<hr /> + +<a name="eng1"></a><h2>RAILROADS TO THE CLOUDS.</h2> + +<p>If George Stephenson, when he placed the first locomotive +on the track and guaranteed it a speed of six +miles an hour, could have foreseen that in less than +eighty years the successors of his rude machine would +be climbing the sides of mountain ranges, piercing +gorges hitherto deemed inaccessible, crossing ravines +on bridges higher than the dome of St. Paul's, and +traversing the bowels of the earth by means of tunnels, +no doubt his big blue eyes would have stood out +with wonder and amazement. But he foresaw nothing +of the kind; the only problem present in his mind was +how to get goods from the seaports in western England +to London as easily and cheaply as possible, and to do +this he substituted for horses, which had for 150 years +been drawing cars along wooden or iron tracks, the +wonderful machine which has revolutionized the +freight and passenger traffic of the world.</p> + +<p>It was, indeed, impossible for any one to foresee the +triumphs of engineering which have accompanied the +advances in transportation. To the engineer of the +present day there are no impossibilities. The engineer +is a wizard at whose command space and matter +are annihilated. The highest mountain, the deepest +valley, has no terrors for him. He can bridge the +latter and encircle or tunnel the former. The only requisites +which he demands are that something in his +line be needed, and that the money is forthcoming to +defray the expense, and the thing will be done. But +the railroad he is asked to construct must be necessary, +and the necessity must be plainly shown, or no funds +will be advanced; and although the theory does not +invariably hold good, especially when a craze for railroad +building is raging, as a rule no expense for the +construction of a road will be incurred without a prospect +of remuneration.</p> + +<p>Hence the need of railroad communication has caused +lines to be constructed through districts where only a +few years ago the thing would have been deemed impossible. +The Pacific roads of this country were a necessity +long before their construction, and in the face +of difficulties almost insuperable were carried to successful +completion. So, also, of the railroads in the +Andes of South America. The famous road from +Callao through the heart of Peru is one of the highest +mountain roads in the world, as well as of the most +difficult construction. The grades are often of 300 +feet and more to the mile, and when the mountains +were reached so great were the difficulties the engineers +were forced to confront that in some places laborers +were lowered from cliffs by ropes in order that, with +toil and difficulty, they might carve a foothold in order +to begin the cutting for the roadway.</p> + +<p>In some sections tunnels are more numerous than +open cuts, and so far as the road has gone sixty-one +tunnels, great and small, have been constructed, aggregating +over 20,000 feet in length. The road attains +a height of 15,000 feet above the level of the sea, and +at the highest point of the track is about as high as +the topmost peak of Mont Blanc. It pierces the range +above it by a tunnel 3,847 feet long. The stern necessities +of business compelled the construction of this +road, otherwise it never would have been begun.</p> + +<p>The tunnels of the Andes, however, do not bear +comparison with the tunnels, bridges, and snow sheds +of the Union Pacific, nor do even these compare with +the vast undertakings in the Alps--three great tunnels +of nine to eleven miles in length, which have been prepared + +for the transit of travelers and freight. The requirements +of business necessitated the piercing of the +Alps, and as soon as the necessity was shown, funds in +abundance were forthcoming for the enterprise.</p> + +<p>But tunneling a mountain is a different thing from +climbing it. Many years ago the attention of inventors +was directed to the practicability of constructing a +railroad up the side of a mountain on grades which, to +an ordinary engine, were quite impossible. The improvements +in locomotives twenty-five and thirty years +ago rendered them capable of climbing grades which, +in the early days of railroad engineering, were deemed +out of the question. The improvements proved a serious +stumbling block in the way of the inventors, who +found that an ordinary locomotive was able to climb +a much steeper grade than was commonly supposed. +The first railroads were laid almost level, but it was +soon discovered that a grade of a few feet to the mile +was no impediment to progress, and gradually the +grade was steepened.</p> + +<p>The inventors of mountain railroad transportation +might have been discouraged by this discovery, but it +is a characteristic of an inventor that he is not set +back by opposition, which, in fact, only serves to +stimulate his zeal. The projectors of inclined roads +and mountain engines kept steadily on, and in France, +Germany, England, and the United States many experimental +roads were constructed, each of a few hundred +yards in length, and locomotive models were +built and put in motion to the amazement of the general +public, who jeered alike at the contrivances and +the contrivers, deeming the former impracticable and +the latter crazy.</p> + +<p>But the idea of building a road up the side of a hill +was not to be dismissed. There was money in it for +the successful man, so the cranky inventors kept on at +work in spite of the jeers of the rabble and the discouragements +of capitalists loath to invest their money +in an uncertain scheme. To the energy and perseverance +of railroad inventors the success of the mountain +railroad is due, as also is the construction of the various +mountain roads, of which the road up Mt. Washington, +finished in 1868, was the first, and the road +up Pike's Peak, completed the other day, was the +latest.</p> + +<p>Of all the mountain roads which have been constructed +since the one up Mt. Washington was finished, +the best known is that which ascends the world-famous +Rigi. With the exception of Mont Blanc, Rigi is, perhaps, +the best known of any peak in the Alps, though +it is by no means the highest, its summit being but +5,905 feet above the level of the sea. Although scarcely +more than a third of the height of some other mountains +in the Alps, it seems much higher because of its +isolated position. Standing as it does between lakes +Lucerne, Zug, and Lowertz, it commands a series of +fine views in every direction, and he who looks from +the summit of Rigi, if he does no other traveling in +Switzerland, can gain a fair idea of the Swiss mountain +scenery. Many of the most noted peaks are in sight, +and from the Rigi can be seen the three lakes beneath, +the villages which here and there dot the shores, and, +further on, the mighty Alps, with their glaciers and +eternal snows.</p> + +<p>Many years ago a hotel was built on the summit of +the Rigi for the benefit of the tourists who daily +flocked to this remarkable peak to enjoy the benefit of +its wonderful scenery. The mountain is densely +wooded save where the trees have been cut away to +clear the land for pastures. The ease of its ascent by +the six or eight mule paths which had been made, the +gradual and almost regular slope, and the throngs of +travelers who resorted to it, made it a favorable place +for an experiment, and to Rigi went the engineers in +order to ascertain the practicability of such a road. +The credit of the designs is due to a German engineer +named Regenbach, who, about the year 1861, designed +the idea of a mountain road, and drew up plans not +only for the bed but also for the engine and cars. The +scheme dragged. Capitalists were slow to invest their +money in what they deemed a wild and impracticable +undertaking, and even the owners of the land on +the Rigi were reluctant for such an experiment to be +tried. But Regenbach persevered, and toward the close +of the decade the inhabitants of Vitznau, at the base +of the Rigi, were astonished to see gangs of laborers +begin the work of making a clearing through the +forests on the mountain slope. They inquired what it +meant, and were told that a road up the Rigi was to be +made. The Vitznauers were delighted, for they had no +roads, and there was not a wheeled vehicle in the +town, nor a highway by which it could be brought +thither. The idea of a railroad in their desolate +mountain region, and, above all, a railroad up the Rigi, +never entered their heads, and a report which some +time after obtained currency in the town, that the +laborers were beginning the construction of a railroad, +was greeted with a shout of derision.</p> + +<p>Nevertheless, that was the beginning of the Rigi +line, and in May, 1871, the road was opened for traffic. +It begins at Vitznau, on Lake Lucerne, and extends to +the border of the canton and almost to the top of the +mountain. It is 19,000 feet long, and during that distance +rises 4,000 feet at an average grade of 1 foot in 4. +Though steep, it is by no means so much so as the Mt. +Washington road, which rises 5,285 feet above the sea, +at an average of 1 foot in 3. There are, however, +stretches of the Rigi road at which the grade is about +1 foot in 2½, which is believed to be the steepest in the +world.</p> + +<p>The Rigi road has several special features aside +from its terrific slopes which entitle it to be considered +a triumph of the engineer's skill. About midway +up the mountains the builders came to a solid +mass of rock, which presented a barrier that to a surface +road was impassable. They determined to tunnel +it, and, after an enormous expenditure of labor, +finished an inclined tunnel 225 feet in length, of the +same gradient as the road. A gorge in the side of the +mountain where a small stream, the Schnurtobel, had +cut itself a passage also hindered their way, and was +crossed by a bridge of lattice girder work in three +spans, each 85 feet long. The entire roadbed, from beginning +to end, was cut in the solid rock. A channel +was chiseled out to admit the central beam, which +contains the cogs fitting the driving wheel of the locomotive. +The engine is in the rear of the train, and +presents the exceedingly curious feature of a boiler +greatly inclined, in order that at the steeper gradients +it may remain almost perpendicular. The coal and + +water are contained in boxes over the driving wheels, +so that all the weight of the engine is really concentrated +on the cogs--a precaution to prevent their +slipping. The cost of the road, including three of +these strangely constructed locomotives, three passenger +coaches, and three open wagons, was $260,000, and +it is a good paying investment. The fare demanded +for the trip up the mountains is 5 francs, while half +that sum is required for the downward passage, and +the road is annually traversed by from 30,000 to 50,000 +passengers.</p> + +<p>Curious sensations are produced by a ride up this remarkable +line. The seats of the cars are inclined like +the boiler of the locomotive, and so long as the cars +are on a level the seats tilt at an angle which renders +it almost impossible to use them. But when the start +is made the frightful tilt places the body in an upright +position, and, with the engine in the rear, the train +starts up the hill with an easy, gliding motion, passing +up the ascent, somewhat steeper than the roof of a +house, without the slightest apparent effort. But if the +going up excites tremor, much more peculiar are the +feelings aroused on the down grade. The trip begins +with a gentle descent, and all at once the traveler +looking ahead sees the road apparently come an end. +On a nearer approach he is undeceived and observes +before him a long decline which appears too steep +even to walk down. Involuntarily he catches at the +seats, expecting a great acceleration of speed. Very +nervous are his feelings as the train approaches this +terrible slope, but on coming to the incline the engine +dips and goes on not a whit faster than before and not +more rapidly on the down than on the up grade. +Many people are made sick by the sensation of falling +experienced on the down run. Some faint, and a few +years ago one traveler, supposed to be afflicted with +heart disease, died of fright when the train was going +over the Schnurtobel bridge. The danger is really +very slight, there not having been a serious accident +since the road was opened. The attendants are watchful, +the brakes are strong, but even with all these +safeguards, men of the steadiest nerves cannot help +wondering what would become of them in case anything +went wrong.</p> + +<p>Bold as was the project of a railroad on the Rigi, a +still bolder scheme was broached ten years later, when +a daring genius proposed a railroad up Mt. Vesuvius. +A railroad up the side of an ordinary mountain seemed +hazardous enough, but to build a line on the slope of a +volcano, which in its eruption had buried cities, and +every few years was subject to a violent spasm, seemed +as hazardous as to trust the rails of an ordinary line +to the rotten river ice in spring time. The proposal +was not, however, so impracticable as it looked. +While the summit of Vesuvius changes from time to +time from the frequent eruptions, and varies in height +and in the size of the crater, the general slope and contour +of the mountain are about the same to-day as +when Vesuvius, a wooded hill, with a valley and lake +in the center of its quiescent crater, served as the +stronghold of Spartacus and his rebel gladiators. There +have been scores of eruptions since that in which Herculaneum +and Pompeii were overthrown, but the sides +of the mountain have never been seriously disturbed.</p> + +<p>A road on Vesuvius gave promise of being a good +speculation. Naples and the other resorts of the +neighborhood annually attracted many thousands of +visitors, and a considerable number of these every +year ascended the volcano, even when forced to contend +with all the difficulties of the way. Many, however, +desiring to ascend, but being unable or unwilling to +walk up, a chair service was established--a peculiar +chair being slung on poles and borne by porters. In +course of time the chair service proved to be inadequate +for the numbers who desired to make the ascent, +and the time was deemed fit for the establishment +of more speedy communication.</p> + +<p>Notwithstanding the necessity, the proposal to establish +a railroad met with general derision, but the +scheme was soon shown to be perfectly practicable, and +a beginning was made in 1879. The road is what is +known as a cable road, there being a single sleeper +with three rails, one on the top which really bore the +weight, and one on each side near the bottom, which +supported the wheels, which coming out from the axle +at a sharp angle, prevented the vehicle from being +overturned. The road covers the last 4,000 feet of the +ascent, and the power house is at the bottom, a steel +cable running up, passing round a wheel at the top +and returning to the engine in the power house. The +ascent to the lower terminus of the road is made on +mules or donkeys; then, in a comfortable car, the traveler +is carried to a point not far from the crater. The +car is a combined grip and a passenger car, similar in +some points to the grip car of the present day, while +the seats of the passenger portion are inclined as in +the cars on the Rigi road. But the angle of the road +being from thirty-three to forty-five degrees, makes +both ascent and descent seem fearfully perilous. Every +precaution, however, is taken to insure the safety +of passengers; each car is provided with several strong +and independent brakes, and thus far no accident +worth recording has occurred. The road was opened +in June, 1880. Although there have been several considerable +eruptions since that date, none of them did +any damage to the line but what was repaired in a few +hours.</p> + +<p>The fashion thus set will, no doubt, be followed in +many other quarters. Wherever there is sufficient travel +to pay working expenses and a profit on a steep +grade mountain road it will probably be built. Already +there is talk of a road on Mont Blanc, of another up +the Yungfrau, and several have been projected in the +Schwartz and Hartz mountains. A route on Ben Nevis, +in Scotland, is already surveyed, and it is said surveys +have also been made up Snowden, with a view to +the establishment of a road to the summit of the highest +Welsh peak. Sufficient travel is all that is necessary, +and when that is guaranteed, whenever a mountain +possesses sufficient interest to induce people to +make its ascent in considerable numbers, means +of transportation, safe and speedy, will soon be +provided. The modern engineer is able, willing and +ready to build a road to the top of Mt. Everest in the +Himalayas if he is paid for doing so.--<i>St. Louis Globe-Democrat.</i></p> + +<hr /> + +<p>To clean hair brushes, wash with weak solution of +washing soda, rinse out all the soda, and expose to +sun.</p> + +<hr /> + + + +<a name="mar1"></a><h2>THE MARCEAU.</h2> + +<p class="ctr"><a href="./images/8-ship.png"><img src="images/8-ship_th.jpg " width="600" height="402" alt="THE FRENCH ARMORED TURRET SHIP MARCEAU" title=""></a><br clear="all" /> +THE FRENCH ARMORED TURRET SHIP MARCEAU</p> + +<p>The Marceau, the last ironclad completed and added +to the French navy, was put in commission at +Toulon in April last, and has lately left that town to +join the French squadron of the north at Brest. The +original designs of this ship were prepared by M. +Huin, of the French Department of Naval Construction, +but since the laying down of the keel in the +year 1882 they have been very considerably modified, +and many improvements have been introduced.</p> + +<p>Both ship and engines were constructed by the celebrated +French firm, the Société des Forges et Chantiers +de la Mediterranée, the former at their shipyard in +La Seyne and the latter at their engine works in Marseilles. +The ship was five years in construction on the +stocks, was launched in May, 1887, and not having +been put in commission until the present year, was +thus nearly nine years in construction. She is a barbette +belted ship of somewhat similar design to the +French ironclads Magenta, now being completed at +the Toulon arsenal, and the Neptune, in construction +at Brest.</p> + +<p>The hull is constructed partly of steel and partly of +iron, and has the principal dimensions as follows. +Length, 330 ft. at the water line; beam, 66 ft. outside +the armor; draught, 27 ft. 6 in. aft.; displacement, +10,430 English or 10,600 French tons. The engines are +two in number, one driving each propeller; they are +of the vertical compound type, and on the speed trials +developed 11,300 indicated horse power under forced +and 5,500 indicated horse power under natural +draught, the former giving a speed of 16.2 knots per +hour with 90 revolutions per minute. The boilers are +eight in number, of the cylindrical marine type, and +work at a pressure of 85.3 lb. per square inch. During +the trials the steering powers of the ship were +found to be excellent, but the bow wave is said, by one +critic, to have been very great.</p> + +<p>The ship is completely belted with Creusot steel armor, +which varies in thickness from 9 in. forward to +17¾ in. midships. In addition to this belt the ship is +protected by an armored deck of 3½ in., while the barbette +gun towers are protected with 15¾ in. steel armor +with a hood of 2½ in. to protect the men against machine +gun fire. As a further means of insuring the life +of the ship in combat and also against accidents at sea, +the Marceau is divided into 102 water-tight compartments +and is fitted with torpedo defense netting. +There are two masts, each carrying double military +tops; and a conning tower is mounted on each mast, +from either of which the ship may be worked in time +of action, and both of which are in telegraphic communication +with the engine rooms and magazines. +Provision is made for carrying 600 tons of coal, which, +at a speed of 10 knots, should be sufficient to supply +the boilers for a voyage of 4,000 miles.</p> + +<p>The armament of the Marceau is good for the tonnage +of the ship and consists principally of four guns +of 34 centimeters (13.39 in.) of the French 1884 model, +having a weight of 52 tons, a length of 28½ calibers, +and being able to pierce 30 in. of iron armor at the muzzle. +The projectiles weigh 924 lb., and are fired with +a charge of 387 lb. of powder. The muzzle velocity has +been calculated to be 1,968 ft. per second. The guns +are entirely of steel and are mounted on Canet carriages +in four barbette towers, one forward, one aft, +and one on each side amidships. On the firing trials +both the guns and all the Canet machinery, for working + +the guns and hoisting the ammunition, gave very +great satisfaction to all present at the time. In addition +to the above four heavy guns there are, in the +broadside battery, sixteen guns of 14 centimeters +(5.51 in.), eight on each side, and a gun of equal caliber +is mounted right forward on the same deck. The +armament is completed by a large number of Hotchkiss +quick-firing and revolver guns and four torpedo +tubes, one forward, one aft, and one on each side.</p> + +<p>The crew of the Marceau has been fixed at 600 men, +and the cost is stated to have been about $3,750,000.--<i>Engineering</i>.</p> + +<hr /> + +<h3>[Continued from SUPPLEMENT, No. 820, page 13097.]</h3> + +<a name="mar2"></a><h2>A REVIEW OF MARINE ENGINEERING DURING +THE PAST DECADE.<a name="FNanchor_1"></a><a href="#Footnote_1"><sup>1</sup></a></h2> + +<h3>By Mr. ALFRED BLECHYNDEN, of Barrow-in-Furness</h3> + + +<p><i>Steam Pipes</i>.--The failures of copper steam pipes on +board the Elbe, Lahn, and other vessels have drawn +serious attention both to the material and to the modes +of construction of the pipes. The want of elastic +strength in copper is an important element in the +matter; and the three following remedies have been +proposed, while still retaining copper as the material. +First, in view of the fact that in the operation of brazing +the copper may be seriously injured, to use solid +drawn tubes. This appears fairly to meet the main +dangers incidental to brazing; but as solid drawn +pipes of over 7 inches diameter are difficult to procure, +it hardly meets the case sufficiently. Secondly, to use +electrically deposited tubes. At first much was promised +in this direction; but up to the present time it +can hardly be regarded as more than in the experimental +stage. Thirdly, to use the ordinary brazed or +solid drawn tubes, and to re-enforce them by serving +with steel cord or steel or copper wire. This has been +tried, and found to answer perfectly. For economical +reasons, as well as for insuring the minimum of torsion +to the material during manufacture, it is important +to make as few bends as possible; but in practice +much less difficulty has been experienced in serving +bent pipes in a machine than would have been +expected. Discarding copper, it has been proposed to +substitute steel or iron. In the early days of the +higher pressures, Mr. Alexander Taylor adopted +wrought iron for steam pipes. One fitted in the +Claremont in February, 1882, was recently removed +from the vessel for experimental purposes, and was +reported upon by Mr. Magnus Sandison in a paper +read before the Northeast Coast Institution of Engineers +and Shipbuilders.<a name="FNanchor_2"></a><a href="#Footnote_2"><sup>2</sup></a> The following is a summary +of the facts. The pipe was 5 inches external diameter, +and 0.375 inch thick. It was lap welded in the works +of Messrs. A. & J. Stewart. The flanges were screwed +on and brazed externally. The pipe was not lagged +or protected in any manner. After eight and a half +years' service the metal measured where cut 0.32 and +0.375 inch in thickness, showing that the wasting during +that time had been very slight. The interior surface +of the tube exhibited no signs of pitting or corrosion. +It was covered by a thin crust of black oxide, +the maximum thickness of which did not exceed 1/32 +inch. Where the deposit was thickest it was curiously +striated by the action of the steam. On the scale being +removed, the original bloom on the surface of the +metal was exposed. It would thus appear that the +danger from corrosion of iron steam pipes is not borne +out in their actual use; and hence so much of the way +is cleared for a stronger and more reliable material +than copper. So far the source of danger seems to be +in the weld, which would be inadmissible in larger +pipes; but there is no reason why these should not be +lapped and riveted. There seems, however, a more +promising way out of the difficulty in the Mannesmann +steel tubes which are now being "spun" out +of solid bars, so as to form weldless tubes.</p> + +<p class="ctr">TABLE I.--TENSILE STRENGTH OF GUN METAL AT HIGH TEMPERATURES.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gun Metal Strength"> +<colgroup><col align="left"><col span="4" align="right"></colgroup> +<tr><th>Composition of gun metal.</th><th>Temperature of oil bath</th><th>Tensile strength per square inch.</th><th>Elastic limit per square inch.</th><th>Elongation in length of 2 inches</th></tr> +<tr><td align="right">Per cent.</td><td>Fahr.</td><td>Tons</td><td>Tons</td><td>Per cent. </td></tr> +<tr><th rowspan="2" align="justify">Copper 87 <br />Tin 8<br />Zinc 3½<br />Lead 1½</th> +<td>50°</td><td>12.34</td><td>8.38</td><td>14.64</td></tr> +<tr><td>400°</td><td>10.83</td><td>6.30</td><td>11.79</td></tr> +<tr><th rowspan="2">Copper 87<br />Tin 8<br />Zinc 5</th> +<td>50°</td><td>13.86</td><td>8.33</td><td>20.30</td></tr> +<tr><td>458°</td><td>10.70</td><td>7.43</td><td>12.42</td></tr> +</table> + + +<p>Cast steel has been freely used by the writer for +bends, junction pieces, etc., of steam pipes, as well as +for steam valve chests; and except for the fact that +steel makers' promises of delivery are generally better +than their performance, the result has thus far been +satisfactory in all respects. These were adopted because +there existed some doubt as to the strength of +gun metal under a high temperature; and as the data +respecting its strength appeared of a doubtful character, +a series of careful tests were made to determine +the tensile strength of gun metal when at atmospheric +and higher temperatures. The test bars were all 0.75 +in diameter, or 0.4417 square inch sectional area; and +those tested at the higher temperatures were broken +while immersed in a bath of oil at the temperature here +stated, each line being the mean of four experiments. +The result of these experiments was to give somewhat +greater faith in gun metal as a material to be used +under a higher temperature; but as steel is much +stronger, it is probably the most advisable material +to use, when the time necessary to procure it can be +allowed.</p> + +<p><i>Feed Heating</i>.--With the double object of obviating +strain on the boiler through the introduction of the +feed water at a low temperature, and also of securing +a greater economy of fuel, the principle of previously +heating the feed water by auxiliary means has received +considerable attention, and the ingenious method +introduced by Mr. James Weir has been widely +adopted. It is founded on the fact that, if the +feed water as it is drawn from the hot well be raised +in temperature by the heat of a portion of steam introduced +into it from one of the steam receivers, +the decrease of the coal necessary to generate steam +from the water of the higher temperature bears a +greater ratio to the coal required without feed heating +than the power which would be developed in the +cylinder by that portion of steam would bear to the + +whole power developed when passing all the steam +through all the cylinders. The temperature of the +feed is of course limited by the temperature of the +steam in the receiver from which the supply for heating +is drawn. Supposing, for example, a triple expansion +engine were working under the following conditions +without feed heating: Boiler pressure, 150 lb.;--indicated +horse power in high pressure cylinder +398, in intermediate and low pressure cylinders +together 790, total, 1,188; and temperature of hot well +100° Fahr. Then with feed heating the same engine +might work as follows: The feed might be heated to +220° Fahr., and the percentage of steam from the first +receiver required to heat it would be 12.2 per cent.; +the indicated horse power in the high pressure cylinder +would be as before 398, and in the intermediate +and low pressure cylinders it would be 12.2 per cent, +less than before, or 694, and the total would be 1,092, +or 92 per cent. of the power developed without feed +heating. Meanwhile the heat to be added to each +pound of the feed water at 220° Fahr. for converting it +into steam would be 1,005 units against 1,125 units with +feed at 100° Fahr., equivalent to an expenditure of +only 89.4 per cent. of the heat required without feed +heating. Hence the expenditure of heat in relation to +power would be 89.4 + 92.0 = 97.2 per cent., equivalent to +a heat economy of 2.8 per cent. If the steam for heating +can be taken from the low pressure receiver, the +economy is about doubled. Other feed heaters, more +or less upon the same principle, have been introduced. +Also others which heat the feed in a series of pipes +within the boiler, so that it is introduced into the +water in the boiler practically at boiling temperature; +this is economical, however, only in the sense that +wear and tear of the boiler is saved; in principle the +plan does not involve economy of fuel.</p> + +<p><i>Auxiliary Supply of Fresh Water</i>.--Intimately associated +with the feed is the means adopted for making +up the losses of fresh water due to leakage of steam +from safety valves, glands, joints, etc., and of water +discharged from the air pumps. A few years ago this +loss was regularly made up from the sea, with the result +that the water in the boilers was gradually increased +in density; whence followed deposit on the +internal surfaces, and consequent loss of efficiency, and +danger of accident through overheating the plates. +With the higher pressures now adopted, the danger +arising from overheating is much more serious, and the +necessity is absolute of maintaining the heating surfaces +free from deposit. This can be done only by +filling the boiler with fresh water in the first instance, +and maintaining it in that condition. To do this two +methods are adopted, either separately or in conjunction. +Either a reserve supply of fresh water is carried +in tanks or the supplementary feed is distilled from +sea water by special apparatus provided for the purpose. +In the construction of the distilling or evaporating +apparatus advantage has been taken of two +important physical facts, namely, that, if water be +heated to a temperature higher than that corresponding +with the pressure on its surface, evaporation will +take place; and that the passage of heat from steam +at one side of a plate to water at the other is very +rapid. In practice the distillation is effected by passing +steam, say from the first receiver, through a nest +of tubes inside a still or evaporator, of which the steam +space is connected either with the second receiver or +with the condenser. The temperature of the steam +inside the tubes being higher than that of the steam +either in the second receiver or in the condenser, the +result is that the water inside the still is evaporated, +and passes with the rest of the steam into the condenser, +where it is condensed, and serves to make up +the loss. This plan localizes the trouble of deposit, +and frees it from its dangerous character, because an +evaporator cannot become overheated like a boiler, +even though it be neglected until it salts up solid; and +if the same precautions are taken in working the +evaporator which used to be adopted with low +pressure boilers when they were fed with salt water, +no serious trouble should result. When the tubes +do become incrusted with deposit, they can be +either withdrawn or exposed, as the apparatus is +generally so arranged; and they can then be cleaned.</p> + +<p><i>Screw Propeller</i>.--In Mr. Marshall's paper of 1881 it +was said that "the screw propeller is still to a great extent +an unsolved problem." This was at the time a +fairly true remark. It was true the problem had been +made the subject of general theoretical investigation +by various eminent mathematicians, notably by Professor +Rankine and Mr. William Froude, and of special +experimental investigation by various engineers. As +examples of the latter may be mentioned the +extended series of investigations in the French +vessel Pelican, and the series made by Mr. +Isherwood on a steam launch about 1874. These +experiments, however, such as they were, did little to +bring out general facts and to reduce the subject to a +practical analysis. Since the date of Mr. Marshall's paper, +the literature on this subject has grown rapidly, +and, has been almost entirely of a practical character. +The screw has been made the subject of most +careful experiments. One of the earliest extensive +series of experiments was made under the writer's +direction in 1881, with a large number of models, +the primary object being to determine what value there +was in a few of the various twists which inventive ingenuity +can give to a screw blade. The results led the +experimenters to the conclusion that in free water such +twists and curves are valueless as serving to augment +efficiency. The experiments were then carried further +with a view to determine quantitative moduli for the +resistance of screws with different ratios of pitch to +diameter, or "pitch ratios," and afterward with different +ratios of surface to the area of the circle described +by the tips of the blades, or "surface ratios." As these +results have to some extent been analyzed and published, +no further reference need be made to them now.</p> + +<p>In 1886, Mr. R.E. Froude published in the Transactions +of the Institution of Naval Architects the deductions +drawn from an extensive series of trials made +with four models of similar form and equal diameter, +but having different pitch ratios. Mr. S.W. Barnaby +has published some of the results of experiments made +under the direction of Mr. J.I. Thornycroft; and in +his paper read before the Institution of Civil Engineers +in 1890 he has also put Mr. R.E. Froude's results into +a shape more suitable for comparison with practice. +Nor ought Mr. G.A. Calvert's carefully planned experiments +to pass unnoticed, of which an account was + +given in the Transactions of the Institution of Naval +Architects in 1887. These experiments were made on +rectangular bodies with sections of propeller blade +form, moved through the water at various velocities in +straight lines, in directions oblique to their plane +faces; and from their results an estimate was formed +of the resistance of a screw.</p> + +<p>One of the most important results deduced from experiments +on model screws is that they appear to have +practically equal efficiencies throughout a wide range +both in pitch ratio and in surface ratio; so that great +latitude is left to the designer in regard to the form of +the propeller. Another important feature is that, although +these experiments are not a direct guide to the +selection of the most efficient propeller for a particular +ship, they supply the means of analyzing the performances +of screws fitted to vessels, and of thus indirectly +determining what are likely to be the best dimensions +of screw for a vessel of a class whose results are known. +Thus a great advance has been made on the old method +of trial upon the ship itself, which was the origin of +almost every conceivable erroneous view respecting +the screw propeller. The fact was lost sight of that +any modification in form, dimensions, or proportions +referred only to that particular combination of ship +and propeller, or to one similar thereto; so something +like chaos was the result. This, however, need not be +the case much longer.</p> + +<p>In regard to the materials used for propellers, steel +has been largely adopted for both solid and loose-bladed +screws; but unless protected in some way, the +tips of the blades are apt to corrode rapidly and become +unserviceable. One of the stronger kinds of +bronze is often judiciously employed for the blades, in +conjunction with a steel boss. Where the first extra +expense can be afforded, bronze seems the preferable +material; the castings are of a reliable character, and +the metal does not rapidly corrode; the bronze blades +can therefore with safety be made lighter than steel +blades, which favors their springing and accommodating +themselves more readily to the various speeds of +the different parts of the wake. This might be expected +to result in some slight increase of efficiency; +of which, however, the writer has never had the opportunity +of satisfactorily determining the exact extent. +Instances can be brought forward where bronze blades +have been substituted for steel or iron with markedly +improved results; but in cases of this kind which the +writer has had the opportunity of analyzing, the whole +improvement might be accounted for by the modified +proportions of the screw when in working condition. +In other words, both experiment and practical working +alike go to show that, although cast iron and steel +blades as usually proportioned are sufficiently stiff to +retain their form while at work, bronze blades, being +made much lighter, are not; and the result is that the +measured or set pitch is less than that which the +blades assume while at work. Some facts relative to +this subject have already been given in a recent paper +by the author.</p> + +<p><i>Twin Screws</i>.--The great question of twin screw propulsion +has been put to the test upon a large scale in +the mercantile marine, or rather in what would usually +be termed the passenger service. While engineers, +however, are prepared to admit its advantages so far +as greater security from total breakdown is concerned, +there is by no means thorough agreement as to +whether single or twin screws have the greater propulsive +efficiency. What is required to form a sound +judgment upon the whole question is a series of examples +of twin and single screw vessels, each of which is +known to be fitted with the most suitable propeller for +the type of vessel and speed; and until this information +is available, little can be said upon the subject with +any certainty. So far the following large passenger +steamers, particulars of which are given in table II., +have been fitted with twin screws. It appears t be a +current opinion that the twin screw arrangement necessitates +a greater weight of machinery. This is not +necessarily so, however; on the contrary, the opportunity +is offered for reducing the weight of all that part +of the machinery of which the weight relatively to +power is inversely proportional to the revolutions for a +given power. This can be reduced in the proportion of +1 to the square root of 2, that is 71 per cent. of its weight in the single +screw engine; for since approximately the same total +disk area is required in both cases with similar proportioned +propellers, the twins will work at a greater +speed of revolution than the single screw. From a commercial +point of view there ought to be little disagreement +as to the advantage of twin screws, so long as the +loss of space incurred by the necessity for double tunnels +is not important; and for the larger passenger +vessels now built for ocean service the disadvantage +should not be great. Besides their superiority in the +matter of immunity from total breakdown, and in +greatly diminished weight of machinery, they also offer +the opportunity of reducing to some extent the cost of +machinery. A slightly greater engine room staff is +necessary; but this seems of little importance compared +with the foregoing advantages.</p> + +<p class="ctr">TABLE II.--PASSENGER STEAMERS FITTED WITH +TWIN SCREWS.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Twin screw passenger stemeaers"> +<colgroup><col align="left" width="25%"><col span="2" align="center" width="10%"><col align="center" width="15%"><col span="2" align="right" width="10%"><col align="right" width="15%"></colgroup> +<tr><td>Vessels.</td><td>Length between perpen- diculars.</td><td>Beam.</td><td colspan="2">Cylinders two sets in all cases.</td><td>Boiler pressure per square inch.</td><td>Indicated horsepower.</td></tr> +<tr><td> </td><td>Feet.</td><td>Feet.</td><td>Diameters.<br />Inches.</td><td>Stroke.<br />Inches.</td><td>Lb.</td><td> </td></tr> +<tr><td>City of Paris.<br />City of New York.</td><td>525</td><td>63¼</td><td> 45, 71, 113</td><td>60</td><td>150</td><td>20,000 </td></tr> +<tr><td>Teutonic.<br /> Majestic.</td><td>565</td><td>58</td><td>43, 68, 110</td><td>60</td><td>180</td><td>18,000 </td></tr> +<tr><td>Normannia.</td><td>500</td><td>57½</td><td> 40, 67, 106</td><td>66</td><td>160</td><td>11,500 </td></tr> +<tr><td>Columbia.</td><td>463½</td><td>55½</td><td> 41, 66, 101</td><td>66</td><td>160</td><td>12,500 </td></tr> +<tr><td>Empress of India.<br />Empress of Japan.<br />Empress of China.</td><td>440</td><td>51</td><td>32, 51, 82</td><td>54</td><td>160</td><td>10,125</td></tr> +<tr><td>Orel.</td><td>415</td><td>48</td><td>34, 54, 85</td><td>51</td><td>160</td><td>10,000 </td></tr> +</table> + +<p><i>Weight of Machinery Relatively to Power</i>.--It is interesting +to compare the weight of machinery relatively + +to the power developed; for this comparison has +sometimes been adopted as the standard of excellence +in design, in respect of economy in the use of material. +The principle, however, on which this has generally +been done is open to some objections. It has been usual +to compare the weight directly with the indicated +horse-power, and to express the comparison in pounds +per horse-power. So long as the machinery thus compared +is for vessels of the same class and working at +about the same speed of revolution, no great fault can +be found; but as speed of revolution is a great factor +in the development of power, and as it is often dependent +on circumstances altogether external to the engine +and concerning rather the speed of the ship, the engines +fitted to high speed ships will thus generally +appear to greater advantage than is their due. Leaving +the condenser out of the question, the weight of an +engine would be much better referred to cylinder +capacity and working pressures, where these are materially +different, than directly to the indicated power. +The advantages of saving weight of machinery, so long +as it can be done with efficiency, are well known and +acknowledged. If weight is to be reduced, it must be +done by care in design, not by reduction of strength, +because safety and saving of repairs are much more +important than the mere capability of carrying a +few tons more of paying load. It must also be +done with economy; but this is a matter which generally +settles itself aright, as no shipowner will pay more +for a saving in weight than will bring in a remunerative +interest on his outlay. In his paper on the weight +of machinery in the mercantile marine,<a name="FNanchor_3"></a><a href="#Footnote_3"><sup>3</sup></a> Mr. William +Boyd discussed this question at some length, and proposed +to attain the end of reducing the weight of machinery +by the legitimate method of augmenting the +speed of revolution and so developing the required +power with smaller engines. This method, while promising, +is limited by the efficiency of the screw, but may +be adopted with advantage so long as the increase in +speed of revolution involves no such change in the +screw as to reduce its efficiency as a propeller. But +when the point is reached beyond which a further +change involves loss of propelling efficiency, it is time +to stop; and the writer ventures to say that in many +cargo vessels now at work the limit has been reached, +while in many others it has certainly been passed.</p> + +<p><i>Economy of Fuel</i>.--Coming to the highly important +question of economy of fuel, the average consumption +of coal per indicated horse-power is 1.522 lb. per hour. +The average working pressure is 158.5 lb. per square +inch. Comparing this working pressure with 77.4 lb. in +1881, a superior economy of 19 per cent. might be expected +now, on account of the higher pressure, or +taking the 1.828 lb. of coal per hour per indicated +horse-power in 1881, the present performance under +similar conditions should be 1.48 lb. per hour per indicated +horse-power. It appears that the working +pressures have been increased twice in the last ten +years, and nearly three times in the last nineteen. The +coal consumptions have been reduced 16.7 per cent. in +the last ten years and 27.9 per cent. in the last nineteen. +The revolutions per minute have increased in the +ratios of 100, 105, 114; and the piston speeds as 100, 124, +140. Although it is quite possible that the further investigations +of the Research Committee on Marine +Engine Trials may show that the present actual consumption +of coal per indicated horse-power is understated, +yet it is hardly probable that the relative +results will be affected thereby.</p> + +<p><i>Dimensions</i>.--In the matter of the power put into +individual vessels, considerable strides have been +made. In 1881, probably the greatest power which has +been put into one vessel was in the case of the Arizona, +whose machinery indicated about 6,360 horse-power. +The following table gives an idea of the dimensions +and power of the larger machinery in the later +passenger vessels:</p> + +<p class="ctr">TABLE III.--DIMENSIONS AND POWER OF MACHINERY +IN LATER PASSENGER VESSELS.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Later Passenger Vessels"> +<colgroup><col align="left"><col align="left" width="25%"><col align="center"><col span="2" align="right"></colgroup> +<tr><td>Year.</td><td>Name of vessel. </td><td>Diameters of cylinders<br />Inches.</td><td>Length of Stroke.<br />Inches.</td><td>Indicated horsepower</td></tr> +<tr><td>1881</td><td>Alaska</td><td>68, 100, 100</td><td>72</td><td>10,686</td></tr> +<tr><td>1881</td><td>City of Rome</td><td>46, 86; 46, 86; 46, 86</td><td>72</td><td>11,800</td></tr> +<tr><td>1881</td><td>Servia</td><td>72, 100, 100</td><td>78</td><td>10,300</td></tr> +<tr><td>1881</td><td>Livadia yacht</td><td>60, 78, 78; 60, 78,78; 60, 78, 78</td><td>39</td><td>12,500</td></tr> +<tr><td>1883</td><td>Oregon</td><td>70, 104, 104</td><td>72</td><td>13,300</td></tr> +<tr><td>1884<br />1884</td><td>Umbria<br />Etruria</td><td>71, 105, 105</td><td>72</td><td>14,320</td></tr> +<tr><td>1888<br />1889</td><td>City of New York<br /> City of Paris</td><td>45, 71, 113; 45, 71, 113</td><td>60</td><td>20,000 about</td></tr> +<tr><td>1889<br />1889</td><td>Majestic<br />Teutonic</td><td>43, 68, 110; 43, 68, 110</td><td>60</td><td>18,000</td></tr> +</table> + + +<p>In war vessels the increase has been equally marked. +In 1881 the maximum power seems to have been in the +Inflexible, namely, 8,485 indicated horse-power. The +following will give an idea of the recent advance made: +Howe (Admiral class), 11,600 indicated horse-power; +Italia and Lepanto, 19,000 indicated horse-power; Re +Umberto, 19,000 indicated horse-power; Blake and +Blenheim (building), 18,000 indicated horse-power; Sardegna +(building), 22,800 indicated horse-power. It is +thus evident that there are vessels at work to-day +having about three times the maximum power of any +before 1881.</p> + +<p><i>General Conclusions</i>.--The progress made during the +last ten years having been sketched out, however +roughly, the general conclusions may be stated briefly +as follows: First, the working pressure has been about +doubled. Second, the increase of working pressure and +other improvements have brought with them their +equivalent in economy of coal, which is about 20 per +cent. Third, marked progress has been made in the +direction of dimension, more than twice the power +having been put into individual vessels. Fourth, substantial +advance has been made in the scientific principles +of engineering. It only remains for the writer to +thank the various friends who have so kindly furnished +him with data for some of the tables which have been +given; and to express the hope that the next ten years +may be marked by such progress as has been witnessed +in the past. But it must be remembered that, if +future progress be equal in merit or ratio, it may well +be less in quantity, because advance becomes more difficult +of achievement as perfection is more nearly approached.</p> + +<a name="Footnote_1"></a><a href="#FNanchor_1">[1]</a><div class="note">Paper read before the Institution of Mechanical Engineers, July 28, +1891.</div> + +<a name="Footnote_2"></a><a href="#FNanchor_2">[2]</a><div class="note">Transactions Northeast Coast Institution of Engineers and Shipbuilders, +vol. 7, 1890-91, p. 179.</div> + +<a name="Footnote_3"></a><a href="#FNanchor_3">[3]</a><div class="note">Transactions Northeast Coast Institution of Engineers and Shipbuilders, +vol. 6, 1889-90, p. 253.</div> + +<hr /> + +<a name="misc1"></a><h2>THE LITTLE HOUSE</h2> + +<h3>By M.M.</h3> + + +<p>One of the highest medical authorities is credited +with the statement that "nine-tenths of the diseases +that afflict humanity are caused by neglect to answer +the calls of Nature."</p> + +<p>This state of affairs is generally admitted, but is +usually attributed to individual indolence. That, +doubtless, has a great deal to do with it, but should +not part of the blame be laid upon the often unpleasant +environments, which make us shrink as from the +performance of a painful duty?</p> + +<p>In social life, unless from absolute necessity or charity, +people of refined habits do not call on those whose +surroundings shock their sense of decency; but when +they go to pay the calls of Nature, they are often compelled +to visit her in the meanest and most offensive +of abodes; built for her by men's hands; for Nature +herself makes no such mistakes in conducting her +operations. She does not always surround herself +with the pomp and pride of life, but she invariably +hedges herself in with the thousand decencies and the +pomp of privacy.</p> + +<p>But what do we often do? We build what is sometimes +aptly termed "an out-house," because it is placed +so that the delicate minded among its frequenters may +be made keenly alive to the fact that they can be +plainly seen by every passer-by and by every idle +neighbor on the lookout. This tiny building is seldom +weatherproof; In consequence, keen cold winds from +above, below, and all around find ready entrance, chill +the uncovered person, frequently check the motions, +and make the strong as well as the weak, the young as +well as the old, very sorry indeed that they are so often +uselessly obliged to answer the calls of Nature. It is +true, the floor is sometimes carpeted with snow, but +the feet feel that to be but cold comfort, though the +door may enjoy rattling its broken hasp and creaking +its loose hinges.</p> + +<p>How often, too, are the nose and the eye offended by +disregard of the Mosaic injunction, found in the +twelfth, thirteenth, and fourteenth verses of the +twenty-third chapter of Deuteronomy! Of course this +injunction was addressed to a people who had been +debased by slavery, but who were being trained to fit +them for their high calling as the chosen of God; but +is not some such sanitary regulation needed in these +times, when a natural office is often made so offensive +to us by its environments that it is difficult for us to +believe that "God made man a little lower than the +angels," or that the human body is the temple of the +Holy Ghost?</p> + +<p>Dwellers in the aristocratic regions of a well drained +city, whose wealth enables them to surround themselves +with all devices tending to a refined seclusion, +may doubt all this, but sanitary inspectors who have +made a round of domiciliary visits in the suburbs, or +the older, neglected parts of a large city, of to any part +of a country town or village, will readily affirm as to its +general truth.</p> + +<p>This unpardonable neglect of one of the minor decencies +by the mass of the people seems to be caused +partly by a feeling of false shame, and partly by an +idea that it is expensive and troublesome to make any +change that will improve their sanitary condition or +dignify their daily lives.</p> + +<p>The Rev. Henry Moule, of Fordington Vicarage, +Dorsetshire, England, was one of the first to turn his +attention to this matter. With the threefold object of +improving the sanitary condition of his people, refining +their habits, and enriching their gardens, he invented +what he called the "dry earth closet."</p> + +<p>"It is based on the power of clay and the decomposed +organic matter found in the soil to absorb and retain +all offensive odors and all fertilizing matters; and it +consists, essentially, of a mechanical contrivance (attached +to the ordinary seat) for measuring out and +discharging into the vault or pan below a sufficient +quantity of sifted dry earth to entirely cover the solid +ordure and to absorb the urine.</p> + +<p>"The discharge of earth is effected by an ordinary +pull-up, similar to that used in the water closet, or (in +the self-acting apparatus) by the rising of the seat +when the weight of the person is removed.</p> + +<p>"The vault or pan under the seat is so arranged that +the accumulation can be removed at pleasure.</p> + +<p>"From the moment when the earth is discharged +and the evacuation covered, all offensive exhalation +entirely ceases. Under certain circumstances there +may be, at times, a slight odor as of guano mixed with +earth, but this is so trifling and so local that a commode +arranged on this plan may, without the least +annoyance, be kept in use in any room."</p> + +<p>The "dry earth closet" of the philanthropic clergyman +was found to work well, and was acceptable to +his parishioners. One reason why it was so was because +dry earth was ready to hand, or could be easily +procured in a country district where labor was cheap. +But where labor was dear and dry earth scarce, those +who had to pay for the carting of the earth and the +removal of the deodorized increment found it both +expensive and troublesome.</p> + +<p>But a modification of this dry earth closet, the joint +contrivance of an English church clergyman and his +brother, "the doctor," residents of a Canadian country +town, who had heard of Moule's invention, is a +good substitute, and is within the reach of all. This +will be briefly described.</p> + +<p>The vault was dug as for an ordinary closet, about +fifteen feet deep, and a rough wooden shell fitted in. +About four feet below the surface of this wooden shell +a stout wide ledge was firmly fastened all around. +Upon this ledge a substantially made wooden box was +placed, just as we place a well fitting tray into our +trunks. About three feet of the back of the wooden +shell was then taken out, leaving the back of the box +exposed. From the center of the back of the box a +square was cut out and a trap door fitted in and hasped +down.</p> + +<p>The tiny building, on which pains, paint, and inventive +genius had not been spared to make it snug, +comfortable, well lighted and well ventilated, was +placed securely on this vault.</p> + +<p>After stones had been embedded in the earth at the +back of the vault, to keep it from falling upon the trap + +door, two or three heavy planks were laid across the +hollow close to the closet. These were first covered +with a barrowful of earth and then with a heap of +brushwood.</p> + +<p>Within the closet, in the left hand corner, a tall +wooden box was placed, about two-thirds full of dry, +well sifted wood ashes. The box also contained a +small long-handled fire shovel. When about six inches +of the ashes had been strewn into the vault the closet +was ready for use. No; not quite; for squares of suitable +paper had to be cut, looped together with twine, +and hung within convenient reaching distance of the +right hand; also a little to the left of this pad of paper, +and above the range of sight when seated, a ten pound +paper bag of the toughest texture had to be hung by a +loop on a nail driven into the corner.</p> + +<p>At first the rector thought that his guests would be +"quick-witted enough to understand the arrangement," +but when he found that the majority of them +were, as the Scotch say, "dull in the uptak," he had +to think of some plan to enforce his rules and regulations. +As by-word-of-mouth instructions would have +been rather embarrassing to both sides, he tacked up +explicit written orders, which must have provoked +many a smile. Above the bin of sifted ashes he nailed +a card which instructed "Those who use this closet +must strew two shovelfuls of ashes into the vault." +Above the pad of clean paper he tacked the thrifty +proverb: "Waste not, want not;" and above the +paper bag he suspended a card bearing this warning: +"All refuse paper must be put into this bag; not a +scrap of clean or unclean paper must be thrown into +the vault."</p> + +<p>This had the desired effect. Some complacently +united to humor their host's whim, as they called it, +and others, immediately recognizing its utility and +decency, took notes with a view to modifying their +own closet arrangements.</p> + +<p>Sarah, the maid of all work, caused a good deal of +amusement in the family circle by writing her instructions +in blue pencil on the front of the ash bin. These +were: "Strew two shuffefuls of ashes into the volt, but +don't spill two shuffefuls onto the floor. By order of +the Gurl who has to sweap up." This order was emphatically +approved of by those fastidious ones who +didn't have to "sweep up."</p> + +<p>This closet opened off the woodshed, and besides being +snugly weatherproof in itself, was sheltered on one +side by the shed and on another by a high board fence. +The other two sides were screened from observation by +lattice work, outside of which evergreens were planted +to give added seclusion and shade. A ventilator in the +roof and two sunny little windows, screened at will +from within by tiny Venetian shutters, gave ample +light and currents of fresh air. For winter use, the +rector's wife and daughters made "hooked" mats for +floor and for foot support. These were hung up every +night in the shed to air and put back first thing in the +morning. For the greater protection and comfort of +invalids, an old-fashioned foot warmer, with a handle +like a basket, was always at hand ready to be filled +with live coals and carried out.</p> + +<p>The little place was always kept as exquisitely clean +as the dainty, old-fashioned drawing room, and so +vigilant was the overseeing care bestowed on every detail, +that the most delicate and acute sense of smell +could not detect the slightest abiding unpleasant odor. +The paper bag was frequently changed, and every +night the accumulated contents were burned; out of +doors in the summer, and in the kitchen stove--after a +strong draught had been secured--in the winter.</p> + +<p>At stated times the deodorized mass of solid increment--in +which there was not or ought not to have +been any refuse paper to add useless bulk--was spaded, +through the trap door, out of the box in the upper +part of the vault, into a wheelbarrow, thrown upon +the garden soil, and thoroughly incorporated with it. +In this cleansing out process there was little to offend, +so well had the ashes done their concealing deodorizing +work.</p> + +<p>In using this modified form of Moule's invention, it +is not necessary to dig a deep vault. The rector, given +to forecasting, thought that some day his property +might be bought by those who preferred the old style, +but his brother, the doctor, not troubling about what +might be, simply fitted his well made, four feet deep +box, with its trap door, into a smoothly dug hole that +exactly held it, and set the closet over it. In all other +respects it was a model of his brother's.</p> + +<p>This last is within the reach of all, even those who +live in other people's houses; for, when they find +themselves in possession of an unspeakably foul closet, +they can cover up the old vault and set the well +cleaned, repaired, fumigated closet upon a vault +fashioned after the doctor's plan. A stout drygoods +box, which can be bought for a trifle, answers well for +this purpose, after a little "tinkering" to form a trap +door.</p> + +<p>Of course, dry earth is by far the best deodorizer +and absorbent, but when it cannot be easily and +cheaply procured, well sifted wood or coal ashes--wood +preferred--is a good substitute. The ashes must be +kept dry. If they are not, they lose their absorbing, +deodorizing powers. They must also be well sifted. If +they are not, the cinders add a useless and very heavy +bulk to the increment.</p> + +<p>An ash sifter can be made by knocking the bottom +out of a shallow box, studding the edge all round with +tacks, and using them to cross and recross with odd +lengths of stovepipe wire to form a sieve.--<i>The Sanitarian</i>.</p> + +<hr /> +<a name="med1"></a><h2>THE HYGIENIC TREATMENT OF OBESITY.<a name="FNm1_anc_1"></a><a href="#FNm1_1"><sup>1</sup></a></h2> + +<h3>By Dr. Paul Cheron.</h3> + + +<p>In order to properly regulate the regimen of the +obese, it is first necessary to determine the source of +the superfluous adipose of the organism, since either +the albuminoids or the hydrocarbons may furnish fat.</p> + +<p>Alimentary fat becomes fixed in the tissues, as has +been proved by Lebede, who fed dogs, emaciated by +long fast, with meat wholly deprived of fat, and substituted +for the latter linseed oil, when he was able to +recover the oil in each instance from the animal; +parallel experiments with mutton fat, <i>in lieu</i> of oil, +afforded like results.</p> + +<p>Hoffman also deprived dogs of fat for a month, causing +them to lose as high as twenty-two pounds weight, + +then began nourishing with bacon fat with but little +lean; the quantity of fat formed in five days, in the +dog that lost twenty-two pounds, was more than three +pounds, which could have been derived only from the +bacon fat.</p> + +<p>It has been stated, however, that alimentary fat +seems to preserve from destruction the fat of the organism +which arises from other sources. Be this as it may, +it is a fact that the pre-existence of fat furthers the +accumulation of more adipose; or in other words, fat +induces fattening!</p> + +<p>That adipose may be formed through the transformation +of albuminous matters (meat) is an extremely +important corollary, one established beyond cavil by +Pettinkofer and Voit, in an indirect way, by first +estimating the nitrogen and carbon ingested, and +second the amount eliminated. Giving a dog meat +that was wholly deprived of fat, they found it impossible +to recover more than a portion of the contained carbon; +hence some must necessarily have been utilized in the +organism, and this would be possible only by the transformation +of the carbon into fat! It goes without +saying, however, that the amount of adipose thus +deposited is meager.</p> + +<p>Other facts also plead in favor of the transformation +of a portion of albumen into fat within the economy, +notably the changing of a portion of dead organism +into what is known as "cadaveric fat," and the very +rapid fatty degeneration of organs that supervenes +upon certain forms of poisoning, as by phosphorus.</p> + +<p>The carbohydrates, or more properly speaking +hydrocarbons, are regarded by all physiologists as +specially capable of producing fat, and numerous alimentary +experiments have been undertaken to prove +this point. Chaniewski, Meissl, and Munk obtained +results that evidenced, apparently, sugar and starch +provide more fat than do the albuminoids. Voit, however, +disapproves this, maintaining the greater part of +the hydrocarbons is burned (furnishes fuel for the +immediate evolution of force), and that fat cannot be +stored up unless a due proportion of albuminoids is +also administered. He believes the hydrocarbons exert +a direct influence only; being more oxidizable than +fats, they guard the latter from oxidation. This protective +role of the hydrocarbons applies also to the +albuminoids.</p> + +<p>We may believe, then, that the three great classes of +aliment yield fat, in some degree; that alimentary fat +may be fixed in the tissues; and that hydrocarbons +favor the deposition of adipose either directly or indirectly.</p> + +<p>It is well understood that fat may disappear with +great rapidity under certain conditions; many maladies +are accompanied by speedy emaciation; therefore, +as fat never passes into the secretions, at least not in +appreciable quantities, it probably undergoes transformation, +perhaps by oxidation or a form of fermentation, +the final results of which are, directly or +indirectly, water and cadaveric acid. It is certain +the process of oxidation favors the destruction of +adipose, and that everything which inhibits such +destruction tends to fat accumulation.</p> + +<p>Since the earliest period of history, there seems to +have been an anxiety to secure some regimen of general +application that would reduce or combat obesity. +Thus Hippocrates says:</p> + +<p>Fat people, and all those who would become lean, +should perform laborious tasks while fasting, and eat +while still breathless from fatigue, without rest, and +after having drunk diluted wine not very cold. Their +meats should be prepared with sesamum, with sweets, +and other similar substances, and these dishes should +be free from fat.</p> + +<p>In this manner one will be satiated through eating +less.</p> + +<p>But, besides, one should take only one meal; take +no bath; sleep on a hard bed; and walk as much as +may be.</p> + +<p>How much has medical science gained in this direction +during the interval of more than two thousand +years? Let us see:</p> + +<p>First among moderns to seek to establish on a scientific +basis a regimen for the obese, was Dancel, who +forbade fats, starchy foods, etc., prescribed soups and +aqueous aliment, and reduced the quantity of beverage +to the lowest possible limit; at the same time he employed +frequent and profuse purgation.</p> + +<p>This regimen, which permits, at most, but seven to +twelve ounces of fluid at each repast, is somewhat +difficult to follow, though it may be obtained, gradually, +with ease. Dr. Constantine Paul records a case +in which this regimen, gradually induced, and followed +for ten years, rewarded the patient with "moderate +flesh and most excellent health."</p> + +<p>In Great Britain, a mode of treatment instituted in +one Banting, by Dr. Harvey, whereby the former was +decreased in weight forty pounds, has obtained somewhat +wide celebrity; and what is more remarkable, it +is known as "Bantingism," taking its name from the +patient instead of the physician who originated it. +The dietary is as follows:</p> + +<p><i>Breakfast</i>.--Five to six ounces of lean meat, broiled +fish, or smoked bacon--veal and pork interdicted; a +cup of tea or coffee without milk or sugar; one ounce +of toast or dry biscuit (crackers).</p> + +<p><i>Dinner</i>.--Five or six ounces of lean meat or fish--excluding +eel, salmon, and herring; a small quantity of +vegetables, but no potatoes, parsnips, carrots, beets, +peas, or beans; one ounce of toast, fruit, or fowl; two +glasses of red wine--beer, champagne, and port forbidden.</p> + +<p><i>Tea</i>.--Two or three ounces of fruit; one kind of +pastry; one cup of tea.</p> + +<p><i>Supper</i>.--Three or four ounces of lean beef or fish; +one or two glasses of red wine.</p> + +<p><i>At bed-time.</i>--Grog without sugar (whisky and water, +or rum and water), and one or two glasses of sherry or +Bordeaux.</p> + +<p>"Bantingism," to be effective, must be most closely +followed, when, unfortunately also, it proves extremely +debilitating; it is suitable only for sturdy, hard +riding gluttons of the Squire Western type. The +patient rapidly loses strength as well as flesh, and +speedily acquires an unconquerable repugnance to the +dietary. Further, from a strictly physiological point +of view, the quantity of meat is greatly in excess, while +with the cessation of the regimen, the fat quickly reappears.</p> + +<p>Next Ebstein formulated a dietary that is certainly +much better tolerated than that of Harvey and Banting, + +and yields as good, or even better, results. He +allows patients to take a definite quantity--two to two +and a half ounces-of fat daily, in the form of bacon +or butter which, theoretically at least, offers several +advantages: It diminishes the sensations of hunger +and thirst, and plays a special role with respect to the +albuminoids; the latter may thus be assimilated by +the economy without being resolved into fat, and thus +the adipose of the organism at this period is drawn +upon without subsequent renewal. The following is +the outline:</p> + +<p><i>Breakfast</i>.--At 6 a.m. in summer; 7:30 in winter:--Eight +ounces of black tea without either milk or sugar; +two ounces of white bread or toast, with a copious layer +of butter.</p> + +<p><i>Dinner</i>.--2 p.m.:--A modicum of beef marrow soup; +four ounces of meat, preferably of fatty character; +moderate quantity of vegetable, especially the legumines, +but no potatoes or anything containing starch; +raw fruits in season, and cooked fruits (stewed, without +sugar); two or three glasses of light wine as a +beverage, and after eating, a cup of black tea without +sugar.</p> + +<p><i>Supper</i>.--7:30 p m.:--An egg, bit of fat roast, ham, +or bacon; a slice of white bread well buttered; a large +cup of black tea without milk or sugar; from time to +time, cheese and fresh fruits.</p> + +<p>Germain See suggests as a modification of this regimen, +the abundant use of beverage, the addition of +gelatins, and at times small doses of potassium iodide +in twenty cases he claims constant and relatively +prompt results.</p> + +<p>Whatever may be urged for Ebstein's system--and it +has afforded most excellent results to Unna and to +Lube, as well as its author--it certainly exposes the +patient to the terrors of dyspepsia, when the routine +must needs be interrupted or modified; hence it is not +always to be depended upon. As between dyspepsia +and obesity, there are few, I fancy, who would not +prefer the latter.</p> + +<p>Another "system" that has acquired no little celebrity, +and which has for its aim the reduction as far +as possible of alimentary hydrocarbons while permitting +a certain proportion of fat, is that, of Denneth, +which necessarily follows somewhat closely the lines +laid down by Ebstein.</p> + +<p>Oertels' treatment, somewhat widely known, and not +without due measure of fame, is based upon a series of +measures having as object the withdrawal from both +circulation and the economy at large, as much of the +fluids as possible. It is especially adapted for the relief +of those obese who are suffering fatty degeneration of +the heart. The <i>menu</i> is as follows:</p> + +<p><i>Breakfast</i>.--Pour to five ounces of tea or coffee with +a little milk; two to two and a half ounces bread.</p> + +<p><i>Dinner</i>.--Three or four ounces of roast or boiled +meat, or moderately fat food; fish, slightly fat; salad +and vegetables at pleasure; one and a half ounces of +bread (in certain cases as much as three ounces of farinaceous +food may be permitted); three to six ounces of +fruit; at times a little pastry for dessert.--In summer, +if fruit is not obtainable, six to eight ounces of light +wine may be allowed.</p> + +<p><i>Tea</i>,--A cupful (four to five ounces) of tea or coffee, +with a trifle of milk, as at breakfast; one and three-fourths +ounces of bread; and exceptionally (and at +most) six ounces of water.</p> + +<p><i>Supper</i>.--One to two soft boiled eggs; four or five +ounces of meat; one and three fourths ounces of bread; +a trifle of cheese, salad, or fruit; six to eight ounces of +light wine diluted with an eighth volume of water. +The quantity of beverage may be slightly augmented +at each meal if necessary, especially if there is no morbid +heart trouble.</p> + +<p>Schwenninger (Bismarck's physician), who opened a +large sanitarium near Berlin a few years since for the +treatment of the obese, employs Oertel's treatment, +modified in that an abundance of beverage is permitted, +provided it is not indulged in at meals; it is forbidden +until two hours after eating.</p> + +<p>Both Oertel's and Schwenninger's methods have procured +grave dyspepsias, and fatal albuminurias as well, +according to Meyer and Rosenfield. It has been +charged the allowance of beverage upon which Schwenninger +lays so much stress in the treatment at his sanitarium +has a pecuniary basis, in other words a commission +upon the sale of wines.<a name="FNm1_anc_2"></a><a href="#FNm1_2"><sup>2</sup></a></p> + + +<p>Thus, it will be observed that while some forbid +beverage, others rather insist upon its employment in +greater or less quantities. Under such circumstances, +it would seem but rational, before undertaking to +relieve obesity, to establish its exact nature, and also +the role taken by fluids in the phenomena of nutrition.</p> + +<p>Physiologists generally admit water facilitates nutritive +exchanges, which is explained by the elimination +of a large quantity of urine; the experiments of Genth +and Robin in this direction appear conclusive.</p> + +<p>Bischoff, Voit, and Hermann have shown that water +increases, not alone the elimination of urine, but also +of sodium chloride, phosphoric acid, etc. Grigoriantz +observed augmentation of disintegration when the +quantity of beverage exceeded forty-six to eighty +ounces ("1,400 to 2,400 cubic centimeters") per diem. +Oppenheim, Fraenkel, and Debove, while believing +water has but little influence upon the exchanges, admit +it certainly need not diminish the latter; and Debove +and Flament, after administering water in quantities +varying from two to eight pints per diem, concluded +that urine was diminished below the former +figure, while above the latter it increased somewhat, +being dependent upon the amount ingested. It was on +the strength of the foregoing that Lallemand declared +water to have no influence upon the exchanges.</p> + +<p>The results claimed by Oppenheim, Debove, <i>et al.</i> +were immediately challenged--and it is now generally +admitted, not without some justice--by Germain See. +It seems certain, to say the least, that water taken during +the repast does tend to augment the quantity and +facilitate the elimination of urine. Abundance of beverage, +moreover, presents other advantages, in that it +facilitates digestion by reason of its diluent action, a +fact well worth bearing in mind when treating the +obese who are possessed of gouty diathesis, and whose +kidneys are accordingly encumbered with uric and +oxalic acids. The foregoing presents the ground upon +which Germain See permits an abundance of beverage; +but he also expresses strong reservation as regards beer + +and alcohol, either of which (more especially the former) +tends to the production of adipose. In his opinion, +the only beverage of the alcoholic class that is at all +permissible, and then only for cases suffering from fatty +heart, is a little <i>liqueur</i> or diluted wine. Coffee and +tea he commends highly, and recommends the ingestion +of large quantities at high temperature, both during +the repasts and their intervals. Coffee in large doses +is undoubtedly a means of de-nutrition, and so, too, in +no less extent, is tea; both act vigorously owing to the +contained alkaloids, though, to be sure, they sometimes, +at first, tend to insomnia and palpitation, to +which no attention need be paid, however. The treatment +outlined by See is:</p> + +<p>1. A physiological regimen comprising four to five +ounces of nitrogenous principles as derived from eight +to ten ounces animal muscle and albuminates; three +to six ounces of fat; eight to ten ounces of hydrocarbons +as yielded by ten to twelve ounces of sugar or +starch food.</p> + +<p>These proportions to be modified in such manner +that the musculo-albuminates shall not sensibly exceed +the normal ratio, for meat in excess itself furnishes +fat during transformation. The fatty substances +of easy digestion may, without inconvenience, be utilized +in doses of two to three ounces. The hydrocarbons +should be reduced to a minimum. As for the herbaceous +elements, they contain nothing nutritive.</p> + +<p>2. Beverage, far from being suppressed, should be +augmented, in order to facilitate stomachal digestion +and promote general nutrition, though alcoholic liquids +must be inhibited; likewise mineral waters, except, +perhaps, for occasional use. Both should be replaced +by infusions of coffee or tea, taken as hot as can be +drank.</p> + +<p>Henrich Kisch insists that any method which promises +rapid and marked decrease of adipose must, <i>per se</i>, +be objectionable, even if not positively injurious, since +it tends to provoke general troubles of nutrition. He +suggests that first the fats and hydrocarbons be reduced +as little as possible; that a moderate mixed +regimen is required, containing a preponderance of +albumen, small quantities of hydrocarbons and gelatinous +matters, with but very little fat. Certain fatty +meats, however, should be generally interdicted, such +as pork sausage, smoked beef tongue, goose breast, +smoked ham, fat salmon, and herring in any form. +Eggs, however, may be partaken of in moderation, +giving preference to the albumen over the yelk. Farinaceous +foods, in the main, should be rejected, even +bread being allowed only in small quantities, and then +preferably in the form of toast. Cheese likewise contains +too much fat; and mushrooms are so rich in hydrocarbons +that they should be rejected. Condiments, +water, vegetable acids (vinegars excepted) may be permitted; +especially pernicious is vinegar where there is +any tendency to gout or gravel. All fatty beverages--<i>bouillon</i>, +unskimmed milk, chocolate, or cacao--and +all alcoholics, are hurtful; breakfast tea is undoubtedly +the best beverage, but, after a little, is advantageously +replaced by light white wine diluted with water.</p> + +<p>Kisch believes in a free and abundant use of water +by the obese, especially where there is a tendency to +plethora, since this fluid facilitates oxidation as the +result of absorption; thus he advocates the inhibition +of large quantities of cold water by all, save those presenting +evidence of cardiac insufficiency. In short, +his regimen is based upon the administration of a +large quantity of albumen, like that of Harvey-Banting.</p> + +<p>E. Munk recommends an almost identical dietary, +save that he prefers great moderation in fluids employed +as beverage.</p> + +<p>M. Robin has sought to harmonize the opposing +views regarding fluids, and therefore declares obesity +arises from two distinct sources: 1. Augmentation of +assimilation. 2. Reduced disassimilation. In the former, +he insists water must be interdicted, while in the +latter it may be allowed <i>ad libitum</i>.</p> + +<p>Again, in order to recognize the exact variety of +obesity, he divides his patients into three classes, each +recognizable by the volume of urea excreted. In the +first there is an increase above normal; in the second +the volume of urea is stationary; in the third decreased, +increased, or stationary.</p> + +<p>When the urea is stationary, which is most frequently +the case, it is necessary to calculate the coefficient of +oxidation; that is, the relation existing between the +solid matters of the urine and the urea. The elevation +of the coefficient is <i>prima facie</i> evidence the obesity +is due to excess of assimilation, while depression of +the coefficient indicates default of assimilation. In the +first case, water and liquids must be denied as far as +possible, the same as if there was no augmentation of +urea; in the second, the same as if there was diminution +of urea, the patients may be permitted to imbibe +fluids at pleasure.</p> + +<p>For the obese from default of disassimilation, Robin +recommends a regimen of green vegetables and bread +chiefly--the latter in small quantities, however, and +fluids as may be desired. By this means, on one occasion, +he was able in the course of one month to diminish +the weight of a female patient by twelve and a half +pounds, her measurement around the waist at the same +time decreasing 5.2 inches and across the stomach 4.8 +inches.</p> + +<p>M. De St. Germain achieved good results by combining +judicious exercise with moderate alimentation, +excluding wine and bread.</p> + +<p>M. Dujardin Beaumetz, who professes to have given +most close and careful study and attention to regimen +for the obese, outlines the following, provided there +is no evidence of fatty degeneration of heart.</p> + +<p><i>Breakfast</i> (at 8 a. m.)--Three-fourths of an ounce of +bread "<i>en flute</i>"--that is abounding with crust; one +and a half ounces of cold meat, ham or beef, six ounces +weak black tea, <i>sans</i> sugar.</p> + +<p><i>Lunch</i> (at 1 p.m.)--An ounce and a half to two ounces +of bread, or a <i>ragout</i>, or two eggs; three ounces green +vegetables; one-half ounce of cheese; fruits at discretion.</p> + +<p><i>Dinner</i> (at 7 p.m.)--An ounce and a half to two +ounces of bread; three to four ounces of meat, or +<i>ragout</i>; ditto of green vegetables, salad, half an ounce +of cheese, fruit <i>ad libitum</i>.</p> + +<p>At meal times the patient may take only a "glass and +a half" of liquid--approximately ten ounces--though +a greater amount may be permitted if he abstains during +the intervals.</p> + +<p>Special alimentary regimen, however, does not constitute + +the sole treatment of obesity. Concurrently +must be employed a number of practical adjuvants +which are oftentimes of the utmost assistance. For +one thing, exercise is indispensable; all authorities +agree on this point. The exercise taken in the gymnasium +is one of the best, notably the "wall exercise," +which is more particularly suited to those afflicted +with pendulous and protuberant abdomens as the result +of feebleness of the hypogastric muscles, to accumulation +of fat under the skin and in the omentum, +and to dilation of the stomach and intestines. In the +"wall exercise," the patient stands erect against an +absolutely straight and plumb wall, lifts his hands +(carrying a weight) straight over the head, and causes +them to describe a semicircle forward. Zantz particularly +insists upon arm and leg exercise for the obese, +especially the former, since with the same amount of +effort a larger amount of oxygen is consumed than is +possible by the latter.</p> + +<p>However, of whatever character, the exercise should +be continued to the point of fatigue or dyspn#oelig;a--three +thousand movements daily, gradually increased to +twenty-five thousand, if the system can bear it; and +under such conditions, not only is there consumption +of hydrocarbons, but there is provided a veritable +greed for air that augments waste. The experiments +of Oertel indicate that loss of weight due to fatiguing +exercise arises more particularly from dehydration, +which is made good by absorption of the fluids employed +as beverage; the fluids are claimed by Germain +See to act as accelerants of oxidation.</p> + +<p>During exercise there is obviously more abundant +absorption of oxygen, and consequently greater elimination +of carbonic acid, and as a consequence (as +shown by researches of Voit), the reserve fat of the +economy is attacked and diminished; in intense labor +there is an average hourly consumption of about 8.2 +percent. of fat. Further physical activity is useful in +exercising the voluntary muscles, and thus opposing +the invasion by interstitial fat of the muscle fibrils. +Extreme exercise also, to a certain degree, exerts a +favorable influence on the cardiac muscle, augmenting +both its nutrition and its capacity for labor. With the +anæmic obese, however, it is necessary to be most circumspect +in prescribing forced exercise; also with the +elderly obese possessed of enfeebled or fatty heart.</p> + +<p>Hydrotherapy, especially in the form of cold douches, +particularly when combined with massage, is often of +considerable value in relieving obesity; the method of +Harmman, of St. Germain, which has in many instances +induced rapid loss of adipose, is of this class. +Tepid saline baths and vapor baths have many advocates, +and may afford material aid when the heart and +circulation do not inhibit their employment. Hot baths +elevate the temperature of the body and increase the +organic exchanges, hence, as Bert and Reynard have +pointed out, tend to the elimination of oxygen and carbonic +acid; but when employed, the patient should be +introduced while the temperature is below 130° F., +when it may be gradually raised in the course of thirty +or forty minutes to 140° F.</p> + +<p>It has already been intimated, the chief feature of +the treatment of obesity is acceleration of the exchanges; +and this is in the main true, though it must +also be borne in mind that, while there are obese who +excrete little urea and have a depressed central nervous +temperature, many may be azoturic, and besides +eliminate phosphate in excess, when an oxidating +treatment will not only fail, but prove positively injurious.</p> + +<p>The bile throws out fat, therefore, to accelerate +nutritive oxidations, the liver and nervous system +must be acted upon, <i>i.e.</i>, stimulated. Everything +that tends to diminish the activity of the former, or +depress the latter, must be avoided. Hence intellectual +labor should be encouraged, or in lieu thereof, travel +advised. Exercise should be taken chiefly while fasting; +the limits of sleep confined to strict necessity, and +<i>siestas</i> after meals and during the day strictly forbidden; +the skin stimulated by hydro-therapeutic +measures, including massage under cold affusions, during +warm salt baths, etc.</p> + +<p>To increase the activity of the liver, salicylate of +soda may often be advantageously administered for its +cholagogue effect; or resort may be had to saline purgatives +such as are afforded by the springs of Marienbad, +Kissengen, Homburg, Carlsbad, Brides, Hunyadi, +or Chatel-Guyon; and it is somewhat remarkable +that while undergoing a course of these waters, there +is often no appreciable change in weight or obesity, +though the decrease becomes most marked almost immediately +upon cessation of treatment.</p> + +<p>Everything tending to increased or fuller respiration +is to be encouraged, for the fats are thus supplied with +oxygen, hastening their disintegration and consumption.</p> + +<p>Direct medicinal treatment presents no very wide +scope. Bouchard imagines lime water may be useful +by accelerating nutrition, but this is problematical, +since fat in emulsion or in droplets does not burn. +Nevertheless, alkalies in general, alkaline carbonates, +liquor potassa, soaps, etc., aid in rendering fat more +soluble, and consequently more susceptible to attack. +The alkaline waters, however, are much less active in +obesity than the saline mineral waters, unless, as sometimes +happens, there is a complication of diabetes and +obesity.</p> + +<p>Purgatives are always more or less useful, and often +required to be renewed with all the regularity of +habit. Then too, the iodides, especially iodide of +sodium or potassium, as recommended by M. Germain +See, frequently prove of excellent service by +aiding elimination and facilitating the mutations.</p> + +<p>According to Kisch, the cold mineral waters containing +an abundance of sulphate of soda, like Hunyadi +and Marienbad, are to be preferred to the hot +mineral waters, such as Carlsbad, because of their lesser +irritant action on the vascular system, and because +they strongly excite diuresis through their low +temperature and contained carbonic acid; Carlsbad +deserves preference only when obesity is combined with +uric acid calculi, or with diabetes. For very anæmic +persons, however, the weak alkaline and saline waters +should be selected; or they should confine themselves +to chalybeate waters containing an excess of sulphate +of soda. Water containing sulphate of soda is also indicated +as a beverage where there are troubles of the +circulatory apparatus; it is contraindicated only in accentuated +arterio-sclerosis.</p> + +<p>As a matter of fact, I find the suggestion of M. + +Dujardin-Beaumetz, that the obese should be divided +into two groups, a most practical one, for some are +strong and vigorous--great eaters, perhaps even gluttons--while +others, on the contrary, are feeble and +debilitated, with flesh soft and flaccid; and upon the +former may be imposed all the rigors of the reducing +system, while the latter must be dealt with more carefully.</p> + +<p>In general, it must be noted, the regimen prescribed +for the obese is insufficient, as the following table prepared +by M.C. Paul abundantly proves:</p> + + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Regimen For Obese"> +<colgroup><col align="left"><col span="3" align="center"></colgroup> +<tr><td align="center">Author.</td><td>Albuminous Matters.</td><td>Fatty Matters.</td><td>Hydrocarbons.</td></tr> +<tr><td>Voit.</td><td>118</td><td>40</td><td>150</td></tr> +<tr><td>Harvey-Banting.</td><td>170</td><td>10</td><td>80</td></tr> +<tr><td>Ebstein.</td><td>100</td><td>85</td><td>50</td></tr> +<tr><td>Oertel.</td><td>155-179</td><td>25-41</td><td>70-110</td></tr> +<tr><td>Kisch (plethoric).</td><td>160</td><td>10</td><td>80</td></tr> +<tr><td>Kisch (anæmic).</td><td>200</td><td>12</td><td>100</td></tr> +<tr><td>Normal ration.</td><td>124</td><td>55</td><td>455</td></tr> +</table> + +<p>There is, therefore, as Dujardin-Beaumetz asserts, +autophagia in the obese, and all these varieties of treatment +have but one end, viz.: Reduction of the daily +ration. But the quantity of nourishment should not +be too greatly curtailed, for, manifestly, if the fat disappears +the more surely, the muscles (rich in albumen) +undergo too rapid modification. It is progressive action +that should always be sought.</p> + +<p>The quantity of aliment may be reduced either by +imposing an always uniform regimen, which soon begets +anorexia and disgust, or by withholding from the +food a considerable quantity of fat, or, finally, by forbidding +beverage during meals. Emaciation is obtained +readily enough in either way, and demands +only the constant exercise of will power on the part of +the patient; but unhappily, severe regimen cannot +always be prescribed. When the obese patient has +passed the age of forty; when the heart suffers from +degeneration; or when the heart is anæmic--in all, +rigorous treatment will serve to still further enfeeble +the central organ of circulation, and tend to precipitate +accidents that, by all means, are to be avoided. +In such cases, by <i>not</i> treating the obesity, the days of +the patient will be prolonged. In degeneration of the +heart, however, the method of Ebstein may be tried; +and when there is renal calculi and gouty diathesis, +that of Germain See may prove satisfactory.</p> + +<h3>Paris, France.</h3> + +<a name="FNm1_1"></a><a href="#FNm1_anc_1">[1]</a><div class="note"> +Translated by Mr. Jos. Helfman, Detroit, Mich.</div> + +<a name="FNm1_2"></a><a href="#FNm1_anc_2">[2]</a><div class="note">The sanitarium is owned by a stock company, Schwenninger being +merely Medical Director.--ED.</div> + +<hr /> + + + +<a name="misc2"></a><h2>STILT WALKING.</h2> + +<p class="ctr"><a href="./images/12-stilt.png"><img src="images/12-stilt_th.jpg " width="256" height="391" alt="THE FRENCH ARMORED TURRET SHIP MARCEAU" title=""></a> +<br clear="all" />SYLVAIN DORNON, THE STILT WALKER OF LANDES.</p> + +<p>Sylvain Dornon, the stilt walker of Landes, started +from Paris on the 12th of last March for Moscow, +and reached the end of his journey at the end of a fifty-eight +days' walk. This long journey upon stilts constitutes +a genuine curiosity, not only to the Russians, +to whom this sort of locomotion is unknown, but also +to many Frenchmen.</p> + +<p>Walking on stilts, in fact, which was common twenty +years ago in certain parts of France, is gradually tending +to become a thing of the past. In the wastes of +Gascony it was formerly a means of locomotion adapted +to the nature of the country. The waste lands +were then great level plains covered with stunted bushes +and dry heath. Moreover, on account of the permeability +of the subsoil, all the declivities were transformed +into marshes after the slightest fall of rain.</p> + +<p>There were no roads of any kind, and the population, +relying upon sheep raising for a living, was much +scattered. It was evidently in order to be able to +move around under these very peculiar conditions +that the shepherds devised and adopted stilts. The +stilts of Landes are called, in the language of the +country, <i>tchangues</i>, which signifies "big legs," and +those who use them are called <i>tchanguès</i>. The stilts +are pieces of wood about five feet in length, provided +with a shoulder and strap to support the foot. The +upper part of the wood is flattened and rests against +the leg, where it is held by a strong strap. The lower +part, that which rests upon the earth, is enlarged and +is sometimes strengthened with a sheep's bone. The +Landese shepherd is provided with a staff which he +uses for numerous purposes, such as a point of support +for getting on to the stilts and as a crook for directing +his flocks. Again, being provided with a board, the +staff constitutes a comfortable seat adapted to the +height of the stilts. Resting in this manner, the shepherd +seems to be upon a gigantic tripod. When he +stops he knits or he spins with the distaff thrust in his +girdle. His usual costume consists of a sort of jacket +without sleeves, made of sheep skin, of canvas gaiters, +and of a drugget cloak. His head gear consists of a +beret or a large hat. This accouterment was formerly +completed by a gun to defend the flock against wolves, +and a stove for preparing meals.</p> + +<p>The aspect of the Landeses is doubtless most picturesque, +but their poverty is extreme. They are generally +spare and sickly, they are poorly fed and are +preyed upon by fever. Mounted on their stilts, the +shepherds of Landes drive their flocks across the wastes, +going through bushes, brush and pools of water, and +traversing marshes with safety, without having to seek +roads or beaten footpaths. Moreover, this elevation +permits them to easily watch their sheep, which are +often scattered over a wide surface. In the morning +the shepherd, in order to get on his stilts, mounts by a +ladder or seats himself upon the sill of a window, or else +climbs upon the mantel of a large chimney. Even in a +flat country, being seated upon the ground, and having +fixed his stilts, he easily rises with the aid of his staff. +To persons accustomed to walking on foot, it is evident +that locomotion upon stilts would be somewhat +appalling.</p> + +<p>One may judge by what results from the fall of a +pedestrian what danger may result from a fall from a +pair of stilts. But the shepherds of Landes, accustomed +from their childhood to this sort of exercise, acquire +an extraordinary freedom and skill therein. The +<i>tchanguè</i> knows very well how to preserve his equilibrium; +he walks with great strides, stands upright, +runs with agility, or executes a few feats of true acrobatism, +such as picking up a pebble from the ground, +plucking a flower, simulating a fall and quickly rising, +running on one foot, etc.</p> + +<p>The speed that the stilt walkers attain is easily explained. +Although the angle of the legs at every step + +is less than that of ordinary walking with the feet on +the ground, the sides prolonged by the stilts are five +or six feet apart at the base. It will be seen that with +steps of such a length, distances must be rapidly +covered.</p> + +<p>When, in 1808, the Empress Josephine went to +Bayonne to rejoin Napoleon I, who resided there by +reason of the affairs of Spain, the municipality sent an +escort of young Landese stilt walkers to meet her. On +the return, these followed the carriages with the greatest +facility, although the horses went at a full trot.</p> + +<p>During the stay of the empress, the shepherds, +mounted upon their stilts, much amused the ladies of +the court, who took delight in making them race, or +in throwing money upon the ground and seeing several +of them go for it at once, the result being a scramble +and a skillful and cunning onset, often accompanied +with falls.</p> + +<p>Up to recent years scarcely any merry-makings occurred +in the villages of Gascony that were not accompanied +with stilt races. The prizes usually consisted +of a gun, a sheep, a cock, etc. The young people vied +with each other in speed and agility, and plucky young +girls often took part in the contests.</p> + +<p>Some of the municipalities of the environs of Bayonne +and Biarritz still organize stilt races, at the period of +the influx of travelers; but the latter claim that the +stiltsmen thus presented are not genuine Landese shepherds, +but simple supernumeraries recruited at hazard, +and in most cases from among strolling acrobats. The +stilt walkers of Landes not only attain a great speed, +but are capable of traveling long distances without appreciable +fatigue.</p> + +<p>Formerly, on the market days at Bayonne and Bordeaux, +long files of peasants were seen coming in on +stilts, and, although they were loaded with bags and +baskets, they came from the villages situated at 10, 15, +or 20 leagues distance. To-day the sight of a stilt +walker is a curiosity almost as great at Bordeaux as at +Paris. The peasant of Landes now comes to the city +in a wagon or even by railway.--<i>La Nature</i>.</p> + +<hr /> +<a name="misc3"></a><h2>REMAINS OF A ROMAN VILLA IN +ENGLAND.</h2> + +<p>A correspondent of the <i>Lincolnshire Chronicle</i> +writes: For some weeks past, remains of a Roman villa +have been exposed to view by Mr. Ramsden's miners in +Greetwell Fields. From, the extent of the tesselated +pavements laid bare there is hardly any doubt +that in the Greetwell Fields, in centuries long gone +by, there stood a Roman mansion, which for magnitude +was perhaps unrivaled in England. Six years +ago I drew attention to it. The digging for iron ore +soon after this was brought to a standstill by the company, +which at the time was working the mines, ceasing +their operations. Then the property came into +other hands, and since then more extensive basement +floors of the villa have from time to time been laid +bare, and from tentative explorations which have +been just made, still more floors remain to be uncovered +which may be of a most interesting and instructive +character. What a pity it is that the inhabitants +of Lincoln have not made an effort to preserve these +precious relics of the grandeur of the Roman occupation, +an occupation to which England owes so much. +From the Romans the people of this country inherit +the sturdy self-reliance and perseverance in action +which have helped to make England what it is, and +from the Romans too, in a great degree, does England +also inherit her colonizing instincts, which impel her +people to cover the waste places of the world with colonies. +If the Roman remains which have been so abundantly +discovered of late years in Lincoln and its vicinity + +had been collected and laid out for exhibition, they +would have formed a most interesting collection of antiquities +worthy of the town, and well worth showing to +visitors who now annually make Lincoln a visitation. +Although these relics of a remote age are being dug +up and are being destroyed, it is not the fault of Mr. +Ramsden, for he not only preserved them as long as he +conveniently could, but he also had the soil removed +from over them, and had them thoroughly washed, in +order that people might have an opportunity of seeing +their extent and beauty. One of these patches of pavement +extended 48 yards northward from what might +be called the main building, which had previously +been broken up. This strip was 13 ft. in breadth, and +down its center ran an intricate pattern worked in blue +tesseræ. The pattern is much used in these days in +fabrics and works of art, and is, I think, called the +Grecian or Roman key pattern. On each side of this +ran alternately broad ribbons of white and narrower +ribbons of red tesseræ. There is also another strip of +pavement to the south of the preceding patch, which +has been laid bare to the extent of 27 yards. This +patch is about 10 ft. in breadth, and its western portion +is cut up in neat patterns, which show that they +formed the floors of rooms. From the eastern extremity +of these floors evidently another long strip of 48 or +50 yards still remains to be uncovered. Doubtless +there are other remains beneath the ground which will +be laid bare as the work of mining goes on. All +these floors were not deeper than from 18 to 30 inches +below the surface of the soil. The bones of animals +and other relics have been found in the covering soil +and have been turned up by the miners from +time to time. The pavement is all worked out with +cubes, varying in size from an inch and a half to two +inches square, each piece being placed in position +with most careful exactness. The strip which extends +48 yards and is 13 ft. wide runs due north and south. +There is a second patch, running east and west, and +this is 27 ft. long by 10 ft. wide, while a third is 27 ft. +long by 11 ft. wide, this also running in a northern +direction. To the north of this latter piece, and separated +only by about two feet (about the width of a +wall, which very possibly was the original division), +there is a strip of tesseræ 16 ft. wide, which had been +laid bare 40 yards. It was thought probable that at +the end of the last named strip still another patch +would be found. Mr. Ramsden, the manager of the +Ironstone Works, is keeping a plan of the whole of the +pavement, which he is coloring in exact imitation of +the original work. This, when completed, will be +most interesting, and he will be quite willing to show +it to any one desirous of inspecting the same. Many +persons have paid a visit to the spot where the discoveries +have been made, and surprise is invariably +expressed at the magnitude and beautiful symmetry +of the work.</p> + +<p>Several interesting fragments of Roman work have +been brought to light in the course of excavations that +are being made for building purposes at Twyford, near +Winchester. About a month ago, a paved way, composed +entirely of small red tiles, six feet in width and +extending probably a considerable distance (a length +of 14 ft. was uncovered), was found while digging on +the site for flints. The more recent excavations are +20 ft. west of this passage, and there is now to be seen, +in a very perfect state of preservation, an oven or kiln +with three openings. Five yards away from this is a +chamber about eight feet square, paved with tiles, and +the sides coated with a reddish plaster. On one side is +a ledge 15 in. from the ground, extending the whole +length of the chamber; on the floor is a sunk channel +with an opening at the end for the water to escape. +This chamber evidently represents the bath. Portions +of the dividing walls of the different chambers have + +also been discovered, together with various bones, +teeth, horns and ornaments, but very few coins. It is +probable that an alteration in the plans of the house +which was about to be built on the spot will be made +so as to preserve all the more interesting features of +these remains in the basement. These discoveries +were made at a depth of only two or three feet from +the surface of the ground, and are within about a +quarter of a mile of other Roman remains which were +similarly brought to light a few months ago.</p> + +<hr /> +<h3>[Continued from SUPPLEMENT, No. 830, page 13110.]</h3> + + +<a name="misc4"></a><h2>GUM ARABIC AND ITS MODERN SUBSTITUTES.<a name="FNms4_anc_1"></a><a href="#FNms4_1"><sup>1</sup></a></h2> + +<h3>By Dr. S. RIDEAL and W.E. YOULE.</h3> + +<p>Subjoined is a table giving the absolute viscosity +of various gums. A comparison of the uncorrected +viscosities with the corrected shows the great importance +of Slotte's correction for dextrins and inferior +gum arabics; in other words, for solutions of low viscosity, +while it will be observed to have little influence +upon the uncorrected η obtained for the Ghatti gums +and the best samples of gum arabic.</p> + +<p class="ctr">TABLE OF ABSOLUTE VISCOSITIES OF 10 PER CENT. GUM +AND DEXTRIN SOLUTIONS.</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gum Viscosity"> +<colgroup><col align="left"><col span="3" align="right"></colgroup> +<tr><td align="center">Sample.</td><td>η Uncorrected.</td><td>η Corrected.</td><td>Z Water = 100.</td></tr> +<tr><td>Gum arabic</td><td>0.1876</td><td>0.1856</td><td>1,233</td></tr> +<tr><td>Cape gum</td><td>0.1575</td><td>0.1555</td><td>1,029</td></tr> +<tr><td>Indian gum</td><td>0.0540</td><td>0.0470</td><td>311</td></tr> +<tr><td>Eastern gum</td><td>0.0689</td><td>0.0639</td><td>417</td></tr> +<tr><td>Gum arabic</td><td>0.0550</td><td>0.0480</td><td>317</td></tr> +<tr><td>Senegal</td><td>0.0494</td><td>0.0410</td><td>271</td></tr> +<tr><td>Senegal</td><td>0.0468</td><td>0.0380</td><td>251</td></tr> +<tr><td>Senegal</td><td>0.0627</td><td>0.0557</td><td>364</td></tr> +<tr><td>Gum arabic</td><td>0.0511</td><td>0.0430</td><td>285</td></tr> +<tr><td>Water</td><td>0.0149</td><td>0.0124</td><td>100</td></tr> +<tr><td>Ghatti</td><td>0.2903</td><td>0.2880</td><td>2,322</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.0903</td><td>0.0828</td><td>688</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1391</td><td>0.1350</td><td>1,089</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1795</td><td>0.1760</td><td>1,420</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1527</td><td>0.1485</td><td>1,198</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1139</td><td>0.1083</td><td>873</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1419</td><td>0.1369</td><td>1,104</td></tr> +<tr><td>Dextrin</td><td>0.0398</td><td>0.0255</td><td>169</td></tr> +<tr><td>Dextrin</td><td>0.0341</td><td>0.0196</td><td>129</td></tr> +<tr><td>Dextrin</td><td>0.0455</td><td>0.0380</td><td>306</td></tr> +<tr><td>Gum substitute</td><td>0.0318</td><td>0.0224</td><td>180</td></tr> +<tr><td>Gum substitute</td><td>0.0318</td><td>0.0224</td><td>180</td></tr> +<tr><td>Amrad</td><td>0.0793</td><td>0.0708</td><td>570</td></tr> +<tr><td>Australian</td><td>0.0378</td><td>0.0283</td><td>228</td></tr> +<tr><td>Australian</td><td>0.0365</td><td>0.0268</td><td>216</td></tr> +<tr><td>Brazilian</td><td>0.0668</td><td>0.0627</td><td>506</td></tr> +<tr><td>Brazilian</td><td>0.0516</td><td>0.0445</td><td>359</td></tr> +<tr><td>Ghatti</td><td>0.3636</td><td>0.3621</td><td>2,920</td></tr> +</table> + + +<p>In the column for η corrected the differences due to +the use of different instruments are of course eliminated. +The absolute viscosity of water at 15° C. determined +in four different instruments is shown below. +Poiseuille's value for water being 0.0122.</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Instrument Differences"> +<colgroup><col align="left"><col span="4" align="right"> +<tr><td align="center">Instrument.</td><td>1.</td><td>2.</td><td>3.</td><td>4.</td></tr> +<tr><td>η corrtd. of water.</td><td>0.0109</td><td>0.01185</td><td>0.0124</td><td>0.0120 </td></tr> +<tr><td>K<sub>1</sub> value.</td><td>0.000000898</td><td>0.000000863</td><td>0.000000932</td><td>0.00000052 </td></tr> +<tr><td>K<sub>2</sub> value.</td><td>0.235</td><td>0.2175</td><td>0.226</td><td>0.0204 </td></tr> +</table> + +<p>The above values for various gums and dextrins were +obtained at a constant temperature of 15° C. and are +compared with water at that temperature. It is of the +utmost importance that the temperature of the water +surrounding the bulbs should be adjusted for each series +of experiments to the temperature at which the absolute +viscosity of the water was determined. As far as +we have ascertained, in gum solutions there is a steady +diminution in viscosity with increase of temperature +until a certain temperature is reached, beyond which +increase of heat does not markedly influence the viscosity, +and it is possible that above this "critical +point," as we may term it, the gum solutions once more +begin to increase in viscosity. The temperature at +which the viscosity becomes stationary varies somewhat +with different gums, but broadly speaking it lies +between 60° C. and 90° C., no gums showing any marked +decrease in viscosity between 80° C. and 90° C.</p> + +<p>The experiments we have made in this direction were +conducted as follows. The 300 c.c. bottle containing +the gum was placed in a capacious beaker full of hot +water, and the viscosity instrument was also surrounded +with water at the same temperature. Thermometers +were suspended both in the beaker and the outer +jar. The viscosity at the highest temperature obtained, +about 90° C., was then taken and repeated for +every fall of 4° C. till the water reached the temperature +of the air.</p> + +<p>The values so obtained gradually diminished with +the increase of temperature. From the η values obtained +the Z values were calculated, using water at 15° C. +as a standard. From the Z values thus obtained +taken as the ordinate, and the temperature of each +experiment as the abscissa, curves were plotted out +embodying the results, examples of which are given +below. The curves yielded by three gums 2, 7, and 8 +changed between 90° C and 100° C., while gum sample +4 has a curve bending between 60° C. and 70° C. Experimentally + +this increase of viscosity of the latter gum +above 60° C. was confirmed, but the critical point of the +other solutions tried approaches too nearly to the boiling +point of water for experiments to be conducted +with accuracy, as the temperature of the bulbs diminishes +sensibly while the experiment is being made.</p> + +<p>If viscosity values have been determined it is possible +to calculate the remaining or intermediate values +for Z at any particular temperature from the general +equation--Zt = A + Bt + Ct²</p> + +<p>As an example of the mode of calculation we may +quote the following. A gum gave the following values +for Z at the temperature stated:</p> + +<blockquote><p>Gum. 50° C. Z<sub>50°</sub> = 228</p> + +<p>Gum. 30° C. Z<sub>30°</sub> = 339</p> + +<p>Gum. 20° C. Z<sub>20°</sub> = 412</p> +</blockquote> + +<p>from which the constants--</p> + +<blockquote><p>A = 592.99 B = -10.2153 C = 0.0583</p></blockquote> + +<p>can be obtained, and thus the value of Z<sub>t°</sub> for any required +temperature. The numbers calculated for gums +all point to a diminution in viscosity up to a certain +point, and then a gradual increase. A comparison of +some of the figures actually obtained in some of these +experiments, compared with the calculated figures for +the same temperature, shows their general agreement.</p> + +<p class="ctr"> <img src="./images/13-gr1.png" height="320" width="306" alt=""> +<br clear="all" /> Curves showing viscosity change with temperature +for three typical gums. A--Arabic VII. B--Senegal +VIII. C--Ghatti 15.</p> + +<p class="ctr">EFFECT OF TEMPERATURE UPON VISCOSITY--GUM VII.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gum VII"> +<colgroup><col align="center"><col span="3" align="right"></colgroup> +<tr><td>Temperature. ºC.</td><td align="center"> η</td><td>Z found.</td><td>Z calculated.</td></tr> +<tr><td>50</td><td>0.0283</td><td>228</td><td>228.00</td></tr> +<tr><td>45</td><td>0.0305</td><td>246</td><td>246.55</td></tr> +<tr><td>42</td><td>0.0352</td><td>284</td><td>266.75</td></tr> +<tr><td>38</td><td>0.0368</td><td>297</td><td>289.00</td></tr> +<tr><td>34</td><td>0.0410</td><td>330</td><td>313.06</td></tr> +<tr><td>30</td><td>0.0419</td><td>339</td><td>339.00</td></tr> +<tr><td>26</td><td>0.0445</td><td>359</td><td>367.80</td></tr> +<tr><td>22</td><td>0.0492</td><td>398</td><td>396.47</td></tr> +<tr><td>20</td><td>0.0511</td><td>412</td><td>412.00</td></tr> +<tr><td>18</td><td>0.0531</td><td>428</td><td>428.00</td></tr> +</table> + + +<p class="ctr">EFFECT OF TEMPERATURE UPON VISCOSITY.--GUM VIII.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gum VIII"> +<colgroup><col align="center"><col span="3" align="right"></colgroup> +<tr><td>Temperature. ºC.</td><td align="center"> η</td><td>Z found.</td><td>Z calculated.</td></tr> +<tr><td>50</td><td>0.0430</td><td>347</td><td>347</td></tr> +<tr><td>46</td><td>0.0475</td><td>383</td><td>371.14</td></tr> +<tr><td>42</td><td>0.0502</td><td>405</td><td>397.09</td></tr> +<tr><td>38</td><td>0.0510</td><td>411</td><td>424.73</td></tr> +<tr><td>34</td><td>0.0575</td><td>463</td><td>454.06</td></tr> +<tr><td>30</td><td>0.0602</td><td>485</td><td>485</td></tr> +<tr><td>26</td><td>0.0637</td><td>513</td><td>517.82</td></tr> +<tr><td>22</td><td>0.0667</td><td>538</td><td>552.25</td></tr> +<tr><td>20</td><td>0.0707</td><td>570</td><td>570</td></tr> +<tr><td>18</td><td>0.0755</td><td>609</td><td>583.07</td></tr> +</table> + +<p>The constants for the first gum are those given in +the preceding column, while for the latter they were--</p> + +<blockquote><p>A = 771.9: B = -11.15: C = 0.053</p></blockquote> + +<p>As will be observed, the effect of heat appears to be +the same upon the two typical gum arabics quoted +above, an increase of temperature from 18° C. to 50° C. +decreasing the viscosity by nearly one half in both +cases, and the same seems to be true of most gum arabics. +Roughly also the same holds good for Ghattis, +as the following numbers show:</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Heat Effect on Gums"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">Gum.</td><td>Z at 18° C.</td><td>Z at 50° C.</td></tr> +<tr><td>Gum arabic.</td><td>1016</td><td>579</td></tr> +<tr><td>Gum arabic.</td><td>428</td><td>228</td></tr> +<tr><td>Gum arabic.</td><td>609</td><td>347</td></tr> +<tr><td>Gum arabic.</td><td>581</td><td>258</td></tr> +<tr><td>Ghatti.</td><td>572</td><td>306</td></tr> +<tr><td>Ghatti.</td><td>782</td><td>418</td></tr> +</table> + + +<p>The following table shows the effect of heat upon +the viscosity of a typical Ghatti:</p> + +<p class="ctr">GHATTI GUM NO. 15.--VISCOSITY.</p> +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Ghatti 15 Viscosity"> +<colgroup><col align="center"><col span="2" align="right"></colgroup> +<tr><td>Temperature. <br/>°C.</td><td>η</td><td>Z.</td></tr> +<tr><td>50</td><td>0.0517</td><td>418 </td></tr> +<tr><td>46</td><td>0.0581</td><td>468 </td></tr> +<tr><td>42</td><td>0.0628</td><td>506 </td></tr> +<tr><td>38</td><td>0.0726</td><td>585 </td></tr> +<tr><td>34</td><td>0.0788</td><td>635 </td></tr> +<tr><td>30</td><td>0.0857</td><td>691 </td></tr> +<tr><td>26</td><td>0.0889</td><td>717 </td></tr> +<tr><td>22</td><td>0.0919</td><td>741 </td></tr> +<tr><td>20</td><td>0.0946</td><td>763 </td></tr> +<tr><td>18</td><td>0.0964</td><td>777 </td></tr> +</table> + + +<p>There is therefore no essential difference in the behavior +of a Ghatti and a gum arabic on heating. Some +interesting results, however, were obtained by heating +gums, both Ghattis and arabics, at a fixed temperature +for the same time, cooling, and then after making the +solutions up to the original volume taking their viscosities +at the ordinary temperature. The effect of heating +for two hours to 60° C., 80° C., or 100° C. was a small +permanent alteration in viscosity of the solution, and +it would therefore seem desirable that gum solutions +should be made up cold to get the maximum results. +The following numbers illustrate this change, viz.:</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Effect of Heating"> +<colgroup><col align="left"><col span="4" align="right"></colgroup> +<tr><td> </td><td> </td><td colspan="3" align="center">After heating to</td></tr> +<tr><td>Gum Arabic<br /> 10 Per Cent.</td><td>Without heat.</td><td>60°C.</td><td>80°C.</td><td>100°C. </td></tr> +<tr><td>Z at 18°C</td><td>570</td><td>468</td><td>470</td><td>517</td></tr> +<tr><td>Z at 30°C</td><td>485</td><td>400</td><td>422</td><td>439</td></tr> +<tr><td>Z at 50°C</td><td>347</td><td>287</td><td>258</td><td>301</td></tr> +<tr><td>Ghatti gum No. 15,<br /> 5 per cent.<br /> Z at 18°C.</td><td>1,104</td><td>780</td><td>660</td><td>758</td></tr> +</table> + +<p>The variation of viscosity with strength of solution +was also studied with one or two typical gums. A 10 +per cent. is invariably more than twice as viscous as a +5 per cent. solution. The following curve was obtained +from one of the Ghattis. Similar results were +shown by other gums.</p> + +<p class="ctr"><img src="./images/13-gr2.png" height="396" width="399" alt="Variation of Viscosity With Dilution"> +<br clear="all" />Variation of Viscosity, with Dilution. +Ghatti No. 888.</p> + +<p>It would seem, therefore, that strong solutions, say of +50 per cent. strength, would be more alike in viscosity +than solutions of 5 per cent. strength of the same +gums. In other words, the viscosity of a gum solution +should be taken as nearly as possible to the strength +it is used at, to obtain an exact quantitative idea of its +gumming value.</p> + +<p>The observation of this fact was one of the circumstances +which decided us to use 5 per cent. solutions +for the determination of Ghatti gum viscosities, the +ratio between the 5 per cent. and 10 per cent. solutions +of gum arabics being roughly the same as that between +the respective weights required for gumming solutions +of equal value.</p> + +<p>From observation of the general nature of the solutions +of Ghatti gums, and from the fact that when +allowed to stand portions of the apparently insoluble +matter passed into solution, the hypothesis suggested +itself that metarabin was soluble in arabin, +although insoluble in cold water. If this hypothesis +were correct, it would explain the apparent anomaly +of Ghattis giving solutions of higher viscosity than +gum arabics, although they leave insoluble matter +behind. The increase in viscosity would be due to +the thickening of the arabic acid by the metarabin. +Moreover, the solutions yielded by various Ghattis +leaving insoluble matter behind would <i>be all of the +same kind</i>, viz., a saturated solution of metarabin in +arabin more or less diluted by water. Still further, if +the insoluble residue of a Ghatti be the residual metarabin +over and above that required to saturate the +arabin, then it will be possible to dissolve this by the +addition of more arabin in the form of ordinary gum +arabic. In order to see if this were the case the following +experiments were performed. Equal parts of a +Ghatti and of a gum arabic were ground up together +and dissolved in water. The resulting solution was +<i>clear</i>. It was diluted until of 10 per cent. strength, +and its viscosity then taken:</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="50-50 Ghatti-Gum"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td> </td><td colspan="2" align="center">Contains 50 per Cent. Ghatti.</td></tr> +<tr><td>A. Pressure 200 mm</td><td>η</td><td>Z</td></tr> +<tr><td>Temperature 15° C</td><td>0.2517</td><td>2,030</td></tr> +</table> + +<p>The viscosity of this solution therefore was considerably +greater than the mean viscosity of the 10 per cent. +solutions of the Ghatti and the gum arabic, viz., +(0.288 + 0.0636)/2 = 0.1758 for the calculated η. Hence it is +evident that the increase in viscosity is due to the +solution of the metarabin.</p> + +<p>Next a solution was made from a mixture of 70 per +cent. Ghatti and 30 per cent. gum arabic. This was +also clear and gave a considerably higher viscosity than +the previous solution.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="70-30 Ghatti-Gum"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td> </td><td colspan="2" align="center">Contains 70 per Cent. Ghatti.</td></tr> +<tr><td>B. Pressure 200 mm</td><td>η</td><td>Z.</td></tr> +<tr><td>Temperature 15° C</td><td>0.3177</td><td>2,562</td></tr> +</table> + + +<p>It will be obvious that the increase of viscosity over +the previous solution in this case must be due to the +smaller amount of the thin gum arabic which is present, +<i>i.e.</i>, in the first case there is more gum arabic than +is required to dissolve the whole of the insoluble metarabin. +Further experiments showed that this is also +true of the second mixture, as the viscosities of the +following mixtures illustrate:</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="High Concentrations of Ghatti"> +<colgroup><col align="left"><col span="2" align="right"> +<tr><td align="center">Strength of Solution.</td><td align="center">η</td><td>Z.</td></tr> +<tr><td>C. 80 per cent. Ghatti.</td><td>0.3642</td><td>2,937 </td></tr> +<tr><td>D. 75 per cent. Ghatti.</td><td>0.33095</td><td>2,669 </td></tr> +<tr><td>E. 77.5 per cent. Ghatti.</td><td>0.4860</td><td>3,819 </td></tr> +</table> + + +<p>This last solution E we called for convenience the +"maximum viscosity" solution, as we believe it to be a +10 per cent. solution containing arabin very nearly +saturated with metarabin. As will be observed, its +viscosity differs widely from those of solutions C and +D, between which it lies in percentage of Ghatti. The +first named solution C contains <i>too little</i> of gum arabic +to dissolve the whole of the metarabin. Consequently +there is a residue left undissolved, which of course diminishes +its viscosity. The second solution D is too +low in viscosity, as it still contains too much of the +weak gum arabic, and as will be seen further on, a +very slight change in the proportions increases or decreases +the viscosity enormously.</p> + +<p>We next tried a series of similar experiments with a +Ghatti containing far less insoluble residue and which +consequently would require less gum arabic to produce +a perfect solution. Mixtures were made in the following +proportions, viz.:</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="13.3% Ghatti"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">----</td><td colspan="2" align="center">13.3 per Cent. Ghatti.</td></tr> +<tr><td>F. Pressure 200 mm</td><td>η</td><td>Z.</td></tr> +<tr><td>Temperature 15° C</td><td> 0.0976</td><td>787</td></tr> +</table> +<br /><br /> +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="86.6% Ghatti"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">----</td><td colspan="2" align="center">86.6 per Cent. Ghatti.</td></tr> +<tr><td>G. Pressure 200 mm</td><td>η</td><td>Z.</td></tr> +<tr><td>Temperature 15° C</td><td> 0.4336</td><td> 3,497</td></tr> +</table> + + +<p>This latter solution is approaching fairly closely to +our "maximum viscosity" with the previous Ghatti, +and probably a very slight decrease in the amount of +gum arabic would bring about the required increase in +viscosity.</p> + +<p>When these experiments were first commenced we +were still under the impression, which several months' +experience of working with gums had produced, namely, +that the Ghattis were quite distinct in their properties +to ordinary gum arabics. But the new hypothesis, +and the experiments undertaken to confirm it, +showed clearly that if the viscosity of a gum solution +depends on the ratio of metarabin to arabin, then +there is no absolute line of demarkation between a +Ghatti and a gum arabic. In other words, there is a +constant gradation between gum arabic and Ghattis, +down to such gums as cherry gum, consisting wholly +of metarabin and quite insoluble in water. Therefore +those gum arabics which are low in viscosity consist +of nearly pure arabin, while as the viscosity increases +so does the amount of metarabin, until we come to +Ghattis which contain more metarabin than their arabin +can hold in solution, when their viscosity goes +down again.</p> + +<p>From these observations it would follow, that by +taking a gum of less viscosity than the gum arabic previously +used to dissolve the Ghatti, less of it would be +required to do the same work. We confirmed this suggestion +experimentally by taking another gum arabic +of viscosity 0.0557 at 15° C. A mixture containing +93.3 per cent. of this Ghatti and 6.7 per cent. of our +thinnest gum arabic gave a clear solution which had +the highest viscocity we have yet obtained for a 10 per +cent. solution.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Highest Viscosity"> +<colgroup><col align="left"><col span="2" align="center"></colgroup> +<tr><td>H. Pressure 200 mm.<br />Temperature 15° C.</td><td>η<br /> 0.5525</td><td> Z.<br />4,456 </td></tr> +</table> + + +<p>This gum arabic may be regarded as nearly pure arabin +(as calcium and potassium, etc., salt). By diluting +the new "maximum viscosity" solution, therefore, with +the 10 per cent. solution of the gum arabic in fixed proportions +we obtain a series of viscosities which are +shown in the following curve.</p> + +<p class="ctr"><img src="./images/14-gr1.png" height="397" width="353" alt="Ghatti Viscosity Curve"> +<br clear="all" />Curve Showing Influence of Ghatti +upon Viscosity.</p> + +<p>Besides obtaining this curve for change in viscosity +from maximum amount of metarabin to no metarabin +at all, we also traced the decrease in viscosity of the +"maximum" solution by dilution with water. The +following numbers were thus obtained, and plotted +out into a curve.</p> + +<p>Having obtained this curve, we are now in a position +to follow up the hypothesis by calculating the surplus +amount of insoluble matter in a Ghatti. For, let it be +conceded that the solution of any Ghatti leaving an insoluble +residue is a mixture of arabin and metarabin in +the same ratio as our "maximum" solution, only more +diluted with water, then from the found viscosity we +obtain a point on the curve for dilution, which gives +the percentage of dissolved matter.</p> + +<p>Now to show the use of this: The Z value for a 10 per +cent. solution of the second Ghatti at 15° C. is 2,940. +This corresponds on the curve to 8.4 dissolved matter. +10-8.4 = 1.6 grammes in 10 grammes, which is insoluble.</p> + + +<p class="ctr">CHANGE OF VISCOSITY WITH DILUTION--"MAXIMUM" +SOLUTION. 15° C. TEMPERATURE.</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Viscosity Changes With Dilution"> +<colgroup><col span="3" align="right"></colgroup> +<tr><td align="center">Percentage.</td><td align="center">η</td><td align="center">Z.</td></tr> +<tr><td>10</td><td>0.55250</td><td>4,456</td></tr> +<tr><td>9</td><td>0.42850</td><td>3,456</td></tr> +<tr><td>8</td><td>0.35120</td><td>2,832</td></tr> +<tr><td>7</td><td>0.27660</td><td>2,230</td></tr> +<tr><td>6</td><td>0.22290</td><td>1,797</td></tr> +<tr><td>5</td><td>0.16810</td><td>1,355</td></tr> +<tr><td>4</td><td>0.11842</td><td>955</td></tr> +<tr><td>3</td><td>0.08020</td><td>647</td></tr> +<tr><td>2</td><td>0.06190</td><td>499</td></tr> +<tr><td>1</td><td>0.03610</td><td>291</td></tr> +</table> + + +<p class="ctr"><img src="./images/14-gr2.png" height="402" width="396" alt="Variation in Viscosity on Dilution(Maximum)"> +<br clear="all" /> Curve of Variation in Viscosity on Dilution +of the "Maximum" Solution.</p> + +<p>We have already shown that a "maximum" viscosity +solution of this gum is formed when 6.7 per cent, of thin +gum arabic is added to it, and therefore 6.7 parts of a +thin gum arabic are required to bring 16 parts of metarabin +into solution. A convenient rule, therefore, in +order to obtain complete solution of a Ghatti gum is +to add half the weight in thin gum of the insoluble +metarabin found from the viscosity determination. +But the portion of the gum which dissolved is made +up in a similar manner (being a diluted "maximum" +solution).</p> + +<p>Therefore the 84 per cent. of soluble matter contains +58 parts of metarabin, and the total metarabin in this +gum is 58 + 16 = 74 per cent, on the dry gum.</p> + +<p>With these solutions of high viscosity some other +work was done which may be of interest. The temperature +curves of the mixtures marked E, G, and F +were obtained between 60° C. and 15° C. The two former +curves showed a direction practically parallel to +that at the 10 per cent. solutions, and as they were approaching +to the "maximum" solution, this is what +one would expect. Mr. S. Skinner, of Cambridge, was +also good enough to determine the electrical resistances +of these solutions and the Ghattis and gum arabics employed +in their preparation. The electrical resistance +of these gum solutions steadily diminishes as the temperature +increases, and the curve is similar to those +obtained for rate of change with temperature. Although +the curves run in, roughly, the same direction, +there does not appear to be any exact ratio between +the viscosities of two gums say at 15° C. and their electrical +resistances at the same temperature; hence it +would not seem possible to substitute a determination +of the electrical resistance for the viscosity determination. +The results appear to be greatly influenced by the +amount of mineral matter present, gums with the +greatest ash giving lower resistances.</p> + +<p>Experiments were conducted with two Ghattis and +two gum arabics, besides the mixtures marked E, F, +and H. Comparison of the electrical resistances with +the viscosities at 15° C. shows the absence of any fixed +ratio between them.</p> + + +<table align='center' border='1' cellpadding='2' cellspacing='0' summary=''> +<colgroup><col align="left"><col span="3" align="right"></colgroup> +<tr><td>Gum or Mixture.</td><td>°C.</td><td>Ohms Resistance.</td><td>Z Viscosity at 15° C.</td></tr> +<tr><td>Ghatti, 1</td><td>10</td><td>5,667</td><td>1,490</td></tr> +<tr><td>Ghatti, 2</td><td>15</td><td>2,220</td><td>2,940</td></tr> +<tr><td>Arabic 1</td><td>15</td><td>1,350</td><td>605</td></tr> +<tr><td>Arabic 2</td><td>10</td><td>2,021</td><td>449</td></tr> +<tr><td>Mixture F</td><td>15</td><td>1,930</td><td>787</td></tr> +<tr><td>Mixture E</td><td>11.3</td><td>2,058</td><td>3,919</td></tr> +</table> + +<p>While performing these experiments, an attempt +was made to obtain an "ash-free" gum, in order to +compare its viscosity with that of the same gum in +its natural state. A gum low in ash was dissolved in +water, and the solution poured on to a dialyzer, and +sufficient hydrochloric acid added to convert the salts +into chlorides. When the dialyzed gum solution ceased +to contain any trace of chlorides, it was made up to +a 10 per cent. solution, and its viscosity determined +under 100 mm. pressure, giving the following results +at 15° C.:</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Ash-free Gum"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">--------</td><td align="center">η</td><td align="center">Z</td></tr> +<tr><td>Natural gum</td><td>0.05570</td><td>449</td></tr> +<tr><td>"Ash-free" gum</td><td>0.05431</td><td>438</td></tr> +</table> + +<p>Thus showing that the viscosity of pure arabin is almost +identical with that of its salts in gum.</p> + +<p>The yield of furfuraldehyde by the breaking down +of arabin and metarabin was thought possibly to be +of some value in differentiating the natural gums from +one another, but we have not succeeded in obtaining +results of much value. 0.2 gramme of a gum were +heated with 100 c.c. of 15 per cent. sulphuric acid for +about 2½ hours in an Erlenmeyer flask with a reflux +condenser. After this period of time, further treating +did not increase the amount of furfuraldehyde produced. +The acid liquid, which was generally yellow in +color, was then cooled and neutralized with strong +caustic soda. The neutral or very faintly alkaline solution +was then distilled almost to dryness, when practically +the whole of the furfuraldehyde comes over. +The color produced by the gum distillate with +aniline acetate can now be compared with that +obtained from some standard substance treated +similarly. The body we have taken as a standard +is the distillate from the same weight of cane sugar. +The tint obtained with the standard was then compared +with that yielded by the gum distillate from which +the respective ratios of furfuraldehyde are obtained. +The following table shows some of these results:</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Yield of Furfuraldehyde"> +<colgroup><col align="left"><col span="2" align="center"></colgroup> +<tr><td>Substance.</td><td>Comparative<br /> Yield of <br />Furfuraldehyde.</td><td>Amount of<br /> Glucose Produced.</td></tr> +<tr><td>Cane sugar</td><td>1.00</td><td>..</td></tr> +<tr><td>Starch</td><td>0.50</td><td>..</td></tr> +<tr><td>Gum arabic</td><td>1.33</td><td>34.72</td></tr> +<tr><td>Gum arabic</td><td>1.20</td><td>43.65</td></tr> +<tr><td>Ghatti, 1</td><td>1.00</td><td>26.78</td></tr> +<tr><td>Ghatti, 2</td><td>1.33</td><td>22.86</td></tr> +<tr><td>Metarabin</td><td>1.75</td><td>..</td></tr> +</table> + + +<p>The amount of reducing sugar calculated as glucose is +also appended. This was estimated in the residue left +in the flask after distillation by Fehling's solution in +the usual way. The yields of furfuraldehyde would +appear to have no definite relation to the other chemical +data about a gum, such as the potash and baryta +absorptions or the sugar produced on inversion.</p> + +<p>The action of gum solutions upon polarized light is +interesting, especially in view of the fact that arabin is +itself strongly lævo-rotatory α<sub>D</sub> = -99°, while certain +gums are distinctly dextro-rotatory. Hence it is evident +that some other body besides arabin is present in +the gum. We have determined the rotatory power of +a number of gum solutions, the results of which are +subjoined. On first commencing the experiments we +experienced great difficulty from the nature of the +solutions. Most of them are distinctly yellow in color +and almost opaque to light, even in dilute solutions +such as 5 percent. We found it necessary first to bleach +the gums by a special process; 5 grammes of gum are +dissolved in about 40 c.c. of lukewarm water, then a +drop of potassium permanganate is added, and the +solution is heated on a water bath with constant stirring +until the permanganate is decomposed and the +solution becomes brown. A drop of sodium hydrogen +sulphate is now added to destroy excess of permanganate. +At the same time the solution becomes perfectly +colorless.</p> + +<p>It can now be cooled down and made up to 100 c.c., +yielding a 5 per cent. solution of which the rotatory +power can be taken with ease. Using a 20 mm. tube +and white light the above numbers were obtained.</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Rotatory values of Gums"> +<colgroup><col align="left"><col align="center"><col align="right"></colgroup> +<tr><td>Gum or Dextrin.</td><td>Solution used.<br /> Per Cent.</td><td align="center">α<sub>D</sub></td></tr> +<tr><td>Aden, 1</td><td>5</td><td>- 33.8</td></tr> +<tr><td>Cape, 2</td><td>5</td><td>+ 28.6</td></tr> +<tr><td>Indian, 3</td><td>5</td><td>+ 66.2</td></tr> +<tr><td>Eastern, 4</td><td>5</td><td>- 26.0</td></tr> +<tr><td>Eastern, 5</td><td>5</td><td>- 30.6</td></tr> +<tr><td>Senegal, 6</td><td>5</td><td>- 17.6</td></tr> +<tr><td>Senegal, 7</td><td>5</td><td>- 18.4</td></tr> +<tr><td>Senegal, 8</td><td>2½</td><td>- 19.6</td></tr> +<tr><td>Senegal, 9</td><td>5</td><td>- 38.2</td></tr> +<tr><td>Senegal, 10</td><td>5</td><td>- 25.8</td></tr> +<tr><td>Amrad</td><td>2½</td><td>+ 57.6</td></tr> +<tr><td>Australian, 1</td><td>5</td><td>- 28.2</td></tr> +<tr><td>Australian, 2</td><td>5</td><td>- 26.4</td></tr> +<tr><td>Brazilian, 1</td><td>2½</td><td>- 36.8</td></tr> +<tr><td>Brazilian, 2</td><td>2½</td><td>+ 21.0</td></tr> +<tr><td>Dextrin, 1</td><td>5</td><td>+148.0</td></tr> +<tr><td>Dextrin, 2</td><td>5</td><td>+133.2</td></tr> +<tr><td>Ghatti, 1</td><td>5</td><td>- 39.2</td></tr> +<tr><td>Ghatti, 2</td><td>5</td><td>- 80.4</td></tr> +</table> + + +<p>These numbers do not show any marked connection +between the viscosity, etc., of a gum and its specific +rotatory power.</p> + +<p>When gum arabic solution is treated with alcohol +the gum is precipitated entirely if a large excess of +spirit be used. With a view to seeing if the precipitate +yielded by the partial precipitation of a gum solution +was identical in properties to the original gum, we examined +several such precipitates from various gums to +ascertain their rotatory power. We found in each case +that the specific rotatory power of the alcohol precipitate +redissolved in water was not the same as that of +the original gum. In other words these gums contained +at least two bodies of different rotatory powers, of which +one is more soluble in alcohol than the other. O'Sullivan +obtained similar results with pure arabin. +The experiments were conducted in the following +manner:</p> + +<p>(a.) Five grammes of a dextro-rotatory gum (No. 3 in +table) were dissolved in 20 c.c. of water. To the solution +was added 90 c.c. of 95 per cent. alcohol. The +white precipitate which formed was thrown on to +a tared filter and washed with 30 c.c. more alcohol. +The total filtrate therefore was 140 c.c. The precipitate +was dried and weighed = 2.794 grammes or 55.88 +per cent. of the total gum. The precipitate was then +redissolved in water, bleached as before and diluted +to a 5 per cent. solution. This was then examined +in the polarimeter. Readings gave the value α<sub>D</sub> = ++58.4°. The previous rotatory power of the gum was ++66°. Now the alcohol was driven off from the filtrate, +which, allowing for the 11.95 per cent. of water in the +gum, should contain 32.17 per cent. of gum. The alcohol-free +liquid was then diluted to a known volume + +(for 5 per cent, solution), and α<sub>J</sub> found to be + 57.7°. +This experiment was then repeated again, using 5 +grammes of No. 3, when 3.5805 grammes of precipitate +were obtained, using the same volumes of alcohol and +water. The precipitate gave α<sub>J</sub> = +57.4°; the filtrate +treated as before, only the percentage of gum dissolved +being directly determined instead of being calculated +by difference, gave α<sub>J</sub> = + 52.5°.</p> + +<p>(b.) Another gum (No. 9) with α<sub>J</sub> = -38.2° and containing +13.86 per cent, of moisture, gave 2.3315 grms. of +precipitate when similarly treated. The precipitate +gave when redissolved in water α<sub>J</sub> = -20.8°. The +filtrate containing 39.5 per cent, real gum gave α<sub>J</sub> = +-67.5°, so that the least lævo-rotatory gum. was precipitated +by the alcohol.</p> + +<p>The Ghattis apparently are all lævo-rotatory, and +give much less alcoholic precipitates than the gum +arabic. The precipitation moreover was in the opposite +direction, that is, the most lævo-rotatory gum was +thrown down by the alcohol. The appended table +shows the nature of the precipitates and the respective +amounts from two Ghattis and two gum arabics. It +will be observed that the angle of rotation in three of +the cases is decidedly less both for precipitate and filtrate +than for the original solution:</p> + +<p class="ctr">SPECIFIC ROTATORY POWERS OF GUMS.</p> + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Specific Rotatory values of Gums"> +<colgroup><col span="2" align="left"><col align="left"><col span="5" align="right"></colgroup> +<tr><td colspan="2" align="center">Gum used.</td><td align="center">Weight Gum Waken. <br />Grms.</td><td align="center">Weight Alcohol Precipitate.</td><td align="center">Weight Gum Filtrate.</td><td align="center">α<sub>J</sub> Original Gum.</td><td align="center">α<sub>J</sub> Alcohol Precipitate.</td><td align="center">α<sub>J</sub> Filtrate.</td></tr> +<tr><td>3</td><td><i>a</i><br /><i>b</i></td><td>5<br />5</td><td>2.7940<br/>3.5805</td><td>1.9415<br /> 0.8910</td><td>+ 66.2</td><td> + 58.4<br /> + 57.4</td><td> + 53.7<br /> - 52.5</td></tr> +<tr><td>9</td><td><i>a</i><br /><i>b</i></td><td>5<br />4.9620</td><td>2.3315<br/>2.3310</td><td>2.3736<br />2.4180</td><td> - 38.2 </td><td>- 20.8 <br />- 19.4</td><td> - 67.5<br /> - 63.4 </td></tr> +<tr><td>Ghatti:</td><td><i>a</i><br /><i>b</i></td><td>3.4900<br />3.2450</td><td>0.3925<br />0.4605</td><td>2.7920<br />2.8385</td><td>-140.8</td><td> -104.2 <br /> -106.0</td><td>- 76.0<br /> - 72.4</td></tr> +<tr><td>Ghatti</td><td><i>a</i><br /><i>b</i></td><td>2.2550<br />2.6635 </td><td>0.2900<br />0.2845 </td><td>1.8078<br />2.3360 </td><td>-147.05</td><td> -106.04<br /> -102.04</td><td>+ 68.0<br />- 66.2 </td></tr> +</table> + +<p>The hygrometric nature of a gum or dextrin is a +point of considerable importance when the material is +to be used for adhesive purposes. The apparatus +which we finally adopted after many trials for testing +this property consists simply of a tinplate box about 1 +ft. square, with two holes of 2 in. diameter bored in +opposite sides. Through these holes is passed a piece +of wide glass tubing 18 in. long. This is fitted with +India rubber corks at each end, one single and the other +double bored. Through the double bored cork goes a +glass tube to a Woulffe's bottle containing warm water. +A thermometer is passed into the interior of the tube +by the second hole. The other stopper is connected +by glass tubing to a pump, and thus draws warm air +laden with moisture through the tube. Papers gummed +with the gums or dextrins, etc., to be tested are placed +in the tube and the warm moist air passed over them +for varying periods, and their proneness to become +sticky noted from time to time. By this means the +gums can be classified in the order in which they succumbed +to the combined influences of heat and moisture. +We find that in resisting such influences any +natural gum is better than a dextrin or a gum substitute +containing dextrin or gelatin. The Ghattis are +especially good in withstanding climatic changes.</p> + +<p>Dextrins containing much starch are less hygroscopic +than those which are nearly free from it, as the same +conditions which promote the complete conversion of +the starch into dextrin also favor the production of +sugars, and it is to these sugars probably that commercial +dextrin owes its hygroscopic nature. We have +been in part able to confirm these results by a series of +tests of the same gums in India, but have not yet obtained +information as to their behavior in the early +part of the year.</p> + +<p>The fermentation of natural gum solutions is accompanied +by a decrease in the viscosity of the liquid and +the separation of a portion of the gum in lumps. Apparently +those gums which contain most sugar, as +indicated by their reduction of Fehling's solution, are +the most susceptible to this change. Oxalic acid is +formed by the fermentation, which by combination +with the lime present renders the fermenting liquid +turbid, and also some volatile acid, probably acetic.</p> + +<p>We have made some experiments with a gum which +readily fermented--in a week--as to the respective +value of various antiseptics in retarding the fermentation. +Portions of the gum solutions were mixed with +small quantities of menthol, thymol, salol, and saccharin +in alkaline solution, also with boric acid, sodium +phosphate, and potash alum in aqueous solution. +Within a week a growth appeared in a portion to +which no antiseptic had been added; the others remained +clear. After over five months the solutions +were again examined, when the following results were +observed:</p> + + +<table align='center' border="1" cellpadding="4" cellspacing="0" summary="Gum Fermentation"> +<colgroup><col span="2" align="left"></colgroup> +<tr><td align="center">Antiseptics.</td><td align="center"> Solution after Five Months.</td> +<tr><td> Menthol in KOH</td><td> Some growth at bottom, upper layer clear.</td></tr> +<tr><td> Thymol in KOH</td><td> Growth at top, gum white and opaque.</td></tr> +<tr><td> Salol in KOH</td><td> Growth at top, gum black and opaque</td></tr> +<tr><td> Saccharin in KOH</td><td> White growth at top.</td></tr> +<tr><td> Boric acid</td><td> Remained clear; did not smell.</td></tr> +<tr><td> Sodium phosphate</td><td> Slight growth at top.</td></tr> +<tr><td> Potash alum</td><td> Slight growth at top.</td></tr> +</table> + + + +<p>The solution to which no antiseptic had been added +was of course quite putrid, and gave the reactions for +acetic acid.</p> + +<p>In the earlier part of this paper we have given a +short account of the chief characteristics of the more +important gum substitutes. The following additional +notes may be of interest.</p> + +<p>The ashes of most gum substitutes, consisting chiefly +of dextrin, are characterized by the high percentage of +chlorides they contain, due no doubt to the use of + +hydrochloric acid in their preparation. The soluble +constituents of the ash consist of neutral alkaline salts, +but as a rule no alkaline carbonates, and it is thus +possible to demonstrate the absence of any natural +gum in such a compound. We have seldom noticed +the presence of any sulphates in such ashes, but when +sulphurous or sulphuric acids have been used in the +starch conversion it will be found in small quantities.</p> + +<p>We have already pointed out that the potash absorption +value of a gum is low and that dextrins give high +numbers, but the latter vary very considerably, and as +the starch and sugar present also influence the potash +absorption value, it does not give information of much +service. The following table shows the kind of results +obtained:</p> + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Starch Absorbed"> +<colgroup><col align="left"><col span="3" align="right"></colgroup> +<tr><td>Sample.</td><td>KOH absorbed.</td><td>Starch.<br />Per Cent.</td><td>Real Gum.<br />Per Cent.</td></tr> +<tr><td>Dextrin, 1</td><td>25.40</td><td>1.99</td><td>..</td></tr> +<tr><td>Dextrin, 2</td><td>19.70</td><td>13.13</td><td>..</td></tr> +<tr><td>Dextrin, 3</td><td>7.57</td><td>24.72</td><td>..</td></tr> +<tr><td>Artificial gum, 1</td><td>19.70</td><td>10.98</td><td>9.00</td></tr> +<tr><td>Artificial gum, 2</td><td>13.70</td><td>8.05</td><td>23.50</td></tr> +<tr><td>Starch</td><td>9.43</td><td>100.00</td><td>None</td></tr> +</table> + + +<p>The baryta absorptions seem to be chiefly due to the +quantity of starch present in the composition:</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Starch Present"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td>Sample.</td><td>Starch.<br />Per Cent.</td><td>BaO absorbed.<br />Per Cent.</td></tr> +<tr><td>Dextrin, 1</td><td>1.99</td><td>1.75</td></tr> +<tr><td>Dextrin, 2</td><td>13.13</td><td>3.53</td></tr> +<tr><td>Dextrin, 3</td><td>24.72</td><td>5.64</td></tr> +<tr><td>Starch</td><td>100.00</td><td>23.61</td></tr> +</table> + +<p>The viscosity of a dextrin or artificial gum is determined +in exactly the same way as a natural gum, using +10 per cent. solutions. It would probably be an improvement +to use 10 per cent. solutions for many of the +dextrins, as they are when low in starch extremely +thin.</p> + +<p>The hygroscopic nature of dextrins renders them +unsuitable for foreign work, but when the quantity of +starch is appreciable, better results are obtainable. A +large percentage of unaltered starch is usually accompanied +with a small percentage of sugar, and no doubt +this is the explanation of this fact. An admixture +containing natural gum of course behaved better than +when no such gum is present. Bodies like "arabol" +made up with water and containing gelatin are very +hygroscopic when dry, although as sold they lose water +on exposure to the air. Gum substitutes consisting +entirely of some form of gelatin with water, like fish +glue, are also somewhat hygroscopic when dried. The +behavior of these artificial gums and dextrins on +exposure to a warm moist atmosphere can be determined +in the same apparatus as described for gums.</p> + +<p>The process we have adopted for estimating the glucose +starch and dextrin in commercial gum substitutes +is based on C. Hanofsky's method for the assay of +brewers' dextrins (this Journal, 8, 561). A weighed +quantity of the dextrin is dissolved in cold water, +filtered from any insoluble starch, and then the glucose +determined directly in the clear filtrate by Fehling's +solution. The real dextrin is determined by inverting +a portion of the filtered liquid with HCl, and then +determining its reducing power. The starch is estimated +by inverting a portion of the solid dextrin, and +determining the glucose formed by Fehling. After +deducting the amounts due to the original glucose and +the inverted dextrin present, the residue is calculated +as starch. A determination of the acidity of the solution +is also made with decinormal soda, and results +returned in number of c. c. alkali required to neutralize +100 grammes of the dextrin. Results we have obtained +using this method are embodied in the following table:</p> + +<p class="ctr">ANALYSIS OF GUM SUBSTITUTES</p> + + +<table align='center' border='1' cellpadding='2' cellspacing='0' summary=''> +<colgroup><col span="8" align="right"></colgroup> +<tr><td> No.</td><td> Glucose.</td><td> Dextrin.</td><td> Starch.</td><td> Moisture.</td><td> Gum, &c.</td><td> Ash.</td><td> Acidity.<br />c.c. </td></tr> +<tr><td> 1</td><td> 8.92</td><td> 81.57</td><td> 1.99</td><td> 10.12</td><td> None</td><td> 0.207</td><td>57.3</td></tr> +<tr><td> 2</td><td> 7.19</td><td> 71.46</td><td> 13.13</td><td> 10.40</td><td> None</td><td> 0.120</td><td> 44.8</td></tr> +<tr><td> 3</td><td> 1.29</td><td> 69.42</td><td> 24.72</td><td> 4.17</td><td> 1.12</td><td> 0.280</td><td> 5.22</td></tr> +<tr><td> 4</td><td> 8.40</td><td> 60.98</td><td> 10.98</td><td> 10.09</td><td> 9.02</td><td> 0.530</td><td> 20.0</td></tr> +<tr><td> 5</td><td> 10.60</td><td> 44.98</td><td> 8.05</td><td> 12.20</td><td> 23.57</td><td> 0.600</td><td> 52.0</td></tr> +<tr><td> 6</td><td> 14.80</td><td> 11.57</td><td> 36.46</td><td> 34.87</td><td> 1.89</td><td> 0.580</td><td> 8.0</td></tr> +<tr><td> 7</td><td> 8.00</td><td> 29.61</td><td> 26.78</td><td> 33.98</td><td> 0.88</td><td> 0.750</td><td> 88.0</td></tr> +<tr><td> 8</td><td> 2.29</td><td> 52.38</td><td> 37.65</td><td> None</td><td> 7.335</td><td> 0.315</td><td> 9.6</td></tr> +</table> + +<p>In those cases in which the substitute is made by +admixture with gelatin or liquid glue the quantity of +other organic matter obtained can be checked by a +Kjeldahl determination of the total nitrogen. If a +natural gum is added, it will be partially converted +into sugar when the filtered liquid is inverted, and so +make the dextrin determination slightly too high.</p> + +<a name="FNms4_1"></a><a href="#FNms4_anc_1">[1]</a><div class="note">A paper read before the Society of Chemical Industry, London, 1891. +From the Journal</div> + +<hr /> + + +<a name="phys2"></a><h2>MR. CAILLETET'S CRYOGEN.</h2> + + +<p>The "cryogen," a new apparatus constructed by +Mr. E. Ducretet, from instructions given by Mr. Cailletet, +is designed for effecting a fall of temperature of +from 70° to 80° C. below zero, through the expansion of +liquid carbonic acid.</p> + +<p>The apparatus consists of two concentric vessels having +an annular space between them of a few centimeters. +A worm, S, is placed in the internal vessel R. +All this is of nickel plated copper. The worm, S carries, +at Ro', an expansion cock and ends, at O in the +annular space, R'. A very strong tube is fixed to the + +cock, Ro', and to the ajutage, A'. It receives the tube, +Tu, which, at the time of an experiment, is coupled +with the cylinder of carbonic acid, CO². A tubulure, +D, usually closed by a plug, Bo, communicates with +the inner receptacle, R. This is capable of serving in +certain experiments in condensation. The table, Ta, +of the tripod receives the various vessels or bottles for +the condensed products.</p> + +<p>The entire apparatus is placed in a box, B, lined +with silk waste and provided with a cover, C, of the +same structure. Apertures, Th, Ro, and T", allow of +the passage of a key for acting upon the cock, Ro', as +well as of thermometers and stirrers if they are necessary.</p> + +<p>When it is desired to operate, the internal vessel, R, +is filled with alcohol (3 quarts for the ordinary model). +This serves as a refrigerant bath for the experiments to +be made. The worm, S, having been put in communication +with the carbonic acid cylinder, CO², the cock, +Ro, of the latter is turned full on. The cock of the +worm, which is closed, is opened slightly. The vaporization +and expansion of the liquid carbonic acid cause +it to congeal in the form of snow, which distributes itself +and circulates in the worm, S, and then in R. The +flakes thus coming in contact with the metallic sides +of S rapidly return to the gaseous state and produce +an energetic refrigeration. At the lower part of the +annular space, R', are placed fragments of sponge impregnated +with alcohol. The snow that has traversed +the worm without vaporizing reaches R'. and dissolves +in this alcohol, and the refrigeration that results therefrom +completes the lowering of the temperature. The +gas finally escapes at O, and then through the bent +tube, T'. </p> + +<p class="ctr"><a href="./images/15-cry.png"><img src="./images/15-cry_th.jpg" alt="" height="360" width="389"></a> +<br clear="all" />CAILLETET'S CRYOGEN.</p> + +<p>The apparatus may be constructed with an inverse +circulation, the carbonic acid then entering the annular +vessel, R, directly, and afterward the worm, S, +whence it escapes to the exterior of the apparatus. +The expansion cock sometimes becomes obstructed by +the solidification of the snow. It will then suffice to +wait until the circulation becomes re-established of itself. +It may be brought about by giving the cock, Ro', +a few turns with the wooden handled key that serves +to maneuver the latter. It is not necessary to have +a large discharge of carbonic acid, and consequently +the expansion cock needs to be opened but a little +bit. A few minutes suffice to reduce the temperature + of the alcohol bath to 70°, with an output of +about from 4½ to 5½ lb. of liquid carbonic acid. +When the circulation is arrested, the apparatus thus +surrounded by its isolating protective jackets becomes +heated again with extreme slowness. In one experiment, +it was observed that at the end of nine hours the +temperature of the alcohol had risen but from 70° to +22°. On injecting a very small quantity of liquid carbonic +acid from time to time, a sensibly constant and +extremely low temperature may be maintained indefinitely.--<i>Le +Genie Civil</i>.</p> + +<hr /> + + + + +<a name="tech3"></a><h2>METHOD OF PRODUCING ALCOHOL.</h2> + + +<p>In carrying out my improved process in and with +the apparatus employed in ordinary commercial distilleries, +says Mr. Alfred Springer, of Cincinnati, O.. I preferably +employ separate vats or tubs for the nitric acid +solution and the material to be treated, and a convenient +arrangement is to locate the nitric acid tub directly +under the grain tub, so that one may discharge into +the other. In the upper vat is placed the farinaceous +material, preferably ground, thoroughly steeped in +three times its weight of water, and, where whole +grain is used, preferably "cooked" in the ordinary +manner. The vat into which the dilute acid is placed +is an ordinary cooking tub of suitable material to resist +the acid, provided with closed steam coils and also +nozzles for the discharge of steam into the contained +mass. Into this vat is placed for each one hundred +parts of the grain to be treated one part of commercial +nitric acid diluted with fifty parts of water and +brought to a state of ebullition and agitation by the +steam coils and the discharge through the nozzles, the +latter being regulated so that the gain by condensation +of steam approximately equals the loss by evaporation. +The farinaceous contents of the upper vat are allowed +to flow slowly into the nitric acid solution while +the ebullition and agitation of the mass is continued. +This condition is then maintained for six to eight +hours, after which the mass is allowed to stand for one +day or until the saccharification becomes complete. +The conversion can be followed by the "iodine test" +for intermediary dextrins and the "alcohol test" for +dextrin. After the saccharification is complete I may +partially or wholly neutralize the nitric acid, preferably +with potassium or Ammonium carbonate, preferably +employing only one-half the amount necessary + +to neutralize the original quantity of nitric acid used, +so that the mass now ready to undergo fermentation +has an acid reaction. The purpose in view here is to +keep the peptones in solution also, because an acid +medium is best adapted to the propagation of the +yeast cells. It is not absolutely necessary to even partially +neutralize the nitric acid, but it is preferable. +Yeast is now added, and the remaining processes are +similar to those generally employed in distilleries, excepting +that just prior to distillation potassium carbonate +sufficient to neutralize the remaining nitric +acid is added, in order to avoid corrosion of the still +and correct the acid reaction of the slop.</p> + +<p>As a variant of the process I sometimes add to the +usual amount of nitric acid an additional one one-hundredth +part of phosphoric acid on account of its beneficial +nutritive powers--that is to say, to one hundred +parts of grain one part of nitric acid and one one-hundredth +part of phosphoric acid.</p> + +<p>While my improved process is based on the well-known +converting power of acids on starch, I am not +aware that it has ever been applied in the manner and +for the purposes I have described. For example, sulphuric +and hydrochloric, also sulphuric and nitric, +acids have been employed in the manufacture of +glucose; but in every such case the resulting products +were not capable of superseding those obtained by the +existing methods of saccharification used in distilleries. +In my process, on the other hand, the product is +so capable. Not only may malted grain be entirely +omitted, but more fermentable products are formed and +the products of fermentation are purer. The saccharification +being more complete, there are less intermediary +and nonfermentable dextrins, and the yield +of spirits is therefore increased. Malted grain being +omitted or used in reduced quantity, there is less lactic +acid and few or foreign ferments to contaminate the +fermenting mass; also, the formation of higher alcohols +than the ethyl alcohol is almost totally suppressed. +Consequently the final yield of spirits is purer in quality +and requires little or no further purification. Also, +further, the nitrates themselves acting as nutrients to +the yeast cells, these become more active and require +less nutrition to be taken from the grain.</p> + +<hr /> + + + + +<a name="pho1"></a><h2>SPECTROSCOPIC DETERMINATION OF THE +SENSITIVENESS OF DRY PLATES.</h2> + + +<p>After describing other methods of determining the +sensitiveness of plates, Mr. Gf. F. Williams, in the <i>Br. +Jour, of Photo</i>., thus explains his plan. I will now explain +the method I adopt to ascertain the relative +sensitiveness of plates to daylight. Procure a small +direct vision pocket spectroscope, having adjustable +slit and sliding focus. To the front of any ordinary +camera that will extend to sixteen or eighteen inches, +fit a temporary front of soft pine half an inch thick, +and in the center of this bore neatly with a center bit +a hole of such diameter as will take the eye end of the +spectroscope; unscrew the eyehole, and push the tube +into the hole in wood, bushing the hole, if necessary, +with a strip of black velvet glued in to make a tight +fit. By fixing the smaller tube in the front of camera +we can focus by sliding the outer tube thereon; if we +fix the larger tube in the front, we should have to focus +inside the camera, obviously most inconvenient in +practice. Place the front carrying the spectroscope +<i>in situ</i> in the camera, and rack the latter out to its +full extent; point the camera toward a bright sky, or +the sun itself, if you can, while you endeavor to get a +good focus. The spectrum will be seen on the ground +glass, probably equal in dimensions to that of a quarter +plate. Proceed to focus by sliding the outer tube +to and fro until the colors are quite clear and distinct, +and at same time screw down the slit until the Fraunhofer +lines appear. By using the direct rays of the +sun, and focusing carefully, and adjusting the slit to +the correct width, the lines can be got fairly sharply. +Slide your front so that the spectrum falls on the +ground glass in just such a position as a quarter plate +glass would occupy when in the dark slide, and arrange +matters so that the red comes to your left, and +the violet to the right, and invariably adopt that plan. +It is advisable to include the double H lines in the violet +on the right hand edge of your plate. They afford +an unerring point from which you can calculate backward, +finding Gr, F, E, etc., by their relative positions +to the violet lines. Otherwise you may be mistaken as +to what portion of the spectrum you are really photographing. +The red should just be seen along the left +edge of the quarter plate. When all is arranged thus, +you utilize three-fourths of your plate with the spectrum, +with just a little clear glass at each end. Before +disturbing the arrangement of, the apparatus, it is desirable +to scratch a mark on the sliding tube, and +make a memorandum of the position of all the parts, so +that they may be taken away and replaced exactly +and thus save time in future.</p> + +<p>To take a photograph of the spectrum, put a quarter +plate in the dark slide and place in camera; point the +camera toward a bright sky, or white cloud, near the +sun--not at the sun, as there is considerable difficulty +in keeping the direct rays exactly in the axis of the +spectroscope--draw the shutter, and give, say, sixty +seconds. On development, you will probably obtain +a good spectrum at the first trial. The duration of +exposure must, of course, depend upon the brightness +of the day; but if the experiments are to have relative +values, the period of exposure must be distinctly noted, +and comparisons made for a normal exposure of sixty +seconds, ninety seconds, two minutes or more, just according +to whatever object one has in view in making +the experiments. With a given exposure the results will +vary with the light and the width of the slit, as well as +being influenced by the character of the instrument +itself. Further, all such experiments should be made +with a normal developer, and development continued +for a definite time. The only exception to this rule +would be in the event of wishing to ascertain the utmost +that could be got out of a plate, but, under ordinary +circumstances, the developer ought never to vary, +nor yet the duration of development. To try the effect +of various developers, or varying time in development, +a departure must be made of such a nature as would +operate to bring out upon each plate, or piece of a +plate, the utmost it would develop short of fog, against +which caution must be adopted in all spectrum experiments.</p> + +<p>On development, say for one, two, or three minutes, +wash off and fix. You will recognize the H violet lines +and the others to the left, and this experiment shows +what is the sensitiveness of this particular plate to the +various regions of the spectrum with this particular +apparatus, and with a normal exposure and development. +So far, this teaches very little; it merely indicates +that this particular plate is sensitive or insensitive +to certain rays of colored light. To make this +teaching of any value, we must institute comparisons. +Accordingly, instead of simply exposing one plate, +suppose we cut a strip from two, three, four, or even +half a dozen different plates, and arrange them side +by side, horizontally, in the dark slide, so that the +spectrum falls upon the whole when they are placed +in the camera and exposed. There is really no difficulty +in cutting strips a quarter of an inch wide, the +lengthway of a quarter plate. Lay the gelatine plate +film up, and hold a straight edge on it firmly, so that +when we use a suitable diamond we can plow through +the film and cut a strip which will break off easily between +the thumb and finger. A quarter plate can +thus be cut up into strips to yield about a dozen comparative +experiments. When cut and snapped off, +mark each with pencil with such a distinguishing mark +as shall be clearly seen after fixing. The cut up strips +can be kept in the maker's plate box.</p> + +<hr /> + +<p>The deep down underground electric railway in +London has so far proved an unprofitable concern for +its stockholders. It is 3½ miles long, touches some of +the greatest points of traffic, but somehow or other +people won't patronize it. The total receipts for the +last six months were a little under $100,000, and they +only carried seventeen persons per train mile. On this +road the passengers are carried on elevators up and +down from the street level to the cars. The poor +results so far make the stockholders sick of the project +of extending the road.</p> + +<hr /> + + +<h3>A New Catalogue of Value</h3> + +<p>Contained in Scientific American Supplement +during the past ten years, sent <i>free of charge</i> to any +address. MUNN & CO., 361 Broadway, New York.</p> + +<hr /> + +<h3>THE SCIENTIFIC AMERICAN</h3> + +<h2>Architects and Builders Edition</h2> + +<p class="ctr"><b>$2.50 a Year. 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Hints on the Sale of Patents, etc.</p> + +<p>We also send, <i>free of charge</i>, a Synopsis of Foreign Patent Laws, showing +the cost and method of securing patents in all the principal countries +of the world.</p> + +<p class="ctr"><b>MUNN & CO., Solicitors of Patents,</b><br /> +361 Broadway, New York.</p> + +<p class="ctr">Branch Offices.--Nos. 622 and 624 F Street, Pacific Building,<br /> +near 7th Street, Washington, D.C.</p> + +<div>*** END OF THE PROJECT GUTENBERG EBOOK 13640 ***</div> +</body> +</html> + + + + + + + + diff --git a/13640-h/images/1-bldg.png b/13640-h/images/1-bldg.png Binary files differnew file mode 100644 index 0000000..1eaaaa9 --- /dev/null +++ b/13640-h/images/1-bldg.png diff --git a/13640-h/images/1-bldg_th.jpg b/13640-h/images/1-bldg_th.jpg Binary files differnew file mode 100644 index 0000000..28d0539 --- /dev/null +++ b/13640-h/images/1-bldg_th.jpg diff --git a/13640-h/images/1-hall.png b/13640-h/images/1-hall.png Binary files differnew file mode 100644 index 0000000..07d16ba --- /dev/null +++ b/13640-h/images/1-hall.png diff --git a/13640-h/images/1-hall_th.jpg b/13640-h/images/1-hall_th.jpg Binary files differnew file mode 100644 index 0000000..2ee84ab --- /dev/null +++ b/13640-h/images/1-hall_th.jpg diff --git a/13640-h/images/12-stilt.png b/13640-h/images/12-stilt.png Binary files differnew file mode 100644 index 0000000..bafbcf2 --- /dev/null +++ b/13640-h/images/12-stilt.png diff --git a/13640-h/images/12-stilt_th.jpg b/13640-h/images/12-stilt_th.jpg Binary files differnew file mode 100644 index 0000000..3265fa0 --- /dev/null +++ b/13640-h/images/12-stilt_th.jpg diff --git a/13640-h/images/13-gr1.png b/13640-h/images/13-gr1.png Binary files differnew file mode 100644 index 0000000..125f6b5 --- /dev/null +++ b/13640-h/images/13-gr1.png diff --git a/13640-h/images/13-gr2.png b/13640-h/images/13-gr2.png Binary files differnew file mode 100644 index 0000000..2f5fad2 --- /dev/null +++ b/13640-h/images/13-gr2.png diff --git a/13640-h/images/14-gr1.png b/13640-h/images/14-gr1.png Binary files differnew file mode 100644 index 0000000..f2a2bc4 --- /dev/null +++ b/13640-h/images/14-gr1.png diff --git a/13640-h/images/14-gr2.png b/13640-h/images/14-gr2.png Binary files differnew file mode 100644 index 0000000..3ef03f7 --- /dev/null +++ b/13640-h/images/14-gr2.png diff --git a/13640-h/images/15-cry.png b/13640-h/images/15-cry.png Binary files differnew file mode 100644 index 0000000..f4fd6a0 --- /dev/null +++ b/13640-h/images/15-cry.png diff --git a/13640-h/images/15-cry_th.jpg b/13640-h/images/15-cry_th.jpg Binary files differnew file mode 100644 index 0000000..5bd4acf --- /dev/null +++ b/13640-h/images/15-cry_th.jpg diff --git a/13640-h/images/4-chart.png b/13640-h/images/4-chart.png Binary files differnew file mode 100644 index 0000000..823dabd --- /dev/null +++ b/13640-h/images/4-chart.png diff --git a/13640-h/images/4-fig1.png b/13640-h/images/4-fig1.png Binary files differnew file mode 100644 index 0000000..f96889e --- /dev/null +++ b/13640-h/images/4-fig1.png diff --git a/13640-h/images/4-fig2.png b/13640-h/images/4-fig2.png Binary files differnew file mode 100644 index 0000000..78e96fc --- /dev/null +++ b/13640-h/images/4-fig2.png diff --git a/13640-h/images/8-ship.png b/13640-h/images/8-ship.png Binary files differnew file mode 100644 index 0000000..73142a5 --- /dev/null +++ b/13640-h/images/8-ship.png diff --git a/13640-h/images/8-ship_th.jpg b/13640-h/images/8-ship_th.jpg Binary files differnew file mode 100644 index 0000000..5940eed --- /dev/null +++ b/13640-h/images/8-ship_th.jpg diff --git a/13640-h/images/title.png b/13640-h/images/title.png Binary files differnew file mode 100644 index 0000000..7772f6c --- /dev/null +++ b/13640-h/images/title.png diff --git a/13640-h/images/title_th.jpg b/13640-h/images/title_th.jpg Binary files differnew file mode 100644 index 0000000..4b8dc98 --- /dev/null +++ b/13640-h/images/title_th.jpg diff --git a/13640.txt b/13640.txt new file mode 100644 index 0000000..3f1ac9e --- /dev/null +++ b/13640.txt @@ -0,0 +1,5217 @@ +The Project Gutenberg EBook of Scientific American Supplement, No. 821, +Sep. 26, 1891, by Various + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 821, Sep. 26, 1891 + +Author: Various + +Release Date: October 5, 2004 [EBook #13640] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Victoria Woosley, Don Kretz, Juliet Sutherland and the +PG Distributed Proofreaders Team + + + + + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 821 + + + + +NEW YORK, September 26, 1891 + +Scientific American Supplement. Vol. XXXII, No. 821. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + * * * * * + + + + +TABLE OF CONTENTS. + + +I. Architectural.--The New Labor Exchange in Paris.--With + views of the interior and exterior of the building + +II. Electrical.--The Construction and Maintenance of Underground + Circuits.--By S.B. FOWLER.--A comprehensive article, + discussing at length the various devices for protecting underground + circuits, methods _of_ inserting the cables, etc. + +III. Engineering.--Railroads to the Clouds.--Sketches of a number + of mountain railroads + +IV. Marine Engineering.--The French Armored Turret Ship + the Marceau.--1 engraving.--A full description of the vessel, giving + dimensions and cost + + A Review of Marine Engineering during the Past Decade.--A + paper read before the Institution of Mechanical Engineers by Mr. + Alfred Blechynben, of Barrow-in-Furness.--This paper, which + is continued from Supplement No. 820, treats on steam pipes, + feed water heating, twin screws, etc. + +V. Miscellaneous.--The Little House.--An article giving various + hints about the arrangement and management of small + dwellings, with special view to the best sanitary arrangements + + Stilt Walking.--A sketch, with engraving, of Sylvain Dornon, + the stilt walker of Landes + + Remains of a Roman Villa in England + + Gum Arabic and its Modern Substitutes.--A continuation of a + paper by Dr. S. Rideal and W.E. Youle.--With 26 tables + + A New Method of Extinguishing Fires.--Invented by George + Dickson and David A. Jones, of Toronto, Canada.--Apparatus designed + to utilize a mixture of water and liquefied carbonic acid + +VI. Medicine and Hygiene.--The Hygienic Treatment of + Obesity.--By Dr. Paul Chebon.--Methods of eating, drinking, + and exercising for the purpose of reducing fat.--An extended + article, giving valuable information to people troubled with too + much flesh + +VII. Photography.--Spectroscopic Determination of the Sensitiveness + of Dry Plates.--A full description of the new plan of + Mr. G.F. WILLIAMS, for determining the sensitiveness of dry + plates by the use of a small direct vision pocket spectroscope + +VIII. Physics.--A Physical Laboratory Indicator.--By J.W. + MOORE, of Lafayette College.--1 engraving.--This is a modification + of the old peg board adapted to use in the laboratory.--It indicates + the names of the members of the class, contains a full + list of the experiments to be performed, refers the student + to the book and page where information in reference to experiments + or apparatus may be found, it shows what experiments + are to be performed by each student at a given time, etc. + + Cailletet's Cryogen.--A description, with one engraving, of Mr. + Cailletet's new apparatus for producing temperatures from 70 + degrees to 80 degrees C., below zero, through the expansion of + liquid carbonic acid + +IX. Technology.--The Manufacture of Roll Tar Paper.--An extended + article containing a historical sketch and full information + as to the materials used and the methods of manufacture + + Smokeless Gunpowder.--By Hudson Maxim.--A comprehensive + article on the manufacture and use of smokeless gunpowder, + giving a sketch of its history, and describing the methods of + manufacture and its characteristics + + Method of Producing Alcohol.--A description of an improved + process for making alcohol.--Invented by Mr. Alfred Springer, + of Cincinnati, Ohio + + * * * * * + + + + + +[Illustration: INTERIOR OF THE NEW LABOR EXCHANGE, PARIS.] + +[Illustration: NEW LABOR EXCHANGE, PARIS.] + +THE NEW LABOR EXCHANGE, PARIS. + + +The new Labor Exchange is soon to be inaugurated. We give herewith a +view of the entrance facade of the meeting hall. The buildings, which +are the work of Mr Bouvard, architect, of the city of Paris, are +comprised within the block of houses whose sharp angle forms upon +Place de la Republique, the intersection of Boulevard Magenta and +Bondy street. One of the entrances of the Exchange is on a level with +this street. The three others are on Chateau d'Eau street, where the +facade of the edifice extends for a length of one hundred feet. From +the facade and above the balcony that projects from the first story, +stand out in bold relief three heads surrounded by foliage and fruit +that dominate the three entrance doors. These sculptures represent the +Republic between Labor and Peace. The windows of the upper stories are +set within nine rows of columns, from between the capitals of which +stand out the names of the manufacturers, inventors, and statesmen +that have sprung from the laboring classes. Upon the same line, at the +two extremities of the facade, two modillions, traversed through their +center by palms, bear the devices "Labor" and "Peace." Above, there is +a dial surmounted by a shield bearing the device of the city of Paris. + +The central door of the ground floor opens upon a large vestibule, +around which are arranged symmetrically the post, telegraph, +telephone, and intelligence offices, etc. Beyond the vestibule there +is a gallery that leads to the central court, upon the site of which +has been erected the grand assembly hall. This latter, which measures +20 meters in length, 22 in width, and 6 in height, is lighted by a +glazed ceiling, and contains ten rows of benches. These latter contain +900 seats, arranged in the form of circular steps, radiating around +the president's platform, which is one meter in height. A special +combination will permit of increasing the number of seats reserved for +the labor associations on occasions of grand reunions to 1,200. The +oak doors forming the lateral bays of the hall will open upon the two +large assembly rooms and the three waiting rooms constructed around +the faces of the large hall. In the assembly rooms forming one with +the central hall will take place the deliberations of the syndic +chambers. The walls of the hall will, ere long, receive decorative +paintings.--_L'Illustration._ + + * * * * * + + + + +MANUFACTURE OF ROLL TAR PAPER. + + +Roofing paper was first used in Scandinavia early as the last century, +the invention being accredited to Faxa, an official of the Swedish +Admiralty. The first tar and gravel roofs in Sweden were very +defective. The impregnation of the paper with a water-proofing liquid +had not been thought of, and the roofs were constructed by laying over +the rafters a boarding, upon which the unsaturated paper, the sides of +which lapped over the other, was fastened with short tacks. The +surface of the paper was next coated with heated pine tar to make it +waterproof. The thin layer of tar was soon destroyed by the weather, +so that the paper, swelled by the absorption of rain water, lost its +cohesiveness and was soon destroyed by the elements. This imperfect +method of roof covering found no great favor and was but seldom +employed. + +In Germany the architect Gilly was first to become interested in tar +paper roofing, and recommended it in his architecture for the country. +Nevertheless the new style of roof covering was but little employed, +and was finally abandoned during the first year of the 19th century. +It was revived again in 1840, when people began to take a renewed +interest in tar paper roofs, the method of manufacturing an +impermeable paper being already so far perfected that the squares of +paper were dipped in tar until thoroughly saturated. The roof +constructed of these waterproof paper sheets proved itself to be a +durable covering, being unimpenetrable to atmospheric precipitations, +and soon several factories commenced manufacturing the paper. The +product was improved continually and its method of manufacture +perfected. The good qualities of tar paper roofs being recognized by +the public, they were gradually adopted. The costly pine tar was soon +replaced by the cheaper coal tar. Square sheets of paper were made at +first; they were dipped sufficiently long in ordinary heated coal tar, +until perfectly saturated. The excess of tar was then permitted to +drip off, and the sheets were dried in the air. The improvement of +passing them through rollers to get rid of the surplus tar was +reserved for a future time, when an enterprising manufacturer +commenced to make endless tar paper in place of sheets. Special +apparatus were constructed to impregnate these rolls with tar; they +were imperfect at first, but gradually improved to a high degree. Much +progress was also made in the construction of the roofs, and several +methods of covering were devised. The defects caused by the old method +of nailing the tar paper direct upon the roof boarding were corrected; +the consequence of this method was that the paper was apt to tear, +caused by the unequal expansion of the roofing boards and paper, and +this soon led to the idea of making the latter independent of the +former by nailing the sides of the paper upon strips running parallel +with the gable. The use of endless tar paper proved to be an essential +advantage, because the number of seams as well as places where it had +to be nailed to the roof boarding was largely decreased. The +manufacture of tar paper has remained at about the same stage and no +essential improvements have been made up to the present. As partial +improvement may be mentioned the preparation of tar, especially since +the introduction of the tar distillery, and the manufacture of special +roof lacquers, which have been used for coating in place of the coal +tar. As an essential progress in the tar paper roofing may be +mentioned the invention of the double tar paper roof, and the wood +cement roof, which is regarded as an offshoot. + +The tar paper industry has, within the last forty years, assumed great +dimensions, and the preferences for this roofing are gaining ground +daily. In view of the small weight of the covering material, the wood +construction of the roof can be much lighter, and the building is +therefore less strained by the weight of the roof than one with the +other kind, so that the outer walls need not be as heavy. Considering +the price, the paper roof is not only cheaper than other fireproof +roofs, but its light weight makes it possible for the whole building +to be constructed lighter and cheaper. The durability of the tar paper +roof is satisfactory, if carefully made of good material; the double +tar paper roof, the gravel double roof, and the wood cement roof are +distinguished by their great durability. + +These roofs may be used for all kinds of buildings, and not only are +factories, storehouses, and country buildings covered with it, but +also many dwellings. The most stylish residences and villas are at +present being inclosed with the more durable kinds; the double roof, +the gravel double roof, and the wood cement roof. For factory +buildings, which are constantly shaken by the vibrations of the +machinery, the tar paper roof is preferable to any other. + +In order to ascertain to what degree tar paper roofs would resist +fire, experiments were instituted at the instigation of some of the +larger manufacturers of roofing paper, in the presence of experts, +architects, and others, embracing the most severe tests, and it was +fully proved that the tar paper roof is as fireproof as any other. +These experiments were made in two different ways; first, the +readiness of ignition of the tar paper roof by a spark or flame from +the outside was considered, and, second, it was tested in how far it +would resist a fire in the interior of the building. In the former +case, it was ascertained that a bright, intense fire could be kept +burning upon the roof for some time, without igniting the woodwork of +the roof, but heat from above caused some of the more volatile +constituents of the tar to be expelled, whereby small flames appeared +upon the surface within the limits of the fire; the roofing paper was +not completely destroyed. There always remained a cohesive substance, +although it was charred and friable, which by reason of its bad +conductivity of heat protected the roof boarding to such an extent +that it was "browned" only by the developed tar vapors. A fire was +next started within a building covered with a tar paper roof; the +flame touched the roof boarding, which partly commenced to char and +smoulder, but the bright burning of the wood was prevented by the +air-tight condition of the roof; the fire gases could not escape from +the building. The smoke collecting under the roof prevented the +entrance of fresh air, in consequence of which the want of oxygen +smothered the fire. The roofing paper remained unchanged. By making +openings in the sides of the building so that the fire gases could +escape, the wood part of the roof was consumed, but the roofing paper +itself was only charred and did not burn. After removing the fire in +contact with the paper, this ceased burning at once and evinced no +disposition whatever to spread. In large conflagrations, also, the tar +paper roofs behaved in identically a similar manner. Many instances +have occurred where the tar paper roof prevented the fire from +spreading inside the building, and developing with sufficient +intensity to work injury. + +As it is of interest to the roofer to know the manner of making the +material he uses, we give in the following a short description of the +manufacture of roofing paper. At first, when square sheets were used +exclusively, the raw paper consisted of ordinary dipped or formed +sheets. The materials used in its manufacture were common woolen rags +and other material. In order to prepare the pulp from the rags it is +necessary to cut them so small that the fabric is entirely dissolved +and converted into short fibers. The rags are for this purpose first +cut into pieces, which are again reduced by special machines. The rags +are cut in a rag cutting machine, which was formerly constructed +similar to a feed cutter; later on, more complicated machines of +various constructions were employed. It is not our task to describe +the various kinds, but we remain content with the general remark that +they are all based on the principles of causing revolving knives to +operate upon the rags. The careful cleansing of the cut rags, +necessary for the manufacture of paper, is not required for roofing +paper. It is sufficient to rinse away the sand and other solid +extraneous matter. The further reduction of the cut rags was formerly +performed in a stamp mill, which is no longer employed, the pulp mill +or rag engine being universally used. + +The construction of this engine may be described as follows: A box or +trough of wood, iron, or stone is by a partition divided into two +parts which are connected at their ends. At one side upon the bottom +of the box lies an oakwood block, called the back fall. In a hollow of +this back fall is sunk the so-called plate, furnished with a number of +sharp steel cutters or knives, lying alongside of each other. A roller +of solid oakwood, the circumference of which is also furnished with +sharp steel cutters or knives, is fastened upon a shaft and revolves +within the hollow. The journal bearings of the shaft are let into and +fastened in movable wooden carriers. The carriers of the bearings may +be raised and lowered by turning suitable thumbscrews, whereby the +distance between the roller and the back fall is increased or +decreased. The whole is above covered with a dome, the so-called case, +to prevent the throwing out of the mass under the operation of +grinding. The roller is revolved with a velocity of from 100 to 150 +revolutions per minute, whereby the rags are sucked in between the +roller and the back fall and cut and torn between the knives. At the +beginning of the operation, the distance between the roller and the +back fall is made as great as possible, the intention being less to +cut the rags than to wash them thoroughly. The dirty water is then +drawn off and replaced by clean, and the space of the grinding +apparatus is lessened gradually, so as to cut the rags between the +knives. The mass is constantly kept in motion and each piece of rag +passes repeatedly between the knives. The case protects the mass from +being thrown out by the centrifugal force. The work of beating the +rags is ended in a few hours, and the ensuing thin paste is drawn off +into the pulp chest, this being a square box lined with lead. + +From the pulp chest it passes to the form of the paper machine. This +form consists of an endless fine web of brass wire, which revolves +around rollers. The upper part of this form rests upon a number of +hollow copper rollers, whereby a level place is formed. The form +revolves uniformly around the two end rollers, and has at the same +time a vibratory motion, by which the pulp running upon the form is +spread out uniformly and conducted along, more flowing on as the +latter progresses. The water escapes rapidly through the close wire +web. In order to limit the form on the sides two endless leather +straps revolve around the rollers on each side, which touch with their +lower parts the form on both sides and confine the fluid within a +proper breadth. The thickness of the pulp is regulated at the head of +the form by a brass rule standing at a certain height; its function is +to level the pulp and distribute it at a certain thickness. The +continually moving pulp layer assumes greater consistency the nearer +it approaches to the dandy roll. This is a cylinder covered with brass +wire, and is for the purpose of compressing the paper, after it has +left the form, and free it from a great part of the water, which +escapes into a box. The paper is now freed of a good deal of the +fluid, and assumes a consistency with which it is enabled to leave the +form, which now commences to return underneath the paper, passing on +to an endless felt, which revolves around rollers and delivers it to +two iron rolls. The paper passes through a second pair of iron +rollers, the interiors of which are heated by steam. These rollers +cause the last of the water to be evaporated, so that it can then be +rolled upon reels. A special arrangement shaves the edges to the exact +size required. + +The paper is made in different thicknesses and designated by numbers +to the size and weight. + +Waste paper, bookbinders' shavings, etc., can be used for making the +paper. As much wool as possible should be employed, because the wool +fiber has a greater resistance than vegetable fiber to the effects of +the temperature. By wool fiber is understood the horny substance +resembling hair, with the difference that the former has no marrowy +tissue. The covering pellicle of the wool fiber consists of flat, +mostly elongated leaves, with more or less corners, lying over each +other like scales, which makes the surface of the fiber rough; this +condition, together with the inclination of curling, renders it +capable of felting readily. Pure wool consists of a horny substance, +containing both nitrogen and sulphur, and dissolves in a potash +solution. In a clean condition, the wool contains from 0.3 to 0.5 per +cent. of ash. It is very hygroscopical, and under ordinary +circumstances it contains from 13 to 16 per cent. humidity, in dry air +from 7 to 11 per cent., which can be entirely expelled at a +temperature of from 226 to 230 degrees Fahrenheit. Wool when ignited +does not burn with a bright flame, as vegetable fiber does, but +consumes with a feeble smouldering glow, soon extinguishes, spreading +a disagreeable pungent vapor, as of burning horn. By placing a test +tube with a solution of five parts caustic potash in 100 parts water, +a mixture of vegetable fibers and wool fibers, the latter dissolve if +the fluid is brought to boiling above an alcohol flame, while the +cotton and linen fibers remain intact. + +The solubility of the woolen fibers in potash lye is a ready means of +ascertaining the percentage of wool fiber in the paper. An exhaustive +analysis of the latter can be performed in the following manner: A +known quantity of the paper is slowly dried in a drying apparatus at +temperature of 230 deg. Fahrenheit, until a sample weighed on a scale +remains constant. The loss of weight indicates the degree of humidity. +To determine the ash percentage, the sample is placed in a platinum +crucible, and held over a lamp until all the organic matter is burned +out and the ash has assumed a light color. The cold ash is then +moistened with a carbonate of ammonia solution, and the crucible again +exposed until it is dark red; the weight of the ash is then taken. To +determine the percentage of wool, a sample of the paper is dried at +230 deg. Fahrenheit and weighed, boiled in a porcelain dish in potash lye +12 deg. B. strong, and frequently stirred with a glass rod. The wool fiber +soon dissolves in the potash lye, while the vegetable fiber remains +unaltered. The pulpy mass resulting is placed upon a filter, dried at +212 deg. Fahrenheit, and after the potash lye has dripped off, the +residue, consisting of vegetable fiber and earthy ash ingredients, is +washed until the water ceases to dissolve anything. The residue dried +at 212 deg. Fahrenheit is weighed with a filter, after which that of the +latter is deducted. The loss of weight experienced is essentially +equal to the loss of the wool fiber. If the filtrate is saturated with +hydrochloric acid, the dissolved wool fiber separates again, and after +having been collected upon a weighed filter, it may be weighed and the +quantity ascertained. + +The weight of the mineral substances in the raw paper is ascertained +by analyzing the ash in a manner similar to that above described. The +several constituents of the ash and the mineral added to the raw paper +are ascertained as follows: Sufficient of the paper is calcined in the +manner described; a known quantity of the ash is weighed and thrown +into a small porcelain dish containing a little distilled water and an +excess of chemically pure hydrochloric acid. In this solution are +dissolved the carbonates, carbonate of lime, carbonate of magnesia, a +little of sulphate of alumina, as well as metallic oxides, while +silicate of magnesia, silicic acid, sulphate of lime (gypsum) remain +undissolved. The substance is heated until the water and excess of +free hydrochloric acid have been driven off; it is then moistened with +a little hydrochloric acid, diluted with distilled water and heated. +The undissolved residue is by filtering separated from the dissolved, +the filter washed with distilled water, and the wash water added to +the filtrate. The undissolved residue is dried, and after the filter +has also been burned in due manner and the ash added, the weight is +ascertained. It consists of clay, sand, silicic acid and gypsum. + +The filtrate is then poured into a cylinder capable of holding 100 +cubic centimeters, and furnished with a scale; sufficient distilled +water is then added until the well-shaken fluid measures precisely 100 +cubic centimeters. By means of this measuring instrument, the filtrate +is then divided into two equal portions. One of these parts is in a +beaker glass over-saturated with chemically pure chloride of ammonia, +whereby any iron of oxide present and a little dissolved alumina fall +down as deposit. The precipitate is separated by filtering, washed, +dried at 212 deg. Fahrenheit and weighed. To the filtrate is then added a +solution of oxalate of ammonia until a white precipitate of oxalate of +lime is formed. This precipitate is separated by filtering, washed, +dried and when separated from the filter, is collected upon dark +satinized paper; the filter itself is burned and the ash added to the +oxalate of lime. This oxalate of lime is then heated to a dark red +heat in a platinum crucible with lid until the oxalate of lime is +converted into carbonate of lime. By the addition of a few drops of +carbonate of ammonia solution and another slight heating of the +crucible, also the caustic lime produced in the filter ash by heating, +is reconverted into carbonate of lime, and after cooling in the +exsiccator, the whole contents of the crucible is weighed as +carbonate of lime, after deducting the known quantity of filter ash. + +Any magnesia present in the filtrate of the oxalate of lime is by the +addition of a solution of phosphate of soda separated as phosphate of +ammonia and magnesia, after having stood twenty-four hours. The +precipitate is filtered off, washed with water to which a little +chloride of ammonia is added, dried, and after calcining the fiber and +adding the filter ash, glow heated in the crucible. The glowed +substance is weighed after cooling, and is pyrophosphate of magnesia, +from which the magnesia or carbonate of magnesia is calculated +stoichiometrically. All the ascertained sums must be multiplied by 2, +if they are to correspond to the analyzed and weighed quantity of ash. + +The second half of the filtrate is used for determining the small +quantity of sulphate of lime still contained in the hydrochlorate +solution. By adding chloride of barium solution the sulphuric acid is +bound to the barytes and sulphate of baryta separates as white +precipitate. This is separated by filtering, washed, dried and weighed +in the customary manner. From the weight of the sulphate of baryta is +then computed the weight of sulphate of lime, which has passed over +into solution. The ascertained sum is also to be multiplied with 2. + +The manufacture of roll tar paper from the roll paper was at first +found to be difficult, as it was impossible to submerge a surface +larger than from ten to fifteen square yards, rolled up, in the tar, +because more would have required too large a pan. Besides this, the +paper tears easily, when it is in the hot tar. All kinds of +experiments were tried, in order to impregnate the surface of the +paper without employing too large a pan. + +The following method was tried at first: The roll paper was cut into +lengths of ten yards, which were rolled up loosely, so that a certain +space was left between the different coils. These loose rolls, of +course, occupied much space and could be put into the tar only in a +standing position, because in a horizontal one the several coils would +have pressed together again. The loose roll was therefore slipped over +a vertical iron rod fastened into a circular perforated wooden foot. +The upper end of this iron rod ended in a ring, in which the hook of a +chain or rope could be fastened. With the aid of a windlass the roll +was raised or lowered. When placed in the pan with boiling tar, it was +left there until thoroughly saturated. It was then taken out, placed +upon a table, and the excess of tar allowed to drip off into a vessel +underneath. After partially drying, the roll was spread out in open +air, occasionally turned, until sufficiently dried, when it was rolled +up again. + +In order to neutralize the smeary, sticky condition of the surface and +avoid the disagreeable drying in open air, the experiment of strewing +sand on the sticky places was tried next. The weight of the paper was +largely increased by the sand, and appeared considerably thicker. For +this reason the method of sanding the paper was at once universally +adopted. To dispense with the process of permitting the surplus tar to +drip off, means were devised by which it was taken off by scrapers, or +by pressing through rollers. The scrapers, two sharp edged rods +fastened across the pan, were then so placed that the paper was drawn +through them. The excess of tar adhering to its surface was thereby +scraped off and ran back into the pan. + +This work, however, was performed better and to more satisfaction by a +pair of rollers fastened to the pan. These performed a double duty; +thoroughly removed the tar from the surface and by reason of their +pressure they caused a more perfect incorporation of the tar with the +fibers of the paper. Finally, different factories employed different +methods of manufacture, one of which was to cut the rolls into +definite lengths of about ten yards; these were then rerolled very +loosely and immersed in the hot tar until sufficiently saturated. The +paper was then passed through the roller, much pressure exerted, and +then loosely rolled up again. Being tarred once, it was then laid into +a second pan with hot tar, reeled out after a time, strewn with sand, +and rolled up again. Another method was to cut clothes lines into +lengths of about fifteen yards, and at a distance of two inches have +knots tied in them. The paper was cut in lengths of ten or fifteen +yards, three pieces of the knotted clothes line were then rolled +between the loose coils of paper, which was then submerged in the tar, +which on account of the knots could penetrate the paper. The paper was +next sanded by permitting its lower surface to pass over dry sand in a +box standing on the floor. A workman rolled off the paper, and with +his hand he strews sand on the upper surface. The rolling taking place +on the edge of a table, by means of a crank, the excess of sand +dropped off. + +It is said by this method two workmen, one of which tends to the +rolling and sanding, the other turning the crank, could turn out +eighty rolls per day. This method is still in use. It is useless to +describe the many antiquated methods in vogue in smaller factories, +and it can truthfully be said that nearly all of them are out of date. +It appears to be the fact of almost all inventions that when reduced +to practical use, the arrangements, apparatus, and working methods +employed are generally of the most complicated nature, and time and +experience only will simplify them. This has been also the case with +the methods in the roofing paper industry, which are at present +gradually being reduced to a practical basis. The method gradually +adopted has been described in the preceding. The pan is of a certain +length, whereby it becomes possible to saturate the paper by slowly +drawing it through the heated tar. This is the chief feature. The work +is much simplified thereby and the workmen need not dip their hands +into the tar or soil them with it. The work of impregnating has become +much cleaner and easier, while at the same time the tar can be heated +to a much higher temperature. The pan is generally filled with +distilled coal tar, and the heating is regulated in such a manner that +the temperature of the impregnating mass is raised far beyond 212 deg. +Fahrenheit. This accelerates the penetration, which takes place more +quickly as the degree of heat is raised, which may be almost up to the +boiling point of the tar, as at this degree the paper is not destroyed +by the heat. In order to prevent the evaporation of the volatile +ingredients of the tar, the pan is covered with a sheet iron cover, +with a slot at the place where the paper enters into the impregnating +mass and another at the place where it issues. The tar is always kept +at the same level, by occasional additions. + +The roll of paper is mounted upon a shaft at the back end of the pan, +and by suitable arrangement of guide rollers it unwinds slowly, passes +into the tar in which it is kept submerged. The guide rollers can be +raised so that when a new roller is set up they can be raised out of +the tar. The end of the paper is then slipped underneath them above +the surface of the tar, when having passed through the squeezing +rollers, it is fastened to the beaming roller, and the guide rollers +are submerged again. A workman slowly turns the crank of the beaming +roller. + +This motion draws the paper slowly through the fluid, the roll at the +back end unwinding. The speed with which the squeezing rollers are +turned is regulated in such a manner that the paper remains +sufficiently long underneath the fluid to be thoroughly impregnated +with it. The workmen quickly learn by experience how fast to turn the +crank. The hotter the tar, the more rapid the saturation; the high +degree of heat expels the air and evaporates the hygroscopic fluid in +the pores of the paper. The strong heating of the tar causes another +advantage connected with this method. The surface of the paper as it +issues from the squeezing rollers is still very hot, and a part of the +volatile oils evaporate very quickly at this high temperature. The +surface is thereby at once dried to a certain degree and at the same +time receives a handsome luster, as if it had been coated with a black +lacquer. The paper is sanded in a very simple manner without the use +of mechanical apparatus; as it is being wrapped into a coil, it passes +with its lower surface over a layer of sand, while the workman who +tends to rolling up strews the inside with sand. The lower surface is +coated very equally. Care only being necessary that the sand lies +smooth and even at all times. When the workman has rolled up ten or +fifteen yards, he cuts it across with a knife and straightedge, so +that the paper is cut at right angles with its sides. + +There are three different sorts of roofing paper, according to the +impregnating fluid used in its manufacture. The ordinary tar paper is +that saturated with clear cold tar. This contains the greatest amount +of fluid ingredients and is very raggy in a fresh condition. It is +easy to see that the volatile hydrocarbons evaporate in a short time, +and when expelled, the paper becomes stiffer and apparently drier. +This drying, or the volatilization of the hydrocarbons, causes pores +between the fibers of the paper. These pores are highly injurious to +it, as they facilitate a process of decomposition which will ruin it +in a short time. + +Roofing paper can be called good only when it is essentially made from +woolen rags, and contains either very few or no earthy additions. It +is beyond doubt that the durability of a roofing paper increases with +the quality of wool fiber it contains--vegetable fibers and earthy +additions cause a direct injury. Reprehensible altogether is any +combination with lime, either in form of a carbonate or sulphate, +because the lime enters into chemical combination with the +decomposition products of the tar. + +The general nature of gravel is too well known to require description. +The grains of quartz sand are either sharp cornered or else rounded +pieces of stone of quartz, occasionally mixed with grains of other +amorphous pieces of silica--such as horn stone, silicious slate, +carnelian, etc.; again, with lustrous pieces of mica, or red and white +pieces of feldspar. The gravel used for a tar paper roof must be of a +special nature and be prepared for the purpose. The size of its grains +must not exceed a certain standard--say, the size of a pea. When found +in the gravel bank, it is frequently mixed with clay, etc., and it +cannot be used in this condition for a roof, but must be washed. The +utensils necessary for this purpose are of so simple and suggestive a +nature that they need not be described. Slag is being successfully +used in place of the gravel. It is easily reduced to suitable size, by +letting the red hot mass, as it runs from the furnace, run into a +vessel with water. The sudden chilling of the slag causes it to burst +into fragments of a sharp cornered structure. It is next passed +through a sieve, and the suitably sized gravel makes an excellent +material, as it gives a clean appearance to the roof. + +The thinking mind can easily go one step further and imagine that, +since the tar contains a number of volatile hydrocarbons, it might be +made more adaptable for impregnation by paper by distilling it, as by +this process the fluid would lose its tendency to evaporate and the +percentage of resinous substances increase. Singular to say, there was +a prejudice against the employment of distilled tar, entertained by +builders and people who had no knowledge of chemistry. Increasing +intelligence and altered business circumstances, however, brought +about the almost universal employment of distilled tar, and every +large factory uses it at present. The roofing paper prepared with +distilled tar is perhaps most suitably called asphaltum paper, as this +has been used in its manufacture. It possesses properties superior to +the ordinary tar paper, one of which is that immediately after its +manufacture, as soon as cold, it is dry and ready for shipment; nor +does it require to be kept in store for a length of time, and it has +also a good, firm body, being as flexible and tough as leather. It is +very durable upon the roof, and remains flexible for a long time. It +is true that asphaltum papers will always in a fresh state contain a +small percentage of volatile ingredients, which after a while make it +hard and friable upon the roof; but, by reason of its greater +percentage of resinous components, it will always preserve a superior +degree of durability and become far less porous. One hundred parts by +weight absorb 140 or 150 parts by weight of coal tar. A factory which +distilled a good standard tar for roofing paper recovered, besides +benzole and naphtha, also about ten per cent. of creosote oil, used +for one hundred parts raw paper, 176.4 partially distilled tar. +Experiments on a larger as well as a smaller scale reduced this +quantity to an average of 141.5 parts for one hundred parts raw paper. +The weight of sanded paper is very variable, as it depends altogether +upon the size of the sand grains. It may be stated generally that the +weight of the sand is as large as that of the tarred paper. + +The kinds of roofing paper saturated with other additions besides coal +tar form a separate class, in order to neutralize the defects inherent +in coal tar. These additions were originally for the purpose of +thickening the paper and making it stiffer and drier. The most +ordinary and cheapest thickener was the coal pitch. Although the +resinous substances are increased thereby, still the light tar oils +remain to evaporate, and the paper prepared with such a substance +readily becomes hard and brittle. A better addition is the natural +asphaltum, because it resists better the destroying influence of the +decomposition process, and also, to a certain degree, protects the +coal tar in which it is dissolved. The addition of natural asphaltum +doubtless caused the name of "asphaltum roofing paper." Resin, +sulphur, wood tar and other substances were also used as additions; +each manufacturer kept his method secret, however, and simply pointed +out by high sounding title in what manner his paper was composed. In +most cases, however, this appellation was applied to the ordinary tar +paper; the impregnating substance was mixed only with coal pitch, or +else a roofing paper saturated with distilled tar. The costly +additions, by the use of which a high grade of roofing paper can +doubtless be produced, largely increased its price, and on account of +the constant fall of prices of the article, its use became rather one +of those things "more honored in the breach than in the observance," +and was dispensed with whenever practicable. The crude paper is the +foundation of the roofing paper. The qualities of a good, +unadulterated paper have already been stated. At times, the crude +paper contains too many earthy ingredients which impair the cohesion +of the felted fibrous substance, and which especially the carbonate of +lime is very injurious, as it readily effects the decomposition of the +coal tar. The percentage of wool, upon which the durability of the +paper depends very largely, is very small in some of the paper found +in the market. In place of woolen rags, cheap substitutes have been +used, such as waste, which contains vegetable fibers. Since this +cannot resist the decomposition process for any length of time, it is +evident that the roofing paper which contains a noticeable quantity of +vegetable fibers cannot be very durable. To judge from the endeavors +made to improve the coal tar, it may be concluded that this material +does not fully comply with its function of making the roofing paper +perfectly and durably waterproof. The coal tar, be it either crude or +distilled, is not a perfect impregnating material, and the roofing +paper, saturated with it, possesses several defects. Let us in the +following try to ascertain their shortcomings, and then express our +idea in what manner the roofing paper may be improved. It was +previously mentioned that every tar roofing paper will, after a +greater or smaller lapse of time, assume a dry, porous, friable +condition, caused by the volatilization of a part of the constituents +of the tar. This alteration is materially assisted by the oxygen of +the air, which causes the latter to become resinous and exerts a +chemical influence upon them. By the volatilization of the lighter tar +oils, pores are generated between the fibers of the roofing paper, +into which the air and humidity penetrate. In consequence of the +greatly enlarged surface, not only the solid ingredients of the tar, +which still remain unaltered, are exposed to the action of the oxygen, +but also the fibers of the roofing paper are exposed to decomposition. +How destructive the alternating influence of the oxygen and the +atmospheric precipitations are for the roofing paper will be shown by +the following results of tests. It will have been observed that the +rain water running from an old paper roof, especially after dry +weather, has a yellowish, sometimes a brown yellow color. The +supposition that this colored rain water might contain decomposition +products of the roofing paper readily prompted itself, and it has been +collected and analyzed at different seasons of the year. After a +period of several weeks of fair weather during the summer, rain fell, +and the sample of water running from a roof was caught and evaporated; +the residue when dried weighed 1.68 grammes. It was of a brownish +black color, fusible in heat and readily soluble, with a yellow brown +color in water. The dark brown substance readily dissolved in ammonia, +alcohol, dilute acid, hydrochloric acid, sulphuric acid, and +decomposed in nitric acid, but did not dissolve in benzine or fat oil. +After several days' rain during the summer, a quantity of the water +was caught, evaporated, and the residue dried. Its characteristics +were similar to those above mentioned. By an experiment instituted in +water under conditions similar to the first mentioned, the dry brown +substance weighed 71 grammes. It possessed the same characteristics. +In the solution effected with water containing some aqua ammonia of +the brown substance, a white precipitate of oxalate of lime occurred +when an oxalate of ammonia solution was added, but the brown substance +remained in solution. A further precipitation of oxalate of lime was +produced by a solution of oxalic acid, but the brown organic substance +remained in solution. This organic substance being liberated from the +lime was evaporated, and left a dry, resinous, fusible brownish black +substance, which also dissolved readily in water. It will be seen from +these trials that the substance obtained from the rain water running +from a paper roof is a combination of an organic acid with lime, which +readily dissolves in water, and that also the free organic acid +combined with the lime dissolves easily in water. + +The question concerning the origin of this organic substance or its +combination with lime can only be answered in one way, viz., that it +must have been washed by the rain water out of the paper. But since +such a solid substance, easily soluble in water, is contained neither +in the fresh roofing paper nor in the coal tar, the only deduction is +that it must have arisen by the decomposition of the tar, in +consequence of the operation of the oxygen. The lime comes from the +coating substance of the roof, for which tar mixed with coal pitch was +used. The latter was fused with carbonate of lime. These analyses +furthermore show that the formation of the organic acid easily soluble +in water depends upon the season; and that a larger quantity of it is +generated in warm, sunny weather than in cold, without sunshine. This +peculiarity of the solid, resinous constituents of the coal tar, to be +by the operation of the atmospheric oxygen altered into such products +that are readily soluble in water, makes the tar very unsuitable as a +saturative substance for a roofing paper. How rapidly a paper roof can +be ruined by the generation of this injurious organic acid will be +seen from the following calculation: Let us suppose that an average +of 132 gallons of rain water falls upon ten square feet roof surface +per year, and that the arithmetical mean 0.932 of the largest (1.680) +and smallest number (0.184) be the quantity of the soluble brown +substance which on an average is dissolved in one quart of rain water; +hence from ten square feet of roof surface are rinsed away with the +rain water per year 466 grammes of the soluble decomposition products +of the tar. The oxidation process will not always occur as intensely +as by a paper roof, ten years old and painted two years ago, which +instigated above described experiment. As long as the roofing paper is +fresh and less porous, especially if the occurring pores are filled +and closed again by repeated coatings, oxidation will take place far +less rapidly. Besides this, the protective coating applied to the roof +surface is exposed most to this oxidation process. Even by assuming +this constantly progressive destructive action of the oxygen on the +roofing paper to be much less than above stated, we can readily +imagine that it must be quite large. If it is desired to produce a +material free of faults, it is first of all indispensable that +unobjectionable raw material be procured. Coal tar was formerly used +almost exclusively for the coating of a roof. It was heated and +applied hot upon the surface. In order to avoid the running off of the +thinly fluid mass, the freshly coated surface was strewn with sand. +The most volatile portion of the tar evaporated soon, whereby the +coating became thicker and finally dried. The bad properties of the +coal tar, pointed out elsewhere, made it very unsuitable even for this +purpose, and experiments were instituted to compound mixtures, by +adding other ingredients to the tar, that should more fully comply +with its function. It may be said in general that the coating masses +for roofs can be divided into two classes: either as lacquers or as +cements. To the former may be classed those of a fairly thinly fluid +consistency, and which contain volatile oils in such quantities that +they will dry quickly. Cements are those of a thickly fluid +consistency, and are rendered thus fluid by heating. It is not +necessary that the coating applied should harden quickly, as it +assumes soon after its application a firmness sufficient to prevent it +from running off the roof. Coal tar is to be classed among lacquers. +If it has been liberated by distillation from the volatile oils, it is +made better suited for the purpose than the ordinary kind. The mass +contains much more asphaltum, and after drying, which takes place +soon, it leaves a far thicker layer upon the roof surface, while the +pores, which had formed in the roofing paper consequent on drying, are +better filled up. Nevertheless, the distilled tar also has retained +the property of drying with time into a hard, vitreous mass, and +ultimately to be destroyed by decomposition.--_The Roofer_. + + * * * * * + + + + +A PHYSICAL LABORATORY INDICATOR. + + +The difficulties attending the management of a physical laboratory are +much greater than those of a chemical one. The cause of this lies in the +fact that in the latter the apparatus is less complicated and the pieces +less varied. Any contrivance that will reduce the labor and worry +connected with the running of a laboratory is valuable. + +A physical laboratory may be arranged in several ways. The apparatus may +be kept in a store room and such as is needed may be given to the +student each day and removed after the experiments are performed; or the +apparatus for each experiment or system of experiments may be kept in a +fixed place in the laboratory ready for assembling; for certain +experiments the apparatus may be kept in a fixed place in the laboratory +and permanently arranged for service. + +Each student may have his own desk and apparatus or he may be required +to pass from desk to desk. The latter method is preferable. + +When a store room is used the services of a man are required to +distribute and afterward to collect. If the apparatus is permanently +distributed, a large room is necessary, but the labor of collecting and +distributing is done away with. + +There are certain general experiments intended to show the use of +measuring instruments which all students must perform. To illustrate the +use of the indicator I have selected an elementary class, although the +instrument is equally applicable to all classes of experiments. + +Having selected a suitable room, tables may be placed against the walls +between the windows and at other convenient places. Shallow closets are +built upon these tables against the wall; they have glass doors and are +fitted with shelves properly spaced. A large number of light wooden +boxes are prepared, numbered from one up to the limit of the storage +capacity of the closets. A number corresponding to that upon the box is +placed upon the shelf, so that each one after removal may be returned to +its proper place without difficulty. On the front of the box is a label +upon which is written the experiment to be performed or the name of the +apparatus whose use is to be learned, references to various books, which +may be found in the laboratory library, and the apparatus necessary for +the experiment, which ought to be found in the box. If any parts of the +apparatus are too large to be placed in the box, the label indicates by +a number where it may be found in the storage case. + +It is evident that, instead of the above arrangement, all the boxes can +be stacked in piles in a general store room. The described arrangement +is preferable, as it prevents confusion in collecting and distributing +apparatus when the class is large. + +_The Indicator_ (see figure).--Some device is evidently desirable to +direct the work of a laboratory with the least trouble and friction +possible. I have found that the old fashioned "peg board," formerly used +in schools to record the demerits of scholars, modified as in the +following description, leaves nothing to be desired. + +The requirements of such an instrument are these: It must show the names +of the members of the class; it must contain a full list of the +experiments to be performed; it must refer the student to the book and +page where information in reference to the experiments or apparatus may +be found; it must show what experiments are to be performed by each +student at a given time; it must give information as to the place in the +laboratory where the apparatus is deposited; it must show to the +instructor what experiments have been performed by each student; it must +prevent the assignment of the same experiment to two students; it must +enable the instructor to assign the same experiment to two or more +students; it must form a complete record of what has been done, what +work is incomplete, and what experiments have not yet been assigned; it +must also be so arranged that new experiments or sets of experiments may +be exhibited. + + +------+---+---+---+---+---+---+---+---+ + | | A | B | C | D | E | F | G | H | + +------+---+---+---+---+---+---+---+---+ + | 1 | * o o * o o o o | + | 2 | * o * * o o o o | + | 3 | + * * * o o o o | + | 4 | + o * * o o o o | + | 5 | o + * * * * o o | + | 6 | o + * * o * o o | + | 7 | o o + * o o o o | + | 8 | o o o + * o o o | + | 9 | o o o * + o o o | + | 10 | o o o o o + o o | + | 11 | o o o * o o + * | + | 12 | o o * * o + + + | + | 13 | o o * o o o o o | + | 14 | o o * o o o o o | + | 15 | o o + o o o o o | + | 16 | o o + + * o o * | + +--------------------------------------+ + + A, B, C, etc., are cards upon which are the names of students. 1, + 2, 3, etc., are cards like the one described in the article. The + small circles (o) represent unassigned experiments. The black + circles (*) (slate nails) represent work done. The caudate circles + (+) (brass nail) represent work assigned. + +The indicator consists of a plank of any convenient length and breadth. +The front surface is divided into squares of such size that the pegs may +be introduced and withdrawn with ease. At each corner of the squares +holes are bored into which nails may be placed. There is a blank border +at the top and another on the left side. At the top of each vertical +column of holes is placed a card holder. This is made of light tin +turned up on the long edges--which are vertical--and tacked to the +board. Opposite each horizontal row of holes is a similar tin card +holder, but of greater length, and having its length horizontal. The +holders at the top of the board contain cards upon which the names of +the class are written. + +Cards, like the following, are prepared for the horizontal holders. + +-------------------------------------------------------------- +Stewart & Gee 229 +Physical Manip. 85 Intensity of Gravity--Borda's Method 39 +Glazebrook & Shaw 132 +-------------------------------------------------------------- + +These cards are numbered from one to any desired number and are arranged +in the holders consecutively. + +Two kinds of nails are provided to fit the holes in the board: An +ordinary slate nail and a common picture frame nail with a brass head. +The latter indicates work to be done, the former work done. + +To prepare the board for service, brass headed nails are placed opposite +each experiment, and below the names, care being taken not to have more +than one nail in the same horizontal row, unless it is intended that two +persons or more are to work upon the same experiment. + +There will be no conflict when the brass nails occupy diagonal lines. If +they do not, a glance will show the fact. + +After an experiment has been performed and a report made upon the usual +blank, the brass nail is removed and a slate nail put in its place. + +The board will show by the slate nails what work has been done by each +student, by the brass nails what is yet to be done, and by the empty +holes, experiments which have been omitted or are yet to be assigned. A +slate nail opposite an experiment card indicates that that experiment +may now be assigned to another person. + +It is evident that the schedule for a whole term may be arranged in a +few minutes and that the daily changes require very little time. + +The board is hung in a convenient place. The student as he enters the +laboratory looks for his name on the upper cards and under it for the +first brass nail in the vertical column: to the left he finds the +experiment card. On the left hand end of the slip he sees the book +references, on the right hand end a number--39 in the sample card given +above. Knowing the number, he proceeds to a desk and finds a box +numbered in the same manner. He removes the box from the closet. On the +label of the box is a list of all the apparatus necessary, which he will +find in the box; the label also contains the book references. He +performs the experiment, fills up a blank which he gives to the +instructor, puts all the materials back in the box, replaces the box in +its proper place in the closet and proceeds with the next experiment. +With this indicator there is no difficulty in managing fifty students or +more. + +Comparatively little apparatus need be duplicated. Where apparatus is +fixed against a wall a number may be tacked upon the wall and a card +containing the information desired. The procedure is then the same as +with the boxes. The cards on the board being removable, other ones may +be inserted containing information in reference to other boxes having +the same number but containing different materials. There can be no +successful tampering with the board, for the record of experiments +performed is upon the blanks which the students turn in and also in the +individual note books which are written up and given to the instructor +for daily examination. + +Lafayette College. J.W. MOORE. + + * * * * * + + + + +NEW METHOD OF EXTINGUISHING FIRES + + +This is by George Dickson, of Toronto, Canada, and David Alanson Jones. + +A mixture of water and liquefied carbon dioxide upon being discharged +through pipes at high pressure causes the rapid expansion of the gas and +converts the mixture into spray more or less frozen, and portions of the +liquid carbon dioxide are frozen, owing to its rapid expansion, and are +thus thrown upon the fire in a solid state, where said frozen carbon +dioxide in its further expansion not only acts to put out the fire, but +cools the surface upon which it falls, and thus tends to prevent +reignition. + +A represents a receptacle sufficiently strong to stand a pressure of not +less than a thousand pounds to the square inch. + +B B water receptacles. + +[Illustration: Fig. 1] + +In the drawings we have shown two receptacles B and only one receptacle +A; but we do not wish to confine ourselves to any particular number, nor +do we wish to confine ourselves to the horizontal position in which the +receptacles are shown. + +C is a pipe leading from the receptacle A to a point at or near the +bottom of the receptacle B. + +F is a pipe through which the mixture of water and liquefied gas from +the receptacle B is forced by the expansion of said liquefied gas, the +said pipe taking the mixture of water and liquefied gas from the bottom +of the receptacle. + +[Illustration: Fig. 2] + +To use the apparatus, open the stop cock D in the pipe C, leading to one +of the receptacles B, whereupon, owing to the lower pressure in the +cylinder B, the liquid carbon dioxide expands and rises to the top of +the cylinder A and forces the liquid carbon dioxide into the cylinder B, +the same as the superior steam of a boiler forces the water of the +boiler out when the same is tapped below the surface of the liquid. Now +upon opening the tap H, this superior gas forces out the mixture of +water and liquid carbon dioxide, which suddenly expanding causes +portions of the globules of liquefied gas to be frozen, and these, being +protected by a rapidly evaporating portion of the liquefied gas, are +thrown on the fire in solid particles. At the same time the water is +blown into a spray, which is more or less frozen. The fire is thus +rapidly extinguished by the vaporization of the carbon dioxide and water +spray. + + * * * * * + + + + +SMOKELESS GUNPOWDER. + +BY HUDSON MAXIM. + + +During the last forty years leading chemists have continued to +experiment with a view to the production of a gunpowder which should be +smokeless. But not until the last few years has any considerable degree +of success been attained. + +To be smokeless, a gunpowder must yield only gaseous products of +combustion. None of the so-called smokeless powders are entirely +smokeless, although some of them are very nearly so. + +The smoke of common black gunpowder is largely due to minute particles +of solid matter which float in the air. About one-half of the total +products of combustion of black gunpowder of ordinary composition +consists of potassium carbonate in a finely divided condition and of +potassium sulphate, which is produced chiefly by the burning in the air +of potassium sulphide, another production of combustion, as on the +outrushing gases it is borne into the air in a fine state of division. + +Another cause for the smoke of gunpowder is the formation of small +liquid vesicles which condense from some of the products of combustion +thrown into the air in a state of vapor, in the same manner as vesicles +of aqueous vapor form in the air on the escape of highly heated steam +from the whistle of a locomotive. + +Broadly speaking, an explosive compound is one which contains, within +itself, all the elements necessary for its complete combustion, and +whose heated gaseous products occupy vastly more space than the original +compound. Such compound usually consists of oxygen, associated with +other elements, for which it has great affinity, and from which it is +held from more intimate union, or direct chemical combination, under +normal conditions, by being in combination as well with other elements +for which it has less affinity, but which it readily gives up for the +stronger affinities when explosion takes place, the other elements +either combining with one another to form new compounds or being set +free in an uncombined state. + +An explosive is said to detonate when the above changes take place +instantaneously, the action being transmitted with the speed of +electricity by a sort of molecular rhythm from molecule to molecule +throughout the entire substance of the compound. + +An explosive is said to explode when the above changes do not occur +instantaneously throughout the whole substance, but whose combustion +takes place from the surface inward of the particles or grains of which +it is composed, thus requiring some definite lapse of time. + +The elements of an explosive compound may be associated chemically as in +nitro-glycerine and gun-cotton, which are chemical compounds, being the +results of definite reactions. Or, an explosive may be a mere mechanical +mixture of different substances comprising the necessary elements, as is +ordinary black gunpowder, which is a compound of charcoal, sulphur and +saltpeter, the saltpeter supplying the necessary oxygen. + +No gunpowder can be smokeless in which saltpeter or any oxygen-bearing +salt having a metallic base is employed, for when the salt gives up its +oxygen, the base combines with other elements to produce a sulphate, a +carbonate, or other salt, which, being solid, produces smoke. Therefore, +to be smokeless, a gunpowder must contain no other elements than oxygen, +hydrogen, nitrogen, and carbon, and in such proportions that the +products of combustion shall be wholly gaseous. The nitric +ethers--gun-cotton and nitro-glycerine--constitute such explosive +compounds. These substances were formerly thought to be +nitro-substitution compounds, but are now known to belong to the +compound ethers of nitric acid. + +Gun-cotton, discovered by Schonbein, in 1845, has since been looked upon +as the most promising material for a smokeless gunpowder, it being a +very powerful explosive and burning with practically no smoke. To-day, +gun-cotton, in some form or other, constitutes the base of substantially +all of the smokeless powders with which have been attained any +considerable degree of success. + +Gun-cotton alone and in its fibrous state has been found to be too +quick, or violent, for propulsive purposes, such as use in firearms; as +under such conditions of confinement it is very likely to detonate and +burst the gun. However, if gun-cotton be dissolved in a suitable +solvent, which is capable of being evaporated out, such as acetone, or +acetate of ethyl, which are very volatile, it becomes, when thus +dissolved and dried, a very hard, horn-like, amorphous substance, which +may be used for a smokeless gunpowder. But this substance taken alone is +very difficult to mould or granulate, and the loss of expensive solvents +must necessarily be quite considerable. + +When gun-cotton is reduced to a collodial solid, as above, and used as a +smokeless gunpowder, the grains must be made comparatively small to +insure prompt and certain ignition, and consequently the pressures +developed in the gun are apt to be too great when charges sufficiently +large are used to give desired velocities. + +If, however, a compound be made of gun-cotton and nitro-glycerine, in +about equal parts, by means of a volatile solvent or combining agent, +such as one of the before mentioned, and the solvent evaporated out, we +obtain practically a new substance and one which, as regards its +explosive nature, is quite unlike either of its two constituents taken +alone. The nitro-glycerine, furthermore, being itself a solvent of +gun-cotton, much less of the volatile ether is necessary to render the +compound of an amorphous character. Being quite plastic this substance +may be wrought or moulded into any desired size or form of grain. + +This simple compound of nitro-glycerine and gun-cotton, or with some +slight modifications, has been found, when properly granulated, to be +the most smokeless powder that has yet been discovered or invented. If +pure chemicals are employed in the manufacture, and the gun-cotton and +nitro-glycerine be made of the highest nitration and best quality, we +have a smokeless powder which will possess the following desirable +qualities: + +1st. It is absolutely smokeless, that is, its products of combustion are +entirely gaseous. + +2d. Its products of combustion are in no way deleterious or unpleasant. + +3d. It is perfectly safe to manufacture, handle and transport. There is +no more danger of its exploding accidentally than there would be of an +explosion of shavings or sawdust; for, unless well confined and set off +with a strong primer, it will not explode at all. In the open its +combustion is so slow as to in no way resemble or partake of the nature +of an explosion. + +4th. It is perfectly stable, and will keep any length of time absolutely +without undergoing any change whatever, under all conditions of +temperature or exposure to which gunpowder would ever be subjected. + +5th. It is not hygroscopic, and may be soaked in water without being at +all affected by it. + +6th. It will not corrode the cartridge case. + +7th. It will not foul the gun. + +8th. It is sure of ignition with a good primer, and may be made to burn +as slowly as desired by varying the character and size of the grains. +Indeed, it may be made to burn so slowly as to fail of complete +combustion before the bullet leaves the gun, and after firing several +rounds, partly burned pieces of the powder may be picked up in front of +the gun. + +9th. In a shoulder arm, a velocity of 2,000 feet per second may be +imparted to the bullet with this powder, and with a pressure in the +chamber of the gun of not more than fifteen English tons. This is, of +course, when the gun, cartridge case, primer, and projectile are adapted +to the use of smokeless powder, and the granulation of the powder is +adapted to them. + +If what I have here claimed for the above smokeless powder be true, it +would appear that it may be taken as really an ideal smokeless powder. +Why, then, has it not already been universally adopted? Surely such a +powder is just what every government is seeking. In reply to this, let +me say that, in order for the above compound to be an effective and +successful smokeless powder, with the manifestation of the many +desirable qualities which I have recited, a great many other conditions +are necessary, some of which I will mention. To arrive at the knowledge +that this compound would constitute the best smokeless powder has +required a great deal of experimenting. It was first thought that +gun-cotton colloid, without any nitro-glycerine, that is, gun-cotton +dissolved and dried, would burn more slowly, keep better, and give +better ballistics than it would if combined with nitro-glycerine. It was +also thought that gun-cotton of a high degree of nitration when made +into colloidal form would even then burn too quickly to be suitable for +use in firearms. Consequently, the first experiments were with low grade +gun-cotton, what is called collodion cotton, such as is employed in the +manufacture of celluloid. But, as this would not explode without the +addition of some oxygen-bearing element, various oxygen-bearing salts +were combined with it, such as nitrate of potassium, nitrate of ammonia, +nitrate of baryta, etc. Also a great many of the first smokeless powders +were made of low grade gun-cotton combined with nitro-glycerine in +varying proportions. These powders would often give very good results +when first made; but low grade gun-cotton or di-nitro-cellulose, as it +is called, is a very unstable compound, and these powders, after giving +very promising results, were found to be constantly undergoing change, +sooner or later resulting in complete decomposition. + +When nitro-glycerine was first combined with gun-cotton in small +quantities, camphor was often added, to lessen the rapidity of +combustion which the nitro-glycerine was supposed to impart and also to +render the compound more plastic, and to tend to prevent the +decomposition of the low grade gun-cotton. But camphor being volatile, +would, by its evaporation, cause the powder to constantly change in +character. Castor oil has been found to be a better diluent, as this +will not evaporate. + +As all of the smokeless powders made of a low grade gun-cotton were +found to deteriorate and spoil, experiments were made with gun-cotton of +the highest degree of nitration, both alone and in combination with +nitro-glycerine. These experiments were first conducted in England by +private parties and by the British government, when it was found that +high grade gun-cotton would give excellent results if made into a +colloidal solid and used alone, or in combination with certain other +constituents. With a view to saving the large quantity of solvents +necessary to reduce the gun-cotton, and to get a more prompt and certain +ignition with a larger grain, experiments were cautiously made by the +admixture of varying proportions of nitro-glycerine to the gun-cotton +when dissolved, or rather along with other solvents in the process of +dissolving it. + +It was soon found that nitro-glycerine added in quantities, even equal +in weight to the gun-cotton itself, did not materially increase the +rapidity of the explosion of the compound. And it was also found that +high grade gun-cotton, when combined with nitro-glycerine, gave very +much better results than low grade gun-cotton. + +I have spoken here of high and low grade gun-cotton, when in fact the +word gun-cotton should be applied only to the highest nitro-compound of +cellulose. The word gun cotton has always been rather loosely used. +Pyroxyline would be a better word, as this applies to all grades. When +cotton fiber is soaked in a large excess of a mixture of the strongest +nitric and sulphuric acids, gun-cotton proper, or that of the highest +grade, is produced. When weaker acids are used, lower grades of +nitro-cellulose are formed. + +The first mentioned or highest grade gun-cotton, when thoroughly freed +from its acids, has always proved to be a perfectly stable compound. The +lower grades have always been found to be unstable and subject to +spontaneous decomposition. Nitro-glycerine has also been erroneously +thought to be a very unstable compound. But experiments have proved +that, when made pure, it is perfectly stable. + +Having now explained how the knowledge came to be arrived at that the +aforementioned compound of highest grade nitro-glycerine and highest +grade gun-cotton would constitute the best basis for a smokeless powder, +I will now mention a few of the other conditions necessary to success +with its use, without assuming that smokeless powder has yet passed its +experimental stage, and is beyond further improvement. Nevertheless, +such is the compound which has come to stay as the basis of all +smokeless powders; and any smokeless powder, if a successful one, may be +counted upon as being made of this compound of gun-cotton and +nitro-glycerine, or of a colloid of gun-cotton, either alone or combined +with diluents, oxygen-bearing salts, or inert matter. The fact that +smokeless powder may still be said to be in somewhat of an experimental +stage is not to admit that it is not a success. Firearms, cartridge +cases, and projectiles are also still in an experimental stage, for they +are constantly being improved; yet their use has been a great success +for a good many years. + +The question of success of a smokeless powder does not rest alone with +the powder itself. The gun, the cartridge case, primer, and bullet have +been as much the subjects of experiments in adapting them to the use of +smokeless powder as has the smokeless powder in being adapted to them. +To impart a velocity of 2,000 feet per second to a rifle ball, with +corresponding long range and accuracy of flight, has been a question as +much of improvement in rifles and projectiles as in the powder. To give +a velocity of 2,000 feet per second to a bullet, requires a pressure of +at least 15 English tons in the chamber of a gun. This would be a +dangerous pressure in an old-fashioned shoulder arm; while a bullet made +only of lead would strip on striking the rifling and pass right through +the barrel of the gun without taking any rotary motion whatever. It +might at first seem that the powder is the only thing to be considered; +but high ballistics can only be obtained when everything else is adapted +to its use. + +The projectile, the cartridge case, the fulminating cap, and the gun +have had to be all built up together, and a very large amount of +experimenting has been necessary to determine what would constitute the +best projectile, best cartridge case, best fulminating cap, and what +should be the character of the rifling and the quality and temper of the +steel of the gun barrel. + +It has been necessary first to conduct experiments to test the smokeless +powders for velocities and pressures, and then with the powders test +various kinds of projectiles and guns. In order to obtain the high +ballistics which have been secured, it has been found necessary to cover +the bullet with something harder than lead and to rifle the gun in a +special manner. + +The French, who were the first to definitely adopt smokeless powder, +were the first also to make a rifle, projectile, cartridge case and +primer suited to its use. + +To obtain long range with a small long bullet such as is now used, it +should rotate at a very high speed. It is well known to artillerists +that a projectile of four or more calibers in length has to be rotated +at a much higher speed than one of half that length, in order to keep +the projectile stiff in the air, and to prevent it from ending over in +its flight. To communicate this very high rotary movement to the bullet +in the instant of time during which it is passing through the barrel, +the rifling of the gun has to exert an enormous torsion on the bullet. +Lead, no matter how hardened, is not sufficiently strong, as it will not +only strip and pass straight through the gun without taking any rotary +movement whatever, but under such very high pressures it behaves like +wax, and is thrown from the gun in a distorted mass. + +The French cover their bullets with German silver, a substance made of +nickel, zinc and copper; and in order to put as little strain upon the +rifling and projectile as possible, the rifling of the gun is made with +an increasing twist, and has no sharp edges. The French rifle is made +very strong at the breech and is of tempered steel throughout. In this +way the French have made smokeless powder a success--a smokeless powder +made substantially of a character such as I have herein described. With +smokeless powder, the French rifle imparts a muzzle velocity of 2,000 +feet per second to the bullet, with a range of about 2,400 meters. + +If smokeless powder be divided into sufficiently small grains to be +ignited by an ordinary fulminating cap, it would burn too quickly, +thereby causing the pressure to mount too high, and without giving the +desired velocity. Consequently very large and strong fulminating caps +have to be employed. Smokeless powder is not ignited in the same manner +as black powder. Something besides ignition is necessary. Black powder +simply requires to be set on fire; while a smokeless powder, on the +contrary, not only requires that it be set on fire, but that a certain +degree of pressure be set up inside of the cartridge case. For instance, +if a primer of a certain size should be found to operate perfectly well, +giving prompt ignition in the cartridge case of a rifle of small +caliber, it would be found that the same primer would not ignite a +charge of the same powder if loaded into a gun of one inch caliber. In +the latter case a few grains only lying near the primer would be +ignited, and these would soon become extinguished by sudden release of +pressure bringing about a cooling effect due to expansion of the gases. +In small cartridges a large fulminating cap is all that is required, but +in large cartridges it is necessary to resort to additional means of +ignition. + +In France, where experiments were conducted with a 37 millimeter Maxim +gun, it was found to be impracticable to use a fulminating cap +sufficiently large to ignite the powder and cause it to burn. Therefore, +a small ignition charge of black powder was employed, it being put in a +capsule or bag and placed next the primer. On firing at the rate of 300 +rounds per minute, the black powder, though small in quantity, produced +a cloud of smoke through which it was quite impossible to see. The +inventor of the gun then prepared for the French some wafers of +pyroxyline canvas, which were placed next to the primer, securing +thereby prompt ignition without the production of any smoke. + +Smokeless powder, made as I have described, cannot be detonated by a +fulminating cap of any size or by any means whatever. A large charge of +fulminate of mercury placed inside the cartridge case next the primer +will not detonate the powder, it serving only to ignite it and cause it +to explode. But even this would not cause the powder to explode except +it be confined behind a projectile, that sufficient pressure may be run +up to make it burn in its own gases. + +Some curious experiments with smokeless powder may be tried with a shot +gun. If the fulminating cap be large, the powder fine, the wads numerous +and hard and the charge of shot heavy, all being well rammed down, and +the paper case well spun over the last pasteboard wad, a charge of +smokeless powder about equal in weight to one-half of what would be +employed of black powder would give about the same results as black +powder. But if the charge of shot be omitted, the primer will only +ignite the powder, and there will be set up sufficient pressure merely +to throw the wads about half way up the barrel of the gun, when the +powder will go out. Now if this same charge of powder be collected and +reloaded into a new cartridge case and well confined behind wads and a +charge of shot, as above explained, it will all burn, giving the same +results as black powder. + +Attempts have been made to use this powder in pistols and revolvers, but +here it has proved a failure, as the pressure is not great enough to +cause the powder to be consumed, unless it be in the form of very fine +grains or dust, in which case the pressure mounts too high. However, +this might be overcome to a degree by making the powder porous. The +chemical conditions of the powder might be the same, but the physical +conditions must be different. A powder suitable for shot guns and +pistols would not be suitable for rifles. + +One not familiar with the characteristics of smokeless powder would be +almost certain to fail in his first attempt to fire it. Many persons +have been convinced by their first experiments that this powder would +not burn at all in a gun, any more than so much sand. + +Smokeless powder is consumed with a rapidity which accords with the +conditions of its confinement. Therefore, the bullets which have been +experimented with by different governments have been the cause of much +of the varying pressures attributed to the smokeless powders. + +The Austrians use the Mannlicher steel jacketed bullet. The steel casing +or jacket is first tinned on the inside and then the lead is cast in, +thus melting the tin and adhering firmly to the jacket. This projectile +sets up enormous friction in the barrel of the gun when used with +smokeless powder; as the smokeless powder leaves the gun barrel +perfectly clean and the two steel surfaces being in absolute contact +cause tremendous friction; and as the coefficient of friction varies +with every shot, the pressure in the gun constantly varies greatly. + +The German silver covered bullet used by the French has the disadvantage +that when firing rapidly the chamber of the barrel becomes nickel plated +and great friction is caused, mounting up the pressures and causing the +muzzle velocities to fall off. + +The Austrians, in order to prevent their steel cased bullets from +rusting and to lessen the friction in the barrel of the gun, cover them +with a heavy lubricant, which gives the cartridges an unsightly +appearance and causes them to gather dust and sand. The French employ a +lubricant at the base of the projectile, with a small copper disk +between the same and the powder. + +Col. A.R. Buffington, commander of the National Armory at Springfield, +Mass., has made a steel covered projectile which he prevents from +rusting by blackening by a niter process. Several grooves are pressed in +the base of the bullet which carry a lubricant, and when the bullet is +inserted in the cartridge case the grooves are covered by it. +Furthermore, these grooves prevent the lead filling from bursting +through the steel casing, leaving the latter in the barrel, as often +occurs with the Austrian and French projectiles when using smokeless +powder. + +A new projectile has lately come out, the invention of Captain Edward +Palliser, of the British army. This bullet consists of a jacket made of +very soft Swedish wrought iron, coated with zinc and filled with lead, +the lead being pressed into this jacket. The bullet is corrugated at its +base, after the manner of the one made by Colonel Buffington. This +projectile has been experimented with very extensively by the British +government, and at the works of the Maxim-Nordenfelt Guns and Ammunition +Company, in England. The zinc coating of the bullet is too soft to stick +to the barrel of the gun, and also in a measure acts as a lubricant. +This projectile has given better results than any other that has been +experimented with. The great velocities and the most uniform pressures +by the use of smokeless powder have been attained with this Palliser +bullet. + + +NOISELESSNESS. + +A great many stories have been told about the noiselessness of smokeless +powder. But there is no such thing as a noiseless gunpowder. The report +of a gun charged with smokeless powder is very sharp, and is as loud as +when black powder is used, yet the volume of sound is much less, so that +the report cannot be heard at so great a distance. + +The report of a gun using smokeless powder is a sound of much higher +pitch than when black powder is used, and consequently cannot be heard +at so great a distance as the lower notes given by black powder. + +As smokeless powder exerts a much greater pressure than common black +powder when burned in a gun, one would naturally think that the recoil +of the barrel would be greater, owing to the greater pressure exerted by +the smokeless powder on the base of the cartridge case and the breech +mechanism. However, such is not the fact; for the barrel actually +recoils very much less when smokeless powder is used. This is due to the +suddenness with which the pressure is exerted by smokeless powder, it +acting more like a very sharp blow on the metal, whereby more of the +energy is converted into heat instead of being spent in overcoming the +inertia of the barrel to give recoil. Similarly when smokeless powder is +fired in a gun, the displacement of the air is so sudden that the sound +waves do not possess the same amplitude of recoil or vibration as is +given by black powder. + + * * * * * + + + + +THE CONSTRUCTION AND MAINTENANCE OF UNDERGROUND CIRCUITS. + +BY S.B. FOWLER. + + +The numerous disastrous storms of the last winter have brought out very +vividly the advantages of having all wires placed underground, and many +inquiries have been addressed to the companies operating underground +circuits as to their success. It is not probable that all of the answers +to these inquiries have been of the most favorable character. To many +central station managers an underground system means frequent +break-downs and interruptions of service, with, perhaps, slow and +expensive repairs, which bring in their turn numerous complaints, loss +of customers, and reduced profits. In many installations burn-outs both +underground and in the station are frequent, with the natural result +that the operating of circuits underground is not there considered an +unqualified success. The writer has in mind two very different +experiences with underground cables. Several miles of cable were bought +by a certain company, carefully laid, and up to to-day not a single +burn-out or interruption of service can be attributed to failure of +cables; at about the same time another company bought about an equal +amount of the same kind of cable, and in a comparatively short time the +current had to be shut off the lines and the whole installation repaired +and parts of it replaced. Both of these experiences have been repeated +many times and will be again, although it is simply a distinction +between a good cable properly laid and a good cable ruined by careless +and incompetent workmanship. + +Every failure can be traced to poor work in the original installation or +to the use of a cheap cable, both causes being due, generally, to that +false economy which looks for too quick returns. A poorly insulated line +wire and a poorly insulated cable are two very different things. +However, it is a fact that by the use of a good cable it is not +difficult to construct an underground system for light, power, telegraph +or telephone uses that will be superior to overhead lines in its service +and in cost of maintenance. The ideal underground system must have as a +starting point a system of subways admitting of the easy drawing in and +out of cables and affording means of making subsidiary connections +readily and with the minimum of expense and interruption of service. +This is practically accomplished by a subway consisting of lines of pipe +terminating at convenient intervals, say at street intersections, in +manholes, for convenience in jointing and in running out house +connections. These pipes, or ducts, as they are called, should be for +two kinds of service; the lower or deeper laid lines for the main or +trunk circuits, and a second series of ducts laid nearer the surface, +running into service boxes placed near together for lines to "house to +house" connections. In some cities where it is allowed to run overhead +lines, the plan of running but one service connection in a block is +followed, all customers in the block being supplied from a line run over +the housetops or strung on the rear walls. + +This makes unnecessary all subsidiary ducts except a short one from the +manhole to the nearest building in the block, and effects a considerable +saving in pipe, service boxes, cables and labor. The manholes should +have their walls built up of brick, the floors should be of concrete, +and there should be an inside lid which can be fastened down and the +manhole thus made water-tight. + +For ducts wood, iron or cement lined pipe may be used. To preserve the +wood it is generally treated with creosote, which, in contact with the +lead cover of the cable, sets up a chemical action, resulting in the +destruction of the lead. Wood offers but little protection for the +cable, as it is too easily damaged and broken through in the frequent +street openings made by companies operating lines of pipe in the +streets, and as one of the main purposes of a subway is that of a +protection to cables, wooden ducts have little to recommend them except +their cheapness. + +Iron pipes are either laid in trenches filled in with earth or are laid +in cement. Iron pipe will of course rust out in time, and if absolute +permanence in construction is desired, should be laid in cement, for +after the pipe rusts out, the duct of cement is still left. However, if +we are going to the expense of laying in cement, it would be much +preferable to use cement lined pipe, which is not only cheaper than iron +pipe, but makes the most perfect cable conduit, as it affords a +perfectly smooth surface to draw the cable over and give a good duct +edge. + +It is not necessary, however, in small installations of cable, +especially where additional connections will not be of frequent +occurrence, to go to the expense of subways, for cable may be safely +laid in the ground in trenches filled in with earth, or can be inclosed +in a plain wooden box or a wooden box filled with pitch. + +There are, of course, many localities where, if the cable is laid in +contact with the earth, a chemical action would take place which might +result in the destruction of the cable. + +Underground cables are of the following classes: 1. Rubber insulated +cables, insulated with rubber or other homogeneous material. 2. Fibrous +cables, so called from the conductors being covered with some fibrous +material, as cotton or paper, which is saturated with the insulating +material, paraffine, resin oil, or some special compound. Under this +latter head is also included the dry core paper cables. + +The first thing to do is to get the cable drawn into the ducts, and on +the proper accomplishment of this depends to a great extent the success +or failure of the whole installation. Probably the ducts have been wired +when the subway was constructed, but if not a wire must be run through +as a means of pulling in the draw rope. There are several kinds of +apparatus for getting a wire through a duct--rods, flexible tapes, +mechanical "creepers," etc.; but probably the best is the sectional rod. +This simply consists of three or four foot lengths of hard wood rods, +having metal tips that screw into each other. A rod is placed in a duct +at a manhole, one screwed to that, both are pushed forward, another one +added and pushed forward, and so on until they extend the entire length +of the duct. Then the wire is attached and the rods are pulled out and +detached one at a time and with the last rod the wire is through. At +least No. 14 galvanized iron or steel wire should be used, for any +smaller size cannot be used a second time, as a rule. In starting to +pull in the draw rope a wire brush should be attached to the wire and to +this again the rope, and when the brush arrives at the distant end of +the duct it very likely will bring with it a miscellaneous collection of +material which for the good of the cable had better be in the manhole +than in the duct. + +The reel or drum carrying the cable should be mounted on wheels or jacks +and placed on the same side of the manhole as the duct into which the +cable is to be drawn, and must always be so placed that the cable will +run off the top of the reel. + +There are several methods of attaching the draw rope to the cable. As +simple and strong a method as any is to punch two of these holes through +the cable, lead and all, and attach the rope by means of an iron +wire--some of the draw wire will do--run through these holes. Depending +on the length and weight of cable to be pulled it can be drawn either by +hand or by a multiplying winch. The rope should run through a block +fastened in the manhole in such a position that the rope shall have a +good straightaway lead from the mouth of the duct. + +The strain on the cable should be perfectly uniform and steady; if the +power is applied by a series of jerks either the lead covering may be +pulled apart or some of the conductors broken. At the reel there must +always be a large enough number of men to turn it and keep the cable +from rubbing on anything, and in the manhole one or more men to see that +the cable feeds into the duct straight and to guide it if necessary. If +the ducts are of iron and are not perfectly smooth at the ends, these +should be made so with a file, and in addition a protector of some sort +should be placed in the mouths of the duct, both above and below the +cable. Six inches of lead pipe, split lengthwise and bent over at one +end to prevent being drawn into the duct with the cable, makes a very +good protector. The cable should be reeled off the drum just fast enough +to prevent any of the power used in pulling the cable through the duct +being utilized in unreeling it. If this latter is allowed to occur the +cable will be bent too short and the lead covering buckled or broken, +and also the cable may be jammed against the upper edge of the duct and +perhaps cut through. + +If the reel is allowed to turn faster than the cable is drawn in, the +first three or four turns on the reel will slacken up, and the lead +covering may either be dented or cut through by scraping on the ground. +If the cable end when pulled through up to the block is not long enough +to bend around the hole more than half way, the rope should be +unfastened from its end, a length of rope with a well frayed out end +should be run through the block, and by fastening to the cable close to +the duct, with a series of half hitches, as much slack as necessary can +be pulled in. If this is properly manipulated there need not be a +scratch on the cable, but unless great care is taken the lead may be +pressed up into ridges and the core itself damaged. + +Immediately after the cable is drawn in, if the joint is not to be at +once made, the open end or ends should be cut off and the cable soldered +up, as most cables are very susceptible to moisture and readily absorb +water even from the atmosphere. Where practicable it is always a good +plan to pull the cable through as many manholes as possible without +cutting the cable; for the joint is, especially in telephone or +telegraph cables, the weak point. To do this the rope should be pulled +through the proper duct in the next section without unfastening it from +the cable; the winch should be moved to the next manhole, and pulling +through then done as before. There should always be a man in every hole +through which the cable is running to see that it does not bind anywhere +and to keep protectors around the cable. + +It is not advisable to pull more than one cable into a duct, and never +advisable to pull a cable into a duct containing another cable, but if +two or more cables have to go into the same duct, they should always be +drawn in together. Lead covered cables and those with no lead on the +outside should never be pulled into the same duct, for if they bind +anywhere the soft cable will suffer where two lead covered cables would +get through all right. Some manufacturers are now putting on their +cables a tape or braid covering, which saves the lead many bad bruises +and cuts, and is a valuable addition to a cable at very little +additional expense. + +Practically all electric light and power cables are either single or +double conductors, and the jointing of these is comparatively a simple +matter, although requiring considerable care. The lead is cut back from +each end about four or five inches, and the conductors bared of +insulation for two or three inches. The bare conductors should be +thoroughly tinned by dipping in the metal pot or pouring the melted +solder over them. A sperm candle is better than resin or acid for any +part of the operations where solder is used. A lead sleeve is here +slipped back over the cable, out of the way, and the ends of the +conductors brought together in a copper sleeve which is then sweated to +a firm joint. This part must be as good a piece of work mechanically as +electrically. The bare splice is then wrapped tightly with cotton or +silk tape to a thickness slightly greater than that of the insulation of +the cable, and is thoroughly saturated with the insulating compound +until all moisture previously absorbed by the tape is driven off. + +The lead sleeve is then brought over the splice and wiped to the cable. +The joint is then filled with the insulating compound poured through +holes in the top of the sleeve; these holes are then closed and the +joint is complete, and there is no reason why, in light and power +cables, that joint should not be as perfect as any other part of the +cable. When the cable ends are prepared for jointing they should be hung +up in such a position that they are in the same plane, both horizontal +and vertically, and firmly secured there, so that when the lead sleeve +is wiped on the conductor may be in its exact center, and great care +must be taken not to move the cables again until the sleeve is filled +and the insulation sufficiently cooled to hold the conductor in +position. + +It is also very important to see that there are no sharp points on the +conductors themselves, on the copper sleeve, on the edges of the lead +covering or on the lead sleeve. All these should be made perfectly +smooth, for points facilitate disruptive discharges. Branch joints had +better be made as T-joints rather than as Y-joints, for they are better +electrically and mechanically, although they occupy more room in the +manholes. They are of course made in the same way as straight joints, a +lead T-sleeve being used, however. For multiple arc circuits copper +T-sleeves and for series circuits copper L-sleeves are used. + +Telephone and telegraph cables are made of any required gauge of wire +and with from 1 to 150 conductors in a cable. In jointing these the +splices are never soldered, the conductors being joined either with a +twist joint or with the so-called Western Union splice. Each splice is +covered with a cotton or silk sleeve or a wrapping of tape, the latter +being preferable, although considerably increasing the time necessary +for making the joint. Great care must be taken that no ends of wire are +left sticking up, for they will surely work their way through the tape +and grounds, and crosses will be the result. The wires should always be +joined layer to layer and each splice very tightly taped in order to get +as much insulating compound around each splice as possible in the +limited space. The splices should be "broken" as much as possible, so as +to avoid having adjoining splices coming over each other. After the +joint has been saturated with insulating compound the wires should have +an outside wrapping of tape to keep them in shape, and then the sleeve +is wiped on and filled. If the insulation resistance of the jointed +telegraph or telephone cable is a quarter of what the cable tested in +the factory, it may be considered that an exceptionally good piece of +work has been done. I have spoken more particularly of fibrous lead +covered cables, as the handling of them includes practically every step +of the work on any other kind of underground cable. In insulating dry +core paper cables a paper sleeve is slipped over the splice, and in +rubber cables the splice is wrapped with rubber tape; all other details +are the same for these as for the fibrous cable. + +In the laying of light and power cables every joint, as made, should be +tested for insulation with a Thomson galvanometer, as the insulation +must necessarily be very high, and if one joint or section of cable is +any weaker than another it may be very important in the future to know +it. All tests must be made after the joint has cooled, for while hot its +insulation resistance will be very low. + +Tests for copper resistance should also be made to determine if the +splices are electrically perfect; an imperfect splice may cause +considerable trouble. In telegraph and telephone cables the conductors +should be of very soft copper, for in stripping the conductor of +insulation it is very easy to nick the wire, and if of hard drawn copper +open wires will be the result. + +All work should be frequently tested for continuity with telephones, +magnetos, or small portable galvanometers. It is only necessary to +ground the conductors at one end and try each wire at the other end. For +this sort of work a telephone receiver used with one cell of some dry +battery is most convenient, and has the additional advantage of +affording a means of communication while testing, and is by far the best +thing for identifying and tagging conductors. + +These cables should be frequently tested during the progress of the work +for grounds and crosses with a Thomson instrument, and when the cable is +complete, a careful series of tests of the capacity, insulation +resistance, and copper resistance of each wire should be made and the +exact condition of the cable determined before it is put in service, and +thereafter an intelligent oversight of the condition of the circuits +can thus be more readily maintained. + +Where a company has extensive underground service, a regular cable gang +should be in its employ, for quick and safe handling of cables demands +the employment of men accustomed to the work. If the cable has been +properly laid and tests show it to be in good condition before current +is turned on, almost the only trouble to be anticipated will be due to +mechanical injury. Disruptive discharge, puncturing the lead, may occur; +but the small chance of its occurring can be greatly lessened by the use +of some kind of "cable protector," which will provide for the spark an +artificial path of less resistance than the dielectric of the condenser, +which the cable in fact becomes. + +If a fault suddenly develops on a circuit, the chances are it will be +found in a manhole, and an inspection of the cable in the manhole will +generally reveal the trouble without resorting to locating with a +Wheatstone bridge. The cable is often cut through at the edge of the +duct, or damaged by something falling on it, or by some one "walking all +over it." To guard against these, the ducts should always be fitted with +protectors both above and below the cable. The cables should never be +left across the manholes, for they then answer the purpose of a ladder, +but should be bent, around the walls of the hole and securely fastened +with lead straps, that they may not be moved and the lead gradually worn +through. + +In telegraph cables, when one or two conductors "go," it will probably +be useless to look for trouble except with instruments; but if several +wires are "lost" at once it will probably be found to be caused by +mechanical injury, which can be located by inspection. If it is ever +necessary to loop out conductors, a joint can be readily opened and the +conductors wanted picked out and connected into the branch cable and the +joint again closed without disturbing the working wires. In doing this a +split sleeve must be used, and the only additional precaution to be +taken is in filling the sleeve to have the insulating compound not hot +enough to melt the solder and open up the split in the sleeve. In +cutting in service on light and power cables it is entirely practicable +to do so without interruption of service on multiple arc circuits, even +those of very high voltage; but they require great precaution and +involve considerable risk to the jointer, and where possible the circuit +to which the connection is to be made should previously be cut dead. +Where the voltage is not dangerous to human life, almost any service +connection can be made without interruption of service. + +I have only indicated a very few of the operations that may be found +necessary, and the probable causes of troubles that may be encountered +in the operating of underground circuits, believing that the different +problems that arise can, with a little experience, be successfully met +by any one who has a fair knowledge of the original construction of +cable lines.--_Electrical World_. + + * * * * * + + + + +RAILROADS TO THE CLOUDS. + + +If George Stephenson, when he placed the first locomotive on the track +and guaranteed it a speed of six miles an hour, could have foreseen that +in less than eighty years the successors of his rude machine would be +climbing the sides of mountain ranges, piercing gorges hitherto deemed +inaccessible, crossing ravines on bridges higher than the dome of St. +Paul's, and traversing the bowels of the earth by means of tunnels, no +doubt his big blue eyes would have stood out with wonder and amazement. +But he foresaw nothing of the kind; the only problem present in his mind +was how to get goods from the seaports in western England to London as +easily and cheaply as possible, and to do this he substituted for +horses, which had for 150 years been drawing cars along wooden or iron +tracks, the wonderful machine which has revolutionized the freight and +passenger traffic of the world. + +It was, indeed, impossible for any one to foresee the triumphs of +engineering which have accompanied the advances in transportation. To +the engineer of the present day there are no impossibilities. The +engineer is a wizard at whose command space and matter are annihilated. +The highest mountain, the deepest valley, has no terrors for him. He can +bridge the latter and encircle or tunnel the former. The only requisites +which he demands are that something in his line be needed, and that the +money is forthcoming to defray the expense, and the thing will be done. +But the railroad he is asked to construct must be necessary, and the +necessity must be plainly shown, or no funds will be advanced; and +although the theory does not invariably hold good, especially when a +craze for railroad building is raging, as a rule no expense for the +construction of a road will be incurred without a prospect of +remuneration. + +Hence the need of railroad communication has caused lines to be +constructed through districts where only a few years ago the thing would +have been deemed impossible. The Pacific roads of this country were a +necessity long before their construction, and in the face of +difficulties almost insuperable were carried to successful completion. +So, also, of the railroads in the Andes of South America. The famous +road from Callao through the heart of Peru is one of the highest +mountain roads in the world, as well as of the most difficult +construction. The grades are often of 300 feet and more to the mile, and +when the mountains were reached so great were the difficulties the +engineers were forced to confront that in some places laborers were +lowered from cliffs by ropes in order that, with toil and difficulty, +they might carve a foothold in order to begin the cutting for the +roadway. + +In some sections tunnels are more numerous than open cuts, and so far as +the road has gone sixty-one tunnels, great and small, have been +constructed, aggregating over 20,000 feet in length. The road attains a +height of 15,000 feet above the level of the sea, and at the highest +point of the track is about as high as the topmost peak of Mont Blanc. +It pierces the range above it by a tunnel 3,847 feet long. The stern +necessities of business compelled the construction of this road, +otherwise it never would have been begun. + +The tunnels of the Andes, however, do not bear comparison with the +tunnels, bridges, and snow sheds of the Union Pacific, nor do even these +compare with the vast undertakings in the Alps--three great tunnels of +nine to eleven miles in length, which have been prepared for the +transit of travelers and freight. The requirements of business +necessitated the piercing of the Alps, and as soon as the necessity was +shown, funds in abundance were forthcoming for the enterprise. + +But tunneling a mountain is a different thing from climbing it. Many +years ago the attention of inventors was directed to the practicability +of constructing a railroad up the side of a mountain on grades which, to +an ordinary engine, were quite impossible. The improvements in +locomotives twenty-five and thirty years ago rendered them capable of +climbing grades which, in the early days of railroad engineering, were +deemed out of the question. The improvements proved a serious stumbling +block in the way of the inventors, who found that an ordinary locomotive +was able to climb a much steeper grade than was commonly supposed. The +first railroads were laid almost level, but it was soon discovered that +a grade of a few feet to the mile was no impediment to progress, and +gradually the grade was steepened. + +The inventors of mountain railroad transportation might have been +discouraged by this discovery, but it is a characteristic of an inventor +that he is not set back by opposition, which, in fact, only serves to +stimulate his zeal. The projectors of inclined roads and mountain +engines kept steadily on, and in France, Germany, England, and the +United States many experimental roads were constructed, each of a few +hundred yards in length, and locomotive models were built and put in +motion to the amazement of the general public, who jeered alike at the +contrivances and the contrivers, deeming the former impracticable and +the latter crazy. + +But the idea of building a road up the side of a hill was not to be +dismissed. There was money in it for the successful man, so the cranky +inventors kept on at work in spite of the jeers of the rabble and the +discouragements of capitalists loath to invest their money in an +uncertain scheme. To the energy and perseverance of railroad inventors +the success of the mountain railroad is due, as also is the construction +of the various mountain roads, of which the road up Mt. Washington, +finished in 1868, was the first, and the road up Pike's Peak, completed +the other day, was the latest. + +Of all the mountain roads which have been constructed since the one up +Mt. Washington was finished, the best known is that which ascends the +world-famous Rigi. With the exception of Mont Blanc, Rigi is, perhaps, +the best known of any peak in the Alps, though it is by no means the +highest, its summit being but 5,905 feet above the level of the sea. +Although scarcely more than a third of the height of some other +mountains in the Alps, it seems much higher because of its isolated +position. Standing as it does between lakes Lucerne, Zug, and Lowertz, +it commands a series of fine views in every direction, and he who looks +from the summit of Rigi, if he does no other traveling in Switzerland, +can gain a fair idea of the Swiss mountain scenery. Many of the most +noted peaks are in sight, and from the Rigi can be seen the three lakes +beneath, the villages which here and there dot the shores, and, further +on, the mighty Alps, with their glaciers and eternal snows. + +Many years ago a hotel was built on the summit of the Rigi for the +benefit of the tourists who daily flocked to this remarkable peak to +enjoy the benefit of its wonderful scenery. The mountain is densely +wooded save where the trees have been cut away to clear the land for +pastures. The ease of its ascent by the six or eight mule paths which +had been made, the gradual and almost regular slope, and the throngs of +travelers who resorted to it, made it a favorable place for an +experiment, and to Rigi went the engineers in order to ascertain the +practicability of such a road. The credit of the designs is due to a +German engineer named Regenbach, who, about the year 1861, designed the +idea of a mountain road, and drew up plans not only for the bed but also +for the engine and cars. The scheme dragged. Capitalists were slow to +invest their money in what they deemed a wild and impracticable +undertaking, and even the owners of the land on the Rigi were reluctant +for such an experiment to be tried. But Regenbach persevered, and toward +the close of the decade the inhabitants of Vitznau, at the base of the +Rigi, were astonished to see gangs of laborers begin the work of making +a clearing through the forests on the mountain slope. They inquired what +it meant, and were told that a road up the Rigi was to be made. The +Vitznauers were delighted, for they had no roads, and there was not a +wheeled vehicle in the town, nor a highway by which it could be brought +thither. The idea of a railroad in their desolate mountain region, and, +above all, a railroad up the Rigi, never entered their heads, and a +report which some time after obtained currency in the town, that the +laborers were beginning the construction of a railroad, was greeted with +a shout of derision. + +Nevertheless, that was the beginning of the Rigi line, and in May, 1871, +the road was opened for traffic. It begins at Vitznau, on Lake Lucerne, +and extends to the border of the canton and almost to the top of the +mountain. It is 19,000 feet long, and during that distance rises 4,000 +feet at an average grade of 1 foot in 4. Though steep, it is by no means +so much so as the Mt. Washington road, which rises 5,285 feet above the +sea, at an average of 1 foot in 3. There are, however, stretches of the +Rigi road at which the grade is about 1 foot in 21/2, which is believed to +be the steepest in the world. + +The Rigi road has several special features aside from its terrific +slopes which entitle it to be considered a triumph of the engineer's +skill. About midway up the mountains the builders came to a solid mass +of rock, which presented a barrier that to a surface road was +impassable. They determined to tunnel it, and, after an enormous +expenditure of labor, finished an inclined tunnel 225 feet in length, of +the same gradient as the road. A gorge in the side of the mountain where +a small stream, the Schnurtobel, had cut itself a passage also hindered +their way, and was crossed by a bridge of lattice girder work in three +spans, each 85 feet long. The entire roadbed, from beginning to end, was +cut in the solid rock. A channel was chiseled out to admit the central +beam, which contains the cogs fitting the driving wheel of the +locomotive. The engine is in the rear of the train, and presents the +exceedingly curious feature of a boiler greatly inclined, in order that +at the steeper gradients it may remain almost perpendicular. The coal +and water are contained in boxes over the driving wheels, so that all +the weight of the engine is really concentrated on the cogs--a +precaution to prevent their slipping. The cost of the road, including +three of these strangely constructed locomotives, three passenger +coaches, and three open wagons, was $260,000, and it is a good paying +investment. The fare demanded for the trip up the mountains is 5 francs, +while half that sum is required for the downward passage, and the road +is annually traversed by from 30,000 to 50,000 passengers. + +Curious sensations are produced by a ride up this remarkable line. The +seats of the cars are inclined like the boiler of the locomotive, and so +long as the cars are on a level the seats tilt at an angle which renders +it almost impossible to use them. But when the start is made the +frightful tilt places the body in an upright position, and, with the +engine in the rear, the train starts up the hill with an easy, gliding +motion, passing up the ascent, somewhat steeper than the roof of a +house, without the slightest apparent effort. But if the going up +excites tremor, much more peculiar are the feelings aroused on the down +grade. The trip begins with a gentle descent, and all at once the +traveler looking ahead sees the road apparently come an end. On a nearer +approach he is undeceived and observes before him a long decline which +appears too steep even to walk down. Involuntarily he catches at the +seats, expecting a great acceleration of speed. Very nervous are his +feelings as the train approaches this terrible slope, but on coming to +the incline the engine dips and goes on not a whit faster than before +and not more rapidly on the down than on the up grade. Many people are +made sick by the sensation of falling experienced on the down run. Some +faint, and a few years ago one traveler, supposed to be afflicted with +heart disease, died of fright when the train was going over the +Schnurtobel bridge. The danger is really very slight, there not having +been a serious accident since the road was opened. The attendants are +watchful, the brakes are strong, but even with all these safeguards, men +of the steadiest nerves cannot help wondering what would become of them +in case anything went wrong. + +Bold as was the project of a railroad on the Rigi, a still bolder scheme +was broached ten years later, when a daring genius proposed a railroad +up Mt. Vesuvius. A railroad up the side of an ordinary mountain seemed +hazardous enough, but to build a line on the slope of a volcano, which +in its eruption had buried cities, and every few years was subject to a +violent spasm, seemed as hazardous as to trust the rails of an ordinary +line to the rotten river ice in spring time. The proposal was not, +however, so impracticable as it looked. While the summit of Vesuvius +changes from time to time from the frequent eruptions, and varies in +height and in the size of the crater, the general slope and contour of +the mountain are about the same to-day as when Vesuvius, a wooded hill, +with a valley and lake in the center of its quiescent crater, served as +the stronghold of Spartacus and his rebel gladiators. There have been +scores of eruptions since that in which Herculaneum and Pompeii were +overthrown, but the sides of the mountain have never been seriously +disturbed. + +A road on Vesuvius gave promise of being a good speculation. Naples and +the other resorts of the neighborhood annually attracted many thousands +of visitors, and a considerable number of these every year ascended the +volcano, even when forced to contend with all the difficulties of the +way. Many, however, desiring to ascend, but being unable or unwilling to +walk up, a chair service was established--a peculiar chair being slung +on poles and borne by porters. In course of time the chair service +proved to be inadequate for the numbers who desired to make the ascent, +and the time was deemed fit for the establishment of more speedy +communication. + +Notwithstanding the necessity, the proposal to establish a railroad met +with general derision, but the scheme was soon shown to be perfectly +practicable, and a beginning was made in 1879. The road is what is known +as a cable road, there being a single sleeper with three rails, one on +the top which really bore the weight, and one on each side near the +bottom, which supported the wheels, which coming out from the axle at a +sharp angle, prevented the vehicle from being overturned. The road +covers the last 4,000 feet of the ascent, and the power house is at the +bottom, a steel cable running up, passing round a wheel at the top and +returning to the engine in the power house. The ascent to the lower +terminus of the road is made on mules or donkeys; then, in a comfortable +car, the traveler is carried to a point not far from the crater. The car +is a combined grip and a passenger car, similar in some points to the +grip car of the present day, while the seats of the passenger portion +are inclined as in the cars on the Rigi road. But the angle of the road +being from thirty-three to forty-five degrees, makes both ascent and +descent seem fearfully perilous. Every precaution, however, is taken to +insure the safety of passengers; each car is provided with several +strong and independent brakes, and thus far no accident worth recording +has occurred. The road was opened in June, 1880. Although there have +been several considerable eruptions since that date, none of them did +any damage to the line but what was repaired in a few hours. + +The fashion thus set will, no doubt, be followed in many other quarters. +Wherever there is sufficient travel to pay working expenses and a profit +on a steep grade mountain road it will probably be built. Already there +is talk of a road on Mont Blanc, of another up the Yungfrau, and several +have been projected in the Schwartz and Hartz mountains. A route on Ben +Nevis, in Scotland, is already surveyed, and it is said surveys have +also been made up Snowden, with a view to the establishment of a road to +the summit of the highest Welsh peak. Sufficient travel is all that is +necessary, and when that is guaranteed, whenever a mountain possesses +sufficient interest to induce people to make its ascent in considerable +numbers, means of transportation, safe and speedy, will soon be +provided. The modern engineer is able, willing and ready to build a road +to the top of Mt. Everest in the Himalayas if he is paid for doing +so.--_St. Louis Globe-Democrat._ + + * * * * * + +To clean hair brushes, wash with weak solution of washing soda, rinse +out all the soda, and expose to sun. + + * * * * * + + + + +THE MARCEAU. + + +[Illustration: THE FRENCH ARMORED TURRET SHIP MARCEAU] + +The Marceau, the last ironclad completed and added to the French navy, +was put in commission at Toulon in April last, and has lately left that +town to join the French squadron of the north at Brest. The original +designs of this ship were prepared by M. Huin, of the French Department +of Naval Construction, but since the laying down of the keel in the year +1882 they have been very considerably modified, and many improvements +have been introduced. + +Both ship and engines were constructed by the celebrated French firm, +the Societe des Forges et Chantiers de la Mediterranee, the former at +their shipyard in La Seyne and the latter at their engine works in +Marseilles. The ship was five years in construction on the stocks, was +launched in May, 1887, and not having been put in commission until the +present year, was thus nearly nine years in construction. She is a +barbette belted ship of somewhat similar design to the French ironclads +Magenta, now being completed at the Toulon arsenal, and the Neptune, in +construction at Brest. + +The hull is constructed partly of steel and partly of iron, and has the +principal dimensions as follows. Length, 330 ft. at the water line; +beam, 66 ft. outside the armor; draught, 27 ft. 6 in. aft.; +displacement, 10,430 English or 10,600 French tons. The engines are two +in number, one driving each propeller; they are of the vertical compound +type, and on the speed trials developed 11,300 indicated horse power +under forced and 5,500 indicated horse power under natural draught, the +former giving a speed of 16.2 knots per hour with 90 revolutions per +minute. The boilers are eight in number, of the cylindrical marine type, +and work at a pressure of 85.3 lb. per square inch. During the trials +the steering powers of the ship were found to be excellent, but the bow +wave is said, by one critic, to have been very great. + +The ship is completely belted with Creusot steel armor, which varies in +thickness from 9 in. forward to 173/4 in. midships. In addition to this +belt the ship is protected by an armored deck of 31/2 in., while the +barbette gun towers are protected with 153/4 in. steel armor with a hood +of 21/2 in. to protect the men against machine gun fire. As a further +means of insuring the life of the ship in combat and also against +accidents at sea, the Marceau is divided into 102 water-tight +compartments and is fitted with torpedo defense netting. There are two +masts, each carrying double military tops; and a conning tower is +mounted on each mast, from either of which the ship may be worked in +time of action, and both of which are in telegraphic communication with +the engine rooms and magazines. Provision is made for carrying 600 tons +of coal, which, at a speed of 10 knots, should be sufficient to supply +the boilers for a voyage of 4,000 miles. + +The armament of the Marceau is good for the tonnage of the ship and +consists principally of four guns of 34 centimeters (13.39 in.) of the +French 1884 model, having a weight of 52 tons, a length of 281/2 calibers, +and being able to pierce 30 in. of iron armor at the muzzle. The +projectiles weigh 924 lb., and are fired with a charge of 387 lb. of +powder. The muzzle velocity has been calculated to be 1,968 ft. per +second. The guns are entirely of steel and are mounted on Canet +carriages in four barbette towers, one forward, one aft, and one on each +side amidships. On the firing trials both the guns and all the Canet +machinery, for working the guns and hoisting the ammunition, gave very +great satisfaction to all present at the time. In addition to the above +four heavy guns there are, in the broadside battery, sixteen guns of 14 +centimeters (5.51 in.), eight on each side, and a gun of equal caliber +is mounted right forward on the same deck. The armament is completed by +a large number of Hotchkiss quick-firing and revolver guns and four +torpedo tubes, one forward, one aft, and one on each side. + +The crew of the Marceau has been fixed at 600 men, and the cost is +stated to have been about $3,750,000.--_Engineering_. + + * * * * * + +[Continued from SUPPLEMENT, No. 820, page 13097.] + + + + +A REVIEW OF MARINE ENGINEERING DURING THE PAST DECADE.[1] + +[Footnote 1: Paper read before the Institution of Mechanical Engineers, +July 28, 1891.] + +BY MR. ALFRED BLECHYNDEN, OF BARROW-IN-FURNESS + + +_Steam Pipes_.--The failures of copper steam pipes on board the Elbe, +Lahn, and other vessels have drawn serious attention both to the +material and to the modes of construction of the pipes. The want of +elastic strength in copper is an important element in the matter; and +the three following remedies have been proposed, while still retaining +copper as the material. First, in view of the fact that in the operation +of brazing the copper may be seriously injured, to use solid drawn +tubes. This appears fairly to meet the main dangers incidental to +brazing; but as solid drawn pipes of over 7 inches diameter are +difficult to procure, it hardly meets the case sufficiently. Secondly, +to use electrically deposited tubes. At first much was promised in this +direction; but up to the present time it can hardly be regarded as more +than in the experimental stage. Thirdly, to use the ordinary brazed or +solid drawn tubes, and to re-enforce them by serving with steel cord or +steel or copper wire. This has been tried, and found to answer +perfectly. For economical reasons, as well as for insuring the minimum +of torsion to the material during manufacture, it is important to make +as few bends as possible; but in practice much less difficulty has been +experienced in serving bent pipes in a machine than would have been +expected. Discarding copper, it has been proposed to substitute steel or +iron. In the early days of the higher pressures, Mr. Alexander Taylor +adopted wrought iron for steam pipes. One fitted in the Claremont in +February, 1882, was recently removed from the vessel for experimental +purposes, and was reported upon by Mr. Magnus Sandison in a paper read +before the Northeast Coast Institution of Engineers and Shipbuilders.[2] +The following is a summary of the facts. The pipe was 5 inches external +diameter, and 0.375 inch thick. It was lap welded in the works of +Messrs. A. & J. Stewart. The flanges were screwed on and brazed +externally. The pipe was not lagged or protected in any manner. After +eight and a half years' service the metal measured where cut 0.32 and +0.375 inch in thickness, showing that the wasting during that time had +been very slight. The interior surface of the tube exhibited no signs of +pitting or corrosion. It was covered by a thin crust of black oxide, the +maximum thickness of which did not exceed 1/32 inch. Where the deposit +was thickest it was curiously striated by the action of the steam. On +the scale being removed, the original bloom on the surface of the metal +was exposed. It would thus appear that the danger from corrosion of iron +steam pipes is not borne out in their actual use; and hence so much of +the way is cleared for a stronger and more reliable material than +copper. So far the source of danger seems to be in the weld, which would +be inadmissible in larger pipes; but there is no reason why these should +not be lapped and riveted. There seems, however, a more promising way +out of the difficulty in the Mannesmann steel tubes which are now being +"spun" out of solid bars, so as to form weldless tubes. + +[Footnote 2: Transactions Northeast Coast Institution of Engineers and +Shipbuilders, vol. 7, 1890-91, p. 179.] + +TABLE I.--TENSILE STRENGTH OF GUN METAL AT HIGH TEMPERATURES. + +--------------+------------+-------------+-------------+------------+ + | | | | | + Composition |Temperature | Tensile | Elastic | Elongation | + of | of oil | strength | limit | in | + gun metal. | bath. | per square | per square | length of | + | | inch. | inch. | 2 inches | +--------------+------------+-------------+-------------+------------+ + Per cent. | Fahr. | Tons | Tons | Per cent. | + Copper 87 /| 50 deg. | 12.34 | 8.38 | 14.64 | + Tin 8 / | | | | | + Zinc 31/2 \ | | | | | + Lead 11/2 \| 400 deg. | 10.83 | 6.30 | 11.79 | +--------------+------------+-------------+-------------+------------+ + Copper 87 /| 50 deg. | 13.86 | 8.33 | 20.30 | + Tin 8 { | | | | | + Zinc 5 \| 458 deg. | 10.70 | 7.43 | 12.42 | +--------------+------------+-------------+-------------+------------+ + +Cast steel has been freely used by the writer for bends, junction +pieces, etc., of steam pipes, as well as for steam valve chests; and +except for the fact that steel makers' promises of delivery are +generally better than their performance, the result has thus far been +satisfactory in all respects. These were adopted because there existed +some doubt as to the strength of gun metal under a high temperature; and +as the data respecting its strength appeared of a doubtful character, a +series of careful tests were made to determine the tensile strength of +gun metal when at atmospheric and higher temperatures. The test bars +were all 0.75 in diameter, or 0.4417 square inch sectional area; and +those tested at the higher temperatures were broken while immersed in a +bath of oil at the temperature here stated, each line being the mean of +four experiments. The result of these experiments was to give somewhat +greater faith in gun metal as a material to be used under a higher +temperature; but as steel is much stronger, it is probably the most +advisable material to use, when the time necessary to procure it can be +allowed. + +_Feed Heating_.--With the double object of obviating strain on the +boiler through the introduction of the feed water at a low temperature, +and also of securing a greater economy of fuel, the principle of +previously heating the feed water by auxiliary means has received +considerable attention, and the ingenious method introduced by Mr. James +Weir has been widely adopted. It is founded on the fact that, if the +feed water as it is drawn from the hot well be raised in temperature by +the heat of a portion of steam introduced into it from one of the steam +receivers, the decrease of the coal necessary to generate steam from the +water of the higher temperature bears a greater ratio to the coal +required without feed heating than the power which would be developed in +the cylinder by that portion of steam would bear to the whole power +developed when passing all the steam through all the cylinders. The +temperature of the feed is of course limited by the temperature of the +steam in the receiver from which the supply for heating is drawn. +Supposing, for example, a triple expansion engine were working under the +following conditions without feed heating: Boiler pressure, 150 +lb.;--indicated horse power in high pressure cylinder 398, in +intermediate and low pressure cylinders together 790, total, 1,188; and +temperature of hot well 100 deg. Fahr. Then with feed heating the same +engine might work as follows: The feed might be heated to 220 deg. Fahr., +and the percentage of steam from the first receiver required to heat it +would be 12.2 per cent.; the indicated horse power in the high pressure +cylinder would be as before 398, and in the intermediate and low +pressure cylinders it would be 12.2 per cent, less than before, or 694, +and the total would be 1,092, or 92 per cent. of the power developed +without feed heating. Meanwhile the heat to be added to each pound of +the feed water at 220 deg. Fahr. for converting it into steam would be 1,005 +units against 1,125 units with feed at 100 deg. Fahr., equivalent to an +expenditure of only 89.4 per cent. of the heat required without feed +heating. Hence the expenditure of heat in relation to power would be +89.4 + 92.0 = 97.2 per cent., equivalent to a heat economy of 2.8 per +cent. If the steam for heating can be taken from the low pressure +receiver, the economy is about doubled. Other feed heaters, more or less +upon the same principle, have been introduced. Also others which heat +the feed in a series of pipes within the boiler, so that it is +introduced into the water in the boiler practically at boiling +temperature; this is economical, however, only in the sense that wear +and tear of the boiler is saved; in principle the plan does not involve +economy of fuel. + +_Auxiliary Supply of Fresh Water_.--Intimately associated with the feed +is the means adopted for making up the losses of fresh water due to +leakage of steam from safety valves, glands, joints, etc., and of water +discharged from the air pumps. A few years ago this loss was regularly +made up from the sea, with the result that the water in the boilers was +gradually increased in density; whence followed deposit on the internal +surfaces, and consequent loss of efficiency, and danger of accident +through overheating the plates. With the higher pressures now adopted, +the danger arising from overheating is much more serious, and the +necessity is absolute of maintaining the heating surfaces free from +deposit. This can be done only by filling the boiler with fresh water in +the first instance, and maintaining it in that condition. To do this two +methods are adopted, either separately or in conjunction. Either a +reserve supply of fresh water is carried in tanks or the supplementary +feed is distilled from sea water by special apparatus provided for the +purpose. In the construction of the distilling or evaporating apparatus +advantage has been taken of two important physical facts, namely, that, +if water be heated to a temperature higher than that corresponding with +the pressure on its surface, evaporation will take place; and that the +passage of heat from steam at one side of a plate to water at the other +is very rapid. In practice the distillation is effected by passing +steam, say from the first receiver, through a nest of tubes inside a +still or evaporator, of which the steam space is connected either with +the second receiver or with the condenser. The temperature of the steam +inside the tubes being higher than that of the steam either in the +second receiver or in the condenser, the result is that the water inside +the still is evaporated, and passes with the rest of the steam into the +condenser, where it is condensed, and serves to make up the loss. This +plan localizes the trouble of deposit, and frees it from its dangerous +character, because an evaporator cannot become overheated like a boiler, +even though it be neglected until it salts up solid; and if the same +precautions are taken in working the evaporator which used to be adopted +with low pressure boilers when they were fed with salt water, no serious +trouble should result. When the tubes do become incrusted with deposit, +they can be either withdrawn or exposed, as the apparatus is generally +so arranged; and they can then be cleaned. + +_Screw Propeller_.--In Mr. Marshall's paper of 1881 it was said that +"the screw propeller is still to a great extent an unsolved problem." +This was at the time a fairly true remark. It was true the problem had +been made the subject of general theoretical investigation by various +eminent mathematicians, notably by Professor Rankine and Mr. William +Froude, and of special experimental investigation by various engineers. +As examples of the latter may be mentioned the extended series of +investigations in the French vessel Pelican, and the series made by Mr. +Isherwood on a steam launch about 1874. These experiments, however, such +as they were, did little to bring out general facts and to reduce the +subject to a practical analysis. Since the date of Mr. Marshall's paper, +the literature on this subject has grown rapidly, and, has been almost +entirely of a practical character. The screw has been made the subject +of most careful experiments. One of the earliest extensive series of +experiments was made under the writer's direction in 1881, with a large +number of models, the primary object being to determine what value there +was in a few of the various twists which inventive ingenuity can give to +a screw blade. The results led the experimenters to the conclusion that +in free water such twists and curves are valueless as serving to augment +efficiency. The experiments were then carried further with a view to +determine quantitative moduli for the resistance of screws with +different ratios of pitch to diameter, or "pitch ratios," and afterward +with different ratios of surface to the area of the circle described by +the tips of the blades, or "surface ratios." As these results have to +some extent been analyzed and published, no further reference need be +made to them now. + +In 1886, Mr. R.E. Froude published in the Transactions of the +Institution of Naval Architects the deductions drawn from an extensive +series of trials made with four models of similar form and equal +diameter, but having different pitch ratios. Mr. S.W. Barnaby has +published some of the results of experiments made under the direction of +Mr. J.I. Thornycroft; and in his paper read before the Institution of +Civil Engineers in 1890 he has also put Mr. R.E. Froude's results into a +shape more suitable for comparison with practice. Nor ought Mr. G.A. +Calvert's carefully planned experiments to pass unnoticed, of which an +account was given in the Transactions of the Institution of Naval +Architects in 1887. These experiments were made on rectangular bodies +with sections of propeller blade form, moved through the water at +various velocities in straight lines, in directions oblique to their +plane faces; and from their results an estimate was formed of the +resistance of a screw. + +One of the most important results deduced from experiments on model +screws is that they appear to have practically equal efficiencies +throughout a wide range both in pitch ratio and in surface ratio; so +that great latitude is left to the designer in regard to the form of the +propeller. Another important feature is that, although these experiments +are not a direct guide to the selection of the most efficient propeller +for a particular ship, they supply the means of analyzing the +performances of screws fitted to vessels, and of thus indirectly +determining what are likely to be the best dimensions of screw for a +vessel of a class whose results are known. Thus a great advance has been +made on the old method of trial upon the ship itself, which was the +origin of almost every conceivable erroneous view respecting the screw +propeller. The fact was lost sight of that any modification in form, +dimensions, or proportions referred only to that particular combination +of ship and propeller, or to one similar thereto; so something like +chaos was the result. This, however, need not be the case much longer. + +In regard to the materials used for propellers, steel has been largely +adopted for both solid and loose-bladed screws; but unless protected in +some way, the tips of the blades are apt to corrode rapidly and become +unserviceable. One of the stronger kinds of bronze is often judiciously +employed for the blades, in conjunction with a steel boss. Where the +first extra expense can be afforded, bronze seems the preferable +material; the castings are of a reliable character, and the metal does +not rapidly corrode; the bronze blades can therefore with safety be made +lighter than steel blades, which favors their springing and +accommodating themselves more readily to the various speeds of the +different parts of the wake. This might be expected to result in some +slight increase of efficiency; of which, however, the writer has never +had the opportunity of satisfactorily determining the exact extent. +Instances can be brought forward where bronze blades have been +substituted for steel or iron with markedly improved results; but in +cases of this kind which the writer has had the opportunity of +analyzing, the whole improvement might be accounted for by the modified +proportions of the screw when in working condition. In other words, both +experiment and practical working alike go to show that, although cast +iron and steel blades as usually proportioned are sufficiently stiff to +retain their form while at work, bronze blades, being made much lighter, +are not; and the result is that the measured or set pitch is less than +that which the blades assume while at work. Some facts relative to this +subject have already been given in a recent paper by the author. + +_Twin Screws_.--The great question of twin screw propulsion has been put +to the test upon a large scale in the mercantile marine, or rather in +what would usually be termed the passenger service. While engineers, +however, are prepared to admit its advantages so far as greater security +from total breakdown is concerned, there is by no means thorough +agreement as to whether single or twin screws have the greater +propulsive efficiency. What is required to form a sound judgment upon +the whole question is a series of examples of twin and single screw +vessels, each of which is known to be fitted with the most suitable +propeller for the type of vessel and speed; and until this information +is available, little can be said upon the subject with any certainty. So +far the following large passenger steamers, particulars of which are +given in table II., have been fitted with twin screws. It appears t be a +current opinion that the twin screw arrangement necessitates a greater +weight of machinery. This is not necessarily so, however; on the +contrary, the opportunity is offered for reducing the weight of all that +part of the machinery of which the weight relatively to power is +inversely proportional to the revolutions for a given power. This can be +reduced in the proportion of 1 to the square root of 2, that is 71 per +cent. of its weight in the single screw engine; for since approximately +the same total disk area is required in both cases with similar +proportioned propellers, the twins will work at a greater speed of +revolution than the single screw. From a commercial point of view there +ought to be little disagreement as to the advantage of twin screws, so +long as the loss of space incurred by the necessity for double tunnels +is not important; and for the larger passenger vessels now built for +ocean service the disadvantage should not be great. Besides their +superiority in the matter of immunity from total breakdown, and in +greatly diminished weight of machinery, they also offer the opportunity +of reducing to some extent the cost of machinery. A slightly greater +engine room staff is necessary; but this seems of little importance +compared with the foregoing advantages. + +TABLE II.--PASSENGER STEAMERS FITTED WITH TWIN SCREWS. + +-----------------+-----------+-----+-----------+-------+--------+-------+ + | Length | | Cylinders, | Boiler |Indi- | + | between | | two sets in all |pressure|cated | + Vessels. | perpen- |Beam.| cases. | per |horse- | + | diculars. | |-----------+-------| square |power. | + | | |Diameters. |Stroke.| inch. | | +-----------------+-----------+-----+-----------+-------+--------+-------+ + | Feet. |Feet.| Inches. |Inches.| Lb. | | +City of Paris. |\ | | | | | | + | } 525 | 631/4 |45, 71, 113| 60 | 150 |20,000 | +City of New York.|/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Teutonic. |\ | | | | | | + | } 565 | 58 |43, 68, 110| 60 | 180 |18,000 | +Majestic. |/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Normannia. | 500 | 571/2 |40, 67, 106| 66 | 160 |11,500 | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Columbia. | 4631/2 | 551/2 |41, 66, 101| 66 | 160 |12,500 | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Empress of India.|\ | | | | | | +Empress of Japan.| } 440 | 51 |32, 51, 82 | 54 | 160 |10,125 | +Empress of China.|/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Orel. | 415 | 48 |34, 54, 85 | 51 | 160 |10,000 | +-----------------+-----------+-----+-----------+-------+--------+-------+ + +_Weight of Machinery Relatively to Power_.--It is interesting to compare +the weight of machinery relatively to the power developed; for this +comparison has sometimes been adopted as the standard of excellence in +design, in respect of economy in the use of material. The principle, +however, on which this has generally been done is open to some +objections. It has been usual to compare the weight directly with the +indicated horse-power, and to express the comparison in pounds per +horse-power. So long as the machinery thus compared is for vessels of +the same class and working at about the same speed of revolution, no +great fault can be found; but as speed of revolution is a great factor +in the development of power, and as it is often dependent on +circumstances altogether external to the engine and concerning rather +the speed of the ship, the engines fitted to high speed ships will thus +generally appear to greater advantage than is their due. Leaving the +condenser out of the question, the weight of an engine would be much +better referred to cylinder capacity and working pressures, where these +are materially different, than directly to the indicated power. The +advantages of saving weight of machinery, so long as it can be done with +efficiency, are well known and acknowledged. If weight is to be reduced, +it must be done by care in design, not by reduction of strength, because +safety and saving of repairs are much more important than the mere +capability of carrying a few tons more of paying load. It must also be +done with economy; but this is a matter which generally settles itself +aright, as no shipowner will pay more for a saving in weight than will +bring in a remunerative interest on his outlay. In his paper on the +weight of machinery in the mercantile marine,[3] Mr. William Boyd +discussed this question at some length, and proposed to attain the end +of reducing the weight of machinery by the legitimate method of +augmenting the speed of revolution and so developing the required power +with smaller engines. This method, while promising, is limited by the +efficiency of the screw, but may be adopted with advantage so long as +the increase in speed of revolution involves no such change in the screw +as to reduce its efficiency as a propeller. But when the point is +reached beyond which a further change involves loss of propelling +efficiency, it is time to stop; and the writer ventures to say that in +many cargo vessels now at work the limit has been reached, while in many +others it has certainly been passed. + +[Footnote 3: Transactions Northeast Coast Institution of Engineers and +Shipbuilders, vol. 6, 1889-90, p. 253.] + +_Economy of Fuel_.--Coming to the highly important question of economy +of fuel, the average consumption of coal per indicated horse-power is +1.522 lb. per hour. The average working pressure is 158.5 lb. per square +inch. Comparing this working pressure with 77.4 lb. in 1881, a superior +economy of 19 per cent. might be expected now, on account of the higher +pressure, or taking the 1.828 lb. of coal per hour per indicated +horse-power in 1881, the present performance under similar conditions +should be 1.48 lb. per hour per indicated horse-power. It appears that +the working pressures have been increased twice in the last ten years, +and nearly three times in the last nineteen. The coal consumptions have +been reduced 16.7 per cent. in the last ten years and 27.9 per cent. in +the last nineteen. The revolutions per minute have increased in the +ratios of 100, 105, 114; and the piston speeds as 100, 124, 140. +Although it is quite possible that the further investigations of the +Research Committee on Marine Engine Trials may show that the present +actual consumption of coal per indicated horse-power is understated, yet +it is hardly probable that the relative results will be affected +thereby. + +_Dimensions_.--In the matter of the power put into individual vessels, +considerable strides have been made. In 1881, probably the greatest +power which has been put into one vessel was in the case of the Arizona, +whose machinery indicated about 6,360 horse-power. The following table +gives an idea of the dimensions and power of the larger machinery in the +later passenger vessels: + +TABLE III.--DIMENSIONS AND POWER OF MACHINERY IN LATER PASSENGER +VESSELS. + +-----+----------------+-----------------------+-------+-----------+ + | | |Length | | +Year.| Name of vessel.| Diameters of | of |Indicated | + | | cylinders. |Stroke.|horsepower.| +-----+----------------+-----------------------+-------+-----------+ + | | Inches. |Inches.| | +1881 |Alaska | 68, 100, 100 | 72 | 10,686 | +-----+----------------+-----------------------+-------+-----------+ +1881 |City of Rome | 46, 86; 46, 86; 46, 86| 72 | 11,800 | +-----+----------------+-----------------------+-------+-----------+ +1881 |Servia | 72, 100, 100 | 78 | 10,300 | +-----+----------------+-----------------------+-------+-----------+ +1881 |Livadia yacht | 60, 78, 78; 60, 78, \| 39 | 12,500 | + | | 78; 60, 78, 78 /| | | +-----+----------------+-----------------------+-------+-----------+ +1883 |Oregon | 70, 104, 104 | 72 | 13,300 | +-----+----------------+-----------------------+-------+-----------+ +1884 |Umbria |\ 71, 105, 105 | 72 | 14,320 | +1884 |Etruria |/ | | | +-----+----------------+-----------------------+-------+-----------+ +1888 |City of New York|\ 45, 71, 113; \| 60 | 20,000 | +1889 |City of Paris |/ 45, 71, 113 /| | about | +-----+----------------+-----------------------+-------+-----------+ +1889 |Majestic |\ 43, 68, 110; \| 60 | 18,000 | +1889 |Teutonic |/ 43, 68, 110 /| | | +-----+----------------+-----------------------+-------+-----------+ + +In war vessels the increase has been equally marked. In 1881 the maximum +power seems to have been in the Inflexible, namely, 8,485 indicated +horse-power. The following will give an idea of the recent advance made: +Howe (Admiral class), 11,600 indicated horse-power; Italia and Lepanto, +19,000 indicated horse-power; Re Umberto, 19,000 indicated horse-power; +Blake and Blenheim (building), 18,000 indicated horse-power; Sardegna +(building), 22,800 indicated horse-power. It is thus evident that there +are vessels at work to-day having about three times the maximum power of +any before 1881. + +_General Conclusions_.--The progress made during the last ten years +having been sketched out, however roughly, the general conclusions may +be stated briefly as follows: First, the working pressure has been about +doubled. Second, the increase of working pressure and other improvements +have brought with them their equivalent in economy of coal, which is +about 20 per cent. Third, marked progress has been made in the direction +of dimension, more than twice the power having been put into individual +vessels. Fourth, substantial advance has been made in the scientific +principles of engineering. It only remains for the writer to thank the +various friends who have so kindly furnished him with data for some of +the tables which have been given; and to express the hope that the next +ten years may be marked by such progress as has been witnessed in the +past. But it must be remembered that, if future progress be equal in +merit or ratio, it may well be less in quantity, because advance becomes +more difficult of achievement as perfection is more nearly approached. + + * * * * * + + + + +THE LITTLE HOUSE. + +BY M.M. + + +One of the highest medical authorities is credited with the statement +that "nine-tenths of the diseases that afflict humanity are caused by +neglect to answer the calls of Nature." + +This state of affairs is generally admitted, but is usually attributed +to individual indolence. That, doubtless, has a great deal to do with +it, but should not part of the blame be laid upon the often unpleasant +environments, which make us shrink as from the performance of a painful +duty? + +In social life, unless from absolute necessity or charity, people of +refined habits do not call on those whose surroundings shock their sense +of decency; but when they go to pay the calls of Nature, they are often +compelled to visit her in the meanest and most offensive of abodes; +built for her by men's hands; for Nature herself makes no such mistakes +in conducting her operations. She does not always surround herself with +the pomp and pride of life, but she invariably hedges herself in with +the thousand decencies and the pomp of privacy. + +But what do we often do? We build what is sometimes aptly termed "an +out-house," because it is placed so that the delicate minded among its +frequenters may be made keenly alive to the fact that they can be +plainly seen by every passer-by and by every idle neighbor on the +lookout. This tiny building is seldom weatherproof; In consequence, keen +cold winds from above, below, and all around find ready entrance, chill +the uncovered person, frequently check the motions, and make the strong +as well as the weak, the young as well as the old, very sorry indeed +that they are so often uselessly obliged to answer the calls of Nature. +It is true, the floor is sometimes carpeted with snow, but the feet feel +that to be but cold comfort, though the door may enjoy rattling its +broken hasp and creaking its loose hinges. + +How often, too, are the nose and the eye offended by disregard of the +Mosaic injunction, found in the twelfth, thirteenth, and fourteenth +verses of the twenty-third chapter of Deuteronomy! Of course this +injunction was addressed to a people who had been debased by slavery, +but who were being trained to fit them for their high calling as the +chosen of God; but is not some such sanitary regulation needed in these +times, when a natural office is often made so offensive to us by its +environments that it is difficult for us to believe that "God made man a +little lower than the angels," or that the human body is the temple of +the Holy Ghost? + +Dwellers in the aristocratic regions of a well drained city, whose +wealth enables them to surround themselves with all devices tending to a +refined seclusion, may doubt all this, but sanitary inspectors who have +made a round of domiciliary visits in the suburbs, or the older, +neglected parts of a large city, of to any part of a country town or +village, will readily affirm as to its general truth. + +This unpardonable neglect of one of the minor decencies by the mass of +the people seems to be caused partly by a feeling of false shame, and +partly by an idea that it is expensive and troublesome to make any +change that will improve their sanitary condition or dignify their daily +lives. + +The Rev. Henry Moule, of Fordington Vicarage, Dorsetshire, England, was +one of the first to turn his attention to this matter. With the +threefold object of improving the sanitary condition of his people, +refining their habits, and enriching their gardens, he invented what he +called the "dry earth closet." + +"It is based on the power of clay and the decomposed organic matter +found in the soil to absorb and retain all offensive odors and all +fertilizing matters; and it consists, essentially, of a mechanical +contrivance (attached to the ordinary seat) for measuring out and +discharging into the vault or pan below a sufficient quantity of sifted +dry earth to entirely cover the solid ordure and to absorb the urine. + +"The discharge of earth is effected by an ordinary pull-up, similar to +that used in the water closet, or (in the self-acting apparatus) by the +rising of the seat when the weight of the person is removed. + +"The vault or pan under the seat is so arranged that the accumulation +can be removed at pleasure. + +"From the moment when the earth is discharged and the evacuation +covered, all offensive exhalation entirely ceases. Under certain +circumstances there may be, at times, a slight odor as of guano mixed +with earth, but this is so trifling and so local that a commode arranged +on this plan may, without the least annoyance, be kept in use in any +room." + +The "dry earth closet" of the philanthropic clergyman was found to work +well, and was acceptable to his parishioners. One reason why it was so +was because dry earth was ready to hand, or could be easily procured in +a country district where labor was cheap. But where labor was dear and +dry earth scarce, those who had to pay for the carting of the earth and +the removal of the deodorized increment found it both expensive and +troublesome. + +But a modification of this dry earth closet, the joint contrivance of an +English church clergyman and his brother, "the doctor," residents of a +Canadian country town, who had heard of Moule's invention, is a good +substitute, and is within the reach of all. This will be briefly +described. + +The vault was dug as for an ordinary closet, about fifteen feet deep, +and a rough wooden shell fitted in. About four feet below the surface of +this wooden shell a stout wide ledge was firmly fastened all around. +Upon this ledge a substantially made wooden box was placed, just as we +place a well fitting tray into our trunks. About three feet of the back +of the wooden shell was then taken out, leaving the back of the box +exposed. From the center of the back of the box a square was cut out and +a trap door fitted in and hasped down. + +The tiny building, on which pains, paint, and inventive genius had not +been spared to make it snug, comfortable, well lighted and well +ventilated, was placed securely on this vault. + +After stones had been embedded in the earth at the back of the vault, to +keep it from falling upon the trap door, two or three heavy planks were +laid across the hollow close to the closet. These were first covered +with a barrowful of earth and then with a heap of brushwood. + +Within the closet, in the left hand corner, a tall wooden box was +placed, about two-thirds full of dry, well sifted wood ashes. The box +also contained a small long-handled fire shovel. When about six inches +of the ashes had been strewn into the vault the closet was ready for +use. No; not quite; for squares of suitable paper had to be cut, looped +together with twine, and hung within convenient reaching distance of the +right hand; also a little to the left of this pad of paper, and above +the range of sight when seated, a ten pound paper bag of the toughest +texture had to be hung by a loop on a nail driven into the corner. + +At first the rector thought that his guests would be "quick-witted +enough to understand the arrangement," but when he found that the +majority of them were, as the Scotch say, "dull in the uptak," he had to +think of some plan to enforce his rules and regulations. As +by-word-of-mouth instructions would have been rather embarrassing to +both sides, he tacked up explicit written orders, which must have +provoked many a smile. Above the bin of sifted ashes he nailed a card +which instructed "Those who use this closet must strew two shovelfuls of +ashes into the vault." Above the pad of clean paper he tacked the +thrifty proverb: "Waste not, want not;" and above the paper bag he +suspended a card bearing this warning: "All refuse paper must be put +into this bag; not a scrap of clean or unclean paper must be thrown into +the vault." + +This had the desired effect. Some complacently united to humor their +host's whim, as they called it, and others, immediately recognizing its +utility and decency, took notes with a view to modifying their own +closet arrangements. + +Sarah, the maid of all work, caused a good deal of amusement in the +family circle by writing her instructions in blue pencil on the front of +the ash bin. These were: "Strew two shuffefuls of ashes into the volt, +but don't spill two shuffefuls onto the floor. By order of the Gurl who +has to sweap up." This order was emphatically approved of by those +fastidious ones who didn't have to "sweep up." + +This closet opened off the woodshed, and besides being snugly +weatherproof in itself, was sheltered on one side by the shed and on +another by a high board fence. The other two sides were screened from +observation by lattice work, outside of which evergreens were planted to +give added seclusion and shade. A ventilator in the roof and two sunny +little windows, screened at will from within by tiny Venetian shutters, +gave ample light and currents of fresh air. For winter use, the rector's +wife and daughters made "hooked" mats for floor and for foot support. +These were hung up every night in the shed to air and put back first +thing in the morning. For the greater protection and comfort of +invalids, an old-fashioned foot warmer, with a handle like a basket, was +always at hand ready to be filled with live coals and carried out. + +The little place was always kept as exquisitely clean as the dainty, +old-fashioned drawing room, and so vigilant was the overseeing care +bestowed on every detail, that the most delicate and acute sense of +smell could not detect the slightest abiding unpleasant odor. The paper +bag was frequently changed, and every night the accumulated contents +were burned; out of doors in the summer, and in the kitchen stove--after +a strong draught had been secured--in the winter. + +At stated times the deodorized mass of solid increment--in which there +was not or ought not to have been any refuse paper to add useless +bulk--was spaded, through the trap door, out of the box in the upper +part of the vault, into a wheelbarrow, thrown upon the garden soil, and +thoroughly incorporated with it. In this cleansing out process there was +little to offend, so well had the ashes done their concealing +deodorizing work. + +In using this modified form of Moule's invention, it is not necessary to +dig a deep vault. The rector, given to forecasting, thought that some +day his property might be bought by those who preferred the old style, +but his brother, the doctor, not troubling about what might be, simply +fitted his well made, four feet deep box, with its trap door, into a +smoothly dug hole that exactly held it, and set the closet over it. In +all other respects it was a model of his brother's. + +This last is within the reach of all, even those who live in other +people's houses; for, when they find themselves in possession of an +unspeakably foul closet, they can cover up the old vault and set the +well cleaned, repaired, fumigated closet upon a vault fashioned after +the doctor's plan. A stout drygoods box, which can be bought for a +trifle, answers well for this purpose, after a little "tinkering" to +form a trap door. + +Of course, dry earth is by far the best deodorizer and absorbent, but +when it cannot be easily and cheaply procured, well sifted wood or coal +ashes--wood preferred--is a good substitute. The ashes must be kept dry. +If they are not, they lose their absorbing, deodorizing powers. They +must also be well sifted. If they are not, the cinders add a useless and +very heavy bulk to the increment. + +An ash sifter can be made by knocking the bottom out of a shallow box, +studding the edge all round with tacks, and using them to cross and +recross with odd lengths of stovepipe wire to form a sieve.--_The +Sanitarian_. + + * * * * * + + + + +THE HYGIENIC TREATMENT OF OBESITY.[1] + +[Footnote 1: Translated by Mr. Jos. Helfman, Detroit, Mich.] + +BY DR. PAUL CHERON. + + +In order to properly regulate the regimen of the obese, it is first +necessary to determine the source of the superfluous adipose of the +organism, since either the albuminoids or the hydrocarbons may furnish +fat. + +Alimentary fat becomes fixed in the tissues, as has been proved by +Lebede, who fed dogs, emaciated by long fast, with meat wholly deprived +of fat, and substituted for the latter linseed oil, when he was able to +recover the oil in each instance from the animal; parallel experiments +with mutton fat, _in lieu_ of oil, afforded like results. + +Hoffman also deprived dogs of fat for a month, causing them to lose as +high as twenty-two pounds weight, then began nourishing with bacon fat +with but little lean; the quantity of fat formed in five days, in the +dog that lost twenty-two pounds, was more than three pounds, which could +have been derived only from the bacon fat. + +It has been stated, however, that alimentary fat seems to preserve from +destruction the fat of the organism which arises from other sources. Be +this as it may, it is a fact that the pre-existence of fat furthers the +accumulation of more adipose; or in other words, fat induces fattening! + +That adipose may be formed through the transformation of albuminous +matters (meat) is an extremely important corollary, one established +beyond cavil by Pettinkofer and Voit, in an indirect way, by first +estimating the nitrogen and carbon ingested, and second the amount +eliminated. Giving a dog meat that was wholly deprived of fat, they +found it impossible to recover more than a portion of the contained +carbon; hence some must necessarily have been utilized in the organism, +and this would be possible only by the transformation of the carbon into +fat! It goes without saying, however, that the amount of adipose thus +deposited is meager. + +Other facts also plead in favor of the transformation of a portion of +albumen into fat within the economy, notably the changing of a portion +of dead organism into what is known as "cadaveric fat," and the very +rapid fatty degeneration of organs that supervenes upon certain forms of +poisoning, as by phosphorus. + +The carbohydrates, or more properly speaking hydrocarbons, are regarded +by all physiologists as specially capable of producing fat, and numerous +alimentary experiments have been undertaken to prove this point. +Chaniewski, Meissl, and Munk obtained results that evidenced, +apparently, sugar and starch provide more fat than do the albuminoids. +Voit, however, disapproves this, maintaining the greater part of the +hydrocarbons is burned (furnishes fuel for the immediate evolution of +force), and that fat cannot be stored up unless a due proportion of +albuminoids is also administered. He believes the hydrocarbons exert a +direct influence only; being more oxidizable than fats, they guard the +latter from oxidation. This protective role of the hydrocarbons applies +also to the albuminoids. + +We may believe, then, that the three great classes of aliment yield fat, +in some degree; that alimentary fat may be fixed in the tissues; and +that hydrocarbons favor the deposition of adipose either directly or +indirectly. + +It is well understood that fat may disappear with great rapidity under +certain conditions; many maladies are accompanied by speedy emaciation; +therefore, as fat never passes into the secretions, at least not in +appreciable quantities, it probably undergoes transformation, perhaps by +oxidation or a form of fermentation, the final results of which are, +directly or indirectly, water and cadaveric acid. It is certain the +process of oxidation favors the destruction of adipose, and that +everything which inhibits such destruction tends to fat accumulation. + +Since the earliest period of history, there seems to have been an +anxiety to secure some regimen of general application that would reduce +or combat obesity. Thus Hippocrates says: + +Fat people, and all those who would become lean, should perform +laborious tasks while fasting, and eat while still breathless from +fatigue, without rest, and after having drunk diluted wine not very +cold. Their meats should be prepared with sesamum, with sweets, and +other similar substances, and these dishes should be free from fat. + +In this manner one will be satiated through eating less. + +But, besides, one should take only one meal; take no bath; sleep on a +hard bed; and walk as much as may be. + +How much has medical science gained in this direction during the +interval of more than two thousand years? Let us see: + +First among moderns to seek to establish on a scientific basis a regimen +for the obese, was Dancel, who forbade fats, starchy foods, etc., +prescribed soups and aqueous aliment, and reduced the quantity of +beverage to the lowest possible limit; at the same time he employed +frequent and profuse purgation. + +This regimen, which permits, at most, but seven to twelve ounces of +fluid at each repast, is somewhat difficult to follow, though it may be +obtained, gradually, with ease. Dr. Constantine Paul records a case in +which this regimen, gradually induced, and followed for ten years, +rewarded the patient with "moderate flesh and most excellent health." + +In Great Britain, a mode of treatment instituted in one Banting, by Dr. +Harvey, whereby the former was decreased in weight forty pounds, has +obtained somewhat wide celebrity; and what is more remarkable, it is +known as "Bantingism," taking its name from the patient instead of the +physician who originated it. The dietary is as follows: + +_Breakfast_.--Five to six ounces of lean meat, broiled fish, or smoked +bacon--veal and pork interdicted; a cup of tea or coffee without milk or +sugar; one ounce of toast or dry biscuit (crackers). + +_Dinner_.--Five or six ounces of lean meat or fish--excluding eel, +salmon, and herring; a small quantity of vegetables, but no potatoes, +parsnips, carrots, beets, peas, or beans; one ounce of toast, fruit, or +fowl; two glasses of red wine--beer, champagne, and port forbidden. + +_Tea_.--Two or three ounces of fruit; one kind of pastry; one cup of +tea. + +_Supper_.--Three or four ounces of lean beef or fish; one or two glasses +of red wine. + +_At bed-time._--Grog without sugar (whisky and water, or rum and water), +and one or two glasses of sherry or Bordeaux. + +"Bantingism," to be effective, must be most closely followed, when, +unfortunately also, it proves extremely debilitating; it is suitable +only for sturdy, hard riding gluttons of the Squire Western type. The +patient rapidly loses strength as well as flesh, and speedily acquires +an unconquerable repugnance to the dietary. Further, from a strictly +physiological point of view, the quantity of meat is greatly in excess, +while with the cessation of the regimen, the fat quickly reappears. + +Next Ebstein formulated a dietary that is certainly much better +tolerated than that of Harvey and Banting, and yields as good, or even +better, results. He allows patients to take a definite quantity--two to +two and a half ounces-of fat daily, in the form of bacon or butter +which, theoretically at least, offers several advantages: It diminishes +the sensations of hunger and thirst, and plays a special role with +respect to the albuminoids; the latter may thus be assimilated by the +economy without being resolved into fat, and thus the adipose of the +organism at this period is drawn upon without subsequent renewal. The +following is the outline: + +_Breakfast_.--At 6 a.m. in summer; 7:30 in winter:--Eight ounces of +black tea without either milk or sugar; two ounces of white bread or +toast, with a copious layer of butter. + +_Dinner_.--2 p.m.:--A modicum of beef marrow soup; four ounces of meat, +preferably of fatty character; moderate quantity of vegetable, +especially the legumines, but no potatoes or anything containing starch; +raw fruits in season, and cooked fruits (stewed, without sugar); two or +three glasses of light wine as a beverage, and after eating, a cup of +black tea without sugar. + +_Supper_.--7:30 p m.:--An egg, bit of fat roast, ham, or bacon; a slice +of white bread well buttered; a large cup of black tea without milk or +sugar; from time to time, cheese and fresh fruits. + +Germain See suggests as a modification of this regimen, the abundant use +of beverage, the addition of gelatins, and at times small doses of +potassium iodide in twenty cases he claims constant and relatively +prompt results. + +Whatever may be urged for Ebstein's system--and it has afforded most +excellent results to Unna and to Lube, as well as its author--it +certainly exposes the patient to the terrors of dyspepsia, when the +routine must needs be interrupted or modified; hence it is not always to +be depended upon. As between dyspepsia and obesity, there are few, I +fancy, who would not prefer the latter. + +Another "system" that has acquired no little celebrity, and which has +for its aim the reduction as far as possible of alimentary hydrocarbons +while permitting a certain proportion of fat, is that, of Denneth, which +necessarily follows somewhat closely the lines laid down by Ebstein. + +Oertels' treatment, somewhat widely known, and not without due measure +of fame, is based upon a series of measures having as object the +withdrawal from both circulation and the economy at large, as much of +the fluids as possible. It is especially adapted for the relief of those +obese who are suffering fatty degeneration of the heart. The _menu_ is +as follows: + +_Breakfast_.--Pour to five ounces of tea or coffee with a little milk; +two to two and a half ounces bread. + +_Dinner_.--Three or four ounces of roast or boiled meat, or moderately +fat food; fish, slightly fat; salad and vegetables at pleasure; one and +a half ounces of bread (in certain cases as much as three ounces of +farinaceous food may be permitted); three to six ounces of fruit; at +times a little pastry for dessert.--In summer, if fruit is not +obtainable, six to eight ounces of light wine may be allowed. + +_Tea_,--A cupful (four to five ounces) of tea or coffee, with a trifle +of milk, as at breakfast; one and three-fourths ounces of bread; and +exceptionally (and at most) six ounces of water. + +_Supper_.--One to two soft boiled eggs; four or five ounces of meat; one +and three fourths ounces of bread; a trifle of cheese, salad, or fruit; +six to eight ounces of light wine diluted with an eighth volume of +water. The quantity of beverage may be slightly augmented at each meal +if necessary, especially if there is no morbid heart trouble. + +Schwenninger (Bismarck's physician), who opened a large sanitarium near +Berlin a few years since for the treatment of the obese, employs +Oertel's treatment, modified in that an abundance of beverage is +permitted, provided it is not indulged in at meals; it is forbidden +until two hours after eating. + +Both Oertel's and Schwenninger's methods have procured grave dyspepsias, +and fatal albuminurias as well, according to Meyer and Rosenfield. It +has been charged the allowance of beverage upon which Schwenninger lays +so much stress in the treatment at his sanitarium has a pecuniary basis, +in other words a commission upon the sale of wines.[2] + +[Footnote 2: The sanitarium is owned by a stock company, Schwenninger +being merely Medical Director.--ED.] + +Thus, it will be observed that while some forbid beverage, others rather +insist upon its employment in greater or less quantities. Under such +circumstances, it would seem but rational, before undertaking to relieve +obesity, to establish its exact nature, and also the role taken by +fluids in the phenomena of nutrition. + +Physiologists generally admit water facilitates nutritive exchanges, +which is explained by the elimination of a large quantity of urine; the +experiments of Genth and Robin in this direction appear conclusive. + +Bischoff, Voit, and Hermann have shown that water increases, not alone +the elimination of urine, but also of sodium chloride, phosphoric acid, +etc. Grigoriantz observed augmentation of disintegration when the +quantity of beverage exceeded forty-six to eighty ounces ("1,400 to +2,400 cubic centimeters") per diem. Oppenheim, Fraenkel, and Debove, +while believing water has but little influence upon the exchanges, admit +it certainly need not diminish the latter; and Debove and Flament, after +administering water in quantities varying from two to eight pints per +diem, concluded that urine was diminished below the former figure, while +above the latter it increased somewhat, being dependent upon the amount +ingested. It was on the strength of the foregoing that Lallemand +declared water to have no influence upon the exchanges. + +The results claimed by Oppenheim, Debove, et al. were immediately +challenged--and it is now generally admitted, not without some +justice--by Germain See. It seems certain, to say the least, that water +taken during the repast does tend to augment the quantity and facilitate +the elimination of urine. Abundance of beverage, moreover, presents +other advantages, in that it facilitates digestion by reason of its +diluent action, a fact well worth bearing in mind when treating the +obese who are possessed of gouty diathesis, and whose kidneys are +accordingly encumbered with uric and oxalic acids. The foregoing +presents the ground upon which Germain See permits an abundance of +beverage; but he also expresses strong reservation as regards beer and +alcohol, either of which (more especially the former) tends to the +production of adipose. In his opinion, the only beverage of the +alcoholic class that is at all permissible, and then only for cases +suffering from fatty heart, is a little _liqueur_ or diluted wine. +Coffee and tea he commends highly, and recommends the ingestion of large +quantities at high temperature, both during the repasts and their +intervals. Coffee in large doses is undoubtedly a means of de-nutrition, +and so, too, in no less extent, is tea; both act vigorously owing to the +contained alkaloids, though, to be sure, they sometimes, at first, tend +to insomnia and palpitation, to which no attention need be paid, +however. The treatment outlined by See is: + +1. A physiological regimen comprising four to five ounces of nitrogenous +principles as derived from eight to ten ounces animal muscle and +albuminates; three to six ounces of fat; eight to ten ounces of +hydrocarbons as yielded by ten to twelve ounces of sugar or starch food. + +These proportions to be modified in such manner that the +musculo-albuminates shall not sensibly exceed the normal ratio, for meat +in excess itself furnishes fat during transformation. The fatty +substances of easy digestion may, without inconvenience, be utilized in +doses of two to three ounces. The hydrocarbons should be reduced to a +minimum. As for the herbaceous elements, they contain nothing nutritive. + +2. Beverage, far from being suppressed, should be augmented, in order to +facilitate stomachal digestion and promote general nutrition, though +alcoholic liquids must be inhibited; likewise mineral waters, except, +perhaps, for occasional use. Both should be replaced by infusions of +coffee or tea, taken as hot as can be drank. + +Henrich Kisch insists that any method which promises rapid and marked +decrease of adipose must, _per se_, be objectionable, even if not +positively injurious, since it tends to provoke general troubles of +nutrition. He suggests that first the fats and hydrocarbons be reduced +as little as possible; that a moderate mixed regimen is required, +containing a preponderance of albumen, small quantities of hydrocarbons +and gelatinous matters, with but very little fat. Certain fatty meats, +however, should be generally interdicted, such as pork sausage, smoked +beef tongue, goose breast, smoked ham, fat salmon, and herring in any +form. Eggs, however, may be partaken of in moderation, giving preference +to the albumen over the yelk. Farinaceous foods, in the main, should be +rejected, even bread being allowed only in small quantities, and then +preferably in the form of toast. Cheese likewise contains too much fat; +and mushrooms are so rich in hydrocarbons that they should be rejected. +Condiments, water, vegetable acids (vinegars excepted) may be permitted; +especially pernicious is vinegar where there is any tendency to gout or +gravel. All fatty beverages--_bouillon_, unskimmed milk, chocolate, or +cacao--and all alcoholics, are hurtful; breakfast tea is undoubtedly the +best beverage, but, after a little, is advantageously replaced by light +white wine diluted with water. + +Kisch believes in a free and abundant use of water by the obese, +especially where there is a tendency to plethora, since this fluid +facilitates oxidation as the result of absorption; thus he advocates the +inhibition of large quantities of cold water by all, save those +presenting evidence of cardiac insufficiency. In short, his regimen is +based upon the administration of a large quantity of albumen, like that +of Harvey-Banting. + +E. Munk recommends an almost identical dietary, save that he prefers +great moderation in fluids employed as beverage. + +M. Robin has sought to harmonize the opposing views regarding fluids, +and therefore declares obesity arises from two distinct sources: 1. +Augmentation of assimilation. 2. Reduced disassimilation. In the former, +he insists water must be interdicted, while in the latter it may be +allowed _ad libitum_. + +Again, in order to recognize the exact variety of obesity, he divides +his patients into three classes, each recognizable by the volume of urea +excreted. In the first there is an increase above normal; in the second +the volume of urea is stationary; in the third decreased, increased, or +stationary. + +When the urea is stationary, which is most frequently the case, it is +necessary to calculate the coefficient of oxidation; that is, the +relation existing between the solid matters of the urine and the urea. +The elevation of the coefficient is _prima facie_ evidence the obesity +is due to excess of assimilation, while depression of the coefficient +indicates default of assimilation. In the first case, water and liquids +must be denied as far as possible, the same as if there was no +augmentation of urea; in the second, the same as if there was diminution +of urea, the patients may be permitted to imbibe fluids at pleasure. + +For the obese from default of disassimilation, Robin recommends a +regimen of green vegetables and bread chiefly--the latter in small +quantities, however, and fluids as may be desired. By this means, on one +occasion, he was able in the course of one month to diminish the weight +of a female patient by twelve and a half pounds, her measurement around +the waist at the same time decreasing 5.2 inches and across the stomach +4.8 inches. + +M. De St. Germain achieved good results by combining judicious exercise +with moderate alimentation, excluding wine and bread. + +M. Dujardin Beaumetz, who professes to have given most close and careful +study and attention to regimen for the obese, outlines the following, +provided there is no evidence of fatty degeneration of heart. + +_Breakfast_ (at 8 a. m.)--Three-fourths of an ounce of bread "_en +flute_"--that is abounding with crust; one and a half ounces of cold +meat, ham or beef, six ounces weak black tea, _sans_ sugar. + +_Lunch_ (at 1 p.m.)--An ounce and a half to two ounces of bread, or a +_ragout_, or two eggs; three ounces green vegetables; one-half ounce of +cheese; fruits at discretion. + +_Dinner_ (at 7 p.m.)--An ounce and a half to two ounces of bread; three +to four ounces of meat, or _ragout_; ditto of green vegetables, salad, +half an ounce of cheese, fruit _ad libitum_. + +At meal times the patient may take only a "glass and a half" of +liquid--approximately ten ounces--though a greater amount may be +permitted if he abstains during the intervals. + +Special alimentary regimen, however, does not constitute the sole +treatment of obesity. Concurrently must be employed a number of +practical adjuvants which are oftentimes of the utmost assistance. For +one thing, exercise is indispensable; all authorities agree on this +point. The exercise taken in the gymnasium is one of the best, notably +the "wall exercise," which is more particularly suited to those +afflicted with pendulous and protuberant abdomens as the result of +feebleness of the hypogastric muscles, to accumulation of fat under the +skin and in the omentum, and to dilation of the stomach and intestines. +In the "wall exercise," the patient stands erect against an absolutely +straight and plumb wall, lifts his hands (carrying a weight) straight +over the head, and causes them to describe a semicircle forward. Zantz +particularly insists upon arm and leg exercise for the obese, especially +the former, since with the same amount of effort a larger amount of +oxygen is consumed than is possible by the latter. + +However, of whatever character, the exercise should be continued to the +point of fatigue or dyspnoea--three thousand movements daily, +gradually increased to twenty-five thousand, if the system can bear it; +and under such conditions, not only is there consumption of +hydrocarbons, but there is provided a veritable greed for air that +augments waste. The experiments of Oertel indicate that loss of weight +due to fatiguing exercise arises more particularly from dehydration, +which is made good by absorption of the fluids employed as beverage; the +fluids are claimed by Germain See to act as accelerants of oxidation. + +During exercise there is obviously more abundant absorption of oxygen, +and consequently greater elimination of carbonic acid, and as a +consequence (as shown by researches of Voit), the reserve fat of the +economy is attacked and diminished; in intense labor there is an average +hourly consumption of about 8.2 percent. of fat. Further physical +activity is useful in exercising the voluntary muscles, and thus +opposing the invasion by interstitial fat of the muscle fibrils. Extreme +exercise also, to a certain degree, exerts a favorable influence on the +cardiac muscle, augmenting both its nutrition and its capacity for +labor. With the anaemic obese, however, it is necessary to be most +circumspect in prescribing forced exercise; also with the elderly obese +possessed of enfeebled or fatty heart. + +Hydrotherapy, especially in the form of cold douches, particularly when +combined with massage, is often of considerable value in relieving +obesity; the method of Harmman, of St. Germain, which has in many +instances induced rapid loss of adipose, is of this class. Tepid saline +baths and vapor baths have many advocates, and may afford material aid +when the heart and circulation do not inhibit their employment. Hot +baths elevate the temperature of the body and increase the organic +exchanges, hence, as Bert and Reynard have pointed out, tend to the +elimination of oxygen and carbonic acid; but when employed, the patient +should be introduced while the temperature is below 130 deg. F., when it may +be gradually raised in the course of thirty or forty minutes to 140 deg. F. + +It has already been intimated, the chief feature of the treatment of +obesity is acceleration of the exchanges; and this is in the main true, +though it must also be borne in mind that, while there are obese who +excrete little urea and have a depressed central nervous temperature, +many may be azoturic, and besides eliminate phosphate in excess, when an +oxidating treatment will not only fail, but prove positively injurious. + +The bile throws out fat, therefore, to accelerate nutritive oxidations, +the liver and nervous system must be acted upon, _i.e._, stimulated. +Everything that tends to diminish the activity of the former, or depress +the latter, must be avoided. Hence intellectual labor should be +encouraged, or in lieu thereof, travel advised. Exercise should be taken +chiefly while fasting; the limits of sleep confined to strict necessity, +and _siestas_ after meals and during the day strictly forbidden; the +skin stimulated by hydro-therapeutic measures, including massage under +cold affusions, during warm salt baths, etc. + +To increase the activity of the liver, salicylate of soda may often be +advantageously administered for its cholagogue effect; or resort may be +had to saline purgatives such as are afforded by the springs of +Marienbad, Kissengen, Homburg, Carlsbad, Brides, Hunyadi, or +Chatel-Guyon; and it is somewhat remarkable that while undergoing a +course of these waters, there is often no appreciable change in weight +or obesity, though the decrease becomes most marked almost immediately +upon cessation of treatment. + +Everything tending to increased or fuller respiration is to be +encouraged, for the fats are thus supplied with oxygen, hastening their +disintegration and consumption. + +Direct medicinal treatment presents no very wide scope. Bouchard +imagines lime water may be useful by accelerating nutrition, but this is +problematical, since fat in emulsion or in droplets does not burn. +Nevertheless, alkalies in general, alkaline carbonates, liquor potassa, +soaps, etc., aid in rendering fat more soluble, and consequently more +susceptible to attack. The alkaline waters, however, are much less +active in obesity than the saline mineral waters, unless, as sometimes +happens, there is a complication of diabetes and obesity. + +Purgatives are always more or less useful, and often required to be +renewed with all the regularity of habit. Then too, the iodides, +especially iodide of sodium or potassium, as recommended by M. Germain +See, frequently prove of excellent service by aiding elimination and +facilitating the mutations. + +According to Kisch, the cold mineral waters containing an abundance of +sulphate of soda, like Hunyadi and Marienbad, are to be preferred to the +hot mineral waters, such as Carlsbad, because of their lesser irritant +action on the vascular system, and because they strongly excite diuresis +through their low temperature and contained carbonic acid; Carlsbad +deserves preference only when obesity is combined with uric acid +calculi, or with diabetes. For very anaemic persons, however, the weak +alkaline and saline waters should be selected; or they should confine +themselves to chalybeate waters containing an excess of sulphate of +soda. Water containing sulphate of soda is also indicated as a beverage +where there are troubles of the circulatory apparatus; it is +contraindicated only in accentuated arterio-sclerosis. + +As a matter of fact, I find the suggestion of M. Dujardin-Beaumetz, +that the obese should be divided into two groups, a most practical one, +for some are strong and vigorous--great eaters, perhaps even +gluttons--while others, on the contrary, are feeble and debilitated, +with flesh soft and flaccid; and upon the former may be imposed all the +rigors of the reducing system, while the latter must be dealt with more +carefully. + +In general, it must be noted, the regimen prescribed for the obese is +insufficient, as the following table prepared by M.C. Paul abundantly +proves: + + -------------------------+----------+----------+--------------- + Author. |Albuminous| Fatty | + | Matters. | Matters. | Hydrocarbons. + -------------------------+----------+----------+--------------- + Voit. | 118 | 40 | 150 + Harvey-Banting. | 170 | 10 | 80 + Ebstein. | 100 | 85 | 50 + Oertel. | 155-179 | 25-41 | 70-110 + Kisch (plethoric). | 160 | 10 | 80 + " (anaemic). | 200 | 12 | 100 + Normal ration. | 124 | 55 | 455 + -------------------------+----------+----------+--------------- + +There is, therefore, as Dujardin-Beaumetz asserts, autophagia in the +obese, and all these varieties of treatment have but one end, viz.: +Reduction of the daily ration. But the quantity of nourishment should +not be too greatly curtailed, for, manifestly, if the fat disappears the +more surely, the muscles (rich in albumen) undergo too rapid +modification. It is progressive action that should always be sought. + +The quantity of aliment may be reduced either by imposing an always +uniform regimen, which soon begets anorexia and disgust, or by +withholding from the food a considerable quantity of fat, or, finally, +by forbidding beverage during meals. Emaciation is obtained readily +enough in either way, and demands only the constant exercise of will +power on the part of the patient; but unhappily, severe regimen cannot +always be prescribed. When the obese patient has passed the age of +forty; when the heart suffers from degeneration; or when the heart is +anaemic--in all, rigorous treatment will serve to still further enfeeble +the central organ of circulation, and tend to precipitate accidents +that, by all means, are to be avoided. In such cases, by _not_ treating +the obesity, the days of the patient will be prolonged. In degeneration +of the heart, however, the method of Ebstein may be tried; and when +there is renal calculi and gouty diathesis, that of Germain See may +prove satisfactory. + +Paris, France. + + * * * * * + + + + +STILT WALKING. + + +[Illustration: SYLVAIN DORNON, THE STILT WALKER OF LANDES.] + +Sylvain Dornon, the stilt walker of Landes, started from Paris on the +12th of last March for Moscow, and reached the end of his journey at the +end of a fifty-eight days' walk. This long journey upon stilts +constitutes a genuine curiosity, not only to the Russians, to whom this +sort of locomotion is unknown, but also to many Frenchmen. + +Walking on stilts, in fact, which was common twenty years ago in certain +parts of France, is gradually tending to become a thing of the past. In +the wastes of Gascony it was formerly a means of locomotion adapted to +the nature of the country. The waste lands were then great level plains +covered with stunted bushes and dry heath. Moreover, on account of the +permeability of the subsoil, all the declivities were transformed into +marshes after the slightest fall of rain. + +There were no roads of any kind, and the population, relying upon sheep +raising for a living, was much scattered. It was evidently in order to +be able to move around under these very peculiar conditions that the +shepherds devised and adopted stilts. The stilts of Landes are called, +in the language of the country, _tchangues_, which signifies "big legs," +and those who use them are called _tchangues_. The stilts are pieces of +wood about five feet in length, provided with a shoulder and strap to +support the foot. The upper part of the wood is flattened and rests +against the leg, where it is held by a strong strap. The lower part, +that which rests upon the earth, is enlarged and is sometimes +strengthened with a sheep's bone. The Landese shepherd is provided with +a staff which he uses for numerous purposes, such as a point of support +for getting on to the stilts and as a crook for directing his flocks. +Again, being provided with a board, the staff constitutes a comfortable +seat adapted to the height of the stilts. Resting in this manner, the +shepherd seems to be upon a gigantic tripod. When he stops he knits or +he spins with the distaff thrust in his girdle. His usual costume +consists of a sort of jacket without sleeves, made of sheep skin, of +canvas gaiters, and of a drugget cloak. His head gear consists of a +beret or a large hat. This accouterment was formerly completed by a gun +to defend the flock against wolves, and a stove for preparing meals. + +The aspect of the Landeses is doubtless most picturesque, but their +poverty is extreme. They are generally spare and sickly, they are poorly +fed and are preyed upon by fever. Mounted on their stilts, the shepherds +of Landes drive their flocks across the wastes, going through bushes, +brush and pools of water, and traversing marshes with safety, without +having to seek roads or beaten footpaths. Moreover, this elevation +permits them to easily watch their sheep, which are often scattered over +a wide surface. In the morning the shepherd, in order to get on his +stilts, mounts by a ladder or seats himself upon the sill of a window, +or else climbs upon the mantel of a large chimney. Even in a flat +country, being seated upon the ground, and having fixed his stilts, he +easily rises with the aid of his staff. To persons accustomed to walking +on foot, it is evident that locomotion upon stilts would be somewhat +appalling. + +One may judge by what results from the fall of a pedestrian what danger +may result from a fall from a pair of stilts. But the shepherds of +Landes, accustomed from their childhood to this sort of exercise, +acquire an extraordinary freedom and skill therein. The _tchangue_ knows +very well how to preserve his equilibrium; he walks with great strides, +stands upright, runs with agility, or executes a few feats of true +acrobatism, such as picking up a pebble from the ground, plucking a +flower, simulating a fall and quickly rising, running on one foot, etc. + +The speed that the stilt walkers attain is easily explained. Although +the angle of the legs at every step is less than that of ordinary +walking with the feet on the ground, the sides prolonged by the stilts +are five or six feet apart at the base. It will be seen that with steps +of such a length, distances must be rapidly covered. + +When, in 1808, the Empress Josephine went to Bayonne to rejoin Napoleon +I, who resided there by reason of the affairs of Spain, the municipality +sent an escort of young Landese stilt walkers to meet her. On the +return, these followed the carriages with the greatest facility, +although the horses went at a full trot. + +During the stay of the empress, the shepherds, mounted upon their +stilts, much amused the ladies of the court, who took delight in making +them race, or in throwing money upon the ground and seeing several of +them go for it at once, the result being a scramble and a skillful and +cunning onset, often accompanied with falls. + +Up to recent years scarcely any merry-makings occurred in the villages +of Gascony that were not accompanied with stilt races. The prizes +usually consisted of a gun, a sheep, a cock, etc. The young people vied +with each other in speed and agility, and plucky young girls often took +part in the contests. + +Some of the municipalities of the environs of Bayonne and Biarritz still +organize stilt races, at the period of the influx of travelers; but the +latter claim that the stiltsmen thus presented are not genuine Landese +shepherds, but simple supernumeraries recruited at hazard, and in most +cases from among strolling acrobats. The stilt walkers of Landes not +only attain a great speed, but are capable of traveling long distances +without appreciable fatigue. + +Formerly, on the market days at Bayonne and Bordeaux, long files of +peasants were seen coming in on stilts, and, although they were loaded +with bags and baskets, they came from the villages situated at 10, 15, +or 20 leagues distance. To-day the sight of a stilt walker is a +curiosity almost as great at Bordeaux as at Paris. The peasant of Landes +now comes to the city in a wagon or even by railway.--_La Nature_. + + * * * * * + + + + +REMAINS OF A ROMAN VILLA IN ENGLAND. + + +A correspondent of the _Lincolnshire Chronicle_ writes: For some weeks +past, remains of a Roman villa have been exposed to view by Mr. +Ramsden's miners in Greetwell Fields. From, the extent of the tesselated +pavements laid bare there is hardly any doubt that in the Greetwell +Fields, in centuries long gone by, there stood a Roman mansion, which +for magnitude was perhaps unrivaled in England. Six years ago I drew +attention to it. The digging for iron ore soon after this was brought to +a standstill by the company, which at the time was working the mines, +ceasing their operations. Then the property came into other hands, and +since then more extensive basement floors of the villa have from time to +time been laid bare, and from tentative explorations which have been +just made, still more floors remain to be uncovered which may be of a +most interesting and instructive character. What a pity it is that the +inhabitants of Lincoln have not made an effort to preserve these +precious relics of the grandeur of the Roman occupation, an occupation +to which England owes so much. From the Romans the people of this +country inherit the sturdy self-reliance and perseverance in action +which have helped to make England what it is, and from the Romans too, +in a great degree, does England also inherit her colonizing instincts, +which impel her people to cover the waste places of the world with +colonies. If the Roman remains which have been so abundantly discovered +of late years in Lincoln and its vicinity had been collected and laid +out for exhibition, they would have formed a most interesting collection +of antiquities worthy of the town, and well worth showing to visitors +who now annually make Lincoln a visitation. Although these relics of a +remote age are being dug up and are being destroyed, it is not the fault +of Mr. Ramsden, for he not only preserved them as long as he +conveniently could, but he also had the soil removed from over them, and +had them thoroughly washed, in order that people might have an +opportunity of seeing their extent and beauty. One of these patches of +pavement extended 48 yards northward from what might be called the main +building, which had previously been broken up. This strip was 13 ft. in +breadth, and down its center ran an intricate pattern worked in blue +tesserae. The pattern is much used in these days in fabrics and works of +art, and is, I think, called the Grecian or Roman key pattern. On each +side of this ran alternately broad ribbons of white and narrower ribbons +of red tesserae. There is also another strip of pavement to the south of +the preceding patch, which has been laid bare to the extent of 27 yards. +This patch is about 10 ft. in breadth, and its western portion is cut up +in neat patterns, which show that they formed the floors of rooms. From +the eastern extremity of these floors evidently another long strip of 48 +or 50 yards still remains to be uncovered. Doubtless there are other +remains beneath the ground which will be laid bare as the work of mining +goes on. All these floors were not deeper than from 18 to 30 inches +below the surface of the soil. The bones of animals and other relics +have been found in the covering soil and have been turned up by the +miners from time to time. The pavement is all worked out with cubes, +varying in size from an inch and a half to two inches square, each piece +being placed in position with most careful exactness. The strip which +extends 48 yards and is 13 ft. wide runs due north and south. There is a +second patch, running east and west, and this is 27 ft. long by 10 ft. +wide, while a third is 27 ft. long by 11 ft. wide, this also running in +a northern direction. To the north of this latter piece, and separated +only by about two feet (about the width of a wall, which very possibly +was the original division), there is a strip of tesserae 16 ft. wide, +which had been laid bare 40 yards. It was thought probable that at the +end of the last named strip still another patch would be found. Mr. +Ramsden, the manager of the Ironstone Works, is keeping a plan of the +whole of the pavement, which he is coloring in exact imitation of the +original work. This, when completed, will be most interesting, and he +will be quite willing to show it to any one desirous of inspecting the +same. Many persons have paid a visit to the spot where the discoveries +have been made, and surprise is invariably expressed at the magnitude +and beautiful symmetry of the work. + +Several interesting fragments of Roman work have been brought to light +in the course of excavations that are being made for building purposes +at Twyford, near Winchester. About a month ago, a paved way, composed +entirely of small red tiles, six feet in width and extending probably a +considerable distance (a length of 14 ft. was uncovered), was found +while digging on the site for flints. The more recent excavations are 20 +ft. west of this passage, and there is now to be seen, in a very perfect +state of preservation, an oven or kiln with three openings. Five yards +away from this is a chamber about eight feet square, paved with tiles, +and the sides coated with a reddish plaster. On one side is a ledge 15 +in. from the ground, extending the whole length of the chamber; on the +floor is a sunk channel with an opening at the end for the water to +escape. This chamber evidently represents the bath. Portions of the +dividing walls of the different chambers have also been discovered, +together with various bones, teeth, horns and ornaments, but very few +coins. It is probable that an alteration in the plans of the house which +was about to be built on the spot will be made so as to preserve all the +more interesting features of these remains in the basement. These +discoveries were made at a depth of only two or three feet from the +surface of the ground, and are within about a quarter of a mile of other +Roman remains which were similarly brought to light a few months ago. + + * * * * * + +[Continued from SUPPLEMENT, No. 830, page 13110.] + + + + +GUM ARABIC AND ITS MODERN SUBSTITUTES.[1] + +[Footnote 1: A paper read before the Society of Chemical Industry, +London, 1891. From the Journal] + +BY DR. S. RIDEAL AND W.E. YOULE. + + +Subjoined is a table giving the absolute viscosity of various gums. A +comparison of the uncorrected viscosities with the corrected shows the +great importance of Slotte's correction for dextrins and inferior gum +arabics; in other words, for solutions of low viscosity, while it will +be observed to have little influence upon the uncorrected [eta] obtained +for the Ghatti gums and the best samples of gum arabic. + +TABLE OF ABSOLUTE VISCOSITIES OF 10 PER CENT. GUM AND DEXTRIN SOLUTIONS. + + ---------------------+--------------+------------+---------- + Sample. | [eta] | [eta] | Z Water + | Uncorrected. | Corrected. | = 100. + ---------------------+--------------+------------+---------- + Gum arabic.......... | 0.1876 | 0.1856 | 1,233 + Cape gum............ | 0.1575 | 0.1555 | 1,029 + Indian gum.......... | 0.0540 | 0.0470 | 311 + Eastern gum......... | 0.0689 | 0.0639 | 417 + Gum arabic.......... | 0.0550 | 0.0480 | 317 + Senegal............. | 0.0494 | 0.0410 | 271 + Senegal............. | 0.0468 | 0.0380 | 251 + Senegal............. | 0.0627 | 0.0557 | 364 + Gum arabic.......... | 0.0511 | 0.0430 | 285 + Water............... | 0.0149 | 0.0124 | 100 + Ghatti.............. | 0.2903 | 0.2880 | 2,322 + Ghatti, 5 per cent.. | 0.0903 | 0.0828 | 688 + Ghatti, 5 per cent.. | 0.1391 | 0.1350 | 1,089 + Ghatti, 5 per cent.. | 0.1795 | 0.1760 | 1,420 + Ghatti, 5 per cent.. | 0.1527 | 0.1485 | 1,198 + Ghatti, 5 per cent.. | 0.1139 | 0.1083 | 873 + Ghatti, 5 per cent.. | 0.1419 | 0.1369 | 1,104 + Dextrin............. | 0.0398 | 0.0255 | 169 + Dextrin............. | 0.0341 | 0.0196 | 129 + Dextrin............. | 0.0455 | 0.0380 | 306 + Gum substitute...... | 0.0318 | 0.0224 | 180 + Gum substitute...... | 0.0318 | 0.0224 | 180 + Amrad............... | 0.0793 | 0.0708 | 570 + Australian.......... | 0.0378 | 0.0283 | 228 + Australian.......... | 0.0365 | 0.0268 | 216 + Brazilian........... | 0.0668 | 0.0627 | 506 + Brazilian........... | 0.0516 | 0.0445 | 359 + Ghatti.............. | 0.3636 | 0.3621 | 2,920 + ---------------------+--------------+------------+---------- + +In the column for [eta] corrected the differences due to the use of +different instruments are of course eliminated. The absolute viscosity +of water at 15 deg. C. determined in four different instruments is shown +below. Poiseuille's value for water being 0.0122. + + --------------+-------------+-------------+-------------+-------------+ + Instrument. | 1. | 2. | 3. | 4. | + --------------+-------------+-------------+-------------+-------------+ + [eta] corrtd. | 0.0109 | 0.01185 | 0.0124 | 0.0120 | + of water. | | | | | + K_{1} value.. | 0.000000898 | 0.000000863 | 0.000000932 | 0.00000052 | + K_{2} value.. | 0.235 | 0.2175 | 0.226 | 0.0204 | + --------------+-------------+-------------+-------------+-------------+ + +The above values for various gums and dextrins were obtained at a +constant temperature of 15 deg. C. and are compared with water at that +temperature. It is of the utmost importance that the temperature of the +water surrounding the bulbs should be adjusted for each series of +experiments to the temperature at which the absolute viscosity of the +water was determined. As far as we have ascertained, in gum solutions +there is a steady diminution in viscosity with increase of temperature +until a certain temperature is reached, beyond which increase of heat +does not markedly influence the viscosity, and it is possible that above +this "critical point," as we may term it, the gum solutions once more +begin to increase in viscosity. The temperature at which the viscosity +becomes stationary varies somewhat with different gums, but broadly +speaking it lies between 60 deg. C. and 90 deg. C., no gums showing any marked +decrease in viscosity between 80 deg. C. and 90 deg. C. + +The experiments we have made in this direction were conducted as +follows. The 300 c.c. bottle containing the gum was placed in a +capacious beaker full of hot water, and the viscosity instrument was +also surrounded with water at the same temperature. Thermometers were +suspended both in the beaker and the outer jar. The viscosity at the +highest temperature obtained, about 90 deg. C., was then taken and repeated +for every fall of 4 deg. C. till the water reached the temperature of the +air. + +The values so obtained gradually diminished with the increase of +temperature. From the [eta] values obtained the Z values were +calculated, using water at 15 deg. C. as a standard. From the Z values thus +obtained taken as the ordinate, and the temperature of each experiment +as the abscissa, curves were plotted out embodying the results, examples +of which are given below. The curves yielded by three gums 2, 7, and 8 +changed between 90 deg. C and 100 deg. C., while gum sample 4 has a curve +bending between 60 deg. C. and 70 deg. C. Experimentally this increase of +viscosity of the latter gum above 60 deg. C. was confirmed, but the critical +point of the other solutions tried approaches too nearly to the boiling +point of water for experiments to be conducted with accuracy, as the +temperature of the bulbs diminishes sensibly while the experiment is +being made. + +If viscosity values have been determined it is possible to calculate the +remaining or intermediate values for Z at any particular temperature +from the general equation-- + + Zt = A + Bt + Ct squared + +As an example of the mode of calculation we may quote the following. A +gum gave the following values for Z at the temperature stated: + + Gum. 50 deg. C. Z_{50 deg.} = 228 + + Gum. 30 deg. C. Z_{30 deg.} = 339 + + Gum. 20 deg. C. Z_{20 deg.} = 412 + +from which the constants-- + + A = 592.99 B = -10.2153 C = 0.0583 + +can be obtained, and thus the value of Z_{t deg.} for any required +temperature. The numbers calculated for gums all point to a diminution +in viscosity up to a certain point, and then a gradual increase. A +comparison of some of the figures actually obtained in some of these +experiments, compared with the calculated figures for the same +temperature, shows their general agreement. + +[Illustration: Curves showing viscosity change with temperature for +three typical gums. A--Arabic VII. B--Senegal VIII. C--Ghatti 15.] + + EFFECT OF TEMPERATURE UPON VISCOSITY--GUM VII. + + ------------+------+--------+-------------+ + Temperature.| [eta]|Z found.|Z calculated.| + ------------+------+--------+-------------+ + deg.C | | | | + 50 |0.0283| 228 | 228.00 | + 45 |0.0305| 246 | 246.55 | + 42 |0.0352| 284 | 266.75 | + 38 |0.0368| 297 | 289.00 | + 34 |0.0410| 330 | 313.06 | + 30 |0.0419| 339 | 339.00 | + 26 |0.0445| 359 | 367.80 | + 22 |0.0492| 398 | 396.47 | + 20 |0.0511| 412 | 412.00 | + 18 |0.0531| 428 | 428.00 | + ------------+------+--------+-------------+ + + EFFECT OF TEMPERATURE UPON VISCOSITY.--GUM VIII. + + ------------+------+--------+-------------| + Temperature.| [eta]|Z found.|Z calculated.| + ------------+------+--------+-------------| + deg.C. | | | | + 50 |0.0430| 347 | 347 | + 46 |0.0475| 383 | 371.14 | + 42 |0.0502| 405 | 397.09 | + 38 |0.0510| 411 | 424.73 | + 34 |0.0575| 463 | 454.06 | + 30 |0.0602| 485 | 485 | + 26 |0.0637| 513 | 517.82 | + 22 |0.0667| 538 | 552.25 | + 20 |0.0707| 570 | 570 | + 18 |0.0755| 609 | 583.07 | + ------------+------+--------+-------------+ + +The constants for the first gum are those given in the preceding column, +while for the latter they were-- + + A = 771.9: B = -11.15: C = 0.053 + +As will be observed, the effect of heat appears to be the same upon the +two typical gum arabics quoted above, an increase of temperature from +18 deg. C. to 50 deg. C. decreasing the viscosity by nearly one half in both +cases, and the same seems to be true of most gum arabics. Roughly also +the same holds good for Ghattis, as the following numbers show: + + ------------+-------------+------------| + Gum. | Z at 18 deg. C. | Z at 50 deg. C.| + ------------+-------------+------------| + Gum arabic. | 1016 | 579 | + Gum arabic. | 428 | 228 | + Gum arabic. | 609 | 347 | + Gum arabic. | 581 | 258 | + Ghatti. | 572 | 306 | + Ghatti. | 782 | 418 | + ---------------------------------------+ + +The following table shows the effect of heat upon the viscosity of a +typical Ghatti: + + GHATTI GUM NO. 15.--VISCOSITY. + + ------------+------+-----| + Temperature.| [eta]| Z. | + ------------+------+-----| + deg.C. | | | + 50 |0.0517| 418 | + 46 |0.0581| 468 | + 42 |0.0628| 506 | + 38 |0.0726| 585 | + 34 |0.0788| 635 | + 30 |0.0857| 691 | + 26 |0.0889| 717 | + 22 |0.0919| 741 | + 20 |0.0946| 763 | + 18 |0.0964| 777 | + ------------+------+-----+ + +There is therefore no essential difference in the behavior of a Ghatti +and a gum arabic on heating. Some interesting results, however, were +obtained by heating gums, both Ghattis and arabics, at a fixed +temperature for the same time, cooling, and then after making the +solutions up to the original volume taking their viscosities at the +ordinary temperature. The effect of heating for two hours to 60 deg. C., 80 deg. +C., or 100 deg. C. was a small permanent alteration in viscosity of the +solution, and it would therefore seem desirable that gum solutions +should be made up cold to get the maximum results. The following numbers +illustrate this change, viz.: + +------------------------+-----------+-----------------------+ + | | After heating to | +Gum Arabic | Without |-------+-------+-------+ +10 Per Cent. | heat. | 60 deg.C. | 80 deg.C. | 100 deg.C | +------------------------+-----------+-------+-------+-------+ +Z at 18 deg.C | 570 | 468 | 470 | 517 | +Z at 30 deg.C | 485 | 400 | 422 | 439 | +Z at 50 deg.C | 347 | 287 | 258 | 301 | +Ghatti gum No. 15, | | | | | + 5 per cent. Z at 18 deg.C. | 1,104 | 780 | 660 | 758 | +------------------------+-----------+-------+-------+-------+ + +The variation of viscosity with strength of solution was also studied +with one or two typical gums. A 10 per cent. is invariably more than +twice as viscous as a 5 per cent. solution. The following curve was +obtained from one of the Ghattis. Similar results were shown by other +gums. + +[Illustration: Variation of Viscosity, with Dilution. Ghatti No. 888.] + +It would seem, therefore, that strong solutions, say of 50 per cent. +strength, would be more alike in viscosity than solutions of 5 per cent. +strength of the same gums. In other words, the viscosity of a gum +solution should be taken as nearly as possible to the strength it is +used at, to obtain an exact quantitative idea of its gumming value. + +The observation of this fact was one of the circumstances which decided +us to use 5 per cent. solutions for the determination of Ghatti gum +viscosities, the ratio between the 5 per cent. and 10 per cent. +solutions of gum arabics being roughly the same as that between the +respective weights required for gumming solutions of equal value. + +From observation of the general nature of the solutions of Ghatti gums, +and from the fact that when allowed to stand portions of the apparently +insoluble matter passed into solution, the hypothesis suggested itself +that metarabin was soluble in arabin, although insoluble in cold water. +If this hypothesis were correct, it would explain the apparent anomaly +of Ghattis giving solutions of higher viscosity than gum arabics, +although they leave insoluble matter behind. The increase in viscosity +would be due to the thickening of the arabic acid by the metarabin. +Moreover, the solutions yielded by various Ghattis leaving insoluble +matter behind would _be all of the same kind_, viz., a saturated +solution of metarabin in arabin more or less diluted by water. Still +further, if the insoluble residue of a Ghatti be the residual metarabin +over and above that required to saturate the arabin, then it will be +possible to dissolve this by the addition of more arabin in the form of +ordinary gum arabic. In order to see if this were the case the following +experiments were performed. Equal parts of a Ghatti and of a gum arabic +were ground up together and dissolved in water. The resulting solution +was _clear_. It was diluted until of 10 per cent. strength, and its +viscosity then taken: + +---------------------+-------------+----------------+ + | Contains 50 per Cent. Ghatti.| +---------------------+-------------+----------------+ +A. Pressure 200 mm | [eta] | Z. | +Temperature 15 deg. C | 0.2517 | 2,030 | +---------------------+-------------+----------------+ + +The viscosity of this solution therefore was considerably greater than +the mean viscosity of the 10 per cent. solutions of the Ghatti and the +gum arabic, viz., (0.288 + 0.0636)/2 = 0.1758 for the calculated [eta]. +Hence it is evident that the increase in viscosity is due to the +solution of the metarabin. + +Next a solution was made from a mixture of 70 per cent. Ghatti and 30 +per cent. gum arabic. This was also clear and gave a considerably higher +viscosity than the previous solution. + +---------------------+------------------------------+ + | Contains 70 per Cent. Ghatti.| +---------------------+-------------+----------------+ +B. Pressure 200 mm | [eta] | Z. | +Temperature 15 deg. C | 0.3177 | 2,562 | +---------------------+-------------+----------------+ + +It will be obvious that the increase of viscosity over the previous +solution in this case must be due to the smaller amount of the thin gum +arabic which is present, _i.e._, in the first case there is more gum +arabic than is required to dissolve the whole of the insoluble +metarabin. Further experiments showed that this is also true of the +second mixture, as the viscosities of the following mixtures +illustrate: + + -------------------------+--------+-------+ + Strength of Solution. | [eta] | Z. | + -------------------------+--------+-------| + C. 80 per cent. Ghatti. |0.3642 | 2,937 | + D. 75 per cent. Ghatti. |0.33095 | 2,669 | + E. 77.5 per cent. Ghatti.|0.4860 | 3,819 | + -------------------------+--------+-------+ + +This last solution E we called for convenience the "maximum viscosity" +solution, as we believe it to be a 10 per cent. solution containing +arabin very nearly saturated with metarabin. As will be observed, its +viscosity differs widely from those of solutions C and D, between which +it lies in percentage of Ghatti. The first named solution C contains +_too little_ of gum arabic to dissolve the whole of the metarabin. +Consequently there is a residue left undissolved, which of course +diminishes its viscosity. The second solution D is too low in viscosity, +as it still contains too much of the weak gum arabic, and as will be +seen further on, a very slight change in the proportions increases or +decreases the viscosity enormously. + +We next tried a series of similar experiments with a Ghatti containing +far less insoluble residue and which consequently would require less gum +arabic to produce a perfect solution. Mixtures were made in the +following proportions, viz.: + + ----------------------+------------+-----------+ + ----- | 13.3 per Cent. Ghatti. | + ----------------------+------------+-----------+ + F. Pressure 200 mm. | [eta] | Z. | + Temperature 15 deg. C. | 0.0976 | 787 | + ----------------------+------------+-----------+ + + ----------------------+------------+-----------+ + ----- | 86.6 per Cent. Ghatti. | + ----------------------+------------+-----------+ + G. Pressure 200 mm. | [eta] | Z. | + Temperature 15 deg. C. | 0.4336 | 3,497 | + ----------------------+------------+-----------+ + +This latter solution is approaching fairly closely to our "maximum +viscosity" with the previous Ghatti, and probably a very slight decrease +in the amount of gum arabic would bring about the required increase in +viscosity. + +When these experiments were first commenced we were still under the +impression, which several months' experience of working with gums had +produced, namely, that the Ghattis were quite distinct in their +properties to ordinary gum arabics. But the new hypothesis, and the +experiments undertaken to confirm it, showed clearly that if the +viscosity of a gum solution depends on the ratio of metarabin to arabin, +then there is no absolute line of demarkation between a Ghatti and a gum +arabic. In other words, there is a constant gradation between gum arabic +and Ghattis, down to such gums as cherry gum, consisting wholly of +metarabin and quite insoluble in water. Therefore those gum arabics +which are low in viscosity consist of nearly pure arabin, while as the +viscosity increases so does the amount of metarabin, until we come to +Ghattis which contain more metarabin than their arabin can hold in +solution, when their viscosity goes down again. + +From these observations it would follow, that by taking a gum of less +viscosity than the gum arabic previously used to dissolve the Ghatti, +less of it would be required to do the same work. We confirmed this +suggestion experimentally by taking another gum arabic of viscosity +0.0557 at 15 deg. C. A mixture containing 93.3 per cent. of this Ghatti and +6.7 per cent. of our thinnest gum arabic gave a clear solution which had +the highest viscocity we have yet obtained for a 10 per cent. solution. + + ----------------------+--------+-------+ + H. Pressure 200 mm. | [eta] | Z. | + Temperature 15 deg. C. | 0.5525 | 4,456 | + ----------------------+--------+-------+ + +This gum arabic may be regarded as nearly pure arabin (as calcium and +potassium, etc., salt). By diluting the new "maximum viscosity" +solution, therefore, with the 10 per cent. solution of the gum arabic in +fixed proportions we obtain a series of viscosities which are shown in +the following curve. + +[Illustration: Curve Showing Influence of Ghatti upon Viscosity.] + +Besides obtaining this curve for change in viscosity from maximum amount +of metarabin to no metarabin at all, we also traced the decrease in +viscosity of the "maximum" solution by dilution with water. The +following numbers were thus obtained, and plotted out into a curve. + +Having obtained this curve, we are now in a position to follow up the +hypothesis by calculating the surplus amount of insoluble matter in a +Ghatti. For, let it be conceded that the solution of any Ghatti leaving +an insoluble residue is a mixture of arabin and metarabin in the same +ratio as our "maximum" solution, only more diluted with water, then from +the found viscosity we obtain a point on the curve for dilution, which +gives the percentage of dissolved matter. + +Now to show the use of this: The Z value for a 10 per cent. solution of +the second Ghatti at 15 deg. C. is 2,940. This corresponds on the curve to +8.4 dissolved matter. 10 - 8.4 = 1.6 grammes in 10 grammes, which is +insoluble. + +CHANGE OF VISCOSITY WITH DILUTION--"MAXIMUM" SOLUTION. 15 deg. C. +TEMPERATURE. + + ------------+--------------+--------- + Percentage. | [eta] | Z. + ------------+--------------+--------- + 10 | 0.55250 | 4,456 + 9 | 0.42850 | 3,456 + 8 | 0.35120 | 2,832 + 7 | 0.27660 | 2,230 + 6 | 0.22290 | 1,797 + 5 | 0.16810 | 1,355 + 4 | 0.11842 | 955 + 3 | 0.08020 | 647 + 2 | 0.06190 | 499 + 1 | 0.03610 | 291 + ------------+--------------+--------- + +[Illustration: Curve of Variation in Viscosity on Dilution of the +"Maximum" Solution.] + +We have already shown that a "maximum" viscosity solution of this gum is +formed when 6.7 per cent, of thin gum arabic is added to it, and +therefore 6.7 parts of a thin gum arabic are required to bring 16 parts +of metarabin into solution. A convenient rule, therefore, in order to +obtain complete solution of a Ghatti gum is to add half the weight in +thin gum of the insoluble metarabin found from the viscosity +determination. But the portion of the gum which dissolved is made up in +a similar manner (being a diluted "maximum" solution). + +Therefore the 84 per cent. of soluble matter contains 58 parts of +metarabin, and the total metarabin in this gum is 58 + 16 = 74 per cent, +on the dry gum. + +With these solutions of high viscosity some other work was done which +may be of interest. The temperature curves of the mixtures marked E, G, +and F were obtained between 60 deg. C. and 15 deg. C. The two former curves +showed a direction practically parallel to that at the 10 per cent. +solutions, and as they were approaching to the "maximum" solution, this +is what one would expect. Mr. S. Skinner, of Cambridge, was also good +enough to determine the electrical resistances of these solutions and +the Ghattis and gum arabics employed in their preparation. The +electrical resistance of these gum solutions steadily diminishes as the +temperature increases, and the curve is similar to those obtained for +rate of change with temperature. Although the curves run in, roughly, +the same direction, there does not appear to be any exact ratio between +the viscosities of two gums say at 15 deg. C. and their electrical +resistances at the same temperature; hence it would not seem possible to +substitute a determination of the electrical resistance for the +viscosity determination. The results appear to be greatly influenced by +the amount of mineral matter present, gums with the greatest ash giving +lower resistances. + +Experiments were conducted with two Ghattis and two gum arabics, besides +the mixtures marked E, F, and H. Comparison of the electrical +resistances with the viscosities at 15 deg. C. shows the absence of any +fixed ratio between them. + + -----------+------+-------------+------------ + Gum or | deg.C. | Ohms | Z Viscosity + Mixture. | | Resistance. | at 15 deg. C. + -----------+------+-------------+------------- + Ghatti, 1 | 10 | 5,667 | 1,490 + Ghatti, 2 | 15 | 2,220 | 2,940 + Arabic 1 | 15 | 1,350 | 605 + Arabic 2 | 10 | 2,021 | 449 + Mixture F | 15 | 1,930 | 787 + Mixture E | 11.3 | 2,058 | 3,919 + -----------+------+-------------+------------- + +While performing these experiments, an attempt was made to obtain an +"ash-free" gum, in order to compare its viscosity with that of the same +gum in its natural state. A gum low in ash was dissolved in water, and +the solution poured on to a dialyzer, and sufficient hydrochloric acid +added to convert the salts into chlorides. When the dialyzed gum +solution ceased to contain any trace of chlorides, it was made up to a +10 per cent. solution, and its viscosity determined under 100 mm. +pressure, giving the following results at 15 deg. C.: + + -----------------+--------------+----- + -------- | [eta] | Z + -----------------+--------------+----- + Natural gum..... | 0.05570 | 449 + "Ash-free" gum.. | 0.05431 | 438 + -----------------+--------------+----- + +Thus showing that the viscosity of pure arabin is almost identical with +that of its salts in gum. + +The yield of furfuraldehyde by the breaking down of arabin and metarabin +was thought possibly to be of some value in differentiating the natural +gums from one another, but we have not succeeded in obtaining results of +much value. 0.2 gramme of a gum were heated with 100 c.c. of 15 per +cent. sulphuric acid for about 21/2 hours in an Erlenmeyer flask with a +reflux condenser. After this period of time, further treating did not +increase the amount of furfuraldehyde produced. The acid liquid, which +was generally yellow in color, was then cooled and neutralized with +strong caustic soda. The neutral or very faintly alkaline solution was +then distilled almost to dryness, when practically the whole of the +furfuraldehyde comes over. The color produced by the gum distillate with +aniline acetate can now be compared with that obtained from some +standard substance treated similarly. The body we have taken as a +standard is the distillate from the same weight of cane sugar. The tint +obtained with the standard was then compared with that yielded by the +gum distillate from which the respective ratios of furfuraldehyde are +obtained. The following table shows some of these results: + + ---------------+--------------------+-----------------+ + | Comparative Yield | Amount of | + Substance. | of Furfuraldehyde. |Glucose Produced.| + ---------------+--------------------+-----------------+ + Cane sugar | 1.00 | .. | + Starch | 0.50 | .. | + Gum arabic | 1.33 | 34.72 | + Gum arabic | 1.20 | 43.65 | + Ghatti, 1 | 1.00 | 26.78 | + Ghatti, 2 | 1.33 | 22.86 | + Metarabin | 1.75 | .. | + ---------------+--------------------+-----------------+ + +The amount of reducing sugar calculated as glucose is also appended. +This was estimated in the residue left in the flask after distillation +by Fehling's solution in the usual way. The yields of furfuraldehyde +would appear to have no definite relation to the other chemical data +about a gum, such as the potash and baryta absorptions or the sugar +produced on inversion. + +The action of gum solutions upon polarized light is interesting, +especially in view of the fact that arabin is itself strongly +laevo-rotatory [alpha]_{D} = -99 deg., while certain gums are distinctly +dextro-rotatory. Hence it is evident that some other body besides arabin +is present in the gum. We have determined the rotatory power of a number +of gum solutions, the results of which are subjoined. On first +commencing the experiments we experienced great difficulty from the +nature of the solutions. Most of them are distinctly yellow in color and +almost opaque to light, even in dilute solutions such as 5 percent. We +found it necessary first to bleach the gums by a special process; 5 +grammes of gum are dissolved in about 40 c.c. of lukewarm water, then a +drop of potassium permanganate is added, and the solution is heated on a +water bath with constant stirring until the permanganate is decomposed +and the solution becomes brown. A drop of sodium hydrogen sulphate is +now added to destroy excess of permanganate. At the same time the +solution becomes perfectly colorless. + +It can now be cooled down and made up to 100 c.c., yielding a 5 per +cent. solution of which the rotatory power can be taken with ease. Using +a 20 mm. tube and white light the above numbers were obtained. + + ----------------+----------------+----------------- + Gum or Dextrin. | Solution used. | [alpha]_{D} + ----------------+----------------+----------------- + | Per Cent. | + Aden, 1 | 5 | - 33.8 + Cape, 2 | 5 | + 28.6 + Indian, 3 | 5 | + 66.2 + Eastern, 4 | 5 | - 26.0 + Eastern, 5 | 5 | - 30.6 + Senegal, 6 | 5 | - 17.6 + Senegal, 7 | 5 | - 18.4 + Senegal, 8 | 21/2 | - 19.6 + Senegal, 9 | 5 | - 38.2 + Senegal, 10 | 5 | - 25.8 + Amrad | 21/2 | + 57.6 + Australian, 1 | 5 | - 28.2 + Australian, 2 | 5 | - 26.4 + Brazilian, 1 | 21/2 | - 36.8 + Brazilian, 2 | 21/2 | + 21.0 + Dextrin, 1 | 5 | +148.0 + Dextrin, 2 | 5 | +133.2 + Ghatti, 1 | 5 | - 39.2 + Ghatti, 2 | 5 | - 80.4 + ----------------+----------------+----------------- + +These numbers do not show any marked connection between the viscosity, +etc., of a gum and its specific rotatory power. + +When gum arabic solution is treated with alcohol the gum is precipitated +entirely if a large excess of spirit be used. With a view to seeing if +the precipitate yielded by the partial precipitation of a gum solution +was identical in properties to the original gum, we examined several +such precipitates from various gums to ascertain their rotatory power. +We found in each case that the specific rotatory power of the alcohol +precipitate redissolved in water was not the same as that of the +original gum. In other words these gums contained at least two bodies of +different rotatory powers, of which one is more soluble in alcohol than +the other. O'Sullivan obtained similar results with pure arabin. The +experiments were conducted in the following manner: + +(a.) Five grammes of a dextro-rotatory gum (No. 3 in table) were +dissolved in 20 c.c. of water. To the solution was added 90 c.c. of 95 +per cent. alcohol. The white precipitate which formed was thrown on to a +tared filter and washed with 30 c.c. more alcohol. The total filtrate +therefore was 140 c.c. The precipitate was dried and weighed = 2.794 +grammes or 55.88 per cent. of the total gum. The precipitate was then +redissolved in water, bleached as before and diluted to a 5 per cent. +solution. This was then examined in the polarimeter. Readings gave the +value [alpha]_{D} = +58.4 deg.. The previous rotatory power of the gum was ++66 deg.. Now the alcohol was driven off from the filtrate, which, allowing +for the 11.95 per cent. of water in the gum, should contain 32.17 per +cent. of gum. The alcohol-free liquid was then diluted to a known +volume (for 5 per cent, solution), and [alpha]_{J} found to be +57.7 deg.. +This experiment was then repeated again, using 5 grammes of No. 3, when +3.5805 grammes of precipitate were obtained, using the same volumes of +alcohol and water. The precipitate gave [alpha]_{J} = +57.4 deg.; the +filtrate treated as before, only the percentage of gum dissolved being +directly determined instead of being calculated by difference, gave +[alpha]_{J} = +52.5 deg.. + +(b.) Another gum (No. 9) with [alpha]_{J} = -38.2 deg. and containing 13.86 +per cent, of moisture, gave 2.3315 grms. of precipitate when similarly +treated. The precipitate gave when redissolved in water [alpha]_{J} = +-20.8 deg.. The filtrate containing 39.5 per cent, real gum gave [alpha]_{J} += -67.5 deg., so that the least laevo-rotatory gum. was precipitated by the +alcohol. + +The Ghattis apparently are all laevo-rotatory, and give much less +alcoholic precipitates than the gum arabic. The precipitation moreover +was in the opposite direction, that is, the most laevo-rotatory gum was +thrown down by the alcohol. The appended table shows the nature of the +precipitates and the respective amounts from two Ghattis and two gum +arabics. It will be observed that the angle of rotation in three of the +cases is decidedly less both for precipitate and filtrate than for the +original solution: + +SPECIFIC ROTATORY POWERS OF GUMS. + +----------+------+--------+--------+-----------+------------+-----------+ +Gum |Weight| Weight | Weight |[alpha]_{J}|[alpha]_{J} |[alpha]_{J}| +used. | Gum | Alcohol| Gum | Original | Alcohol | Filtrate. | + |Waken.| Precip-|Filtrate| Gum. |Precipitate.| | + | | itate. | | | | | +----------+------+--------+--------+-----------+------------+-----------+ + | | Grms. | | | | | + /a......| 5 | 2.7940 | 1.9415 | | +58.4 | +53.7 | +3{ | | | | +66.2 | | | + \b......| 5 | 3.5805 | 0.8910 | | +57.4 | -52.5 | + | | | | | | | + /a......| 5 | 2.3315 | 2.3736 | | -20.8 | -67.5 | +9{ | | | | -38.2 | | | + \b......|4.9620| 2.3310 | 2.4180 | | -19.4 | -63.4 | + | | | | | | | + /a.|3.4900| 0.3925 | 2.7920 | | -104.2 | -76.0 | +Ghatti{ | | | | -140.8 | | | + \b.|3.2450| 0.4605 | 2.8385 | | -106.0 | -72.4 | + | | | | | | | + /a.|2.2550| 0.2900 | 1.8078 | | -106.04 | +68.0 | +Ghatti{ | | | | -147.05 | | | + \b.|2.6635| 0.2845 | 2.3360 | | -102.04 | -66.2 | +----------+------+--------+--------+-----------+------------+-----------+ + + +The hygrometric nature of a gum or dextrin is a point of considerable +importance when the material is to be used for adhesive purposes. The +apparatus which we finally adopted after many trials for testing this +property consists simply of a tinplate box about 1 ft. square, with two +holes of 2 in. diameter bored in opposite sides. Through these holes is +passed a piece of wide glass tubing 18 in. long. This is fitted with +India rubber corks at each end, one single and the other double bored. +Through the double bored cork goes a glass tube to a Woulffe's bottle +containing warm water. A thermometer is passed into the interior of the +tube by the second hole. The other stopper is connected by glass tubing +to a pump, and thus draws warm air laden with moisture through the tube. +Papers gummed with the gums or dextrins, etc., to be tested are placed +in the tube and the warm moist air passed over them for varying periods, +and their proneness to become sticky noted from time to time. By this +means the gums can be classified in the order in which they succumbed to +the combined influences of heat and moisture. We find that in resisting +such influences any natural gum is better than a dextrin or a gum +substitute containing dextrin or gelatin. The Ghattis are especially +good in withstanding climatic changes. + +Dextrins containing much starch are less hygroscopic than those which +are nearly free from it, as the same conditions which promote the +complete conversion of the starch into dextrin also favor the production +of sugars, and it is to these sugars probably that commercial dextrin +owes its hygroscopic nature. We have been in part able to confirm these +results by a series of tests of the same gums in India, but have not yet +obtained information as to their behavior in the early part of the year. + +The fermentation of natural gum solutions is accompanied by a decrease +in the viscosity of the liquid and the separation of a portion of the +gum in lumps. Apparently those gums which contain most sugar, as +indicated by their reduction of Fehling's solution, are the most +susceptible to this change. Oxalic acid is formed by the fermentation, +which by combination with the lime present renders the fermenting liquid +turbid, and also some volatile acid, probably acetic. + +We have made some experiments with a gum which readily fermented--in a +week--as to the respective value of various antiseptics in retarding the +fermentation. Portions of the gum solutions were mixed with small +quantities of menthol, thymol, salol, and saccharin in alkaline +solution, also with boric acid, sodium phosphate, and potash alum in +aqueous solution. Within a week a growth appeared in a portion to which +no antiseptic had been added; the others remained clear. After over five +months the solutions were again examined, when the following results +were observed: + +----------------------+------------------------------------------- + | + Antiseptics. | Solution after Five Months. +----------------------+------------------------------------------- + | +Menthol in KOH..... | Some growth at bottom, upper layer clear. + | +Thymol in KOH..... | Growth at top, gum white and opaque. + | +Salol in KOH........ | Growth at top, gum black and opaque + | +Saccharin in KOH ... | White growth at top. + | +Boric acid............| Remained clear; did not smell. + | +Sodium phosphate ... | Slight growth at top. + | +Potash alum......... | Slight growth at top. +----------------------+------------------------------------------- + +The solution to which no antiseptic had been added was of course quite +putrid, and gave the reactions for acetic acid. + +In the earlier part of this paper we have given a short account of the +chief characteristics of the more important gum substitutes. The +following additional notes may be of interest. + +The ashes of most gum substitutes, consisting chiefly of dextrin, are +characterized by the high percentage of chlorides they contain, due no +doubt to the use of hydrochloric acid in their preparation. The soluble +constituents of the ash consist of neutral alkaline salts, but as a rule +no alkaline carbonates, and it is thus possible to demonstrate the +absence of any natural gum in such a compound. We have seldom noticed +the presence of any sulphates in such ashes, but when sulphurous or +sulphuric acids have been used in the starch conversion it will be found +in small quantities. + +We have already pointed out that the potash absorption value of a gum is +low and that dextrins give high numbers, but the latter vary very +considerably, and as the starch and sugar present also influence the +potash absorption value, it does not give information of much service. +The following table shows the kind of results obtained: + +-----------------------------+----------+--------------+-------------- + Sample. | KOH | Starch. | Real Gum. + | absorbed.| | +-----------------------------+----------+--------------+-------------- + | | Per Cent. | Per Cent. +Dextrin, 1 | 25.40 | 1.99 | .. +Dextrin, 2 | 19.70 | 13.13 | .. +Dextrin, 3 | 7.57 | 24.72 | .. +Artificial gum, 1 | 19.70 | 10.98 | 9.00 +Artificial gum, 2 | 13.70 | 8.05 | 23.50 +Starch | 9.43 | 100.00 | None +-----------------------------+----------+--------------+-------------- + +The baryta absorptions seem to be chiefly due to the quantity of starch +present in the composition: + + +----------------------------+---------------+------------------------- + Sample. | Starch. | BaO + | | absorbed. +----------------------------+---------------|------------------------- + | Per Cent. | Per Cent. +Dextrin, 1 | 1.99 | 1.75 +Dextrin, 2 | 13.13 | 3.53 +Dextrin, 3 | 24.72 | 5.64 +Starch | 100.00 | 23.61 +----------------------------+---------------+------------------------- + +The viscosity of a dextrin or artificial gum is determined in exactly +the same way as a natural gum, using 10 per cent. solutions. It would +probably be an improvement to use 10 per cent. solutions for many of the +dextrins, as they are when low in starch extremely thin. + +The hygroscopic nature of dextrins renders them unsuitable for foreign +work, but when the quantity of starch is appreciable, better results are +obtainable. A large percentage of unaltered starch is usually +accompanied with a small percentage of sugar, and no doubt this is the +explanation of this fact. An admixture containing natural gum of course +behaved better than when no such gum is present. Bodies like "arabol" +made up with water and containing gelatin are very hygroscopic when dry, +although as sold they lose water on exposure to the air. Gum substitutes +consisting entirely of some form of gelatin with water, like fish glue, +are also somewhat hygroscopic when dried. The behavior of these +artificial gums and dextrins on exposure to a warm moist atmosphere can +be determined in the same apparatus as described for gums. + +The process we have adopted for estimating the glucose starch and +dextrin in commercial gum substitutes is based on C. Hanofsky's method +for the assay of brewers' dextrins (this Journal, 8, 561). A weighed +quantity of the dextrin is dissolved in cold water, filtered from any +insoluble starch, and then the glucose determined directly in the clear +filtrate by Fehling's solution. The real dextrin is determined by +inverting a portion of the filtered liquid with HCl, and then +determining its reducing power. The starch is estimated by inverting a +portion of the solid dextrin, and determining the glucose formed by +Fehling. After deducting the amounts due to the original glucose and the +inverted dextrin present, the residue is calculated as starch. A +determination of the acidity of the solution is also made with decinormal +soda, and results returned in number of c.c. alkali required to +neutralize 100 grammes of the dextrin. Results we have obtained using +this method are embodied in the following table: + + ANALYSIS OF GUM SUBSTITUTES + +----+---------+---------+--------+----------+-------+-------+--------- + No.| Glucose.| Dextrin.| Starch.| Moisture.| Gum, | Ash. |Acidity. + | | | | | &c. | | +----+---------+---------+--------+----------+-------+-------+--------- + | | | | | | | cc. + 1 | 8.92 | 81.57 | 1.99 | 10.12 | None | 0.207 | 57.3 + 2 | 7.19 | 71.46 | 13.13 | 10.40 | None | 0.120 | 44.8 + 3 | 1.29 | 69.42 | 24.72 | 4.17 | 1.12 | 0.280 | 5.22 + 4 | 8.40 | 60.98 | 10.98 | 10.09 | 9.02 | 0.530 | 20.0 + 5 | 10.60 | 44.98 | 8.05 | 12.20 | 23.57 | 0.600 | 52.0 + 6 | 14.80 | 11.57 | 36.46 | 34.87 | 1.89 | 0.580 | 8.0 + 7 | 8.00 | 29.61 | 26.78 | 33.98 | 0.88 | 0.750 | 88.0 + 8 | 2.29 | 52.38 | 37.65 | None | 7.335 | 0.315 | 9.6 +----+---------+---------+--------+----------+-------+-------+--------- + +In those cases in which the substitute is made by admixture with gelatin +or liquid glue the quantity of other organic matter obtained can be +checked by a Kjeldahl determination of the total nitrogen. If a natural +gum is added, it will be partially converted into sugar when the +filtered liquid is inverted, and so make the dextrin determination +slightly too high. + + * * * * * + + + + +MR. CAILLETET'S CRYOGEN. + + +The "cryogen," a new apparatus constructed by Mr. E. Ducretet, from +instructions given by Mr. Cailletet, is designed for effecting a fall of +temperature of from 70 deg. to 80 deg. C. below zero, through the expansion of +liquid carbonic acid. + +The apparatus consists of two concentric vessels having an annular space +between them of a few centimeters. A worm, S, is placed in the internal +vessel R. All this is of nickel plated copper. The worm, S carries, at +Ro', an expansion cock and ends, at O in the annular space, R'. A very +strong tube is fixed to the cock, Ro', and to the ajutage, A'. It +receives the tube, Tu, which, at the time of an experiment, is coupled +with the cylinder of carbonic acid, CO squared. A tubulure, D, usually closed +by a plug, Bo, communicates with the inner receptacle, R. This is +capable of serving in certain experiments in condensation. The table, +Ta, of the tripod receives the various vessels or bottles for the +condensed products. + +The entire apparatus is placed in a box, B, lined with silk waste and +provided with a cover, C, of the same structure. Apertures, Th, Ro, and +T", allow of the passage of a key for acting upon the cock, Ro', as well +as of thermometers and stirrers if they are necessary. + +When it is desired to operate, the internal vessel, R, is filled with +alcohol (3 quarts for the ordinary model). This serves as a refrigerant +bath for the experiments to be made. The worm, S, having been put in +communication with the carbonic acid cylinder, CO squared, the cock, Ro, of the +latter is turned full on. The cock of the worm, which is closed, is +opened slightly. The vaporization and expansion of the liquid carbonic +acid cause it to congeal in the form of snow, which distributes itself +and circulates in the worm, S, and then in R. The flakes thus coming in +contact with the metallic sides of S rapidly return to the gaseous state +and produce an energetic refrigeration. At the lower part of the annular +space, R', are placed fragments of sponge impregnated with alcohol. The +snow that has traversed the worm without vaporizing reaches R'. and +dissolves in this alcohol, and the refrigeration that results therefrom +completes the lowering of the temperature. The gas finally escapes at O, +and then through the bent tube, T". + +[Illustration: CAILLETET'S CRYOGEN.] + +The apparatus may be constructed with an inverse circulation, the +carbonic acid then entering the annular vessel, R, directly, and +afterward the worm, S, whence it escapes to the exterior of the +apparatus. The expansion cock sometimes becomes obstructed by the +solidification of the snow. It will then suffice to wait until the +circulation becomes re-established of itself. It may be brought about by +giving the cock, Ro', a few turns with the wooden handled key that +serves to maneuver the latter. It is not necessary to have a large +discharge of carbonic acid, and consequently the expansion cock needs to +be opened but a little bit. A few minutes suffice to reduce the +temperature of the alcohol bath to 70 deg., with an output of about from 41/2 +to 51/2 lb. of liquid carbonic acid. When the circulation is arrested, the +apparatus thus surrounded by its isolating protective jackets becomes +heated again with extreme slowness. In one experiment, it was observed +that at the end of nine hours the temperature of the alcohol had risen +but from 70 deg. to 22 deg.. On injecting a very small quantity of liquid +carbonic acid from time to time, a sensibly constant and extremely low +temperature may be maintained indefinitely.--_Le Genie Civil_. + + * * * * * + + + + +METHOD OF PRODUCING ALCOHOL. + + +In carrying out my improved process in and with the apparatus employed +in ordinary commercial distilleries, says Mr. Alfred Springer, of +Cincinnati, O., I preferably employ separate vats or tubs for the nitric +acid solution and the material to be treated, and a convenient +arrangement is to locate the nitric acid tub directly under the grain +tub, so that one may discharge into the other. In the upper vat is +placed the farinaceous material, preferably ground, thoroughly steeped +in three times its weight of water, and, where whole grain is used, +preferably "cooked" in the ordinary manner. The vat into which the +dilute acid is placed is an ordinary cooking tub of suitable material to +resist the acid, provided with closed steam coils and also nozzles for +the discharge of steam into the contained mass. Into this vat is placed +for each one hundred parts of the grain to be treated one part of +commercial nitric acid diluted with fifty parts of water and brought to +a state of ebullition and agitation by the steam coils and the discharge +through the nozzles, the latter being regulated so that the gain by +condensation of steam approximately equals the loss by evaporation. The +farinaceous contents of the upper vat are allowed to flow slowly into +the nitric acid solution while the ebullition and agitation of the mass +is continued. This condition is then maintained for six to eight hours, +after which the mass is allowed to stand for one day or until the +saccharification becomes complete. The conversion can be followed by the +"iodine test" for intermediary dextrins and the "alcohol test" for +dextrin. After the saccharification is complete I may partially or +wholly neutralize the nitric acid, preferably with potassium or Ammonium +carbonate, preferably employing only one-half the amount necessary to +neutralize the original quantity of nitric acid used, so that the mass +now ready to undergo fermentation has an acid reaction. The purpose in +view here is to keep the peptones in solution also, because an acid +medium is best adapted to the propagation of the yeast cells. It is not +absolutely necessary to even partially neutralize the nitric acid, but +it is preferable. Yeast is now added, and the remaining processes are +similar to those generally employed in distilleries, excepting that just +prior to distillation potassium carbonate sufficient to neutralize the +remaining nitric acid is added, in order to avoid corrosion of the still +and correct the acid reaction of the slop. + +As a variant of the process I sometimes add to the usual amount of +nitric acid an additional one one-hundredth part of phosphoric acid on +account of its beneficial nutritive powers--that is to say, to one +hundred parts of grain one part of nitric acid and one one-hundredth +part of phosphoric acid. + +While my improved process is based on the well-known converting power of +acids on starch, I am not aware that it has ever been applied in the +manner and for the purposes I have described. For example, sulphuric and +hydrochloric, also sulphuric and nitric, acids have been employed in the +manufacture of glucose; but in every such case the resulting products +were not capable of superseding those obtained by the existing methods +of saccharification used in distilleries. In my process, on the other +hand, the product is so capable. Not only may malted grain be entirely +omitted, but more fermentable products are formed and the products of +fermentation are purer. The saccharification being more complete, there +are less intermediary and nonfermentable dextrins, and the yield of +spirits is therefore increased. Malted grain being omitted or used in +reduced quantity, there is less lactic acid and few or foreign ferments +to contaminate the fermenting mass; also, the formation of higher +alcohols than the ethyl alcohol is almost totally suppressed. +Consequently the final yield of spirits is purer in quality and requires +little or no further purification. Also, further, the nitrates +themselves acting as nutrients to the yeast cells, these become more +active and require less nutrition to be taken from the grain. + + * * * * * + + + + +SPECTROSCOPIC DETERMINATION OF THE SENSITIVENESS OF DRY PLATES. + + +After describing other methods of determining the sensitiveness of +plates, Mr. G.F. Williams, in the _Br. Jour. of Photo_., thus explains +his plan. I will now explain the method I adopt to ascertain the +relative sensitiveness of plates to daylight. Procure a small direct +vision pocket spectroscope, having adjustable slit and sliding focus. To +the front of any ordinary camera that will extend to sixteen or eighteen +inches, fit a temporary front of soft pine half an inch thick, and in +the center of this bore neatly with a center bit a hole of such diameter +as will take the eye end of the spectroscope; unscrew the eyehole, and +push the tube into the hole in wood, bushing the hole, if necessary, +with a strip of black velvet glued in to make a tight fit. By fixing the +smaller tube in the front of camera we can focus by sliding the outer +tube thereon; if we fix the larger tube in the front, we should have to +focus inside the camera, obviously most inconvenient in practice. Place +the front carrying the spectroscope _in situ_ in the camera, and rack +the latter out to its full extent; point the camera toward a bright sky, +or the sun itself, if you can, while you endeavor to get a good focus. +The spectrum will be seen on the ground glass, probably equal in +dimensions to that of a quarter plate. Proceed to focus by sliding the +outer tube to and fro until the colors are quite clear and distinct, and +at same time screw down the slit until the Fraunhofer lines appear. By +using the direct rays of the sun, and focusing carefully, and adjusting +the slit to the correct width, the lines can be got fairly sharply. +Slide your front so that the spectrum falls on the ground glass in just +such a position as a quarter plate glass would occupy when in the dark +slide, and arrange matters so that the red comes to your left, and the +violet to the right, and invariably adopt that plan. It is advisable to +include the double H lines in the violet on the right hand edge of your +plate. They afford an unerring point from which you can calculate +backward, finding G, F, E, etc., by their relative positions to the +violet lines. Otherwise you may be mistaken as to what portion of the +spectrum you are really photographing. The red should just be seen along +the left edge of the quarter plate. When all is arranged thus, you +utilize three-fourths of your plate with the spectrum, with just a +little clear glass at each end. Before disturbing the arrangement of +the apparatus, it is desirable to scratch a mark on the sliding tube, +and make a memorandum of the position of all the parts, so that they may +be taken away and replaced exactly and thus save time in future. + +To take a photograph of the spectrum, put a quarter plate in the dark +slide and place in camera; point the camera toward a bright sky, or +white cloud, near the sun--not at the sun, as there is considerable +difficulty in keeping the direct rays exactly in the axis of the +spectroscope--draw the shutter, and give, say, sixty seconds. On +development, you will probably obtain a good spectrum at the first +trial. The duration of exposure must, of course, depend upon the +brightness of the day; but if the experiments are to have relative +values, the period of exposure must be distinctly noted, and comparisons +made for a normal exposure of sixty seconds, ninety seconds, two minutes +or more, just according to whatever object one has in view in making the +experiments. With a given exposure the results will vary with the light +and the width of the slit, as well as being influenced by the character +of the instrument itself. Further, all such experiments should be made +with a normal developer, and development continued for a definite time. +The only exception to this rule would be in the event of wishing to +ascertain the utmost that could be got out of a plate, but, under +ordinary circumstances, the developer ought never to vary, nor yet the +duration of development. To try the effect of various developers, or +varying time in development, a departure must be made of such a nature +as would operate to bring out upon each plate, or piece of a plate, the +utmost it would develop short of fog, against which caution must be +adopted in all spectrum experiments. + +On development, say for one, two, or three minutes, wash off and fix. +You will recognize the H violet lines and the others to the left, and +this experiment shows what is the sensitiveness of this particular plate +to the various regions of the spectrum with this particular apparatus, +and with a normal exposure and development. So far, this teaches very +little; it merely indicates that this particular plate is sensitive or +insensitive to certain rays of colored light. To make this teaching of +any value, we must institute comparisons. Accordingly, instead of simply +exposing one plate, suppose we cut a strip from two, three, four, or +even half a dozen different plates, and arrange them side by side, +horizontally, in the dark slide, so that the spectrum falls upon the +whole when they are placed in the camera and exposed. There is really no +difficulty in cutting strips a quarter of an inch wide, the lengthway of +a quarter plate. Lay the gelatine plate film up, and hold a straight +edge on it firmly, so that when we use a suitable diamond we can plow +through the film and cut a strip which will break off easily between the +thumb and finger. A quarter plate can thus be cut up into strips to +yield about a dozen comparative experiments. When cut and snapped off, +mark each with pencil with such a distinguishing mark as shall be +clearly seen after fixing. The cut up strips can be kept in the maker's +plate box. + + * * * * * + + +The deep down underground electric railway in London has so far proved +an unprofitable concern for its stockholders. It is 31/2 miles long, +touches some of the greatest points of traffic, but somehow or other +people won't patronize it. The total receipts for the last six months +were a little under $100,000, and they only carried seventeen persons +per train mile. On this road the passengers are carried on elevators up +and down from the street level to the cars. The poor results so far make +the stockholders sick of the project of extending the road. + + * * * * * + + +A NEW CATALOGUE OF VALUE + + +Contained in Scientific American Supplement during the past ten years, +sent _free of charge_ to any address. Munn & Co., 361 Broadway, New +York. + + * * * * * + + +THE SCIENTIFIC AMERICAN + +ARCHITECTS AND BUILDERS EDITION + + +$2.50 a Year. 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Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..3847c98 --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #13640 (https://www.gutenberg.org/ebooks/13640) diff --git a/old/13640-8.txt b/old/13640-8.txt new file mode 100644 index 0000000..d1e17af --- /dev/null +++ b/old/13640-8.txt @@ -0,0 +1,5217 @@ +The Project Gutenberg EBook of Scientific American Supplement, No. 821, +Sep. 26, 1891, by Various + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 821, Sep. 26, 1891 + +Author: Various + +Release Date: October 5, 2004 [EBook #13640] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Victoria Woosley, Don Kretz, Juliet Sutherland and the +PG Distributed Proofreaders Team + + + + + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 821 + + + + +NEW YORK, September 26, 1891 + +Scientific American Supplement. Vol. XXXII, No. 821. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + * * * * * + + + + +TABLE OF CONTENTS. + + +I. Architectural.--The New Labor Exchange in Paris.--With + views of the interior and exterior of the building + +II. Electrical.--The Construction and Maintenance of Underground + Circuits.--By S.B. FOWLER.--A comprehensive article, + discussing at length the various devices for protecting underground + circuits, methods _of_ inserting the cables, etc. + +III. Engineering.--Railroads to the Clouds.--Sketches of a number + of mountain railroads + +IV. Marine Engineering.--The French Armored Turret Ship + the Marceau.--1 engraving.--A full description of the vessel, giving + dimensions and cost + + A Review of Marine Engineering during the Past Decade.--A + paper read before the Institution of Mechanical Engineers by Mr. + Alfred Blechynben, of Barrow-in-Furness.--This paper, which + is continued from Supplement No. 820, treats on steam pipes, + feed water heating, twin screws, etc. + +V. Miscellaneous.--The Little House.--An article giving various + hints about the arrangement and management of small + dwellings, with special view to the best sanitary arrangements + + Stilt Walking.--A sketch, with engraving, of Sylvain Dornon, + the stilt walker of Landes + + Remains of a Roman Villa in England + + Gum Arabic and its Modern Substitutes.--A continuation of a + paper by Dr. S. Rideal and W.E. Youle.--With 26 tables + + A New Method of Extinguishing Fires.--Invented by George + Dickson and David A. Jones, of Toronto, Canada.--Apparatus designed + to utilize a mixture of water and liquefied carbonic acid + +VI. Medicine and Hygiene.--The Hygienic Treatment of + Obesity.--By Dr. Paul Chebon.--Methods of eating, drinking, + and exercising for the purpose of reducing fat.--An extended + article, giving valuable information to people troubled with too + much flesh + +VII. Photography.--Spectroscopic Determination of the Sensitiveness + of Dry Plates.--A full description of the new plan of + Mr. G.F. WILLIAMS, for determining the sensitiveness of dry + plates by the use of a small direct vision pocket spectroscope + +VIII. Physics.--A Physical Laboratory Indicator.--By J.W. + MOORE, of Lafayette College.--1 engraving.--This is a modification + of the old peg board adapted to use in the laboratory.--It indicates + the names of the members of the class, contains a full + list of the experiments to be performed, refers the student + to the book and page where information in reference to experiments + or apparatus may be found, it shows what experiments + are to be performed by each student at a given time, etc. + + Cailletet's Cryogen.--A description, with one engraving, of Mr. + Cailletet's new apparatus for producing temperatures from 70 + degrees to 80 degrees C., below zero, through the expansion of + liquid carbonic acid + +IX. Technology.--The Manufacture of Roll Tar Paper.--An extended + article containing a historical sketch and full information + as to the materials used and the methods of manufacture + + Smokeless Gunpowder.--By Hudson Maxim.--A comprehensive + article on the manufacture and use of smokeless gunpowder, + giving a sketch of its history, and describing the methods of + manufacture and its characteristics + + Method of Producing Alcohol.--A description of an improved + process for making alcohol.--Invented by Mr. Alfred Springer, + of Cincinnati, Ohio + + * * * * * + + + + + +[Illustration: INTERIOR OF THE NEW LABOR EXCHANGE, PARIS.] + +[Illustration: NEW LABOR EXCHANGE, PARIS.] + +THE NEW LABOR EXCHANGE, PARIS. + + +The new Labor Exchange is soon to be inaugurated. We give herewith a +view of the entrance facade of the meeting hall. The buildings, which +are the work of Mr Bouvard, architect, of the city of Paris, are +comprised within the block of houses whose sharp angle forms upon +Place de la Republique, the intersection of Boulevard Magenta and +Bondy street. One of the entrances of the Exchange is on a level with +this street. The three others are on Chateau d'Eau street, where the +facade of the edifice extends for a length of one hundred feet. From +the facade and above the balcony that projects from the first story, +stand out in bold relief three heads surrounded by foliage and fruit +that dominate the three entrance doors. These sculptures represent the +Republic between Labor and Peace. The windows of the upper stories are +set within nine rows of columns, from between the capitals of which +stand out the names of the manufacturers, inventors, and statesmen +that have sprung from the laboring classes. Upon the same line, at the +two extremities of the facade, two modillions, traversed through their +center by palms, bear the devices "Labor" and "Peace." Above, there is +a dial surmounted by a shield bearing the device of the city of Paris. + +The central door of the ground floor opens upon a large vestibule, +around which are arranged symmetrically the post, telegraph, +telephone, and intelligence offices, etc. Beyond the vestibule there +is a gallery that leads to the central court, upon the site of which +has been erected the grand assembly hall. This latter, which measures +20 meters in length, 22 in width, and 6 in height, is lighted by a +glazed ceiling, and contains ten rows of benches. These latter contain +900 seats, arranged in the form of circular steps, radiating around +the president's platform, which is one meter in height. A special +combination will permit of increasing the number of seats reserved for +the labor associations on occasions of grand reunions to 1,200. The +oak doors forming the lateral bays of the hall will open upon the two +large assembly rooms and the three waiting rooms constructed around +the faces of the large hall. In the assembly rooms forming one with +the central hall will take place the deliberations of the syndic +chambers. The walls of the hall will, ere long, receive decorative +paintings.--_L'Illustration._ + + * * * * * + + + + +MANUFACTURE OF ROLL TAR PAPER. + + +Roofing paper was first used in Scandinavia early as the last century, +the invention being accredited to Faxa, an official of the Swedish +Admiralty. The first tar and gravel roofs in Sweden were very +defective. The impregnation of the paper with a water-proofing liquid +had not been thought of, and the roofs were constructed by laying over +the rafters a boarding, upon which the unsaturated paper, the sides of +which lapped over the other, was fastened with short tacks. The +surface of the paper was next coated with heated pine tar to make it +waterproof. The thin layer of tar was soon destroyed by the weather, +so that the paper, swelled by the absorption of rain water, lost its +cohesiveness and was soon destroyed by the elements. This imperfect +method of roof covering found no great favor and was but seldom +employed. + +In Germany the architect Gilly was first to become interested in tar +paper roofing, and recommended it in his architecture for the country. +Nevertheless the new style of roof covering was but little employed, +and was finally abandoned during the first year of the 19th century. +It was revived again in 1840, when people began to take a renewed +interest in tar paper roofs, the method of manufacturing an +impermeable paper being already so far perfected that the squares of +paper were dipped in tar until thoroughly saturated. The roof +constructed of these waterproof paper sheets proved itself to be a +durable covering, being unimpenetrable to atmospheric precipitations, +and soon several factories commenced manufacturing the paper. The +product was improved continually and its method of manufacture +perfected. The good qualities of tar paper roofs being recognized by +the public, they were gradually adopted. The costly pine tar was soon +replaced by the cheaper coal tar. Square sheets of paper were made at +first; they were dipped sufficiently long in ordinary heated coal tar, +until perfectly saturated. The excess of tar was then permitted to +drip off, and the sheets were dried in the air. The improvement of +passing them through rollers to get rid of the surplus tar was +reserved for a future time, when an enterprising manufacturer +commenced to make endless tar paper in place of sheets. Special +apparatus were constructed to impregnate these rolls with tar; they +were imperfect at first, but gradually improved to a high degree. Much +progress was also made in the construction of the roofs, and several +methods of covering were devised. The defects caused by the old method +of nailing the tar paper direct upon the roof boarding were corrected; +the consequence of this method was that the paper was apt to tear, +caused by the unequal expansion of the roofing boards and paper, and +this soon led to the idea of making the latter independent of the +former by nailing the sides of the paper upon strips running parallel +with the gable. The use of endless tar paper proved to be an essential +advantage, because the number of seams as well as places where it had +to be nailed to the roof boarding was largely decreased. The +manufacture of tar paper has remained at about the same stage and no +essential improvements have been made up to the present. As partial +improvement may be mentioned the preparation of tar, especially since +the introduction of the tar distillery, and the manufacture of special +roof lacquers, which have been used for coating in place of the coal +tar. As an essential progress in the tar paper roofing may be +mentioned the invention of the double tar paper roof, and the wood +cement roof, which is regarded as an offshoot. + +The tar paper industry has, within the last forty years, assumed great +dimensions, and the preferences for this roofing are gaining ground +daily. In view of the small weight of the covering material, the wood +construction of the roof can be much lighter, and the building is +therefore less strained by the weight of the roof than one with the +other kind, so that the outer walls need not be as heavy. Considering +the price, the paper roof is not only cheaper than other fireproof +roofs, but its light weight makes it possible for the whole building +to be constructed lighter and cheaper. The durability of the tar paper +roof is satisfactory, if carefully made of good material; the double +tar paper roof, the gravel double roof, and the wood cement roof are +distinguished by their great durability. + +These roofs may be used for all kinds of buildings, and not only are +factories, storehouses, and country buildings covered with it, but +also many dwellings. The most stylish residences and villas are at +present being inclosed with the more durable kinds; the double roof, +the gravel double roof, and the wood cement roof. For factory +buildings, which are constantly shaken by the vibrations of the +machinery, the tar paper roof is preferable to any other. + +In order to ascertain to what degree tar paper roofs would resist +fire, experiments were instituted at the instigation of some of the +larger manufacturers of roofing paper, in the presence of experts, +architects, and others, embracing the most severe tests, and it was +fully proved that the tar paper roof is as fireproof as any other. +These experiments were made in two different ways; first, the +readiness of ignition of the tar paper roof by a spark or flame from +the outside was considered, and, second, it was tested in how far it +would resist a fire in the interior of the building. In the former +case, it was ascertained that a bright, intense fire could be kept +burning upon the roof for some time, without igniting the woodwork of +the roof, but heat from above caused some of the more volatile +constituents of the tar to be expelled, whereby small flames appeared +upon the surface within the limits of the fire; the roofing paper was +not completely destroyed. There always remained a cohesive substance, +although it was charred and friable, which by reason of its bad +conductivity of heat protected the roof boarding to such an extent +that it was "browned" only by the developed tar vapors. A fire was +next started within a building covered with a tar paper roof; the +flame touched the roof boarding, which partly commenced to char and +smoulder, but the bright burning of the wood was prevented by the +air-tight condition of the roof; the fire gases could not escape from +the building. The smoke collecting under the roof prevented the +entrance of fresh air, in consequence of which the want of oxygen +smothered the fire. The roofing paper remained unchanged. By making +openings in the sides of the building so that the fire gases could +escape, the wood part of the roof was consumed, but the roofing paper +itself was only charred and did not burn. After removing the fire in +contact with the paper, this ceased burning at once and evinced no +disposition whatever to spread. In large conflagrations, also, the tar +paper roofs behaved in identically a similar manner. Many instances +have occurred where the tar paper roof prevented the fire from +spreading inside the building, and developing with sufficient +intensity to work injury. + +As it is of interest to the roofer to know the manner of making the +material he uses, we give in the following a short description of the +manufacture of roofing paper. At first, when square sheets were used +exclusively, the raw paper consisted of ordinary dipped or formed +sheets. The materials used in its manufacture were common woolen rags +and other material. In order to prepare the pulp from the rags it is +necessary to cut them so small that the fabric is entirely dissolved +and converted into short fibers. The rags are for this purpose first +cut into pieces, which are again reduced by special machines. The rags +are cut in a rag cutting machine, which was formerly constructed +similar to a feed cutter; later on, more complicated machines of +various constructions were employed. It is not our task to describe +the various kinds, but we remain content with the general remark that +they are all based on the principles of causing revolving knives to +operate upon the rags. The careful cleansing of the cut rags, +necessary for the manufacture of paper, is not required for roofing +paper. It is sufficient to rinse away the sand and other solid +extraneous matter. The further reduction of the cut rags was formerly +performed in a stamp mill, which is no longer employed, the pulp mill +or rag engine being universally used. + +The construction of this engine may be described as follows: A box or +trough of wood, iron, or stone is by a partition divided into two +parts which are connected at their ends. At one side upon the bottom +of the box lies an oakwood block, called the back fall. In a hollow of +this back fall is sunk the so-called plate, furnished with a number of +sharp steel cutters or knives, lying alongside of each other. A roller +of solid oakwood, the circumference of which is also furnished with +sharp steel cutters or knives, is fastened upon a shaft and revolves +within the hollow. The journal bearings of the shaft are let into and +fastened in movable wooden carriers. The carriers of the bearings may +be raised and lowered by turning suitable thumbscrews, whereby the +distance between the roller and the back fall is increased or +decreased. The whole is above covered with a dome, the so-called case, +to prevent the throwing out of the mass under the operation of +grinding. The roller is revolved with a velocity of from 100 to 150 +revolutions per minute, whereby the rags are sucked in between the +roller and the back fall and cut and torn between the knives. At the +beginning of the operation, the distance between the roller and the +back fall is made as great as possible, the intention being less to +cut the rags than to wash them thoroughly. The dirty water is then +drawn off and replaced by clean, and the space of the grinding +apparatus is lessened gradually, so as to cut the rags between the +knives. The mass is constantly kept in motion and each piece of rag +passes repeatedly between the knives. The case protects the mass from +being thrown out by the centrifugal force. The work of beating the +rags is ended in a few hours, and the ensuing thin paste is drawn off +into the pulp chest, this being a square box lined with lead. + +From the pulp chest it passes to the form of the paper machine. This +form consists of an endless fine web of brass wire, which revolves +around rollers. The upper part of this form rests upon a number of +hollow copper rollers, whereby a level place is formed. The form +revolves uniformly around the two end rollers, and has at the same +time a vibratory motion, by which the pulp running upon the form is +spread out uniformly and conducted along, more flowing on as the +latter progresses. The water escapes rapidly through the close wire +web. In order to limit the form on the sides two endless leather +straps revolve around the rollers on each side, which touch with their +lower parts the form on both sides and confine the fluid within a +proper breadth. The thickness of the pulp is regulated at the head of +the form by a brass rule standing at a certain height; its function is +to level the pulp and distribute it at a certain thickness. The +continually moving pulp layer assumes greater consistency the nearer +it approaches to the dandy roll. This is a cylinder covered with brass +wire, and is for the purpose of compressing the paper, after it has +left the form, and free it from a great part of the water, which +escapes into a box. The paper is now freed of a good deal of the +fluid, and assumes a consistency with which it is enabled to leave the +form, which now commences to return underneath the paper, passing on +to an endless felt, which revolves around rollers and delivers it to +two iron rolls. The paper passes through a second pair of iron +rollers, the interiors of which are heated by steam. These rollers +cause the last of the water to be evaporated, so that it can then be +rolled upon reels. A special arrangement shaves the edges to the exact +size required. + +The paper is made in different thicknesses and designated by numbers +to the size and weight. + +Waste paper, bookbinders' shavings, etc., can be used for making the +paper. As much wool as possible should be employed, because the wool +fiber has a greater resistance than vegetable fiber to the effects of +the temperature. By wool fiber is understood the horny substance +resembling hair, with the difference that the former has no marrowy +tissue. The covering pellicle of the wool fiber consists of flat, +mostly elongated leaves, with more or less corners, lying over each +other like scales, which makes the surface of the fiber rough; this +condition, together with the inclination of curling, renders it +capable of felting readily. Pure wool consists of a horny substance, +containing both nitrogen and sulphur, and dissolves in a potash +solution. In a clean condition, the wool contains from 0.3 to 0.5 per +cent. of ash. It is very hygroscopical, and under ordinary +circumstances it contains from 13 to 16 per cent. humidity, in dry air +from 7 to 11 per cent., which can be entirely expelled at a +temperature of from 226 to 230 degrees Fahrenheit. Wool when ignited +does not burn with a bright flame, as vegetable fiber does, but +consumes with a feeble smouldering glow, soon extinguishes, spreading +a disagreeable pungent vapor, as of burning horn. By placing a test +tube with a solution of five parts caustic potash in 100 parts water, +a mixture of vegetable fibers and wool fibers, the latter dissolve if +the fluid is brought to boiling above an alcohol flame, while the +cotton and linen fibers remain intact. + +The solubility of the woolen fibers in potash lye is a ready means of +ascertaining the percentage of wool fiber in the paper. An exhaustive +analysis of the latter can be performed in the following manner: A +known quantity of the paper is slowly dried in a drying apparatus at +temperature of 230° Fahrenheit, until a sample weighed on a scale +remains constant. The loss of weight indicates the degree of humidity. +To determine the ash percentage, the sample is placed in a platinum +crucible, and held over a lamp until all the organic matter is burned +out and the ash has assumed a light color. The cold ash is then +moistened with a carbonate of ammonia solution, and the crucible again +exposed until it is dark red; the weight of the ash is then taken. To +determine the percentage of wool, a sample of the paper is dried at +230° Fahrenheit and weighed, boiled in a porcelain dish in potash lye +12° B. strong, and frequently stirred with a glass rod. The wool fiber +soon dissolves in the potash lye, while the vegetable fiber remains +unaltered. The pulpy mass resulting is placed upon a filter, dried at +212° Fahrenheit, and after the potash lye has dripped off, the +residue, consisting of vegetable fiber and earthy ash ingredients, is +washed until the water ceases to dissolve anything. The residue dried +at 212° Fahrenheit is weighed with a filter, after which that of the +latter is deducted. The loss of weight experienced is essentially +equal to the loss of the wool fiber. If the filtrate is saturated with +hydrochloric acid, the dissolved wool fiber separates again, and after +having been collected upon a weighed filter, it may be weighed and the +quantity ascertained. + +The weight of the mineral substances in the raw paper is ascertained +by analyzing the ash in a manner similar to that above described. The +several constituents of the ash and the mineral added to the raw paper +are ascertained as follows: Sufficient of the paper is calcined in the +manner described; a known quantity of the ash is weighed and thrown +into a small porcelain dish containing a little distilled water and an +excess of chemically pure hydrochloric acid. In this solution are +dissolved the carbonates, carbonate of lime, carbonate of magnesia, a +little of sulphate of alumina, as well as metallic oxides, while +silicate of magnesia, silicic acid, sulphate of lime (gypsum) remain +undissolved. The substance is heated until the water and excess of +free hydrochloric acid have been driven off; it is then moistened with +a little hydrochloric acid, diluted with distilled water and heated. +The undissolved residue is by filtering separated from the dissolved, +the filter washed with distilled water, and the wash water added to +the filtrate. The undissolved residue is dried, and after the filter +has also been burned in due manner and the ash added, the weight is +ascertained. It consists of clay, sand, silicic acid and gypsum. + +The filtrate is then poured into a cylinder capable of holding 100 +cubic centimeters, and furnished with a scale; sufficient distilled +water is then added until the well-shaken fluid measures precisely 100 +cubic centimeters. By means of this measuring instrument, the filtrate +is then divided into two equal portions. One of these parts is in a +beaker glass over-saturated with chemically pure chloride of ammonia, +whereby any iron of oxide present and a little dissolved alumina fall +down as deposit. The precipitate is separated by filtering, washed, +dried at 212° Fahrenheit and weighed. To the filtrate is then added a +solution of oxalate of ammonia until a white precipitate of oxalate of +lime is formed. This precipitate is separated by filtering, washed, +dried and when separated from the filter, is collected upon dark +satinized paper; the filter itself is burned and the ash added to the +oxalate of lime. This oxalate of lime is then heated to a dark red +heat in a platinum crucible with lid until the oxalate of lime is +converted into carbonate of lime. By the addition of a few drops of +carbonate of ammonia solution and another slight heating of the +crucible, also the caustic lime produced in the filter ash by heating, +is reconverted into carbonate of lime, and after cooling in the +exsiccator, the whole contents of the crucible is weighed as +carbonate of lime, after deducting the known quantity of filter ash. + +Any magnesia present in the filtrate of the oxalate of lime is by the +addition of a solution of phosphate of soda separated as phosphate of +ammonia and magnesia, after having stood twenty-four hours. The +precipitate is filtered off, washed with water to which a little +chloride of ammonia is added, dried, and after calcining the fiber and +adding the filter ash, glow heated in the crucible. The glowed +substance is weighed after cooling, and is pyrophosphate of magnesia, +from which the magnesia or carbonate of magnesia is calculated +stoichiometrically. All the ascertained sums must be multiplied by 2, +if they are to correspond to the analyzed and weighed quantity of ash. + +The second half of the filtrate is used for determining the small +quantity of sulphate of lime still contained in the hydrochlorate +solution. By adding chloride of barium solution the sulphuric acid is +bound to the barytes and sulphate of baryta separates as white +precipitate. This is separated by filtering, washed, dried and weighed +in the customary manner. From the weight of the sulphate of baryta is +then computed the weight of sulphate of lime, which has passed over +into solution. The ascertained sum is also to be multiplied with 2. + +The manufacture of roll tar paper from the roll paper was at first +found to be difficult, as it was impossible to submerge a surface +larger than from ten to fifteen square yards, rolled up, in the tar, +because more would have required too large a pan. Besides this, the +paper tears easily, when it is in the hot tar. All kinds of +experiments were tried, in order to impregnate the surface of the +paper without employing too large a pan. + +The following method was tried at first: The roll paper was cut into +lengths of ten yards, which were rolled up loosely, so that a certain +space was left between the different coils. These loose rolls, of +course, occupied much space and could be put into the tar only in a +standing position, because in a horizontal one the several coils would +have pressed together again. The loose roll was therefore slipped over +a vertical iron rod fastened into a circular perforated wooden foot. +The upper end of this iron rod ended in a ring, in which the hook of a +chain or rope could be fastened. With the aid of a windlass the roll +was raised or lowered. When placed in the pan with boiling tar, it was +left there until thoroughly saturated. It was then taken out, placed +upon a table, and the excess of tar allowed to drip off into a vessel +underneath. After partially drying, the roll was spread out in open +air, occasionally turned, until sufficiently dried, when it was rolled +up again. + +In order to neutralize the smeary, sticky condition of the surface and +avoid the disagreeable drying in open air, the experiment of strewing +sand on the sticky places was tried next. The weight of the paper was +largely increased by the sand, and appeared considerably thicker. For +this reason the method of sanding the paper was at once universally +adopted. To dispense with the process of permitting the surplus tar to +drip off, means were devised by which it was taken off by scrapers, or +by pressing through rollers. The scrapers, two sharp edged rods +fastened across the pan, were then so placed that the paper was drawn +through them. The excess of tar adhering to its surface was thereby +scraped off and ran back into the pan. + +This work, however, was performed better and to more satisfaction by a +pair of rollers fastened to the pan. These performed a double duty; +thoroughly removed the tar from the surface and by reason of their +pressure they caused a more perfect incorporation of the tar with the +fibers of the paper. Finally, different factories employed different +methods of manufacture, one of which was to cut the rolls into +definite lengths of about ten yards; these were then rerolled very +loosely and immersed in the hot tar until sufficiently saturated. The +paper was then passed through the roller, much pressure exerted, and +then loosely rolled up again. Being tarred once, it was then laid into +a second pan with hot tar, reeled out after a time, strewn with sand, +and rolled up again. Another method was to cut clothes lines into +lengths of about fifteen yards, and at a distance of two inches have +knots tied in them. The paper was cut in lengths of ten or fifteen +yards, three pieces of the knotted clothes line were then rolled +between the loose coils of paper, which was then submerged in the tar, +which on account of the knots could penetrate the paper. The paper was +next sanded by permitting its lower surface to pass over dry sand in a +box standing on the floor. A workman rolled off the paper, and with +his hand he strews sand on the upper surface. The rolling taking place +on the edge of a table, by means of a crank, the excess of sand +dropped off. + +It is said by this method two workmen, one of which tends to the +rolling and sanding, the other turning the crank, could turn out +eighty rolls per day. This method is still in use. It is useless to +describe the many antiquated methods in vogue in smaller factories, +and it can truthfully be said that nearly all of them are out of date. +It appears to be the fact of almost all inventions that when reduced +to practical use, the arrangements, apparatus, and working methods +employed are generally of the most complicated nature, and time and +experience only will simplify them. This has been also the case with +the methods in the roofing paper industry, which are at present +gradually being reduced to a practical basis. The method gradually +adopted has been described in the preceding. The pan is of a certain +length, whereby it becomes possible to saturate the paper by slowly +drawing it through the heated tar. This is the chief feature. The work +is much simplified thereby and the workmen need not dip their hands +into the tar or soil them with it. The work of impregnating has become +much cleaner and easier, while at the same time the tar can be heated +to a much higher temperature. The pan is generally filled with +distilled coal tar, and the heating is regulated in such a manner that +the temperature of the impregnating mass is raised far beyond 212° +Fahrenheit. This accelerates the penetration, which takes place more +quickly as the degree of heat is raised, which may be almost up to the +boiling point of the tar, as at this degree the paper is not destroyed +by the heat. In order to prevent the evaporation of the volatile +ingredients of the tar, the pan is covered with a sheet iron cover, +with a slot at the place where the paper enters into the impregnating +mass and another at the place where it issues. The tar is always kept +at the same level, by occasional additions. + +The roll of paper is mounted upon a shaft at the back end of the pan, +and by suitable arrangement of guide rollers it unwinds slowly, passes +into the tar in which it is kept submerged. The guide rollers can be +raised so that when a new roller is set up they can be raised out of +the tar. The end of the paper is then slipped underneath them above +the surface of the tar, when having passed through the squeezing +rollers, it is fastened to the beaming roller, and the guide rollers +are submerged again. A workman slowly turns the crank of the beaming +roller. + +This motion draws the paper slowly through the fluid, the roll at the +back end unwinding. The speed with which the squeezing rollers are +turned is regulated in such a manner that the paper remains +sufficiently long underneath the fluid to be thoroughly impregnated +with it. The workmen quickly learn by experience how fast to turn the +crank. The hotter the tar, the more rapid the saturation; the high +degree of heat expels the air and evaporates the hygroscopic fluid in +the pores of the paper. The strong heating of the tar causes another +advantage connected with this method. The surface of the paper as it +issues from the squeezing rollers is still very hot, and a part of the +volatile oils evaporate very quickly at this high temperature. The +surface is thereby at once dried to a certain degree and at the same +time receives a handsome luster, as if it had been coated with a black +lacquer. The paper is sanded in a very simple manner without the use +of mechanical apparatus; as it is being wrapped into a coil, it passes +with its lower surface over a layer of sand, while the workman who +tends to rolling up strews the inside with sand. The lower surface is +coated very equally. Care only being necessary that the sand lies +smooth and even at all times. When the workman has rolled up ten or +fifteen yards, he cuts it across with a knife and straightedge, so +that the paper is cut at right angles with its sides. + +There are three different sorts of roofing paper, according to the +impregnating fluid used in its manufacture. The ordinary tar paper is +that saturated with clear cold tar. This contains the greatest amount +of fluid ingredients and is very raggy in a fresh condition. It is +easy to see that the volatile hydrocarbons evaporate in a short time, +and when expelled, the paper becomes stiffer and apparently drier. +This drying, or the volatilization of the hydrocarbons, causes pores +between the fibers of the paper. These pores are highly injurious to +it, as they facilitate a process of decomposition which will ruin it +in a short time. + +Roofing paper can be called good only when it is essentially made from +woolen rags, and contains either very few or no earthy additions. It +is beyond doubt that the durability of a roofing paper increases with +the quality of wool fiber it contains--vegetable fibers and earthy +additions cause a direct injury. Reprehensible altogether is any +combination with lime, either in form of a carbonate or sulphate, +because the lime enters into chemical combination with the +decomposition products of the tar. + +The general nature of gravel is too well known to require description. +The grains of quartz sand are either sharp cornered or else rounded +pieces of stone of quartz, occasionally mixed with grains of other +amorphous pieces of silica--such as horn stone, silicious slate, +carnelian, etc.; again, with lustrous pieces of mica, or red and white +pieces of feldspar. The gravel used for a tar paper roof must be of a +special nature and be prepared for the purpose. The size of its grains +must not exceed a certain standard--say, the size of a pea. When found +in the gravel bank, it is frequently mixed with clay, etc., and it +cannot be used in this condition for a roof, but must be washed. The +utensils necessary for this purpose are of so simple and suggestive a +nature that they need not be described. Slag is being successfully +used in place of the gravel. It is easily reduced to suitable size, by +letting the red hot mass, as it runs from the furnace, run into a +vessel with water. The sudden chilling of the slag causes it to burst +into fragments of a sharp cornered structure. It is next passed +through a sieve, and the suitably sized gravel makes an excellent +material, as it gives a clean appearance to the roof. + +The thinking mind can easily go one step further and imagine that, +since the tar contains a number of volatile hydrocarbons, it might be +made more adaptable for impregnation by paper by distilling it, as by +this process the fluid would lose its tendency to evaporate and the +percentage of resinous substances increase. Singular to say, there was +a prejudice against the employment of distilled tar, entertained by +builders and people who had no knowledge of chemistry. Increasing +intelligence and altered business circumstances, however, brought +about the almost universal employment of distilled tar, and every +large factory uses it at present. The roofing paper prepared with +distilled tar is perhaps most suitably called asphaltum paper, as this +has been used in its manufacture. It possesses properties superior to +the ordinary tar paper, one of which is that immediately after its +manufacture, as soon as cold, it is dry and ready for shipment; nor +does it require to be kept in store for a length of time, and it has +also a good, firm body, being as flexible and tough as leather. It is +very durable upon the roof, and remains flexible for a long time. It +is true that asphaltum papers will always in a fresh state contain a +small percentage of volatile ingredients, which after a while make it +hard and friable upon the roof; but, by reason of its greater +percentage of resinous components, it will always preserve a superior +degree of durability and become far less porous. One hundred parts by +weight absorb 140 or 150 parts by weight of coal tar. A factory which +distilled a good standard tar for roofing paper recovered, besides +benzole and naphtha, also about ten per cent. of creosote oil, used +for one hundred parts raw paper, 176.4 partially distilled tar. +Experiments on a larger as well as a smaller scale reduced this +quantity to an average of 141.5 parts for one hundred parts raw paper. +The weight of sanded paper is very variable, as it depends altogether +upon the size of the sand grains. It may be stated generally that the +weight of the sand is as large as that of the tarred paper. + +The kinds of roofing paper saturated with other additions besides coal +tar form a separate class, in order to neutralize the defects inherent +in coal tar. These additions were originally for the purpose of +thickening the paper and making it stiffer and drier. The most +ordinary and cheapest thickener was the coal pitch. Although the +resinous substances are increased thereby, still the light tar oils +remain to evaporate, and the paper prepared with such a substance +readily becomes hard and brittle. A better addition is the natural +asphaltum, because it resists better the destroying influence of the +decomposition process, and also, to a certain degree, protects the +coal tar in which it is dissolved. The addition of natural asphaltum +doubtless caused the name of "asphaltum roofing paper." Resin, +sulphur, wood tar and other substances were also used as additions; +each manufacturer kept his method secret, however, and simply pointed +out by high sounding title in what manner his paper was composed. In +most cases, however, this appellation was applied to the ordinary tar +paper; the impregnating substance was mixed only with coal pitch, or +else a roofing paper saturated with distilled tar. The costly +additions, by the use of which a high grade of roofing paper can +doubtless be produced, largely increased its price, and on account of +the constant fall of prices of the article, its use became rather one +of those things "more honored in the breach than in the observance," +and was dispensed with whenever practicable. The crude paper is the +foundation of the roofing paper. The qualities of a good, +unadulterated paper have already been stated. At times, the crude +paper contains too many earthy ingredients which impair the cohesion +of the felted fibrous substance, and which especially the carbonate of +lime is very injurious, as it readily effects the decomposition of the +coal tar. The percentage of wool, upon which the durability of the +paper depends very largely, is very small in some of the paper found +in the market. In place of woolen rags, cheap substitutes have been +used, such as waste, which contains vegetable fibers. Since this +cannot resist the decomposition process for any length of time, it is +evident that the roofing paper which contains a noticeable quantity of +vegetable fibers cannot be very durable. To judge from the endeavors +made to improve the coal tar, it may be concluded that this material +does not fully comply with its function of making the roofing paper +perfectly and durably waterproof. The coal tar, be it either crude or +distilled, is not a perfect impregnating material, and the roofing +paper, saturated with it, possesses several defects. Let us in the +following try to ascertain their shortcomings, and then express our +idea in what manner the roofing paper may be improved. It was +previously mentioned that every tar roofing paper will, after a +greater or smaller lapse of time, assume a dry, porous, friable +condition, caused by the volatilization of a part of the constituents +of the tar. This alteration is materially assisted by the oxygen of +the air, which causes the latter to become resinous and exerts a +chemical influence upon them. By the volatilization of the lighter tar +oils, pores are generated between the fibers of the roofing paper, +into which the air and humidity penetrate. In consequence of the +greatly enlarged surface, not only the solid ingredients of the tar, +which still remain unaltered, are exposed to the action of the oxygen, +but also the fibers of the roofing paper are exposed to decomposition. +How destructive the alternating influence of the oxygen and the +atmospheric precipitations are for the roofing paper will be shown by +the following results of tests. It will have been observed that the +rain water running from an old paper roof, especially after dry +weather, has a yellowish, sometimes a brown yellow color. The +supposition that this colored rain water might contain decomposition +products of the roofing paper readily prompted itself, and it has been +collected and analyzed at different seasons of the year. After a +period of several weeks of fair weather during the summer, rain fell, +and the sample of water running from a roof was caught and evaporated; +the residue when dried weighed 1.68 grammes. It was of a brownish +black color, fusible in heat and readily soluble, with a yellow brown +color in water. The dark brown substance readily dissolved in ammonia, +alcohol, dilute acid, hydrochloric acid, sulphuric acid, and +decomposed in nitric acid, but did not dissolve in benzine or fat oil. +After several days' rain during the summer, a quantity of the water +was caught, evaporated, and the residue dried. Its characteristics +were similar to those above mentioned. By an experiment instituted in +water under conditions similar to the first mentioned, the dry brown +substance weighed 71 grammes. It possessed the same characteristics. +In the solution effected with water containing some aqua ammonia of +the brown substance, a white precipitate of oxalate of lime occurred +when an oxalate of ammonia solution was added, but the brown substance +remained in solution. A further precipitation of oxalate of lime was +produced by a solution of oxalic acid, but the brown organic substance +remained in solution. This organic substance being liberated from the +lime was evaporated, and left a dry, resinous, fusible brownish black +substance, which also dissolved readily in water. It will be seen from +these trials that the substance obtained from the rain water running +from a paper roof is a combination of an organic acid with lime, which +readily dissolves in water, and that also the free organic acid +combined with the lime dissolves easily in water. + +The question concerning the origin of this organic substance or its +combination with lime can only be answered in one way, viz., that it +must have been washed by the rain water out of the paper. But since +such a solid substance, easily soluble in water, is contained neither +in the fresh roofing paper nor in the coal tar, the only deduction is +that it must have arisen by the decomposition of the tar, in +consequence of the operation of the oxygen. The lime comes from the +coating substance of the roof, for which tar mixed with coal pitch was +used. The latter was fused with carbonate of lime. These analyses +furthermore show that the formation of the organic acid easily soluble +in water depends upon the season; and that a larger quantity of it is +generated in warm, sunny weather than in cold, without sunshine. This +peculiarity of the solid, resinous constituents of the coal tar, to be +by the operation of the atmospheric oxygen altered into such products +that are readily soluble in water, makes the tar very unsuitable as a +saturative substance for a roofing paper. How rapidly a paper roof can +be ruined by the generation of this injurious organic acid will be +seen from the following calculation: Let us suppose that an average +of 132 gallons of rain water falls upon ten square feet roof surface +per year, and that the arithmetical mean 0.932 of the largest (1.680) +and smallest number (0.184) be the quantity of the soluble brown +substance which on an average is dissolved in one quart of rain water; +hence from ten square feet of roof surface are rinsed away with the +rain water per year 466 grammes of the soluble decomposition products +of the tar. The oxidation process will not always occur as intensely +as by a paper roof, ten years old and painted two years ago, which +instigated above described experiment. As long as the roofing paper is +fresh and less porous, especially if the occurring pores are filled +and closed again by repeated coatings, oxidation will take place far +less rapidly. Besides this, the protective coating applied to the roof +surface is exposed most to this oxidation process. Even by assuming +this constantly progressive destructive action of the oxygen on the +roofing paper to be much less than above stated, we can readily +imagine that it must be quite large. If it is desired to produce a +material free of faults, it is first of all indispensable that +unobjectionable raw material be procured. Coal tar was formerly used +almost exclusively for the coating of a roof. It was heated and +applied hot upon the surface. In order to avoid the running off of the +thinly fluid mass, the freshly coated surface was strewn with sand. +The most volatile portion of the tar evaporated soon, whereby the +coating became thicker and finally dried. The bad properties of the +coal tar, pointed out elsewhere, made it very unsuitable even for this +purpose, and experiments were instituted to compound mixtures, by +adding other ingredients to the tar, that should more fully comply +with its function. It may be said in general that the coating masses +for roofs can be divided into two classes: either as lacquers or as +cements. To the former may be classed those of a fairly thinly fluid +consistency, and which contain volatile oils in such quantities that +they will dry quickly. Cements are those of a thickly fluid +consistency, and are rendered thus fluid by heating. It is not +necessary that the coating applied should harden quickly, as it +assumes soon after its application a firmness sufficient to prevent it +from running off the roof. Coal tar is to be classed among lacquers. +If it has been liberated by distillation from the volatile oils, it is +made better suited for the purpose than the ordinary kind. The mass +contains much more asphaltum, and after drying, which takes place +soon, it leaves a far thicker layer upon the roof surface, while the +pores, which had formed in the roofing paper consequent on drying, are +better filled up. Nevertheless, the distilled tar also has retained +the property of drying with time into a hard, vitreous mass, and +ultimately to be destroyed by decomposition.--_The Roofer_. + + * * * * * + + + + +A PHYSICAL LABORATORY INDICATOR. + + +The difficulties attending the management of a physical laboratory are +much greater than those of a chemical one. The cause of this lies in the +fact that in the latter the apparatus is less complicated and the pieces +less varied. Any contrivance that will reduce the labor and worry +connected with the running of a laboratory is valuable. + +A physical laboratory may be arranged in several ways. The apparatus may +be kept in a store room and such as is needed may be given to the +student each day and removed after the experiments are performed; or the +apparatus for each experiment or system of experiments may be kept in a +fixed place in the laboratory ready for assembling; for certain +experiments the apparatus may be kept in a fixed place in the laboratory +and permanently arranged for service. + +Each student may have his own desk and apparatus or he may be required +to pass from desk to desk. The latter method is preferable. + +When a store room is used the services of a man are required to +distribute and afterward to collect. If the apparatus is permanently +distributed, a large room is necessary, but the labor of collecting and +distributing is done away with. + +There are certain general experiments intended to show the use of +measuring instruments which all students must perform. To illustrate the +use of the indicator I have selected an elementary class, although the +instrument is equally applicable to all classes of experiments. + +Having selected a suitable room, tables may be placed against the walls +between the windows and at other convenient places. Shallow closets are +built upon these tables against the wall; they have glass doors and are +fitted with shelves properly spaced. A large number of light wooden +boxes are prepared, numbered from one up to the limit of the storage +capacity of the closets. A number corresponding to that upon the box is +placed upon the shelf, so that each one after removal may be returned to +its proper place without difficulty. On the front of the box is a label +upon which is written the experiment to be performed or the name of the +apparatus whose use is to be learned, references to various books, which +may be found in the laboratory library, and the apparatus necessary for +the experiment, which ought to be found in the box. If any parts of the +apparatus are too large to be placed in the box, the label indicates by +a number where it may be found in the storage case. + +It is evident that, instead of the above arrangement, all the boxes can +be stacked in piles in a general store room. The described arrangement +is preferable, as it prevents confusion in collecting and distributing +apparatus when the class is large. + +_The Indicator_ (see figure).--Some device is evidently desirable to +direct the work of a laboratory with the least trouble and friction +possible. I have found that the old fashioned "peg board," formerly used +in schools to record the demerits of scholars, modified as in the +following description, leaves nothing to be desired. + +The requirements of such an instrument are these: It must show the names +of the members of the class; it must contain a full list of the +experiments to be performed; it must refer the student to the book and +page where information in reference to the experiments or apparatus may +be found; it must show what experiments are to be performed by each +student at a given time; it must give information as to the place in the +laboratory where the apparatus is deposited; it must show to the +instructor what experiments have been performed by each student; it must +prevent the assignment of the same experiment to two students; it must +enable the instructor to assign the same experiment to two or more +students; it must form a complete record of what has been done, what +work is incomplete, and what experiments have not yet been assigned; it +must also be so arranged that new experiments or sets of experiments may +be exhibited. + + +------+---+---+---+---+---+---+---+---+ + | | A | B | C | D | E | F | G | H | + +------+---+---+---+---+---+---+---+---+ + | 1 | * o o * o o o o | + | 2 | * o * * o o o o | + | 3 | + * * * o o o o | + | 4 | + o * * o o o o | + | 5 | o + * * * * o o | + | 6 | o + * * o * o o | + | 7 | o o + * o o o o | + | 8 | o o o + * o o o | + | 9 | o o o * + o o o | + | 10 | o o o o o + o o | + | 11 | o o o * o o + * | + | 12 | o o * * o + + + | + | 13 | o o * o o o o o | + | 14 | o o * o o o o o | + | 15 | o o + o o o o o | + | 16 | o o + + * o o * | + +--------------------------------------+ + + A, B, C, etc., are cards upon which are the names of students. 1, + 2, 3, etc., are cards like the one described in the article. The + small circles (o) represent unassigned experiments. The black + circles (*) (slate nails) represent work done. The caudate circles + (+) (brass nail) represent work assigned. + +The indicator consists of a plank of any convenient length and breadth. +The front surface is divided into squares of such size that the pegs may +be introduced and withdrawn with ease. At each corner of the squares +holes are bored into which nails may be placed. There is a blank border +at the top and another on the left side. At the top of each vertical +column of holes is placed a card holder. This is made of light tin +turned up on the long edges--which are vertical--and tacked to the +board. Opposite each horizontal row of holes is a similar tin card +holder, but of greater length, and having its length horizontal. The +holders at the top of the board contain cards upon which the names of +the class are written. + +Cards, like the following, are prepared for the horizontal holders. + +-------------------------------------------------------------- +Stewart & Gee 229 +Physical Manip. 85 Intensity of Gravity--Borda's Method 39 +Glazebrook & Shaw 132 +-------------------------------------------------------------- + +These cards are numbered from one to any desired number and are arranged +in the holders consecutively. + +Two kinds of nails are provided to fit the holes in the board: An +ordinary slate nail and a common picture frame nail with a brass head. +The latter indicates work to be done, the former work done. + +To prepare the board for service, brass headed nails are placed opposite +each experiment, and below the names, care being taken not to have more +than one nail in the same horizontal row, unless it is intended that two +persons or more are to work upon the same experiment. + +There will be no conflict when the brass nails occupy diagonal lines. If +they do not, a glance will show the fact. + +After an experiment has been performed and a report made upon the usual +blank, the brass nail is removed and a slate nail put in its place. + +The board will show by the slate nails what work has been done by each +student, by the brass nails what is yet to be done, and by the empty +holes, experiments which have been omitted or are yet to be assigned. A +slate nail opposite an experiment card indicates that that experiment +may now be assigned to another person. + +It is evident that the schedule for a whole term may be arranged in a +few minutes and that the daily changes require very little time. + +The board is hung in a convenient place. The student as he enters the +laboratory looks for his name on the upper cards and under it for the +first brass nail in the vertical column: to the left he finds the +experiment card. On the left hand end of the slip he sees the book +references, on the right hand end a number--39 in the sample card given +above. Knowing the number, he proceeds to a desk and finds a box +numbered in the same manner. He removes the box from the closet. On the +label of the box is a list of all the apparatus necessary, which he will +find in the box; the label also contains the book references. He +performs the experiment, fills up a blank which he gives to the +instructor, puts all the materials back in the box, replaces the box in +its proper place in the closet and proceeds with the next experiment. +With this indicator there is no difficulty in managing fifty students or +more. + +Comparatively little apparatus need be duplicated. Where apparatus is +fixed against a wall a number may be tacked upon the wall and a card +containing the information desired. The procedure is then the same as +with the boxes. The cards on the board being removable, other ones may +be inserted containing information in reference to other boxes having +the same number but containing different materials. There can be no +successful tampering with the board, for the record of experiments +performed is upon the blanks which the students turn in and also in the +individual note books which are written up and given to the instructor +for daily examination. + +Lafayette College. J.W. MOORE. + + * * * * * + + + + +NEW METHOD OF EXTINGUISHING FIRES + + +This is by George Dickson, of Toronto, Canada, and David Alanson Jones. + +A mixture of water and liquefied carbon dioxide upon being discharged +through pipes at high pressure causes the rapid expansion of the gas and +converts the mixture into spray more or less frozen, and portions of the +liquid carbon dioxide are frozen, owing to its rapid expansion, and are +thus thrown upon the fire in a solid state, where said frozen carbon +dioxide in its further expansion not only acts to put out the fire, but +cools the surface upon which it falls, and thus tends to prevent +reignition. + +A represents a receptacle sufficiently strong to stand a pressure of not +less than a thousand pounds to the square inch. + +B B water receptacles. + +[Illustration: Fig. 1] + +In the drawings we have shown two receptacles B and only one receptacle +A; but we do not wish to confine ourselves to any particular number, nor +do we wish to confine ourselves to the horizontal position in which the +receptacles are shown. + +C is a pipe leading from the receptacle A to a point at or near the +bottom of the receptacle B. + +F is a pipe through which the mixture of water and liquefied gas from +the receptacle B is forced by the expansion of said liquefied gas, the +said pipe taking the mixture of water and liquefied gas from the bottom +of the receptacle. + +[Illustration: Fig. 2] + +To use the apparatus, open the stop cock D in the pipe C, leading to one +of the receptacles B, whereupon, owing to the lower pressure in the +cylinder B, the liquid carbon dioxide expands and rises to the top of +the cylinder A and forces the liquid carbon dioxide into the cylinder B, +the same as the superior steam of a boiler forces the water of the +boiler out when the same is tapped below the surface of the liquid. Now +upon opening the tap H, this superior gas forces out the mixture of +water and liquid carbon dioxide, which suddenly expanding causes +portions of the globules of liquefied gas to be frozen, and these, being +protected by a rapidly evaporating portion of the liquefied gas, are +thrown on the fire in solid particles. At the same time the water is +blown into a spray, which is more or less frozen. The fire is thus +rapidly extinguished by the vaporization of the carbon dioxide and water +spray. + + * * * * * + + + + +SMOKELESS GUNPOWDER. + +BY HUDSON MAXIM. + + +During the last forty years leading chemists have continued to +experiment with a view to the production of a gunpowder which should be +smokeless. But not until the last few years has any considerable degree +of success been attained. + +To be smokeless, a gunpowder must yield only gaseous products of +combustion. None of the so-called smokeless powders are entirely +smokeless, although some of them are very nearly so. + +The smoke of common black gunpowder is largely due to minute particles +of solid matter which float in the air. About one-half of the total +products of combustion of black gunpowder of ordinary composition +consists of potassium carbonate in a finely divided condition and of +potassium sulphate, which is produced chiefly by the burning in the air +of potassium sulphide, another production of combustion, as on the +outrushing gases it is borne into the air in a fine state of division. + +Another cause for the smoke of gunpowder is the formation of small +liquid vesicles which condense from some of the products of combustion +thrown into the air in a state of vapor, in the same manner as vesicles +of aqueous vapor form in the air on the escape of highly heated steam +from the whistle of a locomotive. + +Broadly speaking, an explosive compound is one which contains, within +itself, all the elements necessary for its complete combustion, and +whose heated gaseous products occupy vastly more space than the original +compound. Such compound usually consists of oxygen, associated with +other elements, for which it has great affinity, and from which it is +held from more intimate union, or direct chemical combination, under +normal conditions, by being in combination as well with other elements +for which it has less affinity, but which it readily gives up for the +stronger affinities when explosion takes place, the other elements +either combining with one another to form new compounds or being set +free in an uncombined state. + +An explosive is said to detonate when the above changes take place +instantaneously, the action being transmitted with the speed of +electricity by a sort of molecular rhythm from molecule to molecule +throughout the entire substance of the compound. + +An explosive is said to explode when the above changes do not occur +instantaneously throughout the whole substance, but whose combustion +takes place from the surface inward of the particles or grains of which +it is composed, thus requiring some definite lapse of time. + +The elements of an explosive compound may be associated chemically as in +nitro-glycerine and gun-cotton, which are chemical compounds, being the +results of definite reactions. Or, an explosive may be a mere mechanical +mixture of different substances comprising the necessary elements, as is +ordinary black gunpowder, which is a compound of charcoal, sulphur and +saltpeter, the saltpeter supplying the necessary oxygen. + +No gunpowder can be smokeless in which saltpeter or any oxygen-bearing +salt having a metallic base is employed, for when the salt gives up its +oxygen, the base combines with other elements to produce a sulphate, a +carbonate, or other salt, which, being solid, produces smoke. Therefore, +to be smokeless, a gunpowder must contain no other elements than oxygen, +hydrogen, nitrogen, and carbon, and in such proportions that the +products of combustion shall be wholly gaseous. The nitric +ethers--gun-cotton and nitro-glycerine--constitute such explosive +compounds. These substances were formerly thought to be +nitro-substitution compounds, but are now known to belong to the +compound ethers of nitric acid. + +Gun-cotton, discovered by Schonbein, in 1845, has since been looked upon +as the most promising material for a smokeless gunpowder, it being a +very powerful explosive and burning with practically no smoke. To-day, +gun-cotton, in some form or other, constitutes the base of substantially +all of the smokeless powders with which have been attained any +considerable degree of success. + +Gun-cotton alone and in its fibrous state has been found to be too +quick, or violent, for propulsive purposes, such as use in firearms; as +under such conditions of confinement it is very likely to detonate and +burst the gun. However, if gun-cotton be dissolved in a suitable +solvent, which is capable of being evaporated out, such as acetone, or +acetate of ethyl, which are very volatile, it becomes, when thus +dissolved and dried, a very hard, horn-like, amorphous substance, which +may be used for a smokeless gunpowder. But this substance taken alone is +very difficult to mould or granulate, and the loss of expensive solvents +must necessarily be quite considerable. + +When gun-cotton is reduced to a collodial solid, as above, and used as a +smokeless gunpowder, the grains must be made comparatively small to +insure prompt and certain ignition, and consequently the pressures +developed in the gun are apt to be too great when charges sufficiently +large are used to give desired velocities. + +If, however, a compound be made of gun-cotton and nitro-glycerine, in +about equal parts, by means of a volatile solvent or combining agent, +such as one of the before mentioned, and the solvent evaporated out, we +obtain practically a new substance and one which, as regards its +explosive nature, is quite unlike either of its two constituents taken +alone. The nitro-glycerine, furthermore, being itself a solvent of +gun-cotton, much less of the volatile ether is necessary to render the +compound of an amorphous character. Being quite plastic this substance +may be wrought or moulded into any desired size or form of grain. + +This simple compound of nitro-glycerine and gun-cotton, or with some +slight modifications, has been found, when properly granulated, to be +the most smokeless powder that has yet been discovered or invented. If +pure chemicals are employed in the manufacture, and the gun-cotton and +nitro-glycerine be made of the highest nitration and best quality, we +have a smokeless powder which will possess the following desirable +qualities: + +1st. It is absolutely smokeless, that is, its products of combustion are +entirely gaseous. + +2d. Its products of combustion are in no way deleterious or unpleasant. + +3d. It is perfectly safe to manufacture, handle and transport. There is +no more danger of its exploding accidentally than there would be of an +explosion of shavings or sawdust; for, unless well confined and set off +with a strong primer, it will not explode at all. In the open its +combustion is so slow as to in no way resemble or partake of the nature +of an explosion. + +4th. It is perfectly stable, and will keep any length of time absolutely +without undergoing any change whatever, under all conditions of +temperature or exposure to which gunpowder would ever be subjected. + +5th. It is not hygroscopic, and may be soaked in water without being at +all affected by it. + +6th. It will not corrode the cartridge case. + +7th. It will not foul the gun. + +8th. It is sure of ignition with a good primer, and may be made to burn +as slowly as desired by varying the character and size of the grains. +Indeed, it may be made to burn so slowly as to fail of complete +combustion before the bullet leaves the gun, and after firing several +rounds, partly burned pieces of the powder may be picked up in front of +the gun. + +9th. In a shoulder arm, a velocity of 2,000 feet per second may be +imparted to the bullet with this powder, and with a pressure in the +chamber of the gun of not more than fifteen English tons. This is, of +course, when the gun, cartridge case, primer, and projectile are adapted +to the use of smokeless powder, and the granulation of the powder is +adapted to them. + +If what I have here claimed for the above smokeless powder be true, it +would appear that it may be taken as really an ideal smokeless powder. +Why, then, has it not already been universally adopted? Surely such a +powder is just what every government is seeking. In reply to this, let +me say that, in order for the above compound to be an effective and +successful smokeless powder, with the manifestation of the many +desirable qualities which I have recited, a great many other conditions +are necessary, some of which I will mention. To arrive at the knowledge +that this compound would constitute the best smokeless powder has +required a great deal of experimenting. It was first thought that +gun-cotton colloid, without any nitro-glycerine, that is, gun-cotton +dissolved and dried, would burn more slowly, keep better, and give +better ballistics than it would if combined with nitro-glycerine. It was +also thought that gun-cotton of a high degree of nitration when made +into colloidal form would even then burn too quickly to be suitable for +use in firearms. Consequently, the first experiments were with low grade +gun-cotton, what is called collodion cotton, such as is employed in the +manufacture of celluloid. But, as this would not explode without the +addition of some oxygen-bearing element, various oxygen-bearing salts +were combined with it, such as nitrate of potassium, nitrate of ammonia, +nitrate of baryta, etc. Also a great many of the first smokeless powders +were made of low grade gun-cotton combined with nitro-glycerine in +varying proportions. These powders would often give very good results +when first made; but low grade gun-cotton or di-nitro-cellulose, as it +is called, is a very unstable compound, and these powders, after giving +very promising results, were found to be constantly undergoing change, +sooner or later resulting in complete decomposition. + +When nitro-glycerine was first combined with gun-cotton in small +quantities, camphor was often added, to lessen the rapidity of +combustion which the nitro-glycerine was supposed to impart and also to +render the compound more plastic, and to tend to prevent the +decomposition of the low grade gun-cotton. But camphor being volatile, +would, by its evaporation, cause the powder to constantly change in +character. Castor oil has been found to be a better diluent, as this +will not evaporate. + +As all of the smokeless powders made of a low grade gun-cotton were +found to deteriorate and spoil, experiments were made with gun-cotton of +the highest degree of nitration, both alone and in combination with +nitro-glycerine. These experiments were first conducted in England by +private parties and by the British government, when it was found that +high grade gun-cotton would give excellent results if made into a +colloidal solid and used alone, or in combination with certain other +constituents. With a view to saving the large quantity of solvents +necessary to reduce the gun-cotton, and to get a more prompt and certain +ignition with a larger grain, experiments were cautiously made by the +admixture of varying proportions of nitro-glycerine to the gun-cotton +when dissolved, or rather along with other solvents in the process of +dissolving it. + +It was soon found that nitro-glycerine added in quantities, even equal +in weight to the gun-cotton itself, did not materially increase the +rapidity of the explosion of the compound. And it was also found that +high grade gun-cotton, when combined with nitro-glycerine, gave very +much better results than low grade gun-cotton. + +I have spoken here of high and low grade gun-cotton, when in fact the +word gun-cotton should be applied only to the highest nitro-compound of +cellulose. The word gun cotton has always been rather loosely used. +Pyroxyline would be a better word, as this applies to all grades. When +cotton fiber is soaked in a large excess of a mixture of the strongest +nitric and sulphuric acids, gun-cotton proper, or that of the highest +grade, is produced. When weaker acids are used, lower grades of +nitro-cellulose are formed. + +The first mentioned or highest grade gun-cotton, when thoroughly freed +from its acids, has always proved to be a perfectly stable compound. The +lower grades have always been found to be unstable and subject to +spontaneous decomposition. Nitro-glycerine has also been erroneously +thought to be a very unstable compound. But experiments have proved +that, when made pure, it is perfectly stable. + +Having now explained how the knowledge came to be arrived at that the +aforementioned compound of highest grade nitro-glycerine and highest +grade gun-cotton would constitute the best basis for a smokeless powder, +I will now mention a few of the other conditions necessary to success +with its use, without assuming that smokeless powder has yet passed its +experimental stage, and is beyond further improvement. Nevertheless, +such is the compound which has come to stay as the basis of all +smokeless powders; and any smokeless powder, if a successful one, may be +counted upon as being made of this compound of gun-cotton and +nitro-glycerine, or of a colloid of gun-cotton, either alone or combined +with diluents, oxygen-bearing salts, or inert matter. The fact that +smokeless powder may still be said to be in somewhat of an experimental +stage is not to admit that it is not a success. Firearms, cartridge +cases, and projectiles are also still in an experimental stage, for they +are constantly being improved; yet their use has been a great success +for a good many years. + +The question of success of a smokeless powder does not rest alone with +the powder itself. The gun, the cartridge case, primer, and bullet have +been as much the subjects of experiments in adapting them to the use of +smokeless powder as has the smokeless powder in being adapted to them. +To impart a velocity of 2,000 feet per second to a rifle ball, with +corresponding long range and accuracy of flight, has been a question as +much of improvement in rifles and projectiles as in the powder. To give +a velocity of 2,000 feet per second to a bullet, requires a pressure of +at least 15 English tons in the chamber of a gun. This would be a +dangerous pressure in an old-fashioned shoulder arm; while a bullet made +only of lead would strip on striking the rifling and pass right through +the barrel of the gun without taking any rotary motion whatever. It +might at first seem that the powder is the only thing to be considered; +but high ballistics can only be obtained when everything else is adapted +to its use. + +The projectile, the cartridge case, the fulminating cap, and the gun +have had to be all built up together, and a very large amount of +experimenting has been necessary to determine what would constitute the +best projectile, best cartridge case, best fulminating cap, and what +should be the character of the rifling and the quality and temper of the +steel of the gun barrel. + +It has been necessary first to conduct experiments to test the smokeless +powders for velocities and pressures, and then with the powders test +various kinds of projectiles and guns. In order to obtain the high +ballistics which have been secured, it has been found necessary to cover +the bullet with something harder than lead and to rifle the gun in a +special manner. + +The French, who were the first to definitely adopt smokeless powder, +were the first also to make a rifle, projectile, cartridge case and +primer suited to its use. + +To obtain long range with a small long bullet such as is now used, it +should rotate at a very high speed. It is well known to artillerists +that a projectile of four or more calibers in length has to be rotated +at a much higher speed than one of half that length, in order to keep +the projectile stiff in the air, and to prevent it from ending over in +its flight. To communicate this very high rotary movement to the bullet +in the instant of time during which it is passing through the barrel, +the rifling of the gun has to exert an enormous torsion on the bullet. +Lead, no matter how hardened, is not sufficiently strong, as it will not +only strip and pass straight through the gun without taking any rotary +movement whatever, but under such very high pressures it behaves like +wax, and is thrown from the gun in a distorted mass. + +The French cover their bullets with German silver, a substance made of +nickel, zinc and copper; and in order to put as little strain upon the +rifling and projectile as possible, the rifling of the gun is made with +an increasing twist, and has no sharp edges. The French rifle is made +very strong at the breech and is of tempered steel throughout. In this +way the French have made smokeless powder a success--a smokeless powder +made substantially of a character such as I have herein described. With +smokeless powder, the French rifle imparts a muzzle velocity of 2,000 +feet per second to the bullet, with a range of about 2,400 meters. + +If smokeless powder be divided into sufficiently small grains to be +ignited by an ordinary fulminating cap, it would burn too quickly, +thereby causing the pressure to mount too high, and without giving the +desired velocity. Consequently very large and strong fulminating caps +have to be employed. Smokeless powder is not ignited in the same manner +as black powder. Something besides ignition is necessary. Black powder +simply requires to be set on fire; while a smokeless powder, on the +contrary, not only requires that it be set on fire, but that a certain +degree of pressure be set up inside of the cartridge case. For instance, +if a primer of a certain size should be found to operate perfectly well, +giving prompt ignition in the cartridge case of a rifle of small +caliber, it would be found that the same primer would not ignite a +charge of the same powder if loaded into a gun of one inch caliber. In +the latter case a few grains only lying near the primer would be +ignited, and these would soon become extinguished by sudden release of +pressure bringing about a cooling effect due to expansion of the gases. +In small cartridges a large fulminating cap is all that is required, but +in large cartridges it is necessary to resort to additional means of +ignition. + +In France, where experiments were conducted with a 37 millimeter Maxim +gun, it was found to be impracticable to use a fulminating cap +sufficiently large to ignite the powder and cause it to burn. Therefore, +a small ignition charge of black powder was employed, it being put in a +capsule or bag and placed next the primer. On firing at the rate of 300 +rounds per minute, the black powder, though small in quantity, produced +a cloud of smoke through which it was quite impossible to see. The +inventor of the gun then prepared for the French some wafers of +pyroxyline canvas, which were placed next to the primer, securing +thereby prompt ignition without the production of any smoke. + +Smokeless powder, made as I have described, cannot be detonated by a +fulminating cap of any size or by any means whatever. A large charge of +fulminate of mercury placed inside the cartridge case next the primer +will not detonate the powder, it serving only to ignite it and cause it +to explode. But even this would not cause the powder to explode except +it be confined behind a projectile, that sufficient pressure may be run +up to make it burn in its own gases. + +Some curious experiments with smokeless powder may be tried with a shot +gun. If the fulminating cap be large, the powder fine, the wads numerous +and hard and the charge of shot heavy, all being well rammed down, and +the paper case well spun over the last pasteboard wad, a charge of +smokeless powder about equal in weight to one-half of what would be +employed of black powder would give about the same results as black +powder. But if the charge of shot be omitted, the primer will only +ignite the powder, and there will be set up sufficient pressure merely +to throw the wads about half way up the barrel of the gun, when the +powder will go out. Now if this same charge of powder be collected and +reloaded into a new cartridge case and well confined behind wads and a +charge of shot, as above explained, it will all burn, giving the same +results as black powder. + +Attempts have been made to use this powder in pistols and revolvers, but +here it has proved a failure, as the pressure is not great enough to +cause the powder to be consumed, unless it be in the form of very fine +grains or dust, in which case the pressure mounts too high. However, +this might be overcome to a degree by making the powder porous. The +chemical conditions of the powder might be the same, but the physical +conditions must be different. A powder suitable for shot guns and +pistols would not be suitable for rifles. + +One not familiar with the characteristics of smokeless powder would be +almost certain to fail in his first attempt to fire it. Many persons +have been convinced by their first experiments that this powder would +not burn at all in a gun, any more than so much sand. + +Smokeless powder is consumed with a rapidity which accords with the +conditions of its confinement. Therefore, the bullets which have been +experimented with by different governments have been the cause of much +of the varying pressures attributed to the smokeless powders. + +The Austrians use the Mannlicher steel jacketed bullet. The steel casing +or jacket is first tinned on the inside and then the lead is cast in, +thus melting the tin and adhering firmly to the jacket. This projectile +sets up enormous friction in the barrel of the gun when used with +smokeless powder; as the smokeless powder leaves the gun barrel +perfectly clean and the two steel surfaces being in absolute contact +cause tremendous friction; and as the coefficient of friction varies +with every shot, the pressure in the gun constantly varies greatly. + +The German silver covered bullet used by the French has the disadvantage +that when firing rapidly the chamber of the barrel becomes nickel plated +and great friction is caused, mounting up the pressures and causing the +muzzle velocities to fall off. + +The Austrians, in order to prevent their steel cased bullets from +rusting and to lessen the friction in the barrel of the gun, cover them +with a heavy lubricant, which gives the cartridges an unsightly +appearance and causes them to gather dust and sand. The French employ a +lubricant at the base of the projectile, with a small copper disk +between the same and the powder. + +Col. A.R. Buffington, commander of the National Armory at Springfield, +Mass., has made a steel covered projectile which he prevents from +rusting by blackening by a niter process. Several grooves are pressed in +the base of the bullet which carry a lubricant, and when the bullet is +inserted in the cartridge case the grooves are covered by it. +Furthermore, these grooves prevent the lead filling from bursting +through the steel casing, leaving the latter in the barrel, as often +occurs with the Austrian and French projectiles when using smokeless +powder. + +A new projectile has lately come out, the invention of Captain Edward +Palliser, of the British army. This bullet consists of a jacket made of +very soft Swedish wrought iron, coated with zinc and filled with lead, +the lead being pressed into this jacket. The bullet is corrugated at its +base, after the manner of the one made by Colonel Buffington. This +projectile has been experimented with very extensively by the British +government, and at the works of the Maxim-Nordenfelt Guns and Ammunition +Company, in England. The zinc coating of the bullet is too soft to stick +to the barrel of the gun, and also in a measure acts as a lubricant. +This projectile has given better results than any other that has been +experimented with. The great velocities and the most uniform pressures +by the use of smokeless powder have been attained with this Palliser +bullet. + + +NOISELESSNESS. + +A great many stories have been told about the noiselessness of smokeless +powder. But there is no such thing as a noiseless gunpowder. The report +of a gun charged with smokeless powder is very sharp, and is as loud as +when black powder is used, yet the volume of sound is much less, so that +the report cannot be heard at so great a distance. + +The report of a gun using smokeless powder is a sound of much higher +pitch than when black powder is used, and consequently cannot be heard +at so great a distance as the lower notes given by black powder. + +As smokeless powder exerts a much greater pressure than common black +powder when burned in a gun, one would naturally think that the recoil +of the barrel would be greater, owing to the greater pressure exerted by +the smokeless powder on the base of the cartridge case and the breech +mechanism. However, such is not the fact; for the barrel actually +recoils very much less when smokeless powder is used. This is due to the +suddenness with which the pressure is exerted by smokeless powder, it +acting more like a very sharp blow on the metal, whereby more of the +energy is converted into heat instead of being spent in overcoming the +inertia of the barrel to give recoil. Similarly when smokeless powder is +fired in a gun, the displacement of the air is so sudden that the sound +waves do not possess the same amplitude of recoil or vibration as is +given by black powder. + + * * * * * + + + + +THE CONSTRUCTION AND MAINTENANCE OF UNDERGROUND CIRCUITS. + +BY S.B. FOWLER. + + +The numerous disastrous storms of the last winter have brought out very +vividly the advantages of having all wires placed underground, and many +inquiries have been addressed to the companies operating underground +circuits as to their success. It is not probable that all of the answers +to these inquiries have been of the most favorable character. To many +central station managers an underground system means frequent +break-downs and interruptions of service, with, perhaps, slow and +expensive repairs, which bring in their turn numerous complaints, loss +of customers, and reduced profits. In many installations burn-outs both +underground and in the station are frequent, with the natural result +that the operating of circuits underground is not there considered an +unqualified success. The writer has in mind two very different +experiences with underground cables. Several miles of cable were bought +by a certain company, carefully laid, and up to to-day not a single +burn-out or interruption of service can be attributed to failure of +cables; at about the same time another company bought about an equal +amount of the same kind of cable, and in a comparatively short time the +current had to be shut off the lines and the whole installation repaired +and parts of it replaced. Both of these experiences have been repeated +many times and will be again, although it is simply a distinction +between a good cable properly laid and a good cable ruined by careless +and incompetent workmanship. + +Every failure can be traced to poor work in the original installation or +to the use of a cheap cable, both causes being due, generally, to that +false economy which looks for too quick returns. A poorly insulated line +wire and a poorly insulated cable are two very different things. +However, it is a fact that by the use of a good cable it is not +difficult to construct an underground system for light, power, telegraph +or telephone uses that will be superior to overhead lines in its service +and in cost of maintenance. The ideal underground system must have as a +starting point a system of subways admitting of the easy drawing in and +out of cables and affording means of making subsidiary connections +readily and with the minimum of expense and interruption of service. +This is practically accomplished by a subway consisting of lines of pipe +terminating at convenient intervals, say at street intersections, in +manholes, for convenience in jointing and in running out house +connections. These pipes, or ducts, as they are called, should be for +two kinds of service; the lower or deeper laid lines for the main or +trunk circuits, and a second series of ducts laid nearer the surface, +running into service boxes placed near together for lines to "house to +house" connections. In some cities where it is allowed to run overhead +lines, the plan of running but one service connection in a block is +followed, all customers in the block being supplied from a line run over +the housetops or strung on the rear walls. + +This makes unnecessary all subsidiary ducts except a short one from the +manhole to the nearest building in the block, and effects a considerable +saving in pipe, service boxes, cables and labor. The manholes should +have their walls built up of brick, the floors should be of concrete, +and there should be an inside lid which can be fastened down and the +manhole thus made water-tight. + +For ducts wood, iron or cement lined pipe may be used. To preserve the +wood it is generally treated with creosote, which, in contact with the +lead cover of the cable, sets up a chemical action, resulting in the +destruction of the lead. Wood offers but little protection for the +cable, as it is too easily damaged and broken through in the frequent +street openings made by companies operating lines of pipe in the +streets, and as one of the main purposes of a subway is that of a +protection to cables, wooden ducts have little to recommend them except +their cheapness. + +Iron pipes are either laid in trenches filled in with earth or are laid +in cement. Iron pipe will of course rust out in time, and if absolute +permanence in construction is desired, should be laid in cement, for +after the pipe rusts out, the duct of cement is still left. However, if +we are going to the expense of laying in cement, it would be much +preferable to use cement lined pipe, which is not only cheaper than iron +pipe, but makes the most perfect cable conduit, as it affords a +perfectly smooth surface to draw the cable over and give a good duct +edge. + +It is not necessary, however, in small installations of cable, +especially where additional connections will not be of frequent +occurrence, to go to the expense of subways, for cable may be safely +laid in the ground in trenches filled in with earth, or can be inclosed +in a plain wooden box or a wooden box filled with pitch. + +There are, of course, many localities where, if the cable is laid in +contact with the earth, a chemical action would take place which might +result in the destruction of the cable. + +Underground cables are of the following classes: 1. Rubber insulated +cables, insulated with rubber or other homogeneous material. 2. Fibrous +cables, so called from the conductors being covered with some fibrous +material, as cotton or paper, which is saturated with the insulating +material, paraffine, resin oil, or some special compound. Under this +latter head is also included the dry core paper cables. + +The first thing to do is to get the cable drawn into the ducts, and on +the proper accomplishment of this depends to a great extent the success +or failure of the whole installation. Probably the ducts have been wired +when the subway was constructed, but if not a wire must be run through +as a means of pulling in the draw rope. There are several kinds of +apparatus for getting a wire through a duct--rods, flexible tapes, +mechanical "creepers," etc.; but probably the best is the sectional rod. +This simply consists of three or four foot lengths of hard wood rods, +having metal tips that screw into each other. A rod is placed in a duct +at a manhole, one screwed to that, both are pushed forward, another one +added and pushed forward, and so on until they extend the entire length +of the duct. Then the wire is attached and the rods are pulled out and +detached one at a time and with the last rod the wire is through. At +least No. 14 galvanized iron or steel wire should be used, for any +smaller size cannot be used a second time, as a rule. In starting to +pull in the draw rope a wire brush should be attached to the wire and to +this again the rope, and when the brush arrives at the distant end of +the duct it very likely will bring with it a miscellaneous collection of +material which for the good of the cable had better be in the manhole +than in the duct. + +The reel or drum carrying the cable should be mounted on wheels or jacks +and placed on the same side of the manhole as the duct into which the +cable is to be drawn, and must always be so placed that the cable will +run off the top of the reel. + +There are several methods of attaching the draw rope to the cable. As +simple and strong a method as any is to punch two of these holes through +the cable, lead and all, and attach the rope by means of an iron +wire--some of the draw wire will do--run through these holes. Depending +on the length and weight of cable to be pulled it can be drawn either by +hand or by a multiplying winch. The rope should run through a block +fastened in the manhole in such a position that the rope shall have a +good straightaway lead from the mouth of the duct. + +The strain on the cable should be perfectly uniform and steady; if the +power is applied by a series of jerks either the lead covering may be +pulled apart or some of the conductors broken. At the reel there must +always be a large enough number of men to turn it and keep the cable +from rubbing on anything, and in the manhole one or more men to see that +the cable feeds into the duct straight and to guide it if necessary. If +the ducts are of iron and are not perfectly smooth at the ends, these +should be made so with a file, and in addition a protector of some sort +should be placed in the mouths of the duct, both above and below the +cable. Six inches of lead pipe, split lengthwise and bent over at one +end to prevent being drawn into the duct with the cable, makes a very +good protector. The cable should be reeled off the drum just fast enough +to prevent any of the power used in pulling the cable through the duct +being utilized in unreeling it. If this latter is allowed to occur the +cable will be bent too short and the lead covering buckled or broken, +and also the cable may be jammed against the upper edge of the duct and +perhaps cut through. + +If the reel is allowed to turn faster than the cable is drawn in, the +first three or four turns on the reel will slacken up, and the lead +covering may either be dented or cut through by scraping on the ground. +If the cable end when pulled through up to the block is not long enough +to bend around the hole more than half way, the rope should be +unfastened from its end, a length of rope with a well frayed out end +should be run through the block, and by fastening to the cable close to +the duct, with a series of half hitches, as much slack as necessary can +be pulled in. If this is properly manipulated there need not be a +scratch on the cable, but unless great care is taken the lead may be +pressed up into ridges and the core itself damaged. + +Immediately after the cable is drawn in, if the joint is not to be at +once made, the open end or ends should be cut off and the cable soldered +up, as most cables are very susceptible to moisture and readily absorb +water even from the atmosphere. Where practicable it is always a good +plan to pull the cable through as many manholes as possible without +cutting the cable; for the joint is, especially in telephone or +telegraph cables, the weak point. To do this the rope should be pulled +through the proper duct in the next section without unfastening it from +the cable; the winch should be moved to the next manhole, and pulling +through then done as before. There should always be a man in every hole +through which the cable is running to see that it does not bind anywhere +and to keep protectors around the cable. + +It is not advisable to pull more than one cable into a duct, and never +advisable to pull a cable into a duct containing another cable, but if +two or more cables have to go into the same duct, they should always be +drawn in together. Lead covered cables and those with no lead on the +outside should never be pulled into the same duct, for if they bind +anywhere the soft cable will suffer where two lead covered cables would +get through all right. Some manufacturers are now putting on their +cables a tape or braid covering, which saves the lead many bad bruises +and cuts, and is a valuable addition to a cable at very little +additional expense. + +Practically all electric light and power cables are either single or +double conductors, and the jointing of these is comparatively a simple +matter, although requiring considerable care. The lead is cut back from +each end about four or five inches, and the conductors bared of +insulation for two or three inches. The bare conductors should be +thoroughly tinned by dipping in the metal pot or pouring the melted +solder over them. A sperm candle is better than resin or acid for any +part of the operations where solder is used. A lead sleeve is here +slipped back over the cable, out of the way, and the ends of the +conductors brought together in a copper sleeve which is then sweated to +a firm joint. This part must be as good a piece of work mechanically as +electrically. The bare splice is then wrapped tightly with cotton or +silk tape to a thickness slightly greater than that of the insulation of +the cable, and is thoroughly saturated with the insulating compound +until all moisture previously absorbed by the tape is driven off. + +The lead sleeve is then brought over the splice and wiped to the cable. +The joint is then filled with the insulating compound poured through +holes in the top of the sleeve; these holes are then closed and the +joint is complete, and there is no reason why, in light and power +cables, that joint should not be as perfect as any other part of the +cable. When the cable ends are prepared for jointing they should be hung +up in such a position that they are in the same plane, both horizontal +and vertically, and firmly secured there, so that when the lead sleeve +is wiped on the conductor may be in its exact center, and great care +must be taken not to move the cables again until the sleeve is filled +and the insulation sufficiently cooled to hold the conductor in +position. + +It is also very important to see that there are no sharp points on the +conductors themselves, on the copper sleeve, on the edges of the lead +covering or on the lead sleeve. All these should be made perfectly +smooth, for points facilitate disruptive discharges. Branch joints had +better be made as T-joints rather than as Y-joints, for they are better +electrically and mechanically, although they occupy more room in the +manholes. They are of course made in the same way as straight joints, a +lead T-sleeve being used, however. For multiple arc circuits copper +T-sleeves and for series circuits copper L-sleeves are used. + +Telephone and telegraph cables are made of any required gauge of wire +and with from 1 to 150 conductors in a cable. In jointing these the +splices are never soldered, the conductors being joined either with a +twist joint or with the so-called Western Union splice. Each splice is +covered with a cotton or silk sleeve or a wrapping of tape, the latter +being preferable, although considerably increasing the time necessary +for making the joint. Great care must be taken that no ends of wire are +left sticking up, for they will surely work their way through the tape +and grounds, and crosses will be the result. The wires should always be +joined layer to layer and each splice very tightly taped in order to get +as much insulating compound around each splice as possible in the +limited space. The splices should be "broken" as much as possible, so as +to avoid having adjoining splices coming over each other. After the +joint has been saturated with insulating compound the wires should have +an outside wrapping of tape to keep them in shape, and then the sleeve +is wiped on and filled. If the insulation resistance of the jointed +telegraph or telephone cable is a quarter of what the cable tested in +the factory, it may be considered that an exceptionally good piece of +work has been done. I have spoken more particularly of fibrous lead +covered cables, as the handling of them includes practically every step +of the work on any other kind of underground cable. In insulating dry +core paper cables a paper sleeve is slipped over the splice, and in +rubber cables the splice is wrapped with rubber tape; all other details +are the same for these as for the fibrous cable. + +In the laying of light and power cables every joint, as made, should be +tested for insulation with a Thomson galvanometer, as the insulation +must necessarily be very high, and if one joint or section of cable is +any weaker than another it may be very important in the future to know +it. All tests must be made after the joint has cooled, for while hot its +insulation resistance will be very low. + +Tests for copper resistance should also be made to determine if the +splices are electrically perfect; an imperfect splice may cause +considerable trouble. In telegraph and telephone cables the conductors +should be of very soft copper, for in stripping the conductor of +insulation it is very easy to nick the wire, and if of hard drawn copper +open wires will be the result. + +All work should be frequently tested for continuity with telephones, +magnetos, or small portable galvanometers. It is only necessary to +ground the conductors at one end and try each wire at the other end. For +this sort of work a telephone receiver used with one cell of some dry +battery is most convenient, and has the additional advantage of +affording a means of communication while testing, and is by far the best +thing for identifying and tagging conductors. + +These cables should be frequently tested during the progress of the work +for grounds and crosses with a Thomson instrument, and when the cable is +complete, a careful series of tests of the capacity, insulation +resistance, and copper resistance of each wire should be made and the +exact condition of the cable determined before it is put in service, and +thereafter an intelligent oversight of the condition of the circuits +can thus be more readily maintained. + +Where a company has extensive underground service, a regular cable gang +should be in its employ, for quick and safe handling of cables demands +the employment of men accustomed to the work. If the cable has been +properly laid and tests show it to be in good condition before current +is turned on, almost the only trouble to be anticipated will be due to +mechanical injury. Disruptive discharge, puncturing the lead, may occur; +but the small chance of its occurring can be greatly lessened by the use +of some kind of "cable protector," which will provide for the spark an +artificial path of less resistance than the dielectric of the condenser, +which the cable in fact becomes. + +If a fault suddenly develops on a circuit, the chances are it will be +found in a manhole, and an inspection of the cable in the manhole will +generally reveal the trouble without resorting to locating with a +Wheatstone bridge. The cable is often cut through at the edge of the +duct, or damaged by something falling on it, or by some one "walking all +over it." To guard against these, the ducts should always be fitted with +protectors both above and below the cable. The cables should never be +left across the manholes, for they then answer the purpose of a ladder, +but should be bent, around the walls of the hole and securely fastened +with lead straps, that they may not be moved and the lead gradually worn +through. + +In telegraph cables, when one or two conductors "go," it will probably +be useless to look for trouble except with instruments; but if several +wires are "lost" at once it will probably be found to be caused by +mechanical injury, which can be located by inspection. If it is ever +necessary to loop out conductors, a joint can be readily opened and the +conductors wanted picked out and connected into the branch cable and the +joint again closed without disturbing the working wires. In doing this a +split sleeve must be used, and the only additional precaution to be +taken is in filling the sleeve to have the insulating compound not hot +enough to melt the solder and open up the split in the sleeve. In +cutting in service on light and power cables it is entirely practicable +to do so without interruption of service on multiple arc circuits, even +those of very high voltage; but they require great precaution and +involve considerable risk to the jointer, and where possible the circuit +to which the connection is to be made should previously be cut dead. +Where the voltage is not dangerous to human life, almost any service +connection can be made without interruption of service. + +I have only indicated a very few of the operations that may be found +necessary, and the probable causes of troubles that may be encountered +in the operating of underground circuits, believing that the different +problems that arise can, with a little experience, be successfully met +by any one who has a fair knowledge of the original construction of +cable lines.--_Electrical World_. + + * * * * * + + + + +RAILROADS TO THE CLOUDS. + + +If George Stephenson, when he placed the first locomotive on the track +and guaranteed it a speed of six miles an hour, could have foreseen that +in less than eighty years the successors of his rude machine would be +climbing the sides of mountain ranges, piercing gorges hitherto deemed +inaccessible, crossing ravines on bridges higher than the dome of St. +Paul's, and traversing the bowels of the earth by means of tunnels, no +doubt his big blue eyes would have stood out with wonder and amazement. +But he foresaw nothing of the kind; the only problem present in his mind +was how to get goods from the seaports in western England to London as +easily and cheaply as possible, and to do this he substituted for +horses, which had for 150 years been drawing cars along wooden or iron +tracks, the wonderful machine which has revolutionized the freight and +passenger traffic of the world. + +It was, indeed, impossible for any one to foresee the triumphs of +engineering which have accompanied the advances in transportation. To +the engineer of the present day there are no impossibilities. The +engineer is a wizard at whose command space and matter are annihilated. +The highest mountain, the deepest valley, has no terrors for him. He can +bridge the latter and encircle or tunnel the former. The only requisites +which he demands are that something in his line be needed, and that the +money is forthcoming to defray the expense, and the thing will be done. +But the railroad he is asked to construct must be necessary, and the +necessity must be plainly shown, or no funds will be advanced; and +although the theory does not invariably hold good, especially when a +craze for railroad building is raging, as a rule no expense for the +construction of a road will be incurred without a prospect of +remuneration. + +Hence the need of railroad communication has caused lines to be +constructed through districts where only a few years ago the thing would +have been deemed impossible. The Pacific roads of this country were a +necessity long before their construction, and in the face of +difficulties almost insuperable were carried to successful completion. +So, also, of the railroads in the Andes of South America. The famous +road from Callao through the heart of Peru is one of the highest +mountain roads in the world, as well as of the most difficult +construction. The grades are often of 300 feet and more to the mile, and +when the mountains were reached so great were the difficulties the +engineers were forced to confront that in some places laborers were +lowered from cliffs by ropes in order that, with toil and difficulty, +they might carve a foothold in order to begin the cutting for the +roadway. + +In some sections tunnels are more numerous than open cuts, and so far as +the road has gone sixty-one tunnels, great and small, have been +constructed, aggregating over 20,000 feet in length. The road attains a +height of 15,000 feet above the level of the sea, and at the highest +point of the track is about as high as the topmost peak of Mont Blanc. +It pierces the range above it by a tunnel 3,847 feet long. The stern +necessities of business compelled the construction of this road, +otherwise it never would have been begun. + +The tunnels of the Andes, however, do not bear comparison with the +tunnels, bridges, and snow sheds of the Union Pacific, nor do even these +compare with the vast undertakings in the Alps--three great tunnels of +nine to eleven miles in length, which have been prepared for the +transit of travelers and freight. The requirements of business +necessitated the piercing of the Alps, and as soon as the necessity was +shown, funds in abundance were forthcoming for the enterprise. + +But tunneling a mountain is a different thing from climbing it. Many +years ago the attention of inventors was directed to the practicability +of constructing a railroad up the side of a mountain on grades which, to +an ordinary engine, were quite impossible. The improvements in +locomotives twenty-five and thirty years ago rendered them capable of +climbing grades which, in the early days of railroad engineering, were +deemed out of the question. The improvements proved a serious stumbling +block in the way of the inventors, who found that an ordinary locomotive +was able to climb a much steeper grade than was commonly supposed. The +first railroads were laid almost level, but it was soon discovered that +a grade of a few feet to the mile was no impediment to progress, and +gradually the grade was steepened. + +The inventors of mountain railroad transportation might have been +discouraged by this discovery, but it is a characteristic of an inventor +that he is not set back by opposition, which, in fact, only serves to +stimulate his zeal. The projectors of inclined roads and mountain +engines kept steadily on, and in France, Germany, England, and the +United States many experimental roads were constructed, each of a few +hundred yards in length, and locomotive models were built and put in +motion to the amazement of the general public, who jeered alike at the +contrivances and the contrivers, deeming the former impracticable and +the latter crazy. + +But the idea of building a road up the side of a hill was not to be +dismissed. There was money in it for the successful man, so the cranky +inventors kept on at work in spite of the jeers of the rabble and the +discouragements of capitalists loath to invest their money in an +uncertain scheme. To the energy and perseverance of railroad inventors +the success of the mountain railroad is due, as also is the construction +of the various mountain roads, of which the road up Mt. Washington, +finished in 1868, was the first, and the road up Pike's Peak, completed +the other day, was the latest. + +Of all the mountain roads which have been constructed since the one up +Mt. Washington was finished, the best known is that which ascends the +world-famous Rigi. With the exception of Mont Blanc, Rigi is, perhaps, +the best known of any peak in the Alps, though it is by no means the +highest, its summit being but 5,905 feet above the level of the sea. +Although scarcely more than a third of the height of some other +mountains in the Alps, it seems much higher because of its isolated +position. Standing as it does between lakes Lucerne, Zug, and Lowertz, +it commands a series of fine views in every direction, and he who looks +from the summit of Rigi, if he does no other traveling in Switzerland, +can gain a fair idea of the Swiss mountain scenery. Many of the most +noted peaks are in sight, and from the Rigi can be seen the three lakes +beneath, the villages which here and there dot the shores, and, further +on, the mighty Alps, with their glaciers and eternal snows. + +Many years ago a hotel was built on the summit of the Rigi for the +benefit of the tourists who daily flocked to this remarkable peak to +enjoy the benefit of its wonderful scenery. The mountain is densely +wooded save where the trees have been cut away to clear the land for +pastures. The ease of its ascent by the six or eight mule paths which +had been made, the gradual and almost regular slope, and the throngs of +travelers who resorted to it, made it a favorable place for an +experiment, and to Rigi went the engineers in order to ascertain the +practicability of such a road. The credit of the designs is due to a +German engineer named Regenbach, who, about the year 1861, designed the +idea of a mountain road, and drew up plans not only for the bed but also +for the engine and cars. The scheme dragged. Capitalists were slow to +invest their money in what they deemed a wild and impracticable +undertaking, and even the owners of the land on the Rigi were reluctant +for such an experiment to be tried. But Regenbach persevered, and toward +the close of the decade the inhabitants of Vitznau, at the base of the +Rigi, were astonished to see gangs of laborers begin the work of making +a clearing through the forests on the mountain slope. They inquired what +it meant, and were told that a road up the Rigi was to be made. The +Vitznauers were delighted, for they had no roads, and there was not a +wheeled vehicle in the town, nor a highway by which it could be brought +thither. The idea of a railroad in their desolate mountain region, and, +above all, a railroad up the Rigi, never entered their heads, and a +report which some time after obtained currency in the town, that the +laborers were beginning the construction of a railroad, was greeted with +a shout of derision. + +Nevertheless, that was the beginning of the Rigi line, and in May, 1871, +the road was opened for traffic. It begins at Vitznau, on Lake Lucerne, +and extends to the border of the canton and almost to the top of the +mountain. It is 19,000 feet long, and during that distance rises 4,000 +feet at an average grade of 1 foot in 4. Though steep, it is by no means +so much so as the Mt. Washington road, which rises 5,285 feet above the +sea, at an average of 1 foot in 3. There are, however, stretches of the +Rigi road at which the grade is about 1 foot in 2½, which is believed to +be the steepest in the world. + +The Rigi road has several special features aside from its terrific +slopes which entitle it to be considered a triumph of the engineer's +skill. About midway up the mountains the builders came to a solid mass +of rock, which presented a barrier that to a surface road was +impassable. They determined to tunnel it, and, after an enormous +expenditure of labor, finished an inclined tunnel 225 feet in length, of +the same gradient as the road. A gorge in the side of the mountain where +a small stream, the Schnurtobel, had cut itself a passage also hindered +their way, and was crossed by a bridge of lattice girder work in three +spans, each 85 feet long. The entire roadbed, from beginning to end, was +cut in the solid rock. A channel was chiseled out to admit the central +beam, which contains the cogs fitting the driving wheel of the +locomotive. The engine is in the rear of the train, and presents the +exceedingly curious feature of a boiler greatly inclined, in order that +at the steeper gradients it may remain almost perpendicular. The coal +and water are contained in boxes over the driving wheels, so that all +the weight of the engine is really concentrated on the cogs--a +precaution to prevent their slipping. The cost of the road, including +three of these strangely constructed locomotives, three passenger +coaches, and three open wagons, was $260,000, and it is a good paying +investment. The fare demanded for the trip up the mountains is 5 francs, +while half that sum is required for the downward passage, and the road +is annually traversed by from 30,000 to 50,000 passengers. + +Curious sensations are produced by a ride up this remarkable line. The +seats of the cars are inclined like the boiler of the locomotive, and so +long as the cars are on a level the seats tilt at an angle which renders +it almost impossible to use them. But when the start is made the +frightful tilt places the body in an upright position, and, with the +engine in the rear, the train starts up the hill with an easy, gliding +motion, passing up the ascent, somewhat steeper than the roof of a +house, without the slightest apparent effort. But if the going up +excites tremor, much more peculiar are the feelings aroused on the down +grade. The trip begins with a gentle descent, and all at once the +traveler looking ahead sees the road apparently come an end. On a nearer +approach he is undeceived and observes before him a long decline which +appears too steep even to walk down. Involuntarily he catches at the +seats, expecting a great acceleration of speed. Very nervous are his +feelings as the train approaches this terrible slope, but on coming to +the incline the engine dips and goes on not a whit faster than before +and not more rapidly on the down than on the up grade. Many people are +made sick by the sensation of falling experienced on the down run. Some +faint, and a few years ago one traveler, supposed to be afflicted with +heart disease, died of fright when the train was going over the +Schnurtobel bridge. The danger is really very slight, there not having +been a serious accident since the road was opened. The attendants are +watchful, the brakes are strong, but even with all these safeguards, men +of the steadiest nerves cannot help wondering what would become of them +in case anything went wrong. + +Bold as was the project of a railroad on the Rigi, a still bolder scheme +was broached ten years later, when a daring genius proposed a railroad +up Mt. Vesuvius. A railroad up the side of an ordinary mountain seemed +hazardous enough, but to build a line on the slope of a volcano, which +in its eruption had buried cities, and every few years was subject to a +violent spasm, seemed as hazardous as to trust the rails of an ordinary +line to the rotten river ice in spring time. The proposal was not, +however, so impracticable as it looked. While the summit of Vesuvius +changes from time to time from the frequent eruptions, and varies in +height and in the size of the crater, the general slope and contour of +the mountain are about the same to-day as when Vesuvius, a wooded hill, +with a valley and lake in the center of its quiescent crater, served as +the stronghold of Spartacus and his rebel gladiators. There have been +scores of eruptions since that in which Herculaneum and Pompeii were +overthrown, but the sides of the mountain have never been seriously +disturbed. + +A road on Vesuvius gave promise of being a good speculation. Naples and +the other resorts of the neighborhood annually attracted many thousands +of visitors, and a considerable number of these every year ascended the +volcano, even when forced to contend with all the difficulties of the +way. Many, however, desiring to ascend, but being unable or unwilling to +walk up, a chair service was established--a peculiar chair being slung +on poles and borne by porters. In course of time the chair service +proved to be inadequate for the numbers who desired to make the ascent, +and the time was deemed fit for the establishment of more speedy +communication. + +Notwithstanding the necessity, the proposal to establish a railroad met +with general derision, but the scheme was soon shown to be perfectly +practicable, and a beginning was made in 1879. The road is what is known +as a cable road, there being a single sleeper with three rails, one on +the top which really bore the weight, and one on each side near the +bottom, which supported the wheels, which coming out from the axle at a +sharp angle, prevented the vehicle from being overturned. The road +covers the last 4,000 feet of the ascent, and the power house is at the +bottom, a steel cable running up, passing round a wheel at the top and +returning to the engine in the power house. The ascent to the lower +terminus of the road is made on mules or donkeys; then, in a comfortable +car, the traveler is carried to a point not far from the crater. The car +is a combined grip and a passenger car, similar in some points to the +grip car of the present day, while the seats of the passenger portion +are inclined as in the cars on the Rigi road. But the angle of the road +being from thirty-three to forty-five degrees, makes both ascent and +descent seem fearfully perilous. Every precaution, however, is taken to +insure the safety of passengers; each car is provided with several +strong and independent brakes, and thus far no accident worth recording +has occurred. The road was opened in June, 1880. Although there have +been several considerable eruptions since that date, none of them did +any damage to the line but what was repaired in a few hours. + +The fashion thus set will, no doubt, be followed in many other quarters. +Wherever there is sufficient travel to pay working expenses and a profit +on a steep grade mountain road it will probably be built. Already there +is talk of a road on Mont Blanc, of another up the Yungfrau, and several +have been projected in the Schwartz and Hartz mountains. A route on Ben +Nevis, in Scotland, is already surveyed, and it is said surveys have +also been made up Snowden, with a view to the establishment of a road to +the summit of the highest Welsh peak. Sufficient travel is all that is +necessary, and when that is guaranteed, whenever a mountain possesses +sufficient interest to induce people to make its ascent in considerable +numbers, means of transportation, safe and speedy, will soon be +provided. The modern engineer is able, willing and ready to build a road +to the top of Mt. Everest in the Himalayas if he is paid for doing +so.--_St. Louis Globe-Democrat._ + + * * * * * + +To clean hair brushes, wash with weak solution of washing soda, rinse +out all the soda, and expose to sun. + + * * * * * + + + + +THE MARCEAU. + + +[Illustration: THE FRENCH ARMORED TURRET SHIP MARCEAU] + +The Marceau, the last ironclad completed and added to the French navy, +was put in commission at Toulon in April last, and has lately left that +town to join the French squadron of the north at Brest. The original +designs of this ship were prepared by M. Huin, of the French Department +of Naval Construction, but since the laying down of the keel in the year +1882 they have been very considerably modified, and many improvements +have been introduced. + +Both ship and engines were constructed by the celebrated French firm, +the Société des Forges et Chantiers de la Mediterranée, the former at +their shipyard in La Seyne and the latter at their engine works in +Marseilles. The ship was five years in construction on the stocks, was +launched in May, 1887, and not having been put in commission until the +present year, was thus nearly nine years in construction. She is a +barbette belted ship of somewhat similar design to the French ironclads +Magenta, now being completed at the Toulon arsenal, and the Neptune, in +construction at Brest. + +The hull is constructed partly of steel and partly of iron, and has the +principal dimensions as follows. Length, 330 ft. at the water line; +beam, 66 ft. outside the armor; draught, 27 ft. 6 in. aft.; +displacement, 10,430 English or 10,600 French tons. The engines are two +in number, one driving each propeller; they are of the vertical compound +type, and on the speed trials developed 11,300 indicated horse power +under forced and 5,500 indicated horse power under natural draught, the +former giving a speed of 16.2 knots per hour with 90 revolutions per +minute. The boilers are eight in number, of the cylindrical marine type, +and work at a pressure of 85.3 lb. per square inch. During the trials +the steering powers of the ship were found to be excellent, but the bow +wave is said, by one critic, to have been very great. + +The ship is completely belted with Creusot steel armor, which varies in +thickness from 9 in. forward to 17¾ in. midships. In addition to this +belt the ship is protected by an armored deck of 3½ in., while the +barbette gun towers are protected with 15¾ in. steel armor with a hood +of 2½ in. to protect the men against machine gun fire. As a further +means of insuring the life of the ship in combat and also against +accidents at sea, the Marceau is divided into 102 water-tight +compartments and is fitted with torpedo defense netting. There are two +masts, each carrying double military tops; and a conning tower is +mounted on each mast, from either of which the ship may be worked in +time of action, and both of which are in telegraphic communication with +the engine rooms and magazines. Provision is made for carrying 600 tons +of coal, which, at a speed of 10 knots, should be sufficient to supply +the boilers for a voyage of 4,000 miles. + +The armament of the Marceau is good for the tonnage of the ship and +consists principally of four guns of 34 centimeters (13.39 in.) of the +French 1884 model, having a weight of 52 tons, a length of 28½ calibers, +and being able to pierce 30 in. of iron armor at the muzzle. The +projectiles weigh 924 lb., and are fired with a charge of 387 lb. of +powder. The muzzle velocity has been calculated to be 1,968 ft. per +second. The guns are entirely of steel and are mounted on Canet +carriages in four barbette towers, one forward, one aft, and one on each +side amidships. On the firing trials both the guns and all the Canet +machinery, for working the guns and hoisting the ammunition, gave very +great satisfaction to all present at the time. In addition to the above +four heavy guns there are, in the broadside battery, sixteen guns of 14 +centimeters (5.51 in.), eight on each side, and a gun of equal caliber +is mounted right forward on the same deck. The armament is completed by +a large number of Hotchkiss quick-firing and revolver guns and four +torpedo tubes, one forward, one aft, and one on each side. + +The crew of the Marceau has been fixed at 600 men, and the cost is +stated to have been about $3,750,000.--_Engineering_. + + * * * * * + +[Continued from SUPPLEMENT, No. 820, page 13097.] + + + + +A REVIEW OF MARINE ENGINEERING DURING THE PAST DECADE.[1] + +[Footnote 1: Paper read before the Institution of Mechanical Engineers, +July 28, 1891.] + +BY MR. ALFRED BLECHYNDEN, OF BARROW-IN-FURNESS + + +_Steam Pipes_.--The failures of copper steam pipes on board the Elbe, +Lahn, and other vessels have drawn serious attention both to the +material and to the modes of construction of the pipes. The want of +elastic strength in copper is an important element in the matter; and +the three following remedies have been proposed, while still retaining +copper as the material. First, in view of the fact that in the operation +of brazing the copper may be seriously injured, to use solid drawn +tubes. This appears fairly to meet the main dangers incidental to +brazing; but as solid drawn pipes of over 7 inches diameter are +difficult to procure, it hardly meets the case sufficiently. Secondly, +to use electrically deposited tubes. At first much was promised in this +direction; but up to the present time it can hardly be regarded as more +than in the experimental stage. Thirdly, to use the ordinary brazed or +solid drawn tubes, and to re-enforce them by serving with steel cord or +steel or copper wire. This has been tried, and found to answer +perfectly. For economical reasons, as well as for insuring the minimum +of torsion to the material during manufacture, it is important to make +as few bends as possible; but in practice much less difficulty has been +experienced in serving bent pipes in a machine than would have been +expected. Discarding copper, it has been proposed to substitute steel or +iron. In the early days of the higher pressures, Mr. Alexander Taylor +adopted wrought iron for steam pipes. One fitted in the Claremont in +February, 1882, was recently removed from the vessel for experimental +purposes, and was reported upon by Mr. Magnus Sandison in a paper read +before the Northeast Coast Institution of Engineers and Shipbuilders.[2] +The following is a summary of the facts. The pipe was 5 inches external +diameter, and 0.375 inch thick. It was lap welded in the works of +Messrs. A. & J. Stewart. The flanges were screwed on and brazed +externally. The pipe was not lagged or protected in any manner. After +eight and a half years' service the metal measured where cut 0.32 and +0.375 inch in thickness, showing that the wasting during that time had +been very slight. The interior surface of the tube exhibited no signs of +pitting or corrosion. It was covered by a thin crust of black oxide, the +maximum thickness of which did not exceed 1/32 inch. Where the deposit +was thickest it was curiously striated by the action of the steam. On +the scale being removed, the original bloom on the surface of the metal +was exposed. It would thus appear that the danger from corrosion of iron +steam pipes is not borne out in their actual use; and hence so much of +the way is cleared for a stronger and more reliable material than +copper. So far the source of danger seems to be in the weld, which would +be inadmissible in larger pipes; but there is no reason why these should +not be lapped and riveted. There seems, however, a more promising way +out of the difficulty in the Mannesmann steel tubes which are now being +"spun" out of solid bars, so as to form weldless tubes. + +[Footnote 2: Transactions Northeast Coast Institution of Engineers and +Shipbuilders, vol. 7, 1890-91, p. 179.] + +TABLE I.--TENSILE STRENGTH OF GUN METAL AT HIGH TEMPERATURES. + +--------------+------------+-------------+-------------+------------+ + | | | | | + Composition |Temperature | Tensile | Elastic | Elongation | + of | of oil | strength | limit | in | + gun metal. | bath. | per square | per square | length of | + | | inch. | inch. | 2 inches | +--------------+------------+-------------+-------------+------------+ + Per cent. | Fahr. | Tons | Tons | Per cent. | + Copper 87 /| 50° | 12.34 | 8.38 | 14.64 | + Tin 8 / | | | | | + Zinc 3½ \ | | | | | + Lead 1½ \| 400° | 10.83 | 6.30 | 11.79 | +--------------+------------+-------------+-------------+------------+ + Copper 87 /| 50° | 13.86 | 8.33 | 20.30 | + Tin 8 { | | | | | + Zinc 5 \| 458° | 10.70 | 7.43 | 12.42 | +--------------+------------+-------------+-------------+------------+ + +Cast steel has been freely used by the writer for bends, junction +pieces, etc., of steam pipes, as well as for steam valve chests; and +except for the fact that steel makers' promises of delivery are +generally better than their performance, the result has thus far been +satisfactory in all respects. These were adopted because there existed +some doubt as to the strength of gun metal under a high temperature; and +as the data respecting its strength appeared of a doubtful character, a +series of careful tests were made to determine the tensile strength of +gun metal when at atmospheric and higher temperatures. The test bars +were all 0.75 in diameter, or 0.4417 square inch sectional area; and +those tested at the higher temperatures were broken while immersed in a +bath of oil at the temperature here stated, each line being the mean of +four experiments. The result of these experiments was to give somewhat +greater faith in gun metal as a material to be used under a higher +temperature; but as steel is much stronger, it is probably the most +advisable material to use, when the time necessary to procure it can be +allowed. + +_Feed Heating_.--With the double object of obviating strain on the +boiler through the introduction of the feed water at a low temperature, +and also of securing a greater economy of fuel, the principle of +previously heating the feed water by auxiliary means has received +considerable attention, and the ingenious method introduced by Mr. James +Weir has been widely adopted. It is founded on the fact that, if the +feed water as it is drawn from the hot well be raised in temperature by +the heat of a portion of steam introduced into it from one of the steam +receivers, the decrease of the coal necessary to generate steam from the +water of the higher temperature bears a greater ratio to the coal +required without feed heating than the power which would be developed in +the cylinder by that portion of steam would bear to the whole power +developed when passing all the steam through all the cylinders. The +temperature of the feed is of course limited by the temperature of the +steam in the receiver from which the supply for heating is drawn. +Supposing, for example, a triple expansion engine were working under the +following conditions without feed heating: Boiler pressure, 150 +lb.;--indicated horse power in high pressure cylinder 398, in +intermediate and low pressure cylinders together 790, total, 1,188; and +temperature of hot well 100° Fahr. Then with feed heating the same +engine might work as follows: The feed might be heated to 220° Fahr., +and the percentage of steam from the first receiver required to heat it +would be 12.2 per cent.; the indicated horse power in the high pressure +cylinder would be as before 398, and in the intermediate and low +pressure cylinders it would be 12.2 per cent, less than before, or 694, +and the total would be 1,092, or 92 per cent. of the power developed +without feed heating. Meanwhile the heat to be added to each pound of +the feed water at 220° Fahr. for converting it into steam would be 1,005 +units against 1,125 units with feed at 100° Fahr., equivalent to an +expenditure of only 89.4 per cent. of the heat required without feed +heating. Hence the expenditure of heat in relation to power would be +89.4 + 92.0 = 97.2 per cent., equivalent to a heat economy of 2.8 per +cent. If the steam for heating can be taken from the low pressure +receiver, the economy is about doubled. Other feed heaters, more or less +upon the same principle, have been introduced. Also others which heat +the feed in a series of pipes within the boiler, so that it is +introduced into the water in the boiler practically at boiling +temperature; this is economical, however, only in the sense that wear +and tear of the boiler is saved; in principle the plan does not involve +economy of fuel. + +_Auxiliary Supply of Fresh Water_.--Intimately associated with the feed +is the means adopted for making up the losses of fresh water due to +leakage of steam from safety valves, glands, joints, etc., and of water +discharged from the air pumps. A few years ago this loss was regularly +made up from the sea, with the result that the water in the boilers was +gradually increased in density; whence followed deposit on the internal +surfaces, and consequent loss of efficiency, and danger of accident +through overheating the plates. With the higher pressures now adopted, +the danger arising from overheating is much more serious, and the +necessity is absolute of maintaining the heating surfaces free from +deposit. This can be done only by filling the boiler with fresh water in +the first instance, and maintaining it in that condition. To do this two +methods are adopted, either separately or in conjunction. Either a +reserve supply of fresh water is carried in tanks or the supplementary +feed is distilled from sea water by special apparatus provided for the +purpose. In the construction of the distilling or evaporating apparatus +advantage has been taken of two important physical facts, namely, that, +if water be heated to a temperature higher than that corresponding with +the pressure on its surface, evaporation will take place; and that the +passage of heat from steam at one side of a plate to water at the other +is very rapid. In practice the distillation is effected by passing +steam, say from the first receiver, through a nest of tubes inside a +still or evaporator, of which the steam space is connected either with +the second receiver or with the condenser. The temperature of the steam +inside the tubes being higher than that of the steam either in the +second receiver or in the condenser, the result is that the water inside +the still is evaporated, and passes with the rest of the steam into the +condenser, where it is condensed, and serves to make up the loss. This +plan localizes the trouble of deposit, and frees it from its dangerous +character, because an evaporator cannot become overheated like a boiler, +even though it be neglected until it salts up solid; and if the same +precautions are taken in working the evaporator which used to be adopted +with low pressure boilers when they were fed with salt water, no serious +trouble should result. When the tubes do become incrusted with deposit, +they can be either withdrawn or exposed, as the apparatus is generally +so arranged; and they can then be cleaned. + +_Screw Propeller_.--In Mr. Marshall's paper of 1881 it was said that +"the screw propeller is still to a great extent an unsolved problem." +This was at the time a fairly true remark. It was true the problem had +been made the subject of general theoretical investigation by various +eminent mathematicians, notably by Professor Rankine and Mr. William +Froude, and of special experimental investigation by various engineers. +As examples of the latter may be mentioned the extended series of +investigations in the French vessel Pelican, and the series made by Mr. +Isherwood on a steam launch about 1874. These experiments, however, such +as they were, did little to bring out general facts and to reduce the +subject to a practical analysis. Since the date of Mr. Marshall's paper, +the literature on this subject has grown rapidly, and, has been almost +entirely of a practical character. The screw has been made the subject +of most careful experiments. One of the earliest extensive series of +experiments was made under the writer's direction in 1881, with a large +number of models, the primary object being to determine what value there +was in a few of the various twists which inventive ingenuity can give to +a screw blade. The results led the experimenters to the conclusion that +in free water such twists and curves are valueless as serving to augment +efficiency. The experiments were then carried further with a view to +determine quantitative moduli for the resistance of screws with +different ratios of pitch to diameter, or "pitch ratios," and afterward +with different ratios of surface to the area of the circle described by +the tips of the blades, or "surface ratios." As these results have to +some extent been analyzed and published, no further reference need be +made to them now. + +In 1886, Mr. R.E. Froude published in the Transactions of the +Institution of Naval Architects the deductions drawn from an extensive +series of trials made with four models of similar form and equal +diameter, but having different pitch ratios. Mr. S.W. Barnaby has +published some of the results of experiments made under the direction of +Mr. J.I. Thornycroft; and in his paper read before the Institution of +Civil Engineers in 1890 he has also put Mr. R.E. Froude's results into a +shape more suitable for comparison with practice. Nor ought Mr. G.A. +Calvert's carefully planned experiments to pass unnoticed, of which an +account was given in the Transactions of the Institution of Naval +Architects in 1887. These experiments were made on rectangular bodies +with sections of propeller blade form, moved through the water at +various velocities in straight lines, in directions oblique to their +plane faces; and from their results an estimate was formed of the +resistance of a screw. + +One of the most important results deduced from experiments on model +screws is that they appear to have practically equal efficiencies +throughout a wide range both in pitch ratio and in surface ratio; so +that great latitude is left to the designer in regard to the form of the +propeller. Another important feature is that, although these experiments +are not a direct guide to the selection of the most efficient propeller +for a particular ship, they supply the means of analyzing the +performances of screws fitted to vessels, and of thus indirectly +determining what are likely to be the best dimensions of screw for a +vessel of a class whose results are known. Thus a great advance has been +made on the old method of trial upon the ship itself, which was the +origin of almost every conceivable erroneous view respecting the screw +propeller. The fact was lost sight of that any modification in form, +dimensions, or proportions referred only to that particular combination +of ship and propeller, or to one similar thereto; so something like +chaos was the result. This, however, need not be the case much longer. + +In regard to the materials used for propellers, steel has been largely +adopted for both solid and loose-bladed screws; but unless protected in +some way, the tips of the blades are apt to corrode rapidly and become +unserviceable. One of the stronger kinds of bronze is often judiciously +employed for the blades, in conjunction with a steel boss. Where the +first extra expense can be afforded, bronze seems the preferable +material; the castings are of a reliable character, and the metal does +not rapidly corrode; the bronze blades can therefore with safety be made +lighter than steel blades, which favors their springing and +accommodating themselves more readily to the various speeds of the +different parts of the wake. This might be expected to result in some +slight increase of efficiency; of which, however, the writer has never +had the opportunity of satisfactorily determining the exact extent. +Instances can be brought forward where bronze blades have been +substituted for steel or iron with markedly improved results; but in +cases of this kind which the writer has had the opportunity of +analyzing, the whole improvement might be accounted for by the modified +proportions of the screw when in working condition. In other words, both +experiment and practical working alike go to show that, although cast +iron and steel blades as usually proportioned are sufficiently stiff to +retain their form while at work, bronze blades, being made much lighter, +are not; and the result is that the measured or set pitch is less than +that which the blades assume while at work. Some facts relative to this +subject have already been given in a recent paper by the author. + +_Twin Screws_.--The great question of twin screw propulsion has been put +to the test upon a large scale in the mercantile marine, or rather in +what would usually be termed the passenger service. While engineers, +however, are prepared to admit its advantages so far as greater security +from total breakdown is concerned, there is by no means thorough +agreement as to whether single or twin screws have the greater +propulsive efficiency. What is required to form a sound judgment upon +the whole question is a series of examples of twin and single screw +vessels, each of which is known to be fitted with the most suitable +propeller for the type of vessel and speed; and until this information +is available, little can be said upon the subject with any certainty. So +far the following large passenger steamers, particulars of which are +given in table II., have been fitted with twin screws. It appears t be a +current opinion that the twin screw arrangement necessitates a greater +weight of machinery. This is not necessarily so, however; on the +contrary, the opportunity is offered for reducing the weight of all that +part of the machinery of which the weight relatively to power is +inversely proportional to the revolutions for a given power. This can be +reduced in the proportion of 1 to the square root of 2, that is 71 per +cent. of its weight in the single screw engine; for since approximately +the same total disk area is required in both cases with similar +proportioned propellers, the twins will work at a greater speed of +revolution than the single screw. From a commercial point of view there +ought to be little disagreement as to the advantage of twin screws, so +long as the loss of space incurred by the necessity for double tunnels +is not important; and for the larger passenger vessels now built for +ocean service the disadvantage should not be great. Besides their +superiority in the matter of immunity from total breakdown, and in +greatly diminished weight of machinery, they also offer the opportunity +of reducing to some extent the cost of machinery. A slightly greater +engine room staff is necessary; but this seems of little importance +compared with the foregoing advantages. + +TABLE II.--PASSENGER STEAMERS FITTED WITH TWIN SCREWS. + +-----------------+-----------+-----+-----------+-------+--------+-------+ + | Length | | Cylinders, | Boiler |Indi- | + | between | | two sets in all |pressure|cated | + Vessels. | perpen- |Beam.| cases. | per |horse- | + | diculars. | |-----------+-------| square |power. | + | | |Diameters. |Stroke.| inch. | | +-----------------+-----------+-----+-----------+-------+--------+-------+ + | Feet. |Feet.| Inches. |Inches.| Lb. | | +City of Paris. |\ | | | | | | + | } 525 | 63¼ |45, 71, 113| 60 | 150 |20,000 | +City of New York.|/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Teutonic. |\ | | | | | | + | } 565 | 58 |43, 68, 110| 60 | 180 |18,000 | +Majestic. |/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Normannia. | 500 | 57½ |40, 67, 106| 66 | 160 |11,500 | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Columbia. | 463½ | 55½ |41, 66, 101| 66 | 160 |12,500 | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Empress of India.|\ | | | | | | +Empress of Japan.| } 440 | 51 |32, 51, 82 | 54 | 160 |10,125 | +Empress of China.|/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Orel. | 415 | 48 |34, 54, 85 | 51 | 160 |10,000 | +-----------------+-----------+-----+-----------+-------+--------+-------+ + +_Weight of Machinery Relatively to Power_.--It is interesting to compare +the weight of machinery relatively to the power developed; for this +comparison has sometimes been adopted as the standard of excellence in +design, in respect of economy in the use of material. The principle, +however, on which this has generally been done is open to some +objections. It has been usual to compare the weight directly with the +indicated horse-power, and to express the comparison in pounds per +horse-power. So long as the machinery thus compared is for vessels of +the same class and working at about the same speed of revolution, no +great fault can be found; but as speed of revolution is a great factor +in the development of power, and as it is often dependent on +circumstances altogether external to the engine and concerning rather +the speed of the ship, the engines fitted to high speed ships will thus +generally appear to greater advantage than is their due. Leaving the +condenser out of the question, the weight of an engine would be much +better referred to cylinder capacity and working pressures, where these +are materially different, than directly to the indicated power. The +advantages of saving weight of machinery, so long as it can be done with +efficiency, are well known and acknowledged. If weight is to be reduced, +it must be done by care in design, not by reduction of strength, because +safety and saving of repairs are much more important than the mere +capability of carrying a few tons more of paying load. It must also be +done with economy; but this is a matter which generally settles itself +aright, as no shipowner will pay more for a saving in weight than will +bring in a remunerative interest on his outlay. In his paper on the +weight of machinery in the mercantile marine,[3] Mr. William Boyd +discussed this question at some length, and proposed to attain the end +of reducing the weight of machinery by the legitimate method of +augmenting the speed of revolution and so developing the required power +with smaller engines. This method, while promising, is limited by the +efficiency of the screw, but may be adopted with advantage so long as +the increase in speed of revolution involves no such change in the screw +as to reduce its efficiency as a propeller. But when the point is +reached beyond which a further change involves loss of propelling +efficiency, it is time to stop; and the writer ventures to say that in +many cargo vessels now at work the limit has been reached, while in many +others it has certainly been passed. + +[Footnote 3: Transactions Northeast Coast Institution of Engineers and +Shipbuilders, vol. 6, 1889-90, p. 253.] + +_Economy of Fuel_.--Coming to the highly important question of economy +of fuel, the average consumption of coal per indicated horse-power is +1.522 lb. per hour. The average working pressure is 158.5 lb. per square +inch. Comparing this working pressure with 77.4 lb. in 1881, a superior +economy of 19 per cent. might be expected now, on account of the higher +pressure, or taking the 1.828 lb. of coal per hour per indicated +horse-power in 1881, the present performance under similar conditions +should be 1.48 lb. per hour per indicated horse-power. It appears that +the working pressures have been increased twice in the last ten years, +and nearly three times in the last nineteen. The coal consumptions have +been reduced 16.7 per cent. in the last ten years and 27.9 per cent. in +the last nineteen. The revolutions per minute have increased in the +ratios of 100, 105, 114; and the piston speeds as 100, 124, 140. +Although it is quite possible that the further investigations of the +Research Committee on Marine Engine Trials may show that the present +actual consumption of coal per indicated horse-power is understated, yet +it is hardly probable that the relative results will be affected +thereby. + +_Dimensions_.--In the matter of the power put into individual vessels, +considerable strides have been made. In 1881, probably the greatest +power which has been put into one vessel was in the case of the Arizona, +whose machinery indicated about 6,360 horse-power. The following table +gives an idea of the dimensions and power of the larger machinery in the +later passenger vessels: + +TABLE III.--DIMENSIONS AND POWER OF MACHINERY IN LATER PASSENGER +VESSELS. + +-----+----------------+-----------------------+-------+-----------+ + | | |Length | | +Year.| Name of vessel.| Diameters of | of |Indicated | + | | cylinders. |Stroke.|horsepower.| +-----+----------------+-----------------------+-------+-----------+ + | | Inches. |Inches.| | +1881 |Alaska | 68, 100, 100 | 72 | 10,686 | +-----+----------------+-----------------------+-------+-----------+ +1881 |City of Rome | 46, 86; 46, 86; 46, 86| 72 | 11,800 | +-----+----------------+-----------------------+-------+-----------+ +1881 |Servia | 72, 100, 100 | 78 | 10,300 | +-----+----------------+-----------------------+-------+-----------+ +1881 |Livadia yacht | 60, 78, 78; 60, 78, \| 39 | 12,500 | + | | 78; 60, 78, 78 /| | | +-----+----------------+-----------------------+-------+-----------+ +1883 |Oregon | 70, 104, 104 | 72 | 13,300 | +-----+----------------+-----------------------+-------+-----------+ +1884 |Umbria |\ 71, 105, 105 | 72 | 14,320 | +1884 |Etruria |/ | | | +-----+----------------+-----------------------+-------+-----------+ +1888 |City of New York|\ 45, 71, 113; \| 60 | 20,000 | +1889 |City of Paris |/ 45, 71, 113 /| | about | +-----+----------------+-----------------------+-------+-----------+ +1889 |Majestic |\ 43, 68, 110; \| 60 | 18,000 | +1889 |Teutonic |/ 43, 68, 110 /| | | +-----+----------------+-----------------------+-------+-----------+ + +In war vessels the increase has been equally marked. In 1881 the maximum +power seems to have been in the Inflexible, namely, 8,485 indicated +horse-power. The following will give an idea of the recent advance made: +Howe (Admiral class), 11,600 indicated horse-power; Italia and Lepanto, +19,000 indicated horse-power; Re Umberto, 19,000 indicated horse-power; +Blake and Blenheim (building), 18,000 indicated horse-power; Sardegna +(building), 22,800 indicated horse-power. It is thus evident that there +are vessels at work to-day having about three times the maximum power of +any before 1881. + +_General Conclusions_.--The progress made during the last ten years +having been sketched out, however roughly, the general conclusions may +be stated briefly as follows: First, the working pressure has been about +doubled. Second, the increase of working pressure and other improvements +have brought with them their equivalent in economy of coal, which is +about 20 per cent. Third, marked progress has been made in the direction +of dimension, more than twice the power having been put into individual +vessels. Fourth, substantial advance has been made in the scientific +principles of engineering. It only remains for the writer to thank the +various friends who have so kindly furnished him with data for some of +the tables which have been given; and to express the hope that the next +ten years may be marked by such progress as has been witnessed in the +past. But it must be remembered that, if future progress be equal in +merit or ratio, it may well be less in quantity, because advance becomes +more difficult of achievement as perfection is more nearly approached. + + * * * * * + + + + +THE LITTLE HOUSE. + +BY M.M. + + +One of the highest medical authorities is credited with the statement +that "nine-tenths of the diseases that afflict humanity are caused by +neglect to answer the calls of Nature." + +This state of affairs is generally admitted, but is usually attributed +to individual indolence. That, doubtless, has a great deal to do with +it, but should not part of the blame be laid upon the often unpleasant +environments, which make us shrink as from the performance of a painful +duty? + +In social life, unless from absolute necessity or charity, people of +refined habits do not call on those whose surroundings shock their sense +of decency; but when they go to pay the calls of Nature, they are often +compelled to visit her in the meanest and most offensive of abodes; +built for her by men's hands; for Nature herself makes no such mistakes +in conducting her operations. She does not always surround herself with +the pomp and pride of life, but she invariably hedges herself in with +the thousand decencies and the pomp of privacy. + +But what do we often do? We build what is sometimes aptly termed "an +out-house," because it is placed so that the delicate minded among its +frequenters may be made keenly alive to the fact that they can be +plainly seen by every passer-by and by every idle neighbor on the +lookout. This tiny building is seldom weatherproof; In consequence, keen +cold winds from above, below, and all around find ready entrance, chill +the uncovered person, frequently check the motions, and make the strong +as well as the weak, the young as well as the old, very sorry indeed +that they are so often uselessly obliged to answer the calls of Nature. +It is true, the floor is sometimes carpeted with snow, but the feet feel +that to be but cold comfort, though the door may enjoy rattling its +broken hasp and creaking its loose hinges. + +How often, too, are the nose and the eye offended by disregard of the +Mosaic injunction, found in the twelfth, thirteenth, and fourteenth +verses of the twenty-third chapter of Deuteronomy! Of course this +injunction was addressed to a people who had been debased by slavery, +but who were being trained to fit them for their high calling as the +chosen of God; but is not some such sanitary regulation needed in these +times, when a natural office is often made so offensive to us by its +environments that it is difficult for us to believe that "God made man a +little lower than the angels," or that the human body is the temple of +the Holy Ghost? + +Dwellers in the aristocratic regions of a well drained city, whose +wealth enables them to surround themselves with all devices tending to a +refined seclusion, may doubt all this, but sanitary inspectors who have +made a round of domiciliary visits in the suburbs, or the older, +neglected parts of a large city, of to any part of a country town or +village, will readily affirm as to its general truth. + +This unpardonable neglect of one of the minor decencies by the mass of +the people seems to be caused partly by a feeling of false shame, and +partly by an idea that it is expensive and troublesome to make any +change that will improve their sanitary condition or dignify their daily +lives. + +The Rev. Henry Moule, of Fordington Vicarage, Dorsetshire, England, was +one of the first to turn his attention to this matter. With the +threefold object of improving the sanitary condition of his people, +refining their habits, and enriching their gardens, he invented what he +called the "dry earth closet." + +"It is based on the power of clay and the decomposed organic matter +found in the soil to absorb and retain all offensive odors and all +fertilizing matters; and it consists, essentially, of a mechanical +contrivance (attached to the ordinary seat) for measuring out and +discharging into the vault or pan below a sufficient quantity of sifted +dry earth to entirely cover the solid ordure and to absorb the urine. + +"The discharge of earth is effected by an ordinary pull-up, similar to +that used in the water closet, or (in the self-acting apparatus) by the +rising of the seat when the weight of the person is removed. + +"The vault or pan under the seat is so arranged that the accumulation +can be removed at pleasure. + +"From the moment when the earth is discharged and the evacuation +covered, all offensive exhalation entirely ceases. Under certain +circumstances there may be, at times, a slight odor as of guano mixed +with earth, but this is so trifling and so local that a commode arranged +on this plan may, without the least annoyance, be kept in use in any +room." + +The "dry earth closet" of the philanthropic clergyman was found to work +well, and was acceptable to his parishioners. One reason why it was so +was because dry earth was ready to hand, or could be easily procured in +a country district where labor was cheap. But where labor was dear and +dry earth scarce, those who had to pay for the carting of the earth and +the removal of the deodorized increment found it both expensive and +troublesome. + +But a modification of this dry earth closet, the joint contrivance of an +English church clergyman and his brother, "the doctor," residents of a +Canadian country town, who had heard of Moule's invention, is a good +substitute, and is within the reach of all. This will be briefly +described. + +The vault was dug as for an ordinary closet, about fifteen feet deep, +and a rough wooden shell fitted in. About four feet below the surface of +this wooden shell a stout wide ledge was firmly fastened all around. +Upon this ledge a substantially made wooden box was placed, just as we +place a well fitting tray into our trunks. About three feet of the back +of the wooden shell was then taken out, leaving the back of the box +exposed. From the center of the back of the box a square was cut out and +a trap door fitted in and hasped down. + +The tiny building, on which pains, paint, and inventive genius had not +been spared to make it snug, comfortable, well lighted and well +ventilated, was placed securely on this vault. + +After stones had been embedded in the earth at the back of the vault, to +keep it from falling upon the trap door, two or three heavy planks were +laid across the hollow close to the closet. These were first covered +with a barrowful of earth and then with a heap of brushwood. + +Within the closet, in the left hand corner, a tall wooden box was +placed, about two-thirds full of dry, well sifted wood ashes. The box +also contained a small long-handled fire shovel. When about six inches +of the ashes had been strewn into the vault the closet was ready for +use. No; not quite; for squares of suitable paper had to be cut, looped +together with twine, and hung within convenient reaching distance of the +right hand; also a little to the left of this pad of paper, and above +the range of sight when seated, a ten pound paper bag of the toughest +texture had to be hung by a loop on a nail driven into the corner. + +At first the rector thought that his guests would be "quick-witted +enough to understand the arrangement," but when he found that the +majority of them were, as the Scotch say, "dull in the uptak," he had to +think of some plan to enforce his rules and regulations. As +by-word-of-mouth instructions would have been rather embarrassing to +both sides, he tacked up explicit written orders, which must have +provoked many a smile. Above the bin of sifted ashes he nailed a card +which instructed "Those who use this closet must strew two shovelfuls of +ashes into the vault." Above the pad of clean paper he tacked the +thrifty proverb: "Waste not, want not;" and above the paper bag he +suspended a card bearing this warning: "All refuse paper must be put +into this bag; not a scrap of clean or unclean paper must be thrown into +the vault." + +This had the desired effect. Some complacently united to humor their +host's whim, as they called it, and others, immediately recognizing its +utility and decency, took notes with a view to modifying their own +closet arrangements. + +Sarah, the maid of all work, caused a good deal of amusement in the +family circle by writing her instructions in blue pencil on the front of +the ash bin. These were: "Strew two shuffefuls of ashes into the volt, +but don't spill two shuffefuls onto the floor. By order of the Gurl who +has to sweap up." This order was emphatically approved of by those +fastidious ones who didn't have to "sweep up." + +This closet opened off the woodshed, and besides being snugly +weatherproof in itself, was sheltered on one side by the shed and on +another by a high board fence. The other two sides were screened from +observation by lattice work, outside of which evergreens were planted to +give added seclusion and shade. A ventilator in the roof and two sunny +little windows, screened at will from within by tiny Venetian shutters, +gave ample light and currents of fresh air. For winter use, the rector's +wife and daughters made "hooked" mats for floor and for foot support. +These were hung up every night in the shed to air and put back first +thing in the morning. For the greater protection and comfort of +invalids, an old-fashioned foot warmer, with a handle like a basket, was +always at hand ready to be filled with live coals and carried out. + +The little place was always kept as exquisitely clean as the dainty, +old-fashioned drawing room, and so vigilant was the overseeing care +bestowed on every detail, that the most delicate and acute sense of +smell could not detect the slightest abiding unpleasant odor. The paper +bag was frequently changed, and every night the accumulated contents +were burned; out of doors in the summer, and in the kitchen stove--after +a strong draught had been secured--in the winter. + +At stated times the deodorized mass of solid increment--in which there +was not or ought not to have been any refuse paper to add useless +bulk--was spaded, through the trap door, out of the box in the upper +part of the vault, into a wheelbarrow, thrown upon the garden soil, and +thoroughly incorporated with it. In this cleansing out process there was +little to offend, so well had the ashes done their concealing +deodorizing work. + +In using this modified form of Moule's invention, it is not necessary to +dig a deep vault. The rector, given to forecasting, thought that some +day his property might be bought by those who preferred the old style, +but his brother, the doctor, not troubling about what might be, simply +fitted his well made, four feet deep box, with its trap door, into a +smoothly dug hole that exactly held it, and set the closet over it. In +all other respects it was a model of his brother's. + +This last is within the reach of all, even those who live in other +people's houses; for, when they find themselves in possession of an +unspeakably foul closet, they can cover up the old vault and set the +well cleaned, repaired, fumigated closet upon a vault fashioned after +the doctor's plan. A stout drygoods box, which can be bought for a +trifle, answers well for this purpose, after a little "tinkering" to +form a trap door. + +Of course, dry earth is by far the best deodorizer and absorbent, but +when it cannot be easily and cheaply procured, well sifted wood or coal +ashes--wood preferred--is a good substitute. The ashes must be kept dry. +If they are not, they lose their absorbing, deodorizing powers. They +must also be well sifted. If they are not, the cinders add a useless and +very heavy bulk to the increment. + +An ash sifter can be made by knocking the bottom out of a shallow box, +studding the edge all round with tacks, and using them to cross and +recross with odd lengths of stovepipe wire to form a sieve.--_The +Sanitarian_. + + * * * * * + + + + +THE HYGIENIC TREATMENT OF OBESITY.[1] + +[Footnote 1: Translated by Mr. Jos. Helfman, Detroit, Mich.] + +BY DR. PAUL CHERON. + + +In order to properly regulate the regimen of the obese, it is first +necessary to determine the source of the superfluous adipose of the +organism, since either the albuminoids or the hydrocarbons may furnish +fat. + +Alimentary fat becomes fixed in the tissues, as has been proved by +Lebede, who fed dogs, emaciated by long fast, with meat wholly deprived +of fat, and substituted for the latter linseed oil, when he was able to +recover the oil in each instance from the animal; parallel experiments +with mutton fat, _in lieu_ of oil, afforded like results. + +Hoffman also deprived dogs of fat for a month, causing them to lose as +high as twenty-two pounds weight, then began nourishing with bacon fat +with but little lean; the quantity of fat formed in five days, in the +dog that lost twenty-two pounds, was more than three pounds, which could +have been derived only from the bacon fat. + +It has been stated, however, that alimentary fat seems to preserve from +destruction the fat of the organism which arises from other sources. Be +this as it may, it is a fact that the pre-existence of fat furthers the +accumulation of more adipose; or in other words, fat induces fattening! + +That adipose may be formed through the transformation of albuminous +matters (meat) is an extremely important corollary, one established +beyond cavil by Pettinkofer and Voit, in an indirect way, by first +estimating the nitrogen and carbon ingested, and second the amount +eliminated. Giving a dog meat that was wholly deprived of fat, they +found it impossible to recover more than a portion of the contained +carbon; hence some must necessarily have been utilized in the organism, +and this would be possible only by the transformation of the carbon into +fat! It goes without saying, however, that the amount of adipose thus +deposited is meager. + +Other facts also plead in favor of the transformation of a portion of +albumen into fat within the economy, notably the changing of a portion +of dead organism into what is known as "cadaveric fat," and the very +rapid fatty degeneration of organs that supervenes upon certain forms of +poisoning, as by phosphorus. + +The carbohydrates, or more properly speaking hydrocarbons, are regarded +by all physiologists as specially capable of producing fat, and numerous +alimentary experiments have been undertaken to prove this point. +Chaniewski, Meissl, and Munk obtained results that evidenced, +apparently, sugar and starch provide more fat than do the albuminoids. +Voit, however, disapproves this, maintaining the greater part of the +hydrocarbons is burned (furnishes fuel for the immediate evolution of +force), and that fat cannot be stored up unless a due proportion of +albuminoids is also administered. He believes the hydrocarbons exert a +direct influence only; being more oxidizable than fats, they guard the +latter from oxidation. This protective role of the hydrocarbons applies +also to the albuminoids. + +We may believe, then, that the three great classes of aliment yield fat, +in some degree; that alimentary fat may be fixed in the tissues; and +that hydrocarbons favor the deposition of adipose either directly or +indirectly. + +It is well understood that fat may disappear with great rapidity under +certain conditions; many maladies are accompanied by speedy emaciation; +therefore, as fat never passes into the secretions, at least not in +appreciable quantities, it probably undergoes transformation, perhaps by +oxidation or a form of fermentation, the final results of which are, +directly or indirectly, water and cadaveric acid. It is certain the +process of oxidation favors the destruction of adipose, and that +everything which inhibits such destruction tends to fat accumulation. + +Since the earliest period of history, there seems to have been an +anxiety to secure some regimen of general application that would reduce +or combat obesity. Thus Hippocrates says: + +Fat people, and all those who would become lean, should perform +laborious tasks while fasting, and eat while still breathless from +fatigue, without rest, and after having drunk diluted wine not very +cold. Their meats should be prepared with sesamum, with sweets, and +other similar substances, and these dishes should be free from fat. + +In this manner one will be satiated through eating less. + +But, besides, one should take only one meal; take no bath; sleep on a +hard bed; and walk as much as may be. + +How much has medical science gained in this direction during the +interval of more than two thousand years? Let us see: + +First among moderns to seek to establish on a scientific basis a regimen +for the obese, was Dancel, who forbade fats, starchy foods, etc., +prescribed soups and aqueous aliment, and reduced the quantity of +beverage to the lowest possible limit; at the same time he employed +frequent and profuse purgation. + +This regimen, which permits, at most, but seven to twelve ounces of +fluid at each repast, is somewhat difficult to follow, though it may be +obtained, gradually, with ease. Dr. Constantine Paul records a case in +which this regimen, gradually induced, and followed for ten years, +rewarded the patient with "moderate flesh and most excellent health." + +In Great Britain, a mode of treatment instituted in one Banting, by Dr. +Harvey, whereby the former was decreased in weight forty pounds, has +obtained somewhat wide celebrity; and what is more remarkable, it is +known as "Bantingism," taking its name from the patient instead of the +physician who originated it. The dietary is as follows: + +_Breakfast_.--Five to six ounces of lean meat, broiled fish, or smoked +bacon--veal and pork interdicted; a cup of tea or coffee without milk or +sugar; one ounce of toast or dry biscuit (crackers). + +_Dinner_.--Five or six ounces of lean meat or fish--excluding eel, +salmon, and herring; a small quantity of vegetables, but no potatoes, +parsnips, carrots, beets, peas, or beans; one ounce of toast, fruit, or +fowl; two glasses of red wine--beer, champagne, and port forbidden. + +_Tea_.--Two or three ounces of fruit; one kind of pastry; one cup of +tea. + +_Supper_.--Three or four ounces of lean beef or fish; one or two glasses +of red wine. + +_At bed-time._--Grog without sugar (whisky and water, or rum and water), +and one or two glasses of sherry or Bordeaux. + +"Bantingism," to be effective, must be most closely followed, when, +unfortunately also, it proves extremely debilitating; it is suitable +only for sturdy, hard riding gluttons of the Squire Western type. The +patient rapidly loses strength as well as flesh, and speedily acquires +an unconquerable repugnance to the dietary. Further, from a strictly +physiological point of view, the quantity of meat is greatly in excess, +while with the cessation of the regimen, the fat quickly reappears. + +Next Ebstein formulated a dietary that is certainly much better +tolerated than that of Harvey and Banting, and yields as good, or even +better, results. He allows patients to take a definite quantity--two to +two and a half ounces-of fat daily, in the form of bacon or butter +which, theoretically at least, offers several advantages: It diminishes +the sensations of hunger and thirst, and plays a special role with +respect to the albuminoids; the latter may thus be assimilated by the +economy without being resolved into fat, and thus the adipose of the +organism at this period is drawn upon without subsequent renewal. The +following is the outline: + +_Breakfast_.--At 6 a.m. in summer; 7:30 in winter:--Eight ounces of +black tea without either milk or sugar; two ounces of white bread or +toast, with a copious layer of butter. + +_Dinner_.--2 p.m.:--A modicum of beef marrow soup; four ounces of meat, +preferably of fatty character; moderate quantity of vegetable, +especially the legumines, but no potatoes or anything containing starch; +raw fruits in season, and cooked fruits (stewed, without sugar); two or +three glasses of light wine as a beverage, and after eating, a cup of +black tea without sugar. + +_Supper_.--7:30 p m.:--An egg, bit of fat roast, ham, or bacon; a slice +of white bread well buttered; a large cup of black tea without milk or +sugar; from time to time, cheese and fresh fruits. + +Germain See suggests as a modification of this regimen, the abundant use +of beverage, the addition of gelatins, and at times small doses of +potassium iodide in twenty cases he claims constant and relatively +prompt results. + +Whatever may be urged for Ebstein's system--and it has afforded most +excellent results to Unna and to Lube, as well as its author--it +certainly exposes the patient to the terrors of dyspepsia, when the +routine must needs be interrupted or modified; hence it is not always to +be depended upon. As between dyspepsia and obesity, there are few, I +fancy, who would not prefer the latter. + +Another "system" that has acquired no little celebrity, and which has +for its aim the reduction as far as possible of alimentary hydrocarbons +while permitting a certain proportion of fat, is that, of Denneth, which +necessarily follows somewhat closely the lines laid down by Ebstein. + +Oertels' treatment, somewhat widely known, and not without due measure +of fame, is based upon a series of measures having as object the +withdrawal from both circulation and the economy at large, as much of +the fluids as possible. It is especially adapted for the relief of those +obese who are suffering fatty degeneration of the heart. The _menu_ is +as follows: + +_Breakfast_.--Pour to five ounces of tea or coffee with a little milk; +two to two and a half ounces bread. + +_Dinner_.--Three or four ounces of roast or boiled meat, or moderately +fat food; fish, slightly fat; salad and vegetables at pleasure; one and +a half ounces of bread (in certain cases as much as three ounces of +farinaceous food may be permitted); three to six ounces of fruit; at +times a little pastry for dessert.--In summer, if fruit is not +obtainable, six to eight ounces of light wine may be allowed. + +_Tea_,--A cupful (four to five ounces) of tea or coffee, with a trifle +of milk, as at breakfast; one and three-fourths ounces of bread; and +exceptionally (and at most) six ounces of water. + +_Supper_.--One to two soft boiled eggs; four or five ounces of meat; one +and three fourths ounces of bread; a trifle of cheese, salad, or fruit; +six to eight ounces of light wine diluted with an eighth volume of +water. The quantity of beverage may be slightly augmented at each meal +if necessary, especially if there is no morbid heart trouble. + +Schwenninger (Bismarck's physician), who opened a large sanitarium near +Berlin a few years since for the treatment of the obese, employs +Oertel's treatment, modified in that an abundance of beverage is +permitted, provided it is not indulged in at meals; it is forbidden +until two hours after eating. + +Both Oertel's and Schwenninger's methods have procured grave dyspepsias, +and fatal albuminurias as well, according to Meyer and Rosenfield. It +has been charged the allowance of beverage upon which Schwenninger lays +so much stress in the treatment at his sanitarium has a pecuniary basis, +in other words a commission upon the sale of wines.[2] + +[Footnote 2: The sanitarium is owned by a stock company, Schwenninger +being merely Medical Director.--ED.] + +Thus, it will be observed that while some forbid beverage, others rather +insist upon its employment in greater or less quantities. Under such +circumstances, it would seem but rational, before undertaking to relieve +obesity, to establish its exact nature, and also the role taken by +fluids in the phenomena of nutrition. + +Physiologists generally admit water facilitates nutritive exchanges, +which is explained by the elimination of a large quantity of urine; the +experiments of Genth and Robin in this direction appear conclusive. + +Bischoff, Voit, and Hermann have shown that water increases, not alone +the elimination of urine, but also of sodium chloride, phosphoric acid, +etc. Grigoriantz observed augmentation of disintegration when the +quantity of beverage exceeded forty-six to eighty ounces ("1,400 to +2,400 cubic centimeters") per diem. Oppenheim, Fraenkel, and Debove, +while believing water has but little influence upon the exchanges, admit +it certainly need not diminish the latter; and Debove and Flament, after +administering water in quantities varying from two to eight pints per +diem, concluded that urine was diminished below the former figure, while +above the latter it increased somewhat, being dependent upon the amount +ingested. It was on the strength of the foregoing that Lallemand +declared water to have no influence upon the exchanges. + +The results claimed by Oppenheim, Debove, et al. were immediately +challenged--and it is now generally admitted, not without some +justice--by Germain See. It seems certain, to say the least, that water +taken during the repast does tend to augment the quantity and facilitate +the elimination of urine. Abundance of beverage, moreover, presents +other advantages, in that it facilitates digestion by reason of its +diluent action, a fact well worth bearing in mind when treating the +obese who are possessed of gouty diathesis, and whose kidneys are +accordingly encumbered with uric and oxalic acids. The foregoing +presents the ground upon which Germain See permits an abundance of +beverage; but he also expresses strong reservation as regards beer and +alcohol, either of which (more especially the former) tends to the +production of adipose. In his opinion, the only beverage of the +alcoholic class that is at all permissible, and then only for cases +suffering from fatty heart, is a little _liqueur_ or diluted wine. +Coffee and tea he commends highly, and recommends the ingestion of large +quantities at high temperature, both during the repasts and their +intervals. Coffee in large doses is undoubtedly a means of de-nutrition, +and so, too, in no less extent, is tea; both act vigorously owing to the +contained alkaloids, though, to be sure, they sometimes, at first, tend +to insomnia and palpitation, to which no attention need be paid, +however. The treatment outlined by See is: + +1. A physiological regimen comprising four to five ounces of nitrogenous +principles as derived from eight to ten ounces animal muscle and +albuminates; three to six ounces of fat; eight to ten ounces of +hydrocarbons as yielded by ten to twelve ounces of sugar or starch food. + +These proportions to be modified in such manner that the +musculo-albuminates shall not sensibly exceed the normal ratio, for meat +in excess itself furnishes fat during transformation. The fatty +substances of easy digestion may, without inconvenience, be utilized in +doses of two to three ounces. The hydrocarbons should be reduced to a +minimum. As for the herbaceous elements, they contain nothing nutritive. + +2. Beverage, far from being suppressed, should be augmented, in order to +facilitate stomachal digestion and promote general nutrition, though +alcoholic liquids must be inhibited; likewise mineral waters, except, +perhaps, for occasional use. Both should be replaced by infusions of +coffee or tea, taken as hot as can be drank. + +Henrich Kisch insists that any method which promises rapid and marked +decrease of adipose must, _per se_, be objectionable, even if not +positively injurious, since it tends to provoke general troubles of +nutrition. He suggests that first the fats and hydrocarbons be reduced +as little as possible; that a moderate mixed regimen is required, +containing a preponderance of albumen, small quantities of hydrocarbons +and gelatinous matters, with but very little fat. Certain fatty meats, +however, should be generally interdicted, such as pork sausage, smoked +beef tongue, goose breast, smoked ham, fat salmon, and herring in any +form. Eggs, however, may be partaken of in moderation, giving preference +to the albumen over the yelk. Farinaceous foods, in the main, should be +rejected, even bread being allowed only in small quantities, and then +preferably in the form of toast. Cheese likewise contains too much fat; +and mushrooms are so rich in hydrocarbons that they should be rejected. +Condiments, water, vegetable acids (vinegars excepted) may be permitted; +especially pernicious is vinegar where there is any tendency to gout or +gravel. All fatty beverages--_bouillon_, unskimmed milk, chocolate, or +cacao--and all alcoholics, are hurtful; breakfast tea is undoubtedly the +best beverage, but, after a little, is advantageously replaced by light +white wine diluted with water. + +Kisch believes in a free and abundant use of water by the obese, +especially where there is a tendency to plethora, since this fluid +facilitates oxidation as the result of absorption; thus he advocates the +inhibition of large quantities of cold water by all, save those +presenting evidence of cardiac insufficiency. In short, his regimen is +based upon the administration of a large quantity of albumen, like that +of Harvey-Banting. + +E. Munk recommends an almost identical dietary, save that he prefers +great moderation in fluids employed as beverage. + +M. Robin has sought to harmonize the opposing views regarding fluids, +and therefore declares obesity arises from two distinct sources: 1. +Augmentation of assimilation. 2. Reduced disassimilation. In the former, +he insists water must be interdicted, while in the latter it may be +allowed _ad libitum_. + +Again, in order to recognize the exact variety of obesity, he divides +his patients into three classes, each recognizable by the volume of urea +excreted. In the first there is an increase above normal; in the second +the volume of urea is stationary; in the third decreased, increased, or +stationary. + +When the urea is stationary, which is most frequently the case, it is +necessary to calculate the coefficient of oxidation; that is, the +relation existing between the solid matters of the urine and the urea. +The elevation of the coefficient is _prima facie_ evidence the obesity +is due to excess of assimilation, while depression of the coefficient +indicates default of assimilation. In the first case, water and liquids +must be denied as far as possible, the same as if there was no +augmentation of urea; in the second, the same as if there was diminution +of urea, the patients may be permitted to imbibe fluids at pleasure. + +For the obese from default of disassimilation, Robin recommends a +regimen of green vegetables and bread chiefly--the latter in small +quantities, however, and fluids as may be desired. By this means, on one +occasion, he was able in the course of one month to diminish the weight +of a female patient by twelve and a half pounds, her measurement around +the waist at the same time decreasing 5.2 inches and across the stomach +4.8 inches. + +M. De St. Germain achieved good results by combining judicious exercise +with moderate alimentation, excluding wine and bread. + +M. Dujardin Beaumetz, who professes to have given most close and careful +study and attention to regimen for the obese, outlines the following, +provided there is no evidence of fatty degeneration of heart. + +_Breakfast_ (at 8 a. m.)--Three-fourths of an ounce of bread "_en +flute_"--that is abounding with crust; one and a half ounces of cold +meat, ham or beef, six ounces weak black tea, _sans_ sugar. + +_Lunch_ (at 1 p.m.)--An ounce and a half to two ounces of bread, or a +_ragout_, or two eggs; three ounces green vegetables; one-half ounce of +cheese; fruits at discretion. + +_Dinner_ (at 7 p.m.)--An ounce and a half to two ounces of bread; three +to four ounces of meat, or _ragout_; ditto of green vegetables, salad, +half an ounce of cheese, fruit _ad libitum_. + +At meal times the patient may take only a "glass and a half" of +liquid--approximately ten ounces--though a greater amount may be +permitted if he abstains during the intervals. + +Special alimentary regimen, however, does not constitute the sole +treatment of obesity. Concurrently must be employed a number of +practical adjuvants which are oftentimes of the utmost assistance. For +one thing, exercise is indispensable; all authorities agree on this +point. The exercise taken in the gymnasium is one of the best, notably +the "wall exercise," which is more particularly suited to those +afflicted with pendulous and protuberant abdomens as the result of +feebleness of the hypogastric muscles, to accumulation of fat under the +skin and in the omentum, and to dilation of the stomach and intestines. +In the "wall exercise," the patient stands erect against an absolutely +straight and plumb wall, lifts his hands (carrying a weight) straight +over the head, and causes them to describe a semicircle forward. Zantz +particularly insists upon arm and leg exercise for the obese, especially +the former, since with the same amount of effort a larger amount of +oxygen is consumed than is possible by the latter. + +However, of whatever character, the exercise should be continued to the +point of fatigue or dyspnoea--three thousand movements daily, +gradually increased to twenty-five thousand, if the system can bear it; +and under such conditions, not only is there consumption of +hydrocarbons, but there is provided a veritable greed for air that +augments waste. The experiments of Oertel indicate that loss of weight +due to fatiguing exercise arises more particularly from dehydration, +which is made good by absorption of the fluids employed as beverage; the +fluids are claimed by Germain See to act as accelerants of oxidation. + +During exercise there is obviously more abundant absorption of oxygen, +and consequently greater elimination of carbonic acid, and as a +consequence (as shown by researches of Voit), the reserve fat of the +economy is attacked and diminished; in intense labor there is an average +hourly consumption of about 8.2 percent. of fat. Further physical +activity is useful in exercising the voluntary muscles, and thus +opposing the invasion by interstitial fat of the muscle fibrils. Extreme +exercise also, to a certain degree, exerts a favorable influence on the +cardiac muscle, augmenting both its nutrition and its capacity for +labor. With the anæmic obese, however, it is necessary to be most +circumspect in prescribing forced exercise; also with the elderly obese +possessed of enfeebled or fatty heart. + +Hydrotherapy, especially in the form of cold douches, particularly when +combined with massage, is often of considerable value in relieving +obesity; the method of Harmman, of St. Germain, which has in many +instances induced rapid loss of adipose, is of this class. Tepid saline +baths and vapor baths have many advocates, and may afford material aid +when the heart and circulation do not inhibit their employment. Hot +baths elevate the temperature of the body and increase the organic +exchanges, hence, as Bert and Reynard have pointed out, tend to the +elimination of oxygen and carbonic acid; but when employed, the patient +should be introduced while the temperature is below 130° F., when it may +be gradually raised in the course of thirty or forty minutes to 140° F. + +It has already been intimated, the chief feature of the treatment of +obesity is acceleration of the exchanges; and this is in the main true, +though it must also be borne in mind that, while there are obese who +excrete little urea and have a depressed central nervous temperature, +many may be azoturic, and besides eliminate phosphate in excess, when an +oxidating treatment will not only fail, but prove positively injurious. + +The bile throws out fat, therefore, to accelerate nutritive oxidations, +the liver and nervous system must be acted upon, _i.e._, stimulated. +Everything that tends to diminish the activity of the former, or depress +the latter, must be avoided. Hence intellectual labor should be +encouraged, or in lieu thereof, travel advised. Exercise should be taken +chiefly while fasting; the limits of sleep confined to strict necessity, +and _siestas_ after meals and during the day strictly forbidden; the +skin stimulated by hydro-therapeutic measures, including massage under +cold affusions, during warm salt baths, etc. + +To increase the activity of the liver, salicylate of soda may often be +advantageously administered for its cholagogue effect; or resort may be +had to saline purgatives such as are afforded by the springs of +Marienbad, Kissengen, Homburg, Carlsbad, Brides, Hunyadi, or +Chatel-Guyon; and it is somewhat remarkable that while undergoing a +course of these waters, there is often no appreciable change in weight +or obesity, though the decrease becomes most marked almost immediately +upon cessation of treatment. + +Everything tending to increased or fuller respiration is to be +encouraged, for the fats are thus supplied with oxygen, hastening their +disintegration and consumption. + +Direct medicinal treatment presents no very wide scope. Bouchard +imagines lime water may be useful by accelerating nutrition, but this is +problematical, since fat in emulsion or in droplets does not burn. +Nevertheless, alkalies in general, alkaline carbonates, liquor potassa, +soaps, etc., aid in rendering fat more soluble, and consequently more +susceptible to attack. The alkaline waters, however, are much less +active in obesity than the saline mineral waters, unless, as sometimes +happens, there is a complication of diabetes and obesity. + +Purgatives are always more or less useful, and often required to be +renewed with all the regularity of habit. Then too, the iodides, +especially iodide of sodium or potassium, as recommended by M. Germain +See, frequently prove of excellent service by aiding elimination and +facilitating the mutations. + +According to Kisch, the cold mineral waters containing an abundance of +sulphate of soda, like Hunyadi and Marienbad, are to be preferred to the +hot mineral waters, such as Carlsbad, because of their lesser irritant +action on the vascular system, and because they strongly excite diuresis +through their low temperature and contained carbonic acid; Carlsbad +deserves preference only when obesity is combined with uric acid +calculi, or with diabetes. For very anæmic persons, however, the weak +alkaline and saline waters should be selected; or they should confine +themselves to chalybeate waters containing an excess of sulphate of +soda. Water containing sulphate of soda is also indicated as a beverage +where there are troubles of the circulatory apparatus; it is +contraindicated only in accentuated arterio-sclerosis. + +As a matter of fact, I find the suggestion of M. Dujardin-Beaumetz, +that the obese should be divided into two groups, a most practical one, +for some are strong and vigorous--great eaters, perhaps even +gluttons--while others, on the contrary, are feeble and debilitated, +with flesh soft and flaccid; and upon the former may be imposed all the +rigors of the reducing system, while the latter must be dealt with more +carefully. + +In general, it must be noted, the regimen prescribed for the obese is +insufficient, as the following table prepared by M.C. Paul abundantly +proves: + + -------------------------+----------+----------+--------------- + Author. |Albuminous| Fatty | + | Matters. | Matters. | Hydrocarbons. + -------------------------+----------+----------+--------------- + Voit. | 118 | 40 | 150 + Harvey-Banting. | 170 | 10 | 80 + Ebstein. | 100 | 85 | 50 + Oertel. | 155-179 | 25-41 | 70-110 + Kisch (plethoric). | 160 | 10 | 80 + " (anæmic). | 200 | 12 | 100 + Normal ration. | 124 | 55 | 455 + -------------------------+----------+----------+--------------- + +There is, therefore, as Dujardin-Beaumetz asserts, autophagia in the +obese, and all these varieties of treatment have but one end, viz.: +Reduction of the daily ration. But the quantity of nourishment should +not be too greatly curtailed, for, manifestly, if the fat disappears the +more surely, the muscles (rich in albumen) undergo too rapid +modification. It is progressive action that should always be sought. + +The quantity of aliment may be reduced either by imposing an always +uniform regimen, which soon begets anorexia and disgust, or by +withholding from the food a considerable quantity of fat, or, finally, +by forbidding beverage during meals. Emaciation is obtained readily +enough in either way, and demands only the constant exercise of will +power on the part of the patient; but unhappily, severe regimen cannot +always be prescribed. When the obese patient has passed the age of +forty; when the heart suffers from degeneration; or when the heart is +anæmic--in all, rigorous treatment will serve to still further enfeeble +the central organ of circulation, and tend to precipitate accidents +that, by all means, are to be avoided. In such cases, by _not_ treating +the obesity, the days of the patient will be prolonged. In degeneration +of the heart, however, the method of Ebstein may be tried; and when +there is renal calculi and gouty diathesis, that of Germain See may +prove satisfactory. + +Paris, France. + + * * * * * + + + + +STILT WALKING. + + +[Illustration: SYLVAIN DORNON, THE STILT WALKER OF LANDES.] + +Sylvain Dornon, the stilt walker of Landes, started from Paris on the +12th of last March for Moscow, and reached the end of his journey at the +end of a fifty-eight days' walk. This long journey upon stilts +constitutes a genuine curiosity, not only to the Russians, to whom this +sort of locomotion is unknown, but also to many Frenchmen. + +Walking on stilts, in fact, which was common twenty years ago in certain +parts of France, is gradually tending to become a thing of the past. In +the wastes of Gascony it was formerly a means of locomotion adapted to +the nature of the country. The waste lands were then great level plains +covered with stunted bushes and dry heath. Moreover, on account of the +permeability of the subsoil, all the declivities were transformed into +marshes after the slightest fall of rain. + +There were no roads of any kind, and the population, relying upon sheep +raising for a living, was much scattered. It was evidently in order to +be able to move around under these very peculiar conditions that the +shepherds devised and adopted stilts. The stilts of Landes are called, +in the language of the country, _tchangues_, which signifies "big legs," +and those who use them are called _tchanguès_. The stilts are pieces of +wood about five feet in length, provided with a shoulder and strap to +support the foot. The upper part of the wood is flattened and rests +against the leg, where it is held by a strong strap. The lower part, +that which rests upon the earth, is enlarged and is sometimes +strengthened with a sheep's bone. The Landese shepherd is provided with +a staff which he uses for numerous purposes, such as a point of support +for getting on to the stilts and as a crook for directing his flocks. +Again, being provided with a board, the staff constitutes a comfortable +seat adapted to the height of the stilts. Resting in this manner, the +shepherd seems to be upon a gigantic tripod. When he stops he knits or +he spins with the distaff thrust in his girdle. His usual costume +consists of a sort of jacket without sleeves, made of sheep skin, of +canvas gaiters, and of a drugget cloak. His head gear consists of a +beret or a large hat. This accouterment was formerly completed by a gun +to defend the flock against wolves, and a stove for preparing meals. + +The aspect of the Landeses is doubtless most picturesque, but their +poverty is extreme. They are generally spare and sickly, they are poorly +fed and are preyed upon by fever. Mounted on their stilts, the shepherds +of Landes drive their flocks across the wastes, going through bushes, +brush and pools of water, and traversing marshes with safety, without +having to seek roads or beaten footpaths. Moreover, this elevation +permits them to easily watch their sheep, which are often scattered over +a wide surface. In the morning the shepherd, in order to get on his +stilts, mounts by a ladder or seats himself upon the sill of a window, +or else climbs upon the mantel of a large chimney. Even in a flat +country, being seated upon the ground, and having fixed his stilts, he +easily rises with the aid of his staff. To persons accustomed to walking +on foot, it is evident that locomotion upon stilts would be somewhat +appalling. + +One may judge by what results from the fall of a pedestrian what danger +may result from a fall from a pair of stilts. But the shepherds of +Landes, accustomed from their childhood to this sort of exercise, +acquire an extraordinary freedom and skill therein. The _tchanguè_ knows +very well how to preserve his equilibrium; he walks with great strides, +stands upright, runs with agility, or executes a few feats of true +acrobatism, such as picking up a pebble from the ground, plucking a +flower, simulating a fall and quickly rising, running on one foot, etc. + +The speed that the stilt walkers attain is easily explained. Although +the angle of the legs at every step is less than that of ordinary +walking with the feet on the ground, the sides prolonged by the stilts +are five or six feet apart at the base. It will be seen that with steps +of such a length, distances must be rapidly covered. + +When, in 1808, the Empress Josephine went to Bayonne to rejoin Napoleon +I, who resided there by reason of the affairs of Spain, the municipality +sent an escort of young Landese stilt walkers to meet her. On the +return, these followed the carriages with the greatest facility, +although the horses went at a full trot. + +During the stay of the empress, the shepherds, mounted upon their +stilts, much amused the ladies of the court, who took delight in making +them race, or in throwing money upon the ground and seeing several of +them go for it at once, the result being a scramble and a skillful and +cunning onset, often accompanied with falls. + +Up to recent years scarcely any merry-makings occurred in the villages +of Gascony that were not accompanied with stilt races. The prizes +usually consisted of a gun, a sheep, a cock, etc. The young people vied +with each other in speed and agility, and plucky young girls often took +part in the contests. + +Some of the municipalities of the environs of Bayonne and Biarritz still +organize stilt races, at the period of the influx of travelers; but the +latter claim that the stiltsmen thus presented are not genuine Landese +shepherds, but simple supernumeraries recruited at hazard, and in most +cases from among strolling acrobats. The stilt walkers of Landes not +only attain a great speed, but are capable of traveling long distances +without appreciable fatigue. + +Formerly, on the market days at Bayonne and Bordeaux, long files of +peasants were seen coming in on stilts, and, although they were loaded +with bags and baskets, they came from the villages situated at 10, 15, +or 20 leagues distance. To-day the sight of a stilt walker is a +curiosity almost as great at Bordeaux as at Paris. The peasant of Landes +now comes to the city in a wagon or even by railway.--_La Nature_. + + * * * * * + + + + +REMAINS OF A ROMAN VILLA IN ENGLAND. + + +A correspondent of the _Lincolnshire Chronicle_ writes: For some weeks +past, remains of a Roman villa have been exposed to view by Mr. +Ramsden's miners in Greetwell Fields. From, the extent of the tesselated +pavements laid bare there is hardly any doubt that in the Greetwell +Fields, in centuries long gone by, there stood a Roman mansion, which +for magnitude was perhaps unrivaled in England. Six years ago I drew +attention to it. The digging for iron ore soon after this was brought to +a standstill by the company, which at the time was working the mines, +ceasing their operations. Then the property came into other hands, and +since then more extensive basement floors of the villa have from time to +time been laid bare, and from tentative explorations which have been +just made, still more floors remain to be uncovered which may be of a +most interesting and instructive character. What a pity it is that the +inhabitants of Lincoln have not made an effort to preserve these +precious relics of the grandeur of the Roman occupation, an occupation +to which England owes so much. From the Romans the people of this +country inherit the sturdy self-reliance and perseverance in action +which have helped to make England what it is, and from the Romans too, +in a great degree, does England also inherit her colonizing instincts, +which impel her people to cover the waste places of the world with +colonies. If the Roman remains which have been so abundantly discovered +of late years in Lincoln and its vicinity had been collected and laid +out for exhibition, they would have formed a most interesting collection +of antiquities worthy of the town, and well worth showing to visitors +who now annually make Lincoln a visitation. Although these relics of a +remote age are being dug up and are being destroyed, it is not the fault +of Mr. Ramsden, for he not only preserved them as long as he +conveniently could, but he also had the soil removed from over them, and +had them thoroughly washed, in order that people might have an +opportunity of seeing their extent and beauty. One of these patches of +pavement extended 48 yards northward from what might be called the main +building, which had previously been broken up. This strip was 13 ft. in +breadth, and down its center ran an intricate pattern worked in blue +tesseræ. The pattern is much used in these days in fabrics and works of +art, and is, I think, called the Grecian or Roman key pattern. On each +side of this ran alternately broad ribbons of white and narrower ribbons +of red tesseræ. There is also another strip of pavement to the south of +the preceding patch, which has been laid bare to the extent of 27 yards. +This patch is about 10 ft. in breadth, and its western portion is cut up +in neat patterns, which show that they formed the floors of rooms. From +the eastern extremity of these floors evidently another long strip of 48 +or 50 yards still remains to be uncovered. Doubtless there are other +remains beneath the ground which will be laid bare as the work of mining +goes on. All these floors were not deeper than from 18 to 30 inches +below the surface of the soil. The bones of animals and other relics +have been found in the covering soil and have been turned up by the +miners from time to time. The pavement is all worked out with cubes, +varying in size from an inch and a half to two inches square, each piece +being placed in position with most careful exactness. The strip which +extends 48 yards and is 13 ft. wide runs due north and south. There is a +second patch, running east and west, and this is 27 ft. long by 10 ft. +wide, while a third is 27 ft. long by 11 ft. wide, this also running in +a northern direction. To the north of this latter piece, and separated +only by about two feet (about the width of a wall, which very possibly +was the original division), there is a strip of tesseræ 16 ft. wide, +which had been laid bare 40 yards. It was thought probable that at the +end of the last named strip still another patch would be found. Mr. +Ramsden, the manager of the Ironstone Works, is keeping a plan of the +whole of the pavement, which he is coloring in exact imitation of the +original work. This, when completed, will be most interesting, and he +will be quite willing to show it to any one desirous of inspecting the +same. Many persons have paid a visit to the spot where the discoveries +have been made, and surprise is invariably expressed at the magnitude +and beautiful symmetry of the work. + +Several interesting fragments of Roman work have been brought to light +in the course of excavations that are being made for building purposes +at Twyford, near Winchester. About a month ago, a paved way, composed +entirely of small red tiles, six feet in width and extending probably a +considerable distance (a length of 14 ft. was uncovered), was found +while digging on the site for flints. The more recent excavations are 20 +ft. west of this passage, and there is now to be seen, in a very perfect +state of preservation, an oven or kiln with three openings. Five yards +away from this is a chamber about eight feet square, paved with tiles, +and the sides coated with a reddish plaster. On one side is a ledge 15 +in. from the ground, extending the whole length of the chamber; on the +floor is a sunk channel with an opening at the end for the water to +escape. This chamber evidently represents the bath. Portions of the +dividing walls of the different chambers have also been discovered, +together with various bones, teeth, horns and ornaments, but very few +coins. It is probable that an alteration in the plans of the house which +was about to be built on the spot will be made so as to preserve all the +more interesting features of these remains in the basement. These +discoveries were made at a depth of only two or three feet from the +surface of the ground, and are within about a quarter of a mile of other +Roman remains which were similarly brought to light a few months ago. + + * * * * * + +[Continued from SUPPLEMENT, No. 830, page 13110.] + + + + +GUM ARABIC AND ITS MODERN SUBSTITUTES.[1] + +[Footnote 1: A paper read before the Society of Chemical Industry, +London, 1891. From the Journal] + +BY DR. S. RIDEAL AND W.E. YOULE. + + +Subjoined is a table giving the absolute viscosity of various gums. A +comparison of the uncorrected viscosities with the corrected shows the +great importance of Slotte's correction for dextrins and inferior gum +arabics; in other words, for solutions of low viscosity, while it will +be observed to have little influence upon the uncorrected [eta] obtained +for the Ghatti gums and the best samples of gum arabic. + +TABLE OF ABSOLUTE VISCOSITIES OF 10 PER CENT. GUM AND DEXTRIN SOLUTIONS. + + ---------------------+--------------+------------+---------- + Sample. | [eta] | [eta] | Z Water + | Uncorrected. | Corrected. | = 100. + ---------------------+--------------+------------+---------- + Gum arabic.......... | 0.1876 | 0.1856 | 1,233 + Cape gum............ | 0.1575 | 0.1555 | 1,029 + Indian gum.......... | 0.0540 | 0.0470 | 311 + Eastern gum......... | 0.0689 | 0.0639 | 417 + Gum arabic.......... | 0.0550 | 0.0480 | 317 + Senegal............. | 0.0494 | 0.0410 | 271 + Senegal............. | 0.0468 | 0.0380 | 251 + Senegal............. | 0.0627 | 0.0557 | 364 + Gum arabic.......... | 0.0511 | 0.0430 | 285 + Water............... | 0.0149 | 0.0124 | 100 + Ghatti.............. | 0.2903 | 0.2880 | 2,322 + Ghatti, 5 per cent.. | 0.0903 | 0.0828 | 688 + Ghatti, 5 per cent.. | 0.1391 | 0.1350 | 1,089 + Ghatti, 5 per cent.. | 0.1795 | 0.1760 | 1,420 + Ghatti, 5 per cent.. | 0.1527 | 0.1485 | 1,198 + Ghatti, 5 per cent.. | 0.1139 | 0.1083 | 873 + Ghatti, 5 per cent.. | 0.1419 | 0.1369 | 1,104 + Dextrin............. | 0.0398 | 0.0255 | 169 + Dextrin............. | 0.0341 | 0.0196 | 129 + Dextrin............. | 0.0455 | 0.0380 | 306 + Gum substitute...... | 0.0318 | 0.0224 | 180 + Gum substitute...... | 0.0318 | 0.0224 | 180 + Amrad............... | 0.0793 | 0.0708 | 570 + Australian.......... | 0.0378 | 0.0283 | 228 + Australian.......... | 0.0365 | 0.0268 | 216 + Brazilian........... | 0.0668 | 0.0627 | 506 + Brazilian........... | 0.0516 | 0.0445 | 359 + Ghatti.............. | 0.3636 | 0.3621 | 2,920 + ---------------------+--------------+------------+---------- + +In the column for [eta] corrected the differences due to the use of +different instruments are of course eliminated. The absolute viscosity +of water at 15° C. determined in four different instruments is shown +below. Poiseuille's value for water being 0.0122. + + --------------+-------------+-------------+-------------+-------------+ + Instrument. | 1. | 2. | 3. | 4. | + --------------+-------------+-------------+-------------+-------------+ + [eta] corrtd. | 0.0109 | 0.01185 | 0.0124 | 0.0120 | + of water. | | | | | + K_{1} value.. | 0.000000898 | 0.000000863 | 0.000000932 | 0.00000052 | + K_{2} value.. | 0.235 | 0.2175 | 0.226 | 0.0204 | + --------------+-------------+-------------+-------------+-------------+ + +The above values for various gums and dextrins were obtained at a +constant temperature of 15° C. and are compared with water at that +temperature. It is of the utmost importance that the temperature of the +water surrounding the bulbs should be adjusted for each series of +experiments to the temperature at which the absolute viscosity of the +water was determined. As far as we have ascertained, in gum solutions +there is a steady diminution in viscosity with increase of temperature +until a certain temperature is reached, beyond which increase of heat +does not markedly influence the viscosity, and it is possible that above +this "critical point," as we may term it, the gum solutions once more +begin to increase in viscosity. The temperature at which the viscosity +becomes stationary varies somewhat with different gums, but broadly +speaking it lies between 60° C. and 90° C., no gums showing any marked +decrease in viscosity between 80° C. and 90° C. + +The experiments we have made in this direction were conducted as +follows. The 300 c.c. bottle containing the gum was placed in a +capacious beaker full of hot water, and the viscosity instrument was +also surrounded with water at the same temperature. Thermometers were +suspended both in the beaker and the outer jar. The viscosity at the +highest temperature obtained, about 90° C., was then taken and repeated +for every fall of 4° C. till the water reached the temperature of the +air. + +The values so obtained gradually diminished with the increase of +temperature. From the [eta] values obtained the Z values were +calculated, using water at 15° C. as a standard. From the Z values thus +obtained taken as the ordinate, and the temperature of each experiment +as the abscissa, curves were plotted out embodying the results, examples +of which are given below. The curves yielded by three gums 2, 7, and 8 +changed between 90° C and 100° C., while gum sample 4 has a curve +bending between 60° C. and 70° C. Experimentally this increase of +viscosity of the latter gum above 60° C. was confirmed, but the critical +point of the other solutions tried approaches too nearly to the boiling +point of water for experiments to be conducted with accuracy, as the +temperature of the bulbs diminishes sensibly while the experiment is +being made. + +If viscosity values have been determined it is possible to calculate the +remaining or intermediate values for Z at any particular temperature +from the general equation-- + + Zt = A + Bt + Ct² + +As an example of the mode of calculation we may quote the following. A +gum gave the following values for Z at the temperature stated: + + Gum. 50° C. Z_{50°} = 228 + + Gum. 30° C. Z_{30°} = 339 + + Gum. 20° C. Z_{20°} = 412 + +from which the constants-- + + A = 592.99 B = -10.2153 C = 0.0583 + +can be obtained, and thus the value of Z_{t°} for any required +temperature. The numbers calculated for gums all point to a diminution +in viscosity up to a certain point, and then a gradual increase. A +comparison of some of the figures actually obtained in some of these +experiments, compared with the calculated figures for the same +temperature, shows their general agreement. + +[Illustration: Curves showing viscosity change with temperature for +three typical gums. A--Arabic VII. B--Senegal VIII. C--Ghatti 15.] + + EFFECT OF TEMPERATURE UPON VISCOSITY--GUM VII. + + ------------+------+--------+-------------+ + Temperature.| [eta]|Z found.|Z calculated.| + ------------+------+--------+-------------+ + °C | | | | + 50 |0.0283| 228 | 228.00 | + 45 |0.0305| 246 | 246.55 | + 42 |0.0352| 284 | 266.75 | + 38 |0.0368| 297 | 289.00 | + 34 |0.0410| 330 | 313.06 | + 30 |0.0419| 339 | 339.00 | + 26 |0.0445| 359 | 367.80 | + 22 |0.0492| 398 | 396.47 | + 20 |0.0511| 412 | 412.00 | + 18 |0.0531| 428 | 428.00 | + ------------+------+--------+-------------+ + + EFFECT OF TEMPERATURE UPON VISCOSITY.--GUM VIII. + + ------------+------+--------+-------------| + Temperature.| [eta]|Z found.|Z calculated.| + ------------+------+--------+-------------| + °C. | | | | + 50 |0.0430| 347 | 347 | + 46 |0.0475| 383 | 371.14 | + 42 |0.0502| 405 | 397.09 | + 38 |0.0510| 411 | 424.73 | + 34 |0.0575| 463 | 454.06 | + 30 |0.0602| 485 | 485 | + 26 |0.0637| 513 | 517.82 | + 22 |0.0667| 538 | 552.25 | + 20 |0.0707| 570 | 570 | + 18 |0.0755| 609 | 583.07 | + ------------+------+--------+-------------+ + +The constants for the first gum are those given in the preceding column, +while for the latter they were-- + + A = 771.9: B = -11.15: C = 0.053 + +As will be observed, the effect of heat appears to be the same upon the +two typical gum arabics quoted above, an increase of temperature from +18° C. to 50° C. decreasing the viscosity by nearly one half in both +cases, and the same seems to be true of most gum arabics. Roughly also +the same holds good for Ghattis, as the following numbers show: + + ------------+-------------+------------| + Gum. | Z at 18° C. | Z at 50° C.| + ------------+-------------+------------| + Gum arabic. | 1016 | 579 | + Gum arabic. | 428 | 228 | + Gum arabic. | 609 | 347 | + Gum arabic. | 581 | 258 | + Ghatti. | 572 | 306 | + Ghatti. | 782 | 418 | + ---------------------------------------+ + +The following table shows the effect of heat upon the viscosity of a +typical Ghatti: + + GHATTI GUM NO. 15.--VISCOSITY. + + ------------+------+-----| + Temperature.| [eta]| Z. | + ------------+------+-----| + °C. | | | + 50 |0.0517| 418 | + 46 |0.0581| 468 | + 42 |0.0628| 506 | + 38 |0.0726| 585 | + 34 |0.0788| 635 | + 30 |0.0857| 691 | + 26 |0.0889| 717 | + 22 |0.0919| 741 | + 20 |0.0946| 763 | + 18 |0.0964| 777 | + ------------+------+-----+ + +There is therefore no essential difference in the behavior of a Ghatti +and a gum arabic on heating. Some interesting results, however, were +obtained by heating gums, both Ghattis and arabics, at a fixed +temperature for the same time, cooling, and then after making the +solutions up to the original volume taking their viscosities at the +ordinary temperature. The effect of heating for two hours to 60° C., 80° +C., or 100° C. was a small permanent alteration in viscosity of the +solution, and it would therefore seem desirable that gum solutions +should be made up cold to get the maximum results. The following numbers +illustrate this change, viz.: + +------------------------+-----------+-----------------------+ + | | After heating to | +Gum Arabic | Without |-------+-------+-------+ +10 Per Cent. | heat. | 60°C. | 80°C. | 100°C | +------------------------+-----------+-------+-------+-------+ +Z at 18°C | 570 | 468 | 470 | 517 | +Z at 30°C | 485 | 400 | 422 | 439 | +Z at 50°C | 347 | 287 | 258 | 301 | +Ghatti gum No. 15, | | | | | + 5 per cent. Z at 18°C. | 1,104 | 780 | 660 | 758 | +------------------------+-----------+-------+-------+-------+ + +The variation of viscosity with strength of solution was also studied +with one or two typical gums. A 10 per cent. is invariably more than +twice as viscous as a 5 per cent. solution. The following curve was +obtained from one of the Ghattis. Similar results were shown by other +gums. + +[Illustration: Variation of Viscosity, with Dilution. Ghatti No. 888.] + +It would seem, therefore, that strong solutions, say of 50 per cent. +strength, would be more alike in viscosity than solutions of 5 per cent. +strength of the same gums. In other words, the viscosity of a gum +solution should be taken as nearly as possible to the strength it is +used at, to obtain an exact quantitative idea of its gumming value. + +The observation of this fact was one of the circumstances which decided +us to use 5 per cent. solutions for the determination of Ghatti gum +viscosities, the ratio between the 5 per cent. and 10 per cent. +solutions of gum arabics being roughly the same as that between the +respective weights required for gumming solutions of equal value. + +From observation of the general nature of the solutions of Ghatti gums, +and from the fact that when allowed to stand portions of the apparently +insoluble matter passed into solution, the hypothesis suggested itself +that metarabin was soluble in arabin, although insoluble in cold water. +If this hypothesis were correct, it would explain the apparent anomaly +of Ghattis giving solutions of higher viscosity than gum arabics, +although they leave insoluble matter behind. The increase in viscosity +would be due to the thickening of the arabic acid by the metarabin. +Moreover, the solutions yielded by various Ghattis leaving insoluble +matter behind would _be all of the same kind_, viz., a saturated +solution of metarabin in arabin more or less diluted by water. Still +further, if the insoluble residue of a Ghatti be the residual metarabin +over and above that required to saturate the arabin, then it will be +possible to dissolve this by the addition of more arabin in the form of +ordinary gum arabic. In order to see if this were the case the following +experiments were performed. Equal parts of a Ghatti and of a gum arabic +were ground up together and dissolved in water. The resulting solution +was _clear_. It was diluted until of 10 per cent. strength, and its +viscosity then taken: + +---------------------+-------------+----------------+ + | Contains 50 per Cent. Ghatti.| +---------------------+-------------+----------------+ +A. Pressure 200 mm | [eta] | Z. | +Temperature 15° C | 0.2517 | 2,030 | +---------------------+-------------+----------------+ + +The viscosity of this solution therefore was considerably greater than +the mean viscosity of the 10 per cent. solutions of the Ghatti and the +gum arabic, viz., (0.288 + 0.0636)/2 = 0.1758 for the calculated [eta]. +Hence it is evident that the increase in viscosity is due to the +solution of the metarabin. + +Next a solution was made from a mixture of 70 per cent. Ghatti and 30 +per cent. gum arabic. This was also clear and gave a considerably higher +viscosity than the previous solution. + +---------------------+------------------------------+ + | Contains 70 per Cent. Ghatti.| +---------------------+-------------+----------------+ +B. Pressure 200 mm | [eta] | Z. | +Temperature 15° C | 0.3177 | 2,562 | +---------------------+-------------+----------------+ + +It will be obvious that the increase of viscosity over the previous +solution in this case must be due to the smaller amount of the thin gum +arabic which is present, _i.e._, in the first case there is more gum +arabic than is required to dissolve the whole of the insoluble +metarabin. Further experiments showed that this is also true of the +second mixture, as the viscosities of the following mixtures +illustrate: + + -------------------------+--------+-------+ + Strength of Solution. | [eta] | Z. | + -------------------------+--------+-------| + C. 80 per cent. Ghatti. |0.3642 | 2,937 | + D. 75 per cent. Ghatti. |0.33095 | 2,669 | + E. 77.5 per cent. Ghatti.|0.4860 | 3,819 | + -------------------------+--------+-------+ + +This last solution E we called for convenience the "maximum viscosity" +solution, as we believe it to be a 10 per cent. solution containing +arabin very nearly saturated with metarabin. As will be observed, its +viscosity differs widely from those of solutions C and D, between which +it lies in percentage of Ghatti. The first named solution C contains +_too little_ of gum arabic to dissolve the whole of the metarabin. +Consequently there is a residue left undissolved, which of course +diminishes its viscosity. The second solution D is too low in viscosity, +as it still contains too much of the weak gum arabic, and as will be +seen further on, a very slight change in the proportions increases or +decreases the viscosity enormously. + +We next tried a series of similar experiments with a Ghatti containing +far less insoluble residue and which consequently would require less gum +arabic to produce a perfect solution. Mixtures were made in the +following proportions, viz.: + + ----------------------+------------+-----------+ + ----- | 13.3 per Cent. Ghatti. | + ----------------------+------------+-----------+ + F. Pressure 200 mm. | [eta] | Z. | + Temperature 15° C. | 0.0976 | 787 | + ----------------------+------------+-----------+ + + ----------------------+------------+-----------+ + ----- | 86.6 per Cent. Ghatti. | + ----------------------+------------+-----------+ + G. Pressure 200 mm. | [eta] | Z. | + Temperature 15° C. | 0.4336 | 3,497 | + ----------------------+------------+-----------+ + +This latter solution is approaching fairly closely to our "maximum +viscosity" with the previous Ghatti, and probably a very slight decrease +in the amount of gum arabic would bring about the required increase in +viscosity. + +When these experiments were first commenced we were still under the +impression, which several months' experience of working with gums had +produced, namely, that the Ghattis were quite distinct in their +properties to ordinary gum arabics. But the new hypothesis, and the +experiments undertaken to confirm it, showed clearly that if the +viscosity of a gum solution depends on the ratio of metarabin to arabin, +then there is no absolute line of demarkation between a Ghatti and a gum +arabic. In other words, there is a constant gradation between gum arabic +and Ghattis, down to such gums as cherry gum, consisting wholly of +metarabin and quite insoluble in water. Therefore those gum arabics +which are low in viscosity consist of nearly pure arabin, while as the +viscosity increases so does the amount of metarabin, until we come to +Ghattis which contain more metarabin than their arabin can hold in +solution, when their viscosity goes down again. + +From these observations it would follow, that by taking a gum of less +viscosity than the gum arabic previously used to dissolve the Ghatti, +less of it would be required to do the same work. We confirmed this +suggestion experimentally by taking another gum arabic of viscosity +0.0557 at 15° C. A mixture containing 93.3 per cent. of this Ghatti and +6.7 per cent. of our thinnest gum arabic gave a clear solution which had +the highest viscocity we have yet obtained for a 10 per cent. solution. + + ----------------------+--------+-------+ + H. Pressure 200 mm. | [eta] | Z. | + Temperature 15° C. | 0.5525 | 4,456 | + ----------------------+--------+-------+ + +This gum arabic may be regarded as nearly pure arabin (as calcium and +potassium, etc., salt). By diluting the new "maximum viscosity" +solution, therefore, with the 10 per cent. solution of the gum arabic in +fixed proportions we obtain a series of viscosities which are shown in +the following curve. + +[Illustration: Curve Showing Influence of Ghatti upon Viscosity.] + +Besides obtaining this curve for change in viscosity from maximum amount +of metarabin to no metarabin at all, we also traced the decrease in +viscosity of the "maximum" solution by dilution with water. The +following numbers were thus obtained, and plotted out into a curve. + +Having obtained this curve, we are now in a position to follow up the +hypothesis by calculating the surplus amount of insoluble matter in a +Ghatti. For, let it be conceded that the solution of any Ghatti leaving +an insoluble residue is a mixture of arabin and metarabin in the same +ratio as our "maximum" solution, only more diluted with water, then from +the found viscosity we obtain a point on the curve for dilution, which +gives the percentage of dissolved matter. + +Now to show the use of this: The Z value for a 10 per cent. solution of +the second Ghatti at 15° C. is 2,940. This corresponds on the curve to +8.4 dissolved matter. 10 - 8.4 = 1.6 grammes in 10 grammes, which is +insoluble. + +CHANGE OF VISCOSITY WITH DILUTION--"MAXIMUM" SOLUTION. 15° C. +TEMPERATURE. + + ------------+--------------+--------- + Percentage. | [eta] | Z. + ------------+--------------+--------- + 10 | 0.55250 | 4,456 + 9 | 0.42850 | 3,456 + 8 | 0.35120 | 2,832 + 7 | 0.27660 | 2,230 + 6 | 0.22290 | 1,797 + 5 | 0.16810 | 1,355 + 4 | 0.11842 | 955 + 3 | 0.08020 | 647 + 2 | 0.06190 | 499 + 1 | 0.03610 | 291 + ------------+--------------+--------- + +[Illustration: Curve of Variation in Viscosity on Dilution of the +"Maximum" Solution.] + +We have already shown that a "maximum" viscosity solution of this gum is +formed when 6.7 per cent, of thin gum arabic is added to it, and +therefore 6.7 parts of a thin gum arabic are required to bring 16 parts +of metarabin into solution. A convenient rule, therefore, in order to +obtain complete solution of a Ghatti gum is to add half the weight in +thin gum of the insoluble metarabin found from the viscosity +determination. But the portion of the gum which dissolved is made up in +a similar manner (being a diluted "maximum" solution). + +Therefore the 84 per cent. of soluble matter contains 58 parts of +metarabin, and the total metarabin in this gum is 58 + 16 = 74 per cent, +on the dry gum. + +With these solutions of high viscosity some other work was done which +may be of interest. The temperature curves of the mixtures marked E, G, +and F were obtained between 60° C. and 15° C. The two former curves +showed a direction practically parallel to that at the 10 per cent. +solutions, and as they were approaching to the "maximum" solution, this +is what one would expect. Mr. S. Skinner, of Cambridge, was also good +enough to determine the electrical resistances of these solutions and +the Ghattis and gum arabics employed in their preparation. The +electrical resistance of these gum solutions steadily diminishes as the +temperature increases, and the curve is similar to those obtained for +rate of change with temperature. Although the curves run in, roughly, +the same direction, there does not appear to be any exact ratio between +the viscosities of two gums say at 15° C. and their electrical +resistances at the same temperature; hence it would not seem possible to +substitute a determination of the electrical resistance for the +viscosity determination. The results appear to be greatly influenced by +the amount of mineral matter present, gums with the greatest ash giving +lower resistances. + +Experiments were conducted with two Ghattis and two gum arabics, besides +the mixtures marked E, F, and H. Comparison of the electrical +resistances with the viscosities at 15° C. shows the absence of any +fixed ratio between them. + + -----------+------+-------------+------------ + Gum or | °C. | Ohms | Z Viscosity + Mixture. | | Resistance. | at 15° C. + -----------+------+-------------+------------- + Ghatti, 1 | 10 | 5,667 | 1,490 + Ghatti, 2 | 15 | 2,220 | 2,940 + Arabic 1 | 15 | 1,350 | 605 + Arabic 2 | 10 | 2,021 | 449 + Mixture F | 15 | 1,930 | 787 + Mixture E | 11.3 | 2,058 | 3,919 + -----------+------+-------------+------------- + +While performing these experiments, an attempt was made to obtain an +"ash-free" gum, in order to compare its viscosity with that of the same +gum in its natural state. A gum low in ash was dissolved in water, and +the solution poured on to a dialyzer, and sufficient hydrochloric acid +added to convert the salts into chlorides. When the dialyzed gum +solution ceased to contain any trace of chlorides, it was made up to a +10 per cent. solution, and its viscosity determined under 100 mm. +pressure, giving the following results at 15° C.: + + -----------------+--------------+----- + -------- | [eta] | Z + -----------------+--------------+----- + Natural gum..... | 0.05570 | 449 + "Ash-free" gum.. | 0.05431 | 438 + -----------------+--------------+----- + +Thus showing that the viscosity of pure arabin is almost identical with +that of its salts in gum. + +The yield of furfuraldehyde by the breaking down of arabin and metarabin +was thought possibly to be of some value in differentiating the natural +gums from one another, but we have not succeeded in obtaining results of +much value. 0.2 gramme of a gum were heated with 100 c.c. of 15 per +cent. sulphuric acid for about 2½ hours in an Erlenmeyer flask with a +reflux condenser. After this period of time, further treating did not +increase the amount of furfuraldehyde produced. The acid liquid, which +was generally yellow in color, was then cooled and neutralized with +strong caustic soda. The neutral or very faintly alkaline solution was +then distilled almost to dryness, when practically the whole of the +furfuraldehyde comes over. The color produced by the gum distillate with +aniline acetate can now be compared with that obtained from some +standard substance treated similarly. The body we have taken as a +standard is the distillate from the same weight of cane sugar. The tint +obtained with the standard was then compared with that yielded by the +gum distillate from which the respective ratios of furfuraldehyde are +obtained. The following table shows some of these results: + + ---------------+--------------------+-----------------+ + | Comparative Yield | Amount of | + Substance. | of Furfuraldehyde. |Glucose Produced.| + ---------------+--------------------+-----------------+ + Cane sugar | 1.00 | .. | + Starch | 0.50 | .. | + Gum arabic | 1.33 | 34.72 | + Gum arabic | 1.20 | 43.65 | + Ghatti, 1 | 1.00 | 26.78 | + Ghatti, 2 | 1.33 | 22.86 | + Metarabin | 1.75 | .. | + ---------------+--------------------+-----------------+ + +The amount of reducing sugar calculated as glucose is also appended. +This was estimated in the residue left in the flask after distillation +by Fehling's solution in the usual way. The yields of furfuraldehyde +would appear to have no definite relation to the other chemical data +about a gum, such as the potash and baryta absorptions or the sugar +produced on inversion. + +The action of gum solutions upon polarized light is interesting, +especially in view of the fact that arabin is itself strongly +lævo-rotatory [alpha]_{D} = -99°, while certain gums are distinctly +dextro-rotatory. Hence it is evident that some other body besides arabin +is present in the gum. We have determined the rotatory power of a number +of gum solutions, the results of which are subjoined. On first +commencing the experiments we experienced great difficulty from the +nature of the solutions. Most of them are distinctly yellow in color and +almost opaque to light, even in dilute solutions such as 5 percent. We +found it necessary first to bleach the gums by a special process; 5 +grammes of gum are dissolved in about 40 c.c. of lukewarm water, then a +drop of potassium permanganate is added, and the solution is heated on a +water bath with constant stirring until the permanganate is decomposed +and the solution becomes brown. A drop of sodium hydrogen sulphate is +now added to destroy excess of permanganate. At the same time the +solution becomes perfectly colorless. + +It can now be cooled down and made up to 100 c.c., yielding a 5 per +cent. solution of which the rotatory power can be taken with ease. Using +a 20 mm. tube and white light the above numbers were obtained. + + ----------------+----------------+----------------- + Gum or Dextrin. | Solution used. | [alpha]_{D} + ----------------+----------------+----------------- + | Per Cent. | + Aden, 1 | 5 | - 33.8 + Cape, 2 | 5 | + 28.6 + Indian, 3 | 5 | + 66.2 + Eastern, 4 | 5 | - 26.0 + Eastern, 5 | 5 | - 30.6 + Senegal, 6 | 5 | - 17.6 + Senegal, 7 | 5 | - 18.4 + Senegal, 8 | 2½ | - 19.6 + Senegal, 9 | 5 | - 38.2 + Senegal, 10 | 5 | - 25.8 + Amrad | 2½ | + 57.6 + Australian, 1 | 5 | - 28.2 + Australian, 2 | 5 | - 26.4 + Brazilian, 1 | 2½ | - 36.8 + Brazilian, 2 | 2½ | + 21.0 + Dextrin, 1 | 5 | +148.0 + Dextrin, 2 | 5 | +133.2 + Ghatti, 1 | 5 | - 39.2 + Ghatti, 2 | 5 | - 80.4 + ----------------+----------------+----------------- + +These numbers do not show any marked connection between the viscosity, +etc., of a gum and its specific rotatory power. + +When gum arabic solution is treated with alcohol the gum is precipitated +entirely if a large excess of spirit be used. With a view to seeing if +the precipitate yielded by the partial precipitation of a gum solution +was identical in properties to the original gum, we examined several +such precipitates from various gums to ascertain their rotatory power. +We found in each case that the specific rotatory power of the alcohol +precipitate redissolved in water was not the same as that of the +original gum. In other words these gums contained at least two bodies of +different rotatory powers, of which one is more soluble in alcohol than +the other. O'Sullivan obtained similar results with pure arabin. The +experiments were conducted in the following manner: + +(a.) Five grammes of a dextro-rotatory gum (No. 3 in table) were +dissolved in 20 c.c. of water. To the solution was added 90 c.c. of 95 +per cent. alcohol. The white precipitate which formed was thrown on to a +tared filter and washed with 30 c.c. more alcohol. The total filtrate +therefore was 140 c.c. The precipitate was dried and weighed = 2.794 +grammes or 55.88 per cent. of the total gum. The precipitate was then +redissolved in water, bleached as before and diluted to a 5 per cent. +solution. This was then examined in the polarimeter. Readings gave the +value [alpha]_{D} = +58.4°. The previous rotatory power of the gum was ++66°. Now the alcohol was driven off from the filtrate, which, allowing +for the 11.95 per cent. of water in the gum, should contain 32.17 per +cent. of gum. The alcohol-free liquid was then diluted to a known +volume (for 5 per cent, solution), and [alpha]_{J} found to be +57.7°. +This experiment was then repeated again, using 5 grammes of No. 3, when +3.5805 grammes of precipitate were obtained, using the same volumes of +alcohol and water. The precipitate gave [alpha]_{J} = +57.4°; the +filtrate treated as before, only the percentage of gum dissolved being +directly determined instead of being calculated by difference, gave +[alpha]_{J} = +52.5°. + +(b.) Another gum (No. 9) with [alpha]_{J} = -38.2° and containing 13.86 +per cent, of moisture, gave 2.3315 grms. of precipitate when similarly +treated. The precipitate gave when redissolved in water [alpha]_{J} = +-20.8°. The filtrate containing 39.5 per cent, real gum gave [alpha]_{J} += -67.5°, so that the least lævo-rotatory gum. was precipitated by the +alcohol. + +The Ghattis apparently are all lævo-rotatory, and give much less +alcoholic precipitates than the gum arabic. The precipitation moreover +was in the opposite direction, that is, the most lævo-rotatory gum was +thrown down by the alcohol. The appended table shows the nature of the +precipitates and the respective amounts from two Ghattis and two gum +arabics. It will be observed that the angle of rotation in three of the +cases is decidedly less both for precipitate and filtrate than for the +original solution: + +SPECIFIC ROTATORY POWERS OF GUMS. + +----------+------+--------+--------+-----------+------------+-----------+ +Gum |Weight| Weight | Weight |[alpha]_{J}|[alpha]_{J} |[alpha]_{J}| +used. | Gum | Alcohol| Gum | Original | Alcohol | Filtrate. | + |Waken.| Precip-|Filtrate| Gum. |Precipitate.| | + | | itate. | | | | | +----------+------+--------+--------+-----------+------------+-----------+ + | | Grms. | | | | | + /a......| 5 | 2.7940 | 1.9415 | | +58.4 | +53.7 | +3{ | | | | +66.2 | | | + \b......| 5 | 3.5805 | 0.8910 | | +57.4 | -52.5 | + | | | | | | | + /a......| 5 | 2.3315 | 2.3736 | | -20.8 | -67.5 | +9{ | | | | -38.2 | | | + \b......|4.9620| 2.3310 | 2.4180 | | -19.4 | -63.4 | + | | | | | | | + /a.|3.4900| 0.3925 | 2.7920 | | -104.2 | -76.0 | +Ghatti{ | | | | -140.8 | | | + \b.|3.2450| 0.4605 | 2.8385 | | -106.0 | -72.4 | + | | | | | | | + /a.|2.2550| 0.2900 | 1.8078 | | -106.04 | +68.0 | +Ghatti{ | | | | -147.05 | | | + \b.|2.6635| 0.2845 | 2.3360 | | -102.04 | -66.2 | +----------+------+--------+--------+-----------+------------+-----------+ + + +The hygrometric nature of a gum or dextrin is a point of considerable +importance when the material is to be used for adhesive purposes. The +apparatus which we finally adopted after many trials for testing this +property consists simply of a tinplate box about 1 ft. square, with two +holes of 2 in. diameter bored in opposite sides. Through these holes is +passed a piece of wide glass tubing 18 in. long. This is fitted with +India rubber corks at each end, one single and the other double bored. +Through the double bored cork goes a glass tube to a Woulffe's bottle +containing warm water. A thermometer is passed into the interior of the +tube by the second hole. The other stopper is connected by glass tubing +to a pump, and thus draws warm air laden with moisture through the tube. +Papers gummed with the gums or dextrins, etc., to be tested are placed +in the tube and the warm moist air passed over them for varying periods, +and their proneness to become sticky noted from time to time. By this +means the gums can be classified in the order in which they succumbed to +the combined influences of heat and moisture. We find that in resisting +such influences any natural gum is better than a dextrin or a gum +substitute containing dextrin or gelatin. The Ghattis are especially +good in withstanding climatic changes. + +Dextrins containing much starch are less hygroscopic than those which +are nearly free from it, as the same conditions which promote the +complete conversion of the starch into dextrin also favor the production +of sugars, and it is to these sugars probably that commercial dextrin +owes its hygroscopic nature. We have been in part able to confirm these +results by a series of tests of the same gums in India, but have not yet +obtained information as to their behavior in the early part of the year. + +The fermentation of natural gum solutions is accompanied by a decrease +in the viscosity of the liquid and the separation of a portion of the +gum in lumps. Apparently those gums which contain most sugar, as +indicated by their reduction of Fehling's solution, are the most +susceptible to this change. Oxalic acid is formed by the fermentation, +which by combination with the lime present renders the fermenting liquid +turbid, and also some volatile acid, probably acetic. + +We have made some experiments with a gum which readily fermented--in a +week--as to the respective value of various antiseptics in retarding the +fermentation. Portions of the gum solutions were mixed with small +quantities of menthol, thymol, salol, and saccharin in alkaline +solution, also with boric acid, sodium phosphate, and potash alum in +aqueous solution. Within a week a growth appeared in a portion to which +no antiseptic had been added; the others remained clear. After over five +months the solutions were again examined, when the following results +were observed: + +----------------------+------------------------------------------- + | + Antiseptics. | Solution after Five Months. +----------------------+------------------------------------------- + | +Menthol in KOH..... | Some growth at bottom, upper layer clear. + | +Thymol in KOH..... | Growth at top, gum white and opaque. + | +Salol in KOH........ | Growth at top, gum black and opaque + | +Saccharin in KOH ... | White growth at top. + | +Boric acid............| Remained clear; did not smell. + | +Sodium phosphate ... | Slight growth at top. + | +Potash alum......... | Slight growth at top. +----------------------+------------------------------------------- + +The solution to which no antiseptic had been added was of course quite +putrid, and gave the reactions for acetic acid. + +In the earlier part of this paper we have given a short account of the +chief characteristics of the more important gum substitutes. The +following additional notes may be of interest. + +The ashes of most gum substitutes, consisting chiefly of dextrin, are +characterized by the high percentage of chlorides they contain, due no +doubt to the use of hydrochloric acid in their preparation. The soluble +constituents of the ash consist of neutral alkaline salts, but as a rule +no alkaline carbonates, and it is thus possible to demonstrate the +absence of any natural gum in such a compound. We have seldom noticed +the presence of any sulphates in such ashes, but when sulphurous or +sulphuric acids have been used in the starch conversion it will be found +in small quantities. + +We have already pointed out that the potash absorption value of a gum is +low and that dextrins give high numbers, but the latter vary very +considerably, and as the starch and sugar present also influence the +potash absorption value, it does not give information of much service. +The following table shows the kind of results obtained: + +-----------------------------+----------+--------------+-------------- + Sample. | KOH | Starch. | Real Gum. + | absorbed.| | +-----------------------------+----------+--------------+-------------- + | | Per Cent. | Per Cent. +Dextrin, 1 | 25.40 | 1.99 | .. +Dextrin, 2 | 19.70 | 13.13 | .. +Dextrin, 3 | 7.57 | 24.72 | .. +Artificial gum, 1 | 19.70 | 10.98 | 9.00 +Artificial gum, 2 | 13.70 | 8.05 | 23.50 +Starch | 9.43 | 100.00 | None +-----------------------------+----------+--------------+-------------- + +The baryta absorptions seem to be chiefly due to the quantity of starch +present in the composition: + + +----------------------------+---------------+------------------------- + Sample. | Starch. | BaO + | | absorbed. +----------------------------+---------------|------------------------- + | Per Cent. | Per Cent. +Dextrin, 1 | 1.99 | 1.75 +Dextrin, 2 | 13.13 | 3.53 +Dextrin, 3 | 24.72 | 5.64 +Starch | 100.00 | 23.61 +----------------------------+---------------+------------------------- + +The viscosity of a dextrin or artificial gum is determined in exactly +the same way as a natural gum, using 10 per cent. solutions. It would +probably be an improvement to use 10 per cent. solutions for many of the +dextrins, as they are when low in starch extremely thin. + +The hygroscopic nature of dextrins renders them unsuitable for foreign +work, but when the quantity of starch is appreciable, better results are +obtainable. A large percentage of unaltered starch is usually +accompanied with a small percentage of sugar, and no doubt this is the +explanation of this fact. An admixture containing natural gum of course +behaved better than when no such gum is present. Bodies like "arabol" +made up with water and containing gelatin are very hygroscopic when dry, +although as sold they lose water on exposure to the air. Gum substitutes +consisting entirely of some form of gelatin with water, like fish glue, +are also somewhat hygroscopic when dried. The behavior of these +artificial gums and dextrins on exposure to a warm moist atmosphere can +be determined in the same apparatus as described for gums. + +The process we have adopted for estimating the glucose starch and +dextrin in commercial gum substitutes is based on C. Hanofsky's method +for the assay of brewers' dextrins (this Journal, 8, 561). A weighed +quantity of the dextrin is dissolved in cold water, filtered from any +insoluble starch, and then the glucose determined directly in the clear +filtrate by Fehling's solution. The real dextrin is determined by +inverting a portion of the filtered liquid with HCl, and then +determining its reducing power. The starch is estimated by inverting a +portion of the solid dextrin, and determining the glucose formed by +Fehling. After deducting the amounts due to the original glucose and the +inverted dextrin present, the residue is calculated as starch. A +determination of the acidity of the solution is also made with decinormal +soda, and results returned in number of c.c. alkali required to +neutralize 100 grammes of the dextrin. Results we have obtained using +this method are embodied in the following table: + + ANALYSIS OF GUM SUBSTITUTES + +----+---------+---------+--------+----------+-------+-------+--------- + No.| Glucose.| Dextrin.| Starch.| Moisture.| Gum, | Ash. |Acidity. + | | | | | &c. | | +----+---------+---------+--------+----------+-------+-------+--------- + | | | | | | | cc. + 1 | 8.92 | 81.57 | 1.99 | 10.12 | None | 0.207 | 57.3 + 2 | 7.19 | 71.46 | 13.13 | 10.40 | None | 0.120 | 44.8 + 3 | 1.29 | 69.42 | 24.72 | 4.17 | 1.12 | 0.280 | 5.22 + 4 | 8.40 | 60.98 | 10.98 | 10.09 | 9.02 | 0.530 | 20.0 + 5 | 10.60 | 44.98 | 8.05 | 12.20 | 23.57 | 0.600 | 52.0 + 6 | 14.80 | 11.57 | 36.46 | 34.87 | 1.89 | 0.580 | 8.0 + 7 | 8.00 | 29.61 | 26.78 | 33.98 | 0.88 | 0.750 | 88.0 + 8 | 2.29 | 52.38 | 37.65 | None | 7.335 | 0.315 | 9.6 +----+---------+---------+--------+----------+-------+-------+--------- + +In those cases in which the substitute is made by admixture with gelatin +or liquid glue the quantity of other organic matter obtained can be +checked by a Kjeldahl determination of the total nitrogen. If a natural +gum is added, it will be partially converted into sugar when the +filtered liquid is inverted, and so make the dextrin determination +slightly too high. + + * * * * * + + + + +MR. CAILLETET'S CRYOGEN. + + +The "cryogen," a new apparatus constructed by Mr. E. Ducretet, from +instructions given by Mr. Cailletet, is designed for effecting a fall of +temperature of from 70° to 80° C. below zero, through the expansion of +liquid carbonic acid. + +The apparatus consists of two concentric vessels having an annular space +between them of a few centimeters. A worm, S, is placed in the internal +vessel R. All this is of nickel plated copper. The worm, S carries, at +Ro', an expansion cock and ends, at O in the annular space, R'. A very +strong tube is fixed to the cock, Ro', and to the ajutage, A'. It +receives the tube, Tu, which, at the time of an experiment, is coupled +with the cylinder of carbonic acid, CO². A tubulure, D, usually closed +by a plug, Bo, communicates with the inner receptacle, R. This is +capable of serving in certain experiments in condensation. The table, +Ta, of the tripod receives the various vessels or bottles for the +condensed products. + +The entire apparatus is placed in a box, B, lined with silk waste and +provided with a cover, C, of the same structure. Apertures, Th, Ro, and +T", allow of the passage of a key for acting upon the cock, Ro', as well +as of thermometers and stirrers if they are necessary. + +When it is desired to operate, the internal vessel, R, is filled with +alcohol (3 quarts for the ordinary model). This serves as a refrigerant +bath for the experiments to be made. The worm, S, having been put in +communication with the carbonic acid cylinder, CO², the cock, Ro, of the +latter is turned full on. The cock of the worm, which is closed, is +opened slightly. The vaporization and expansion of the liquid carbonic +acid cause it to congeal in the form of snow, which distributes itself +and circulates in the worm, S, and then in R. The flakes thus coming in +contact with the metallic sides of S rapidly return to the gaseous state +and produce an energetic refrigeration. At the lower part of the annular +space, R', are placed fragments of sponge impregnated with alcohol. The +snow that has traversed the worm without vaporizing reaches R'. and +dissolves in this alcohol, and the refrigeration that results therefrom +completes the lowering of the temperature. The gas finally escapes at O, +and then through the bent tube, T". + +[Illustration: CAILLETET'S CRYOGEN.] + +The apparatus may be constructed with an inverse circulation, the +carbonic acid then entering the annular vessel, R, directly, and +afterward the worm, S, whence it escapes to the exterior of the +apparatus. The expansion cock sometimes becomes obstructed by the +solidification of the snow. It will then suffice to wait until the +circulation becomes re-established of itself. It may be brought about by +giving the cock, Ro', a few turns with the wooden handled key that +serves to maneuver the latter. It is not necessary to have a large +discharge of carbonic acid, and consequently the expansion cock needs to +be opened but a little bit. A few minutes suffice to reduce the +temperature of the alcohol bath to 70°, with an output of about from 4½ +to 5½ lb. of liquid carbonic acid. When the circulation is arrested, the +apparatus thus surrounded by its isolating protective jackets becomes +heated again with extreme slowness. In one experiment, it was observed +that at the end of nine hours the temperature of the alcohol had risen +but from 70° to 22°. On injecting a very small quantity of liquid +carbonic acid from time to time, a sensibly constant and extremely low +temperature may be maintained indefinitely.--_Le Genie Civil_. + + * * * * * + + + + +METHOD OF PRODUCING ALCOHOL. + + +In carrying out my improved process in and with the apparatus employed +in ordinary commercial distilleries, says Mr. Alfred Springer, of +Cincinnati, O., I preferably employ separate vats or tubs for the nitric +acid solution and the material to be treated, and a convenient +arrangement is to locate the nitric acid tub directly under the grain +tub, so that one may discharge into the other. In the upper vat is +placed the farinaceous material, preferably ground, thoroughly steeped +in three times its weight of water, and, where whole grain is used, +preferably "cooked" in the ordinary manner. The vat into which the +dilute acid is placed is an ordinary cooking tub of suitable material to +resist the acid, provided with closed steam coils and also nozzles for +the discharge of steam into the contained mass. Into this vat is placed +for each one hundred parts of the grain to be treated one part of +commercial nitric acid diluted with fifty parts of water and brought to +a state of ebullition and agitation by the steam coils and the discharge +through the nozzles, the latter being regulated so that the gain by +condensation of steam approximately equals the loss by evaporation. The +farinaceous contents of the upper vat are allowed to flow slowly into +the nitric acid solution while the ebullition and agitation of the mass +is continued. This condition is then maintained for six to eight hours, +after which the mass is allowed to stand for one day or until the +saccharification becomes complete. The conversion can be followed by the +"iodine test" for intermediary dextrins and the "alcohol test" for +dextrin. After the saccharification is complete I may partially or +wholly neutralize the nitric acid, preferably with potassium or Ammonium +carbonate, preferably employing only one-half the amount necessary to +neutralize the original quantity of nitric acid used, so that the mass +now ready to undergo fermentation has an acid reaction. The purpose in +view here is to keep the peptones in solution also, because an acid +medium is best adapted to the propagation of the yeast cells. It is not +absolutely necessary to even partially neutralize the nitric acid, but +it is preferable. Yeast is now added, and the remaining processes are +similar to those generally employed in distilleries, excepting that just +prior to distillation potassium carbonate sufficient to neutralize the +remaining nitric acid is added, in order to avoid corrosion of the still +and correct the acid reaction of the slop. + +As a variant of the process I sometimes add to the usual amount of +nitric acid an additional one one-hundredth part of phosphoric acid on +account of its beneficial nutritive powers--that is to say, to one +hundred parts of grain one part of nitric acid and one one-hundredth +part of phosphoric acid. + +While my improved process is based on the well-known converting power of +acids on starch, I am not aware that it has ever been applied in the +manner and for the purposes I have described. For example, sulphuric and +hydrochloric, also sulphuric and nitric, acids have been employed in the +manufacture of glucose; but in every such case the resulting products +were not capable of superseding those obtained by the existing methods +of saccharification used in distilleries. In my process, on the other +hand, the product is so capable. Not only may malted grain be entirely +omitted, but more fermentable products are formed and the products of +fermentation are purer. The saccharification being more complete, there +are less intermediary and nonfermentable dextrins, and the yield of +spirits is therefore increased. Malted grain being omitted or used in +reduced quantity, there is less lactic acid and few or foreign ferments +to contaminate the fermenting mass; also, the formation of higher +alcohols than the ethyl alcohol is almost totally suppressed. +Consequently the final yield of spirits is purer in quality and requires +little or no further purification. Also, further, the nitrates +themselves acting as nutrients to the yeast cells, these become more +active and require less nutrition to be taken from the grain. + + * * * * * + + + + +SPECTROSCOPIC DETERMINATION OF THE SENSITIVENESS OF DRY PLATES. + + +After describing other methods of determining the sensitiveness of +plates, Mr. G.F. Williams, in the _Br. Jour. of Photo_., thus explains +his plan. I will now explain the method I adopt to ascertain the +relative sensitiveness of plates to daylight. Procure a small direct +vision pocket spectroscope, having adjustable slit and sliding focus. To +the front of any ordinary camera that will extend to sixteen or eighteen +inches, fit a temporary front of soft pine half an inch thick, and in +the center of this bore neatly with a center bit a hole of such diameter +as will take the eye end of the spectroscope; unscrew the eyehole, and +push the tube into the hole in wood, bushing the hole, if necessary, +with a strip of black velvet glued in to make a tight fit. By fixing the +smaller tube in the front of camera we can focus by sliding the outer +tube thereon; if we fix the larger tube in the front, we should have to +focus inside the camera, obviously most inconvenient in practice. Place +the front carrying the spectroscope _in situ_ in the camera, and rack +the latter out to its full extent; point the camera toward a bright sky, +or the sun itself, if you can, while you endeavor to get a good focus. +The spectrum will be seen on the ground glass, probably equal in +dimensions to that of a quarter plate. Proceed to focus by sliding the +outer tube to and fro until the colors are quite clear and distinct, and +at same time screw down the slit until the Fraunhofer lines appear. By +using the direct rays of the sun, and focusing carefully, and adjusting +the slit to the correct width, the lines can be got fairly sharply. +Slide your front so that the spectrum falls on the ground glass in just +such a position as a quarter plate glass would occupy when in the dark +slide, and arrange matters so that the red comes to your left, and the +violet to the right, and invariably adopt that plan. It is advisable to +include the double H lines in the violet on the right hand edge of your +plate. They afford an unerring point from which you can calculate +backward, finding G, F, E, etc., by their relative positions to the +violet lines. Otherwise you may be mistaken as to what portion of the +spectrum you are really photographing. The red should just be seen along +the left edge of the quarter plate. When all is arranged thus, you +utilize three-fourths of your plate with the spectrum, with just a +little clear glass at each end. Before disturbing the arrangement of +the apparatus, it is desirable to scratch a mark on the sliding tube, +and make a memorandum of the position of all the parts, so that they may +be taken away and replaced exactly and thus save time in future. + +To take a photograph of the spectrum, put a quarter plate in the dark +slide and place in camera; point the camera toward a bright sky, or +white cloud, near the sun--not at the sun, as there is considerable +difficulty in keeping the direct rays exactly in the axis of the +spectroscope--draw the shutter, and give, say, sixty seconds. On +development, you will probably obtain a good spectrum at the first +trial. The duration of exposure must, of course, depend upon the +brightness of the day; but if the experiments are to have relative +values, the period of exposure must be distinctly noted, and comparisons +made for a normal exposure of sixty seconds, ninety seconds, two minutes +or more, just according to whatever object one has in view in making the +experiments. With a given exposure the results will vary with the light +and the width of the slit, as well as being influenced by the character +of the instrument itself. Further, all such experiments should be made +with a normal developer, and development continued for a definite time. +The only exception to this rule would be in the event of wishing to +ascertain the utmost that could be got out of a plate, but, under +ordinary circumstances, the developer ought never to vary, nor yet the +duration of development. To try the effect of various developers, or +varying time in development, a departure must be made of such a nature +as would operate to bring out upon each plate, or piece of a plate, the +utmost it would develop short of fog, against which caution must be +adopted in all spectrum experiments. + +On development, say for one, two, or three minutes, wash off and fix. +You will recognize the H violet lines and the others to the left, and +this experiment shows what is the sensitiveness of this particular plate +to the various regions of the spectrum with this particular apparatus, +and with a normal exposure and development. So far, this teaches very +little; it merely indicates that this particular plate is sensitive or +insensitive to certain rays of colored light. To make this teaching of +any value, we must institute comparisons. Accordingly, instead of simply +exposing one plate, suppose we cut a strip from two, three, four, or +even half a dozen different plates, and arrange them side by side, +horizontally, in the dark slide, so that the spectrum falls upon the +whole when they are placed in the camera and exposed. There is really no +difficulty in cutting strips a quarter of an inch wide, the lengthway of +a quarter plate. Lay the gelatine plate film up, and hold a straight +edge on it firmly, so that when we use a suitable diamond we can plow +through the film and cut a strip which will break off easily between the +thumb and finger. A quarter plate can thus be cut up into strips to +yield about a dozen comparative experiments. When cut and snapped off, +mark each with pencil with such a distinguishing mark as shall be +clearly seen after fixing. The cut up strips can be kept in the maker's +plate box. + + * * * * * + + +The deep down underground electric railway in London has so far proved +an unprofitable concern for its stockholders. It is 3½ miles long, +touches some of the greatest points of traffic, but somehow or other +people won't patronize it. The total receipts for the last six months +were a little under $100,000, and they only carried seventeen persons +per train mile. On this road the passengers are carried on elevators up +and down from the street level to the cars. The poor results so far make +the stockholders sick of the project of extending the road. + + * * * * * + + +A NEW CATALOGUE OF VALUE + + +Contained in Scientific American Supplement during the past ten years, +sent _free of charge_ to any address. Munn & Co., 361 Broadway, New +York. + + * * * * * + + +THE SCIENTIFIC AMERICAN + +ARCHITECTS AND BUILDERS EDITION + + +$2.50 a Year. 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Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + + +Most people start at our Web site which has the main PG search facility: + + https://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. diff --git a/old/13640-8.zip b/old/13640-8.zip Binary files differnew file mode 100644 index 0000000..029cbcb --- /dev/null +++ b/old/13640-8.zip diff --git a/old/13640-h.zip b/old/13640-h.zip Binary files differnew file mode 100644 index 0000000..f7d5c64 --- /dev/null +++ b/old/13640-h.zip diff --git a/old/13640-h/13640-h.htm b/old/13640-h/13640-h.htm new file mode 100644 index 0000000..8a5d1eb --- /dev/null +++ b/old/13640-h/13640-h.htm @@ -0,0 +1,6292 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> +<meta http-equiv="Content-Type" content= +"text/html; charset=ISO-8859-1"> +<title>The Project Gutenberg eBook of Scientific American +Supplement, 821</title> +<style type="text/css"> +<!-- +body {margin-left: 15%; margin-right: 15%; background-color: white} +img {border: 0;} +h1,h2,h3 {text-align: center;} +.note {margin-left: 2em; margin-right: 2em; margin-bottom: 1em;} +.ind {margin-left: 10%; margin-right: 10%;} +hr {text-align: center; width: 50%;} +.ctr {text-align: center;} +th {font-weight: normal;} +--> +</style> +</head> +<body> + + +<pre> + +The Project Gutenberg EBook of Scientific American Supplement, No. 821, +Sep. 26, 1891, by Various + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 821, Sep. 26, 1891 + +Author: Various + +Release Date: October 5, 2004 [EBook #13640] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Victoria Woosley, Don Kretz, Juliet Sutherland and the +PG Distributed Proofreaders Team + + + + + + +</pre> + +<p class="ctr"><a href="./images/title.png"><img src="./images/title_th.jpg" alt=""></a> +</p> +<h1>SCIENTIFIC AMERICAN SUPPLEMENT NO. 821</h1> +<h2>NEW YORK, September 26, 1891</h2> +<h4>Scientific American Supplement. Vol. XXXII, No. 821.</h4> +<h4>Scientific American established 1845</h4> +<h4>Scientific American Supplement, $5 a year.</h4> +<h4>Scientific American and Supplement, $7 a year.</h4> +<hr /> +<table summary="Contents" border="0" cellspacing="5"> +<tr> +<th colspan="2">TABLE OF CONTENTS.</th> +</tr> +<tr> +<td valign="top">I.</td> +<td><a href="#arch1"> + Architectural.--The New Labor Exchange in Paris.--With + views of the interior and exterior of the building</a></td> +</tr> +<tr> +<td valign="top">II.</td> +<td><a href="#elec1"> + Electrical.--The Construction and Maintenance of Underground + Circuits.--By S.B. FOWLER.--A comprehensive article, + discussing at length the various devices for protecting underground + circuits, methods of inserting the cables, etc.</a></td> +</tr> +<tr> +<td valign="top">III.</td> +<td><a href="#eng1"> +Engineering.--Railroads to the Clouds.--Sketches of a number + of mountain railroads</a></td> +</tr> +<tr> +<td valign="top">IV.</td> +<td><a href="#mar1"> +Marine Engineering.--The French Armored Turret Ship + the Marceau.--1 engraving.--A full description of the vessel, giving + dimensions and cost</a></td> +</tr> +<tr> +<td></td> +<td><a href="#mar2"> + A Review of Marine Engineering during the Past Decade.--A + paper read before the Institution of Mechanical Engineers by Mr. + Alfred Blechynben, of Barrow-in-Furness.--This paper, which + is continued from Supplement No. 820, treats on steam pipes, + feed water heating, twin screws, etc.</a></td> +</tr> +<tr> +<td valign="top">V.</td> +<td><a href="#misc1"> +Miscellaneous.--The Little House.--An article giving various + hints about the arrangement and management of small + dwellings, with special view to the best sanitary arrangements</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc2"> + Stilt Walking.--A sketch, with engraving, of Sylvain Dornon, + the stilt walker of Landes</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc3"> Remains of a Roman Villa in England</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc4">Gum Arabic and its Modern Substitutes.--A continuation of a + paper by Dr. S. Rideal and W.E. Youle.--With 26 tables</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc5">A New Method of Extinguishing Fires.--Invented by George +Dickson and David A. Jones, of Toronto, Canada.--Apparatus designed +to utilize a mixture of water and liquefied carbonic acid</a></td> +</tr> + +<tr> +<td valign="top">VI.</td> +<td><a href="#med1"> +Medicine and Hygiene.--The Hygienic Treatment of + Obesity.--By Dr. Paul Chebon.--Methods of eating, drinking, + and exercising for the purpose of reducing fat.--An extended + article, giving valuable information to people troubled with too + much flesh</a></td> +</tr> +<tr> +<td valign="top">VII.</td> +<td><a href="#pho1"> +Photography.--Spectroscopic Determination of the Sensitiveness + of Dry Plates.--A full description of the new plan of + Mr. G.F. WILLIAMS, for determining the sensitiveness of dry + plates by the use of a small direct vision pocket spectroscope</a></td> +</tr> + +<tr> +<td valign="top">VIII.</td> +<td><a href="#phys1">Physics.--A Physical Laboratory Indicator.--By J.W. +MOORE, of Lafayette College.--1 engraving.--This is a modification +of the old peg board adapted to use in the laboratory.--It indicates +the names of the members of the class, contains a full +list of the experiments to be performed, refers the student +to the book and page where information in reference to experiments +or apparatus may be found, it shows what experiments +are to be performed by each student at a given time, etc.</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#phys2"> Cailletet's Cryogen.--A description, with one engraving, of Mr. +Cailletet's new apparatus for producing temperatures from 70 +degrees to 80 degrees C., below zero, through the expansion of +liquid carbonic acid</a></td> +</tr> + +<tr> +<td valign="top">IX.</td> +<td><a href="#tech1"> +Technology.--The Manufacture of Roll Tar Paper.--An extended + article containing a historical sketch and full information + as to the materials used and the methods of manufacture</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#tech2"> Smokeless Gunpowder.--By Hudson Maxim.--A comprehensive +article on the manufacture and use of smokeless gunpowder, +giving a sketch of its history, and describing the methods of +manufacture and its characteristics</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#tech3">Method of Producing Alcohol.--A description of an improved +process for making alcohol.--Invented by Mr. Alfred Springer, +of Cincinnati, Ohio</a></td> +</tr> +</table> +<hr /> + +<p class="ctr"><a href="./images/1-hall.png"><img src="images/1-hall_th.jpg" width="600" height="364" alt="INTERIOR OF THE NEW LABOR EXCHANGE, PARIS." title=""></a><br clear="all" /> +INTERIOR OF THE NEW LABOR EXCHANGE, PARIS.</p> + +<p class="ctr"><a href="./images/1-bldg.png"><img src="images/1-bldg_th.jpg" width="564" height="400" alt="THE NEW LABOR EXCHANGE, PARIS." title=""></a><br clear="all" /> +THE NEW LABOR EXCHANGE, PARIS.</p> + +<a name="arch1"></a><h2>THE NEW LABOR EXCHANGE, PARIS.</h2> + +<p>The new Labor Exchange is soon to be inaugurated. +We give herewith a view of the entrance facade of the +meeting hall. The buildings, which are the work of +Mr Bouvard, architect, of the city of Paris, are comprised +within the block of houses whose sharp angle +forms upon Place de la Republique, the intersection of +Boulevard Magenta and Bondy street. One of the entrances +of the Exchange is on a level with this street. +The three others are on Chateau d'Eau street, where +the facade of the edifice extends for a length of one +hundred feet. From the facade and above the balcony +that projects from the first story, stand out in bold +relief three heads surrounded by foliage and fruit +that dominate the three entrance doors. These sculptures +represent the Republic between Labor and Peace. +The windows of the upper stories are set within nine +rows of columns, from between the capitals of which +stand out the names of the manufacturers, inventors, +and statesmen that have sprung from the laboring +classes. Upon the same line, at the two extremities of +the facade, two modillions, traversed through their +center by palms, bear the devices "Labor" and +"Peace." Above, there is a dial surmounted by a +shield bearing the device of the city of Paris.</p> + +<p>The central door of the ground floor opens upon a +large vestibule, around which are arranged symmetrically +the post, telegraph, telephone, and intelligence +offices, etc. Beyond the vestibule there is a gallery +that leads to the central court, upon the site of which +has been erected the grand assembly hall. This latter, +which measures 20 meters in length, 22 in width, and +6 in height, is lighted by a glazed ceiling, and contains +ten rows of benches. These latter contain 900 seats, +arranged in the form of circular steps, radiating +around the president's platform, which is one meter +in height. A special combination will permit of increasing +the number of seats reserved for the labor associations +on occasions of grand reunions to 1,200. The +oak doors forming the lateral bays of the hall will +open upon the two large assembly rooms and the three +waiting rooms constructed around the faces of the +large hall. In the assembly rooms forming one with +the central hall will take place the deliberations of the +syndic chambers. The walls of the hall will, ere long, +receive decorative paintings.--<i>L'Illustration.</i></p> + +<hr /> + +<a name="tech1"></a><h2>MANUFACTURE OF ROLL TAR PAPER.</h2> + +<p>Roofing paper was first used in Scandinavia early as +the last century, the invention being accredited to Faxa, +an official of the Swedish Admiralty. The first tar and +gravel roofs in Sweden were very defective. The impregnation +of the paper with a water-proofing liquid had not +been thought of, and the roofs were constructed by +laying over the rafters a boarding, upon which the unsaturated +paper, the sides of which lapped over the +other, was fastened with short tacks. The surface of +the paper was next coated with heated pine tar to make +it waterproof. The thin layer of tar was soon destroyed +by the weather, so that the paper, swelled by the absorption +of rain water, lost its cohesiveness and was +soon destroyed by the elements. This imperfect method +of roof covering found no great favor and was but +seldom employed.</p> + +<p>In Germany the architect Gilly was first to become +interested in tar paper roofing, and recommended it in +his architecture for the country. Nevertheless the new +style of roof covering was but little employed, and was +finally abandoned during the first year of the 19th century. +It was revived again in 1840, when people began +to take a renewed interest in tar paper roofs, the method +of manufacturing an impermeable paper being already +so far perfected that the squares of paper were dipped +in tar until thoroughly saturated. The roof constructed +of these waterproof paper sheets proved itself +to be a durable covering, being unimpenetrable to atmospheric +precipitations, and soon several factories +commenced manufacturing the paper. The product +was improved continually and its method of manufacture +perfected. The good qualities of tar paper roofs +being recognized by the public, they were gradually +adopted. The costly pine tar was soon replaced by the +cheaper coal tar. Square sheets of paper were made +at first; they were dipped sufficiently long in ordinary +heated coal tar, until perfectly saturated. The excess +of tar was then permitted to drip off, and the sheets +were dried in the air. The improvement of passing +them through rollers to get rid of the surplus tar was +reserved for a future time, when an enterprising manufacturer +commenced to make endless tar paper in +place of sheets. Special apparatus were constructed +to impregnate these rolls with tar; they were imperfect +at first, but gradually improved to a high degree. +Much progress was also made in the construction of +the roofs, and several methods of covering were devised. +The defects caused by the old method of nailing +the tar paper direct upon the roof boarding were +corrected; the consequence of this method was that +the paper was apt to tear, caused by the unequal expansion +of the roofing boards and paper, and this soon +led to the idea of making the latter independent of the +former by nailing the sides of the paper upon strips +running parallel with the gable. The use of endless +tar paper proved to be an essential advantage, because +the number of seams as well as places where it had to +be nailed to the roof boarding was largely decreased. +The manufacture of tar paper has remained at about +the same stage and no essential improvements have +been made up to the present. As partial improvement +may be mentioned the preparation of tar, especially +since the introduction of the tar distillery, and the +manufacture of special roof lacquers, which have been +used for coating in place of the coal tar. As an essential +progress in the tar paper roofing may be mentioned +the invention of the double tar paper roof, and the +wood cement roof, which is regarded as an offshoot.</p> + +<p>The tar paper industry has, within the last forty +years, assumed great dimensions, and the preferences +for this roofing are gaining ground daily. In view of +the small weight of the covering material, the wood +construction of the roof can be much lighter, and the +building is therefore less strained by the weight of the +roof than one with the other kind, so that the outer +walls need not be as heavy. Considering the price, the +paper roof is not only cheaper than other fireproof +roofs, but its light weight makes it possible for the +whole building to be constructed lighter and cheaper. +The durability of the tar paper roof is satisfactory, if + +carefully made of good material; the double tar paper +roof, the gravel double roof, and the wood cement +roof are distinguished by their great durability.</p> + +<p>These roofs may be used for all kinds of buildings, +and not only are factories, storehouses, and country +buildings covered with it, but also many dwellings. +The most stylish residences and villas are at present +being inclosed with the more durable kinds; the double +roof, the gravel double roof, and the wood cement +roof. For factory buildings, which are constantly +shaken by the vibrations of the machinery, the tar paper +roof is preferable to any other.</p> + +<p>In order to ascertain to what degree tar paper roofs +would resist fire, experiments were instituted at the +instigation of some of the larger manufacturers of roofing +paper, in the presence of experts, architects, and +others, embracing the most severe tests, and it was +fully proved that the tar paper roof is as fireproof as +any other. These experiments were made in two different +ways; first, the readiness of ignition of the tar +paper roof by a spark or flame from the outside was +considered, and, second, it was tested in how far it +would resist a fire in the interior of the building. In +the former case, it was ascertained that a bright, intense +fire could be kept burning upon the roof for some +time, without igniting the woodwork of the roof, but +heat from above caused some of the more volatile constituents +of the tar to be expelled, whereby small +flames appeared upon the surface within the limits of +the fire; the roofing paper was not completely destroyed. +There always remained a cohesive substance, +although it was charred and friable, which by reason +of its bad conductivity of heat protected the roof +boarding to such an extent that it was "browned" +only by the developed tar vapors. A fire was next +started within a building covered with a tar paper +roof; the flame touched the roof boarding, which partly +commenced to char and smoulder, but the bright burning +of the wood was prevented by the air-tight condition +of the roof; the fire gases could not escape from +the building. The smoke collecting under the roof +prevented the entrance of fresh air, in consequence of +which the want of oxygen smothered the fire. The +roofing paper remained unchanged. By making openings +in the sides of the building so that the fire gases +could escape, the wood part of the roof was consumed, +but the roofing paper itself was only charred and did +not burn. After removing the fire in contact with the +paper, this ceased burning at once and evinced no disposition +whatever to spread. In large conflagrations, +also, the tar paper roofs behaved in identically a similar +manner. Many instances have occurred where the +tar paper roof prevented the fire from spreading inside +the building, and developing with sufficient intensity +to work injury.</p> + +<p>As it is of interest to the roofer to know the manner +of making the material he uses, we give in the following +a short description of the manufacture of roofing +paper. At first, when square sheets were used exclusively, +the raw paper consisted of ordinary dipped or +formed sheets. The materials used in its manufacture +were common woolen rags and other material. In order +to prepare the pulp from the rags it is necessary to +cut them so small that the fabric is entirely dissolved +and converted into short fibers. The rags are for this +purpose first cut into pieces, which are again reduced by +special machines. The rags are cut in a rag cutting +machine, which was formerly constructed similar to a +feed cutter; later on, more complicated machines of +various constructions were employed. It is not our +task to describe the various kinds, but we remain content +with the general remark that they are all based +on the principles of causing revolving knives to operate +upon the rags. The careful cleansing of the cut rags, +necessary for the manufacture of paper, is not required +for roofing paper. It is sufficient to rinse away +the sand and other solid extraneous matter. The further +reduction of the cut rags was formerly performed +in a stamp mill, which is no longer employed, the pulp +mill or rag engine being universally used.</p> + +<p>The construction of this engine may be described as +follows: A box or trough of wood, iron, or stone is by +a partition divided into two parts which are connected +at their ends. At one side upon the bottom of the +box lies an oakwood block, called the back fall. In a +hollow of this back fall is sunk the so-called plate, +furnished with a number of sharp steel cutters or +knives, lying alongside of each other. A roller of solid +oakwood, the circumference of which is also furnished +with sharp steel cutters or knives, is fastened upon a +shaft and revolves within the hollow. The journal +bearings of the shaft are let into and fastened in movable +wooden carriers. The carriers of the bearings +may be raised and lowered by turning suitable thumbscrews, +whereby the distance between the roller and +the back fall is increased or decreased. The whole is +above covered with a dome, the so-called case, to prevent +the throwing out of the mass under the operation +of grinding. The roller is revolved with a velocity +of from 100 to 150 revolutions per minute, whereby +the rags are sucked in between the roller and the back +fall and cut and torn between the knives. At the beginning +of the operation, the distance between the +roller and the back fall is made as great as possible, +the intention being less to cut the rags than to wash +them thoroughly. The dirty water is then drawn off +and replaced by clean, and the space of the grinding +apparatus is lessened gradually, so as to cut the rags +between the knives. The mass is constantly kept in +motion and each piece of rag passes repeatedly between +the knives. The case protects the mass from +being thrown out by the centrifugal force. The work +of beating the rags is ended in a few hours, and the +ensuing thin paste is drawn off into the pulp chest, +this being a square box lined with lead.</p> + +<p>From the pulp chest it passes to the form of the +paper machine. This form consists of an endless fine +web of brass wire, which revolves around rollers. The +upper part of this form rests upon a number of hollow +copper rollers, whereby a level place is formed. The +form revolves uniformly around the two end rollers, +and has at the same time a vibratory motion, by which +the pulp running upon the form is spread out uniformly +and conducted along, more flowing on as the +latter progresses. The water escapes rapidly through +the close wire web. In order to limit the form on the +sides two endless leather straps revolve around the +rollers on each side, which touch with their lower +parts the form on both sides and confine the fluid within +a proper breadth. The thickness of the pulp is regulated + +at the head of the form by a brass rule standing +at a certain height; its function is to level the +pulp and distribute it at a certain thickness. The +continually moving pulp layer assumes greater consistency +the nearer it approaches to the dandy roll. +This is a cylinder covered with brass wire, and is for +the purpose of compressing the paper, after it has left +the form, and free it from a great part of the water, +which escapes into a box. The paper is now freed of a +good deal of the fluid, and assumes a consistency with +which it is enabled to leave the form, which now commences +to return underneath the paper, passing on to +an endless felt, which revolves around rollers and delivers +it to two iron rolls. The paper passes through a +second pair of iron rollers, the interiors of which are +heated by steam. These rollers cause the last of the +water to be evaporated, so that it can then be rolled +upon reels. A special arrangement shaves the edges +to the exact size required.</p> + +<p>The paper is made in different thicknesses and designated +by numbers to the size and weight.</p> + +<p>Waste paper, bookbinders' shavings, etc., can be +used for making the paper. As much wool as possible +should be employed, because the wool fiber has a +greater resistance than vegetable fiber to the effects of +the temperature. By wool fiber is understood the +horny substance resembling hair, with the difference +that the former has no marrowy tissue. The covering +pellicle of the wool fiber consists of flat, mostly elongated +leaves, with more or less corners, lying over +each other like scales, which makes the surface of the +fiber rough; this condition, together with the inclination +of curling, renders it capable of felting readily. +Pure wool consists of a horny substance, containing +both nitrogen and sulphur, and dissolves in a potash +solution. In a clean condition, the wool contains +from 0.3 to 0.5 per cent. of ash. It is very hygroscopical, +and under ordinary circumstances it contains +from 13 to 16 per cent. humidity, in dry air from 7 to +11 per cent., which can be entirely expelled at a temperature +of from 226 to 230 degrees Fahrenheit. Wool +when ignited does not burn with a bright flame, as +vegetable fiber does, but consumes with a feeble +smouldering glow, soon extinguishes, spreading a disagreeable +pungent vapor, as of burning horn. By +placing a test tube with a solution of five parts caustic +potash in 100 parts water, a mixture of vegetable fibers +and wool fibers, the latter dissolve if the fluid is +brought to boiling above an alcohol flame, while the +cotton and linen fibers remain intact.</p> + +<p>The solubility of the woolen fibers in potash lye is a +ready means of ascertaining the percentage of wool +fiber in the paper. An exhaustive analysis of the latter +can be performed in the following manner: A +known quantity of the paper is slowly dried in a drying +apparatus at temperature of 230° Fahrenheit, until +a sample weighed on a scale remains constant. The +loss of weight indicates the degree of humidity. To +determine the ash percentage, the sample is placed in a +platinum crucible, and held over a lamp until all the +organic matter is burned out and the ash has assumed +a light color. The cold ash is then moistened with a +carbonate of ammonia solution, and the crucible +again exposed until it is dark red; the weight of the +ash is then taken. To determine the percentage of +wool, a sample of the paper is dried at 230° Fahrenheit +and weighed, boiled in a porcelain dish in potash +lye 12° B. strong, and frequently stirred with a glass +rod. The wool fiber soon dissolves in the potash lye, +while the vegetable fiber remains unaltered. The +pulpy mass resulting is placed upon a filter, dried at +212° Fahrenheit, and after the potash lye has dripped +off, the residue, consisting of vegetable fiber and earthy +ash ingredients, is washed until the water ceases to +dissolve anything. The residue dried at 212° Fahrenheit +is weighed with a filter, after which that of the +latter is deducted. The loss of weight experienced is +essentially equal to the loss of the wool fiber. If the +filtrate is saturated with hydrochloric acid, the dissolved +wool fiber separates again, and after having +been collected upon a weighed filter, it may be weighed +and the quantity ascertained.</p> + +<p>The weight of the mineral substances in the raw +paper is ascertained by analyzing the ash in a manner +similar to that above described. The several constituents +of the ash and the mineral added to the raw +paper are ascertained as follows: Sufficient of the +paper is calcined in the manner described; a known +quantity of the ash is weighed and thrown into a +small porcelain dish containing a little distilled water +and an excess of chemically pure hydrochloric acid. In +this solution are dissolved the carbonates, carbonate of +lime, carbonate of magnesia, a little of sulphate of +alumina, as well as metallic oxides, while silicate +of magnesia, silicic acid, sulphate of lime (gypsum) remain +undissolved. The substance is heated until the +water and excess of free hydrochloric acid have been +driven off; it is then moistened with a little hydrochloric +acid, diluted with distilled water and heated. +The undissolved residue is by filtering separated from +the dissolved, the filter washed with distilled water, +and the wash water added to the filtrate. The undissolved +residue is dried, and after the filter has also +been burned in due manner and the ash added, the +weight is ascertained. It consists of clay, sand, silicic +acid and gypsum.</p> + +<p>The filtrate is then poured into a cylinder capable of +holding 100 cubic centimeters, and furnished with a +scale; sufficient distilled water is then added until the +well-shaken fluid measures precisely 100 cubic centimeters. +By means of this measuring instrument, the +filtrate is then divided into two equal portions. One +of these parts is in a beaker glass over-saturated with +chemically pure chloride of ammonia, whereby any +iron of oxide present and a little dissolved alumina fall +down as deposit. The precipitate is separated by filtering, +washed, dried at 212° Fahrenheit and weighed. +To the filtrate is then added a solution of oxalate of +ammonia until a white precipitate of oxalate of lime is +formed. This precipitate is separated by filtering, +washed, dried and when separated from the filter, is +collected upon dark satinized paper; the filter itself is +burned and the ash added to the oxalate of lime. This +oxalate of lime is then heated to a dark red heat in a +platinum crucible with lid until the oxalate of lime is +converted into carbonate of lime. By the addition of +a few drops of carbonate of ammonia solution and another +slight heating of the crucible, also the caustic lime +produced in the filter ash by heating, is reconverted into +carbonate of lime, and after cooling in the exsiccator, + +the whole contents of the crucible is weighed as carbonate +of lime, after deducting the known quantity of filter +ash.</p> + +<p>Any magnesia present in the filtrate of the oxalate of +lime is by the addition of a solution of phosphate of +soda separated as phosphate of ammonia and magnesia, +after having stood twenty-four hours. The precipitate +is filtered off, washed with water to which a +little chloride of ammonia is added, dried, and after +calcining the fiber and adding the filter ash, glow +heated in the crucible. The glowed substance is +weighed after cooling, and is pyrophosphate of magnesia, +from which the magnesia or carbonate of magnesia +is calculated stoichiometrically. All the ascertained +sums must be multiplied by 2, if they are to correspond +to the analyzed and weighed quantity of +ash.</p> + +<p>The second half of the filtrate is used for determining +the small quantity of sulphate of lime still contained +in the hydrochlorate solution. By adding +chloride of barium solution the sulphuric acid is bound +to the barytes and sulphate of baryta separates as +white precipitate. This is separated by filtering, +washed, dried and weighed in the customary manner. +From the weight of the sulphate of baryta is then +computed the weight of sulphate of lime, which has +passed over into solution. The ascertained sum is also +to be multiplied with 2.</p> + +<p>The manufacture of roll tar paper from the roll paper +was at first found to be difficult, as it was impossible +to submerge a surface larger than from ten to fifteen +square yards, rolled up, in the tar, because more would +have required too large a pan. Besides this, the +paper tears easily, when it is in the hot tar. All kinds +of experiments were tried, in order to impregnate the +surface of the paper without employing too large a +pan.</p> + +<p>The following method was tried at first: The roll +paper was cut into lengths of ten yards, which were +rolled up loosely, so that a certain space was left between +the different coils. These loose rolls, of course, +occupied much space and could be put into the tar +only in a standing position, because in a horizontal +one the several coils would have pressed together +again. The loose roll was therefore slipped over a vertical +iron rod fastened into a circular perforated +wooden foot. The upper end of this iron rod ended in +a ring, in which the hook of a chain or rope could be +fastened. With the aid of a windlass the roll was +raised or lowered. When placed in the pan with boiling +tar, it was left there until thoroughly saturated. +It was then taken out, placed upon a table, and the +excess of tar allowed to drip off into a vessel underneath. +After partially drying, the roll was spread out +in open air, occasionally turned, until sufficiently dried, +when it was rolled up again.</p> + +<p>In order to neutralize the smeary, sticky condition +of the surface and avoid the disagreeable drying in +open air, the experiment of strewing sand on the sticky +places was tried next. The weight of the paper was +largely increased by the sand, and appeared considerably +thicker. For this reason the method of sanding +the paper was at once universally adopted. To dispense +with the process of permitting the surplus tar to +drip off, means were devised by which it was taken off +by scrapers, or by pressing through rollers. The +scrapers, two sharp edged rods fastened across the pan, +were then so placed that the paper was drawn through +them. The excess of tar adhering to its surface was +thereby scraped off and ran back into the pan.</p> + +<p>This work, however, was performed better and to +more satisfaction by a pair of rollers fastened to the pan. +These performed a double duty; thoroughly removed +the tar from the surface and by reason of their pressure +they caused a more perfect incorporation of the +tar with the fibers of the paper. Finally, different +factories employed different methods of manufacture, +one of which was to cut the rolls into definite lengths +of about ten yards; these were then rerolled very +loosely and immersed in the hot tar until sufficiently +saturated. The paper was then passed through the +roller, much pressure exerted, and then loosely rolled +up again. Being tarred once, it was then laid into a +second pan with hot tar, reeled out after a time, strewn +with sand, and rolled up again. Another method was +to cut clothes lines into lengths of about fifteen yards, +and at a distance of two inches have knots tied in +them. The paper was cut in lengths of ten or fifteen +yards, three pieces of the knotted clothes line were +then rolled between the loose coils of paper, which was +then submerged in the tar, which on account of the +knots could penetrate the paper. The paper was next +sanded by permitting its lower surface to pass over dry +sand in a box standing on the floor. A workman rolled +off the paper, and with his hand he strews sand on the +upper surface. The rolling taking place on the edge +of a table, by means of a crank, the excess of sand +dropped off.</p> + +<p>It is said by this method two workmen, one of which +tends to the rolling and sanding, the other turning +the crank, could turn out eighty rolls per day. This +method is still in use. It is useless to describe the +many antiquated methods in vogue in smaller factories, +and it can truthfully be said that nearly all of them +are out of date. It appears to be the fact of almost +all inventions that when reduced to practical use, +the arrangements, apparatus, and working methods +employed are generally of the most complicated nature, +and time and experience only will simplify them. +This has been also the case with the methods in the +roofing paper industry, which are at present gradually +being reduced to a practical basis. The method gradually +adopted has been described in the preceding. The +pan is of a certain length, whereby it becomes possible +to saturate the paper by slowly drawing it through +the heated tar. This is the chief feature. The work +is much simplified thereby and the workmen need not +dip their hands into the tar or soil them with it. The +work of impregnating has become much cleaner and +easier, while at the same time the tar can be heated to +a much higher temperature. The pan is generally +filled with distilled coal tar, and the heating is regulated +in such a manner that the temperature of the +impregnating mass is raised far beyond 212° Fahrenheit. +This accelerates the penetration, which takes +place more quickly as the degree of heat is raised, +which may be almost up to the boiling point of the tar, +as at this degree the paper is not destroyed by the +heat. In order to prevent the evaporation of the volatile +ingredients of the tar, the pan is covered with a + +sheet iron cover, with a slot at the place where the +paper enters into the impregnating mass and another +at the place where it issues. The tar is always kept +at the same level, by occasional additions.</p> + +<p>The roll of paper is mounted upon a shaft at the +back end of the pan, and by suitable arrangement of +guide rollers it unwinds slowly, passes into the tar in +which it is kept submerged. The guide rollers can be +raised so that when a new roller is set up they can be +raised out of the tar. The end of the paper is then +slipped underneath them above the surface of the tar, +when having passed through the squeezing rollers, it +is fastened to the beaming roller, and the guide rollers +are submerged again. A workman slowly turns the +crank of the beaming roller.</p> + +<p>This motion draws the paper slowly through the +fluid, the roll at the back end unwinding. The speed +with which the squeezing rollers are turned is regulated +in such a manner that the paper remains sufficiently +long underneath the fluid to be thoroughly +impregnated with it. The workmen quickly learn by +experience how fast to turn the crank. The hotter the +tar, the more rapid the saturation; the high degree of +heat expels the air and evaporates the hygroscopic +fluid in the pores of the paper. The strong heating of +the tar causes another advantage connected with this +method. The surface of the paper as it issues from the +squeezing rollers is still very hot, and a part of the +volatile oils evaporate very quickly at this high temperature. +The surface is thereby at once dried to a +certain degree and at the same time receives a handsome +luster, as if it had been coated with a black lacquer. +The paper is sanded in a very simple manner +without the use of mechanical apparatus; as it is being +wrapped into a coil, it passes with its lower surface +over a layer of sand, while the workman who tends to +rolling up strews the inside with sand. The lower +surface is coated very equally. Care only being necessary +that the sand lies smooth and even at all times. +When the workman has rolled up ten or fifteen yards, +he cuts it across with a knife and straightedge, so that +the paper is cut at right angles with its sides.</p> + +<p>There are three different sorts of roofing paper, +according to the impregnating fluid used in its manufacture. +The ordinary tar paper is that saturated with +clear cold tar. This contains the greatest amount of +fluid ingredients and is very raggy in a fresh condition. +It is easy to see that the volatile hydrocarbons evaporate +in a short time, and when expelled, the paper +becomes stiffer and apparently drier. This drying, +or the volatilization of the hydrocarbons, causes pores +between the fibers of the paper. These pores are +highly injurious to it, as they facilitate a process of +decomposition which will ruin it in a short time.</p> + +<p>Roofing paper can be called good only when it is +essentially made from woolen rags, and contains either +very few or no earthy additions. It is beyond doubt +that the durability of a roofing paper increases with +the quality of wool fiber it contains--vegetable fibers +and earthy additions cause a direct injury. Reprehensible +altogether is any combination with lime, +either in form of a carbonate or sulphate, because the +lime enters into chemical combination with the decomposition +products of the tar.</p> + +<p>The general nature of gravel is too well known to +require description. The grains of quartz sand are +either sharp cornered or else rounded pieces of stone of +quartz, occasionally mixed with grains of other amorphous +pieces of silica--such as horn stone, silicious +slate, carnelian, etc.; again, with lustrous pieces of +mica, or red and white pieces of feldspar. The gravel +used for a tar paper roof must be of a special nature +and be prepared for the purpose. The size of its grains +must not exceed a certain standard--say, the size of a +pea. When found in the gravel bank, it is frequently +mixed with clay, etc., and it cannot be used in this +condition for a roof, but must be washed. The utensils +necessary for this purpose are of so simple and suggestive +a nature that they need not be described. Slag +is being successfully used in place of the gravel. It is +easily reduced to suitable size, by letting the red hot +mass, as it runs from the furnace, run into a vessel +with water. The sudden chilling of the slag causes it +to burst into fragments of a sharp cornered structure. +It is next passed through a sieve, and the suitably +sized gravel makes an excellent material, as it gives a +clean appearance to the roof.</p> + +<p>The thinking mind can easily go one step further +and imagine that, since the tar contains a number of +volatile hydrocarbons, it might be made more adaptable +for impregnation by paper by distilling it, as by +this process the fluid would lose its tendency to evaporate +and the percentage of resinous substances increase. +Singular to say, there was a prejudice against +the employment of distilled tar, entertained by builders +and people who had no knowledge of chemistry. +Increasing intelligence and altered business circumstances, +however, brought about the almost universal +employment of distilled tar, and every large factory +uses it at present. The roofing paper prepared with +distilled tar is perhaps most suitably called asphaltum +paper, as this has been used in its manufacture. It +possesses properties superior to the ordinary tar paper, +one of which is that immediately after its manufacture, +as soon as cold, it is dry and ready for shipment; +nor does it require to be kept in store for a length of +time, and it has also a good, firm body, being as flexible +and tough as leather. It is very durable upon the roof, +and remains flexible for a long time. It is true that +asphaltum papers will always in a fresh state contain +a small percentage of volatile ingredients, which after +a while make it hard and friable upon the roof; but, +by reason of its greater percentage of resinous components, +it will always preserve a superior degree of +durability and become far less porous. One hundred +parts by weight absorb 140 or 150 parts by weight of coal +tar. A factory which distilled a good standard tar for +roofing paper recovered, besides benzole and naphtha, +also about ten per cent. of creosote oil, used for one +hundred parts raw paper, 176.4 partially distilled tar. +Experiments on a larger as well as a smaller scale +reduced this quantity to an average of 141.5 parts for +one hundred parts raw paper. The weight of sanded +paper is very variable, as it depends altogether upon +the size of the sand grains. It may be stated generally +that the weight of the sand is as large as that of the +tarred paper.</p> + +<p>The kinds of roofing paper saturated with other additions +besides coal tar form a separate class, in order +to neutralize the defects inherent in coal tar. These + +additions were originally for the purpose of thickening +the paper and making it stiffer and drier. The most +ordinary and cheapest thickener was the coal pitch. +Although the resinous substances are increased thereby, +still the light tar oils remain to evaporate, and the +paper prepared with such a substance readily becomes +hard and brittle. A better addition is the natural asphaltum, +because it resists better the destroying influence +of the decomposition process, and also, to a +certain degree, protects the coal tar in which it is dissolved. +The addition of natural asphaltum doubtless +caused the name of "asphaltum roofing paper." +Resin, sulphur, wood tar and other substances were +also used as additions; each manufacturer kept his +method secret, however, and simply pointed out by +high sounding title in what manner his paper was +composed. In most cases, however, this appellation +was applied to the ordinary tar paper; the impregnating +substance was mixed only with coal pitch, or +else a roofing paper saturated with distilled tar. The +costly additions, by the use of which a high grade of +roofing paper can doubtless be produced, largely +increased its price, and on account of the constant fall +of prices of the article, its use became rather one of +those things "more honored in the breach than in the +observance," and was dispensed with whenever practicable. +The crude paper is the foundation of the +roofing paper. The qualities of a good, unadulterated +paper have already been stated. At times, the crude +paper contains too many earthy ingredients which +impair the cohesion of the felted fibrous substance, +and which especially the carbonate of lime is very +injurious, as it readily effects the decomposition of the +coal tar. The percentage of wool, upon which the +durability of the paper depends very largely, is very +small in some of the paper found in the market. In +place of woolen rags, cheap substitutes have been +used, such as waste, which contains vegetable fibers. +Since this cannot resist the decomposition process for +any length of time, it is evident that the roofing paper +which contains a noticeable quantity of vegetable +fibers cannot be very durable. To judge from the endeavors +made to improve the coal tar, it may be concluded +that this material does not fully comply with +its function of making the roofing paper perfectly and +durably waterproof. The coal tar, be it either crude +or distilled, is not a perfect impregnating material, +and the roofing paper, saturated with it, possesses +several defects. Let us in the following try to ascertain +their shortcomings, and then express our idea in +what manner the roofing paper may be improved. It +was previously mentioned that every tar roofing paper +will, after a greater or smaller lapse of time, assume a +dry, porous, friable condition, caused by the volatilization +of a part of the constituents of the tar. This +alteration is materially assisted by the oxygen of the +air, which causes the latter to become resinous and +exerts a chemical influence upon them. By the volatilization +of the lighter tar oils, pores are generated between +the fibers of the roofing paper, into which the +air and humidity penetrate. In consequence of the +greatly enlarged surface, not only the solid ingredients +of the tar, which still remain unaltered, are exposed +to the action of the oxygen, but also the fibers of the +roofing paper are exposed to decomposition. How destructive +the alternating influence of the oxygen and +the atmospheric precipitations are for the roofing +paper will be shown by the following results of tests. +It will have been observed that the rain water running +from an old paper roof, especially after dry weather, +has a yellowish, sometimes a brown yellow color. The +supposition that this colored rain water might contain +decomposition products of the roofing paper readily +prompted itself, and it has been collected and analyzed +at different seasons of the year. After a period of +several weeks of fair weather during the summer, rain +fell, and the sample of water running from a roof was +caught and evaporated; the residue when dried +weighed 1.68 grammes. It was of a brownish black color, +fusible in heat and readily soluble, with a yellow brown +color in water. The dark brown substance readily +dissolved in ammonia, alcohol, dilute acid, hydrochloric +acid, sulphuric acid, and decomposed in nitric +acid, but did not dissolve in benzine or fat oil. After +several days' rain during the summer, a quantity of +the water was caught, evaporated, and the residue +dried. Its characteristics were similar to those above +mentioned. By an experiment instituted in water +under conditions similar to the first mentioned, the +dry brown substance weighed 71 grammes. It possessed +the same characteristics. In the solution effected with +water containing some aqua ammonia of the brown +substance, a white precipitate of oxalate of lime occurred +when an oxalate of ammonia solution was +added, but the brown substance remained in solution. +A further precipitation of oxalate of lime was produced +by a solution of oxalic acid, but the brown organic +substance remained in solution. This organic +substance being liberated from the lime was evaporated, +and left a dry, resinous, fusible brownish black +substance, which also dissolved readily in water. It +will be seen from these trials that the substance obtained +from the rain water running from a paper roof +is a combination of an organic acid with lime, which +readily dissolves in water, and that also the free organic +acid combined with the lime dissolves easily in +water.</p> + +<p>The question concerning the origin of this organic +substance or its combination with lime can only be +answered in one way, viz., that it must have been +washed by the rain water out of the paper. But since +such a solid substance, easily soluble in water, is contained +neither in the fresh roofing paper nor in the +coal tar, the only deduction is that it must have +arisen by the decomposition of the tar, in consequence +of the operation of the oxygen. The lime comes from +the coating substance of the roof, for which tar mixed +with coal pitch was used. The latter was fused with +carbonate of lime. These analyses furthermore show +that the formation of the organic acid easily soluble in +water depends upon the season; and that a larger +quantity of it is generated in warm, sunny weather +than in cold, without sunshine. This peculiarity of +the solid, resinous constituents of the coal tar, to be by +the operation of the atmospheric oxygen altered into +such products that are readily soluble in water, makes +the tar very unsuitable as a saturative substance for a +roofing paper. How rapidly a paper roof can be +ruined by the generation of this injurious organic acid +will be seen from the following calculation: Let us + +suppose that an average of 132 gallons of rain water +falls upon ten square feet roof surface per year, and +that the arithmetical mean 0.932 of the largest (1.680) +and smallest number (0.184) be the quantity of the +soluble brown substance which on an average is dissolved +in one quart of rain water; hence from ten +square feet of roof surface are rinsed away with the +rain water per year 466 grammes of the soluble decomposition +products of the tar. The oxidation process +will not always occur as intensely as by a paper roof, +ten years old and painted two years ago, which instigated +above described experiment. As long as the +roofing paper is fresh and less porous, especially if the +occurring pores are filled and closed again by repeated +coatings, oxidation will take place far less rapidly. +Besides this, the protective coating applied to the roof +surface is exposed most to this oxidation process. +Even by assuming this constantly progressive destructive +action of the oxygen on the roofing paper to be +much less than above stated, we can readily imagine +that it must be quite large. If it is desired to produce +a material free of faults, it is first of all indispensable +that unobjectionable raw material be procured. Coal +tar was formerly used almost exclusively for the coating +of a roof. It was heated and applied hot upon the +surface. In order to avoid the running off of the thinly +fluid mass, the freshly coated surface was strewn with +sand. The most volatile portion of the tar evaporated +soon, whereby the coating became thicker and finally +dried. The bad properties of the coal tar, pointed out +elsewhere, made it very unsuitable even for this purpose, +and experiments were instituted to compound +mixtures, by adding other ingredients to the tar, that +should more fully comply with its function. It may +be said in general that the coating masses for roofs can +be divided into two classes: either as lacquers or as +cements. To the former may be classed those of a +fairly thinly fluid consistency, and which contain +volatile oils in such quantities that they will dry +quickly. Cements are those of a thickly fluid consistency, +and are rendered thus fluid by heating. It is +not necessary that the coating applied should harden +quickly, as it assumes soon after its application a firmness +sufficient to prevent it from running off the roof. +Coal tar is to be classed among lacquers. If it has been +liberated by distillation from the volatile oils, it is +made better suited for the purpose than the ordinary +kind. The mass contains much more asphaltum, and +after drying, which takes place soon, it leaves a far +thicker layer upon the roof surface, while the pores, +which had formed in the roofing paper consequent on +drying, are better filled up. Nevertheless, the distilled +tar also has retained the property of drying with time +into a hard, vitreous mass, and ultimately to be destroyed +by decomposition.--<i>The Roofer</i>.</p> + +<hr /> + +<a name="phys1"></a><h2>A PHYSICAL LABORATORY INDICATOR.</h2> + +<p>The difficulties attending the management of a +physical laboratory are much greater than those of a +chemical one. The cause of this lies in the fact that +in the latter the apparatus is less complicated and the +pieces less varied. Any contrivance that will reduce +the labor and worry connected with the running of a +laboratory is valuable.</p> + +<p>A physical laboratory may be arranged in several +ways. The apparatus may be kept in a store room +and such as is needed may be given to the student each +day and removed after the experiments are performed; +or the apparatus for each experiment or system of experiments +may be kept in a fixed place in the laboratory +ready for assembling; for certain experiments +the apparatus may be kept in a fixed place in the laboratory +and permanently arranged for service.</p> + +<p>Each student may have his own desk and apparatus +or he may be required to pass from desk to desk. The +latter method is preferable.</p> + +<p>When a store room is used the services of a man are +required to distribute and afterward to collect. If the +apparatus is permanently distributed, a large room is +necessary, but the labor of collecting and distributing +is done away with.</p> + +<p>There are certain general experiments intended to +show the use of measuring instruments which all students +must perform. To illustrate the use of the indicator +I have selected an elementary class, although +the instrument is equally applicable to all classes of +experiments.</p> + +<p>Having selected a suitable room, tables may be +placed against the walls between the windows and at +other convenient places. Shallow closets are built +upon these tables against the wall; they have glass +doors and are fitted with shelves properly spaced. A +large number of light wooden boxes are prepared, +numbered from one up to the limit of the storage +capacity of the closets. A number corresponding to +that upon the box is placed upon the shelf, so that +each one after removal may be returned to its proper +place without difficulty. On the front of the box is a +label upon which is written the experiment to be +performed or the name of the apparatus whose use +is to be learned, references to various books, which may +be found in the laboratory library, and the apparatus +necessary for the experiment, which ought to be +found in the box. If any parts of the apparatus are +too large to be placed in the box, the label indicates +by a number where it may be found in the storage +case.</p> + +<p>It is evident that, instead of the above arrangement, +all the boxes can be stacked in piles in a general +store room. The described arrangement is preferable, +as it prevents confusion in collecting and distributing +apparatus when the class is large.</p> + +<p><i>The Indicator</i> (see figure).--Some device is evidently +desirable to direct the work of a laboratory with the +least trouble and friction possible. I have found that +the old fashioned "peg board," formerly used in schools +to record the demerits of scholars, modified as in the +following description, leaves nothing to be desired.</p> + +<p>The requirements of such an instrument are these: +It must show the names of the members of the class; +it must contain a full list of the experiments to be performed; +it must refer the student to the book and +page where information in reference to the experiments +or apparatus may be found; it must show what +experiments are to be performed by each student at a +given time; it must give information as to the place +in the laboratory where the apparatus is deposited; it +must show to the instructor what experiments have +been performed by each student; it must prevent the + +assignment of the same experiment to two students; +it must enable the instructor to assign the same experiment +to two or more students; it must form a complete +record of what has been done, what work is incomplete, +and what experiments have not yet been assigned; +it must also be so arranged that new experiments +or sets of experiments may be exhibited.</p> + +<p class="ctr"><img src="images/4-chart.png" width="264" height="397" alt="" title=""> +<br clear="all" />A, B, C, etc., are cards upon which are the names of +students. 1, 2, 3, etc., are cards like the one +described in the article. The small circles represent +unassigned experiments. The black circles (slate +nails) represent work done. The caudate circles +(brass nail) represent work assigned.</p> + +<p>The indicator consists of a plank of any convenient +length and breadth. The front surface is divided into +squares of such size that the pegs may be introduced +and withdrawn with ease. At each corner of the +squares holes are bored into which nails may be +placed. There is a blank border at the top and another +on the left side. At the top of each vertical +column of holes is placed a card holder. This is made +of light tin turned up on the long edges--which are +vertical--and tacked to the board. Opposite each +horizontal row of holes is a similar tin card holder, +but of greater length, and having its length horizontal. +The holders at the top of the board contain +cards upon which the names of the class are written.</p> + +<p>Cards, like the following, are prepared for the horizontal +holders.</p> + +<pre> +-------------------------------------------------------------- +Stewart & Gee 229 +Physical Manip. 85 Intensity of Gravity--Borda's Method 39 +Glazebrook & Shaw 132 +-------------------------------------------------------------- +</pre> + +<p>These cards are numbered from one to any desired +number and are arranged in the holders consecutively.</p> + +<p>Two kinds of nails are provided to fit the holes in +the board: An ordinary slate nail and a common picture +frame nail with a brass head. The latter indicates +work to be done, the former work done.</p> + +<p>To prepare the board for service, brass headed nails +are placed opposite each experiment, and below the +names, care being taken not to have more than one +nail in the same horizontal row, unless it is intended +that two persons or more are to work upon the same +experiment.</p> + +<p>There will be no conflict when the brass nails occupy +diagonal lines. If they do not, a glance will show the +fact.</p> + +<p>After an experiment has been performed and a report +made upon the usual blank, the brass nail is removed +and a slate nail put in its place.</p> + +<p>The board will show by the slate nails what work +has been done by each student, by the brass nails what +is yet to be done, and by the empty holes, experiments +which have been omitted or are yet to be assigned. A +slate nail opposite an experiment card indicates that +that experiment may now be assigned to another person.</p> + +<p>It is evident that the schedule for a whole term may +be arranged in a few minutes and that the daily +changes require very little time.</p> + +<p>The board is hung in a convenient place. The student +as he enters the laboratory looks for his name on +the upper cards and under it for the first brass nail in +the vertical column: to the left he finds the experiment +card. On the left hand end of the slip he sees the book +references, on the right hand end a number--39 in the +sample card given above. Knowing the number, he +proceeds to a desk and finds a box numbered in the +same manner. He removes the box from the closet. +On the label of the box is a list of all the apparatus +necessary, which he will find in the box; the label also +contains the book references. He performs the experiment, +fills up a blank which he gives to the instructor, +puts all the materials back in the box, replaces the +box in its proper place in the closet and proceeds with +the next experiment. With this indicator there is no +difficulty in managing fifty students or more.</p> + +<p>Comparatively little apparatus need be duplicated. +Where apparatus is fixed against a wall a number may +be tacked upon the wall and a card containing the +information desired. The procedure is then the same as +with the boxes. The cards on the board being removable, +other ones may be inserted containing information +in reference to other boxes having the same number +but containing different materials. + +There can be no successful tampering with the board, +for the record of experiments performed is upon the +blanks which the students turn in and also in the individual +note books which are written up and given +to the instructor for daily examination.</p> + +<p class="ctr"><b>Lafayette College.<br /> J.W. MOORE.</b></p> + +<hr /> + +<a name="misc5"></a><h2>NEW METHOD OF EXTINGUISHING FIRES</h2> + +<p>This is by George Dickson, of Toronto, Canada, and +David Alanson Jones.</p> + +<p>A mixture of water and liquefied carbon dioxide upon +being discharged through pipes at high pressure +causes the rapid expansion of the gas and converts the +mixture into spray more or less frozen, and portions of +the liquid carbon dioxide are frozen, owing to its +rapid expansion, and are thus thrown upon the fire +in a solid state, where said frozen carbon dioxide in its +further expansion not only acts to put out the fire, +but cools the surface upon which it falls, and thus +tends to prevent reignition.</p> + +<p>A represents a receptacle sufficiently strong to stand +a pressure of not less than a thousand pounds to the +square inch.</p> + +<p>B B water receptacles.</p> + +<p class="ctr"><img src="images/4-fig1.png" width="356" height="154" alt="Fig. 1" title=""> +<br clear="all" />FIG. 1</p> + +<p>In the drawings we have shown two receptacles B +and only one receptacle A; but we do not wish to confine +ourselves to any particular number, nor do we +wish to confine ourselves to the horizontal position in +which the receptacles are shown.</p> + +<p>C is a pipe leading from the receptacle A to a point +at or near the bottom of the receptacle B.</p> + +<p>F is a pipe through which the mixture of water and +liquefied gas from the receptacle B is forced by the +expansion of said liquefied gas, the said pipe taking +the mixture of water and liquefied gas from the bottom +of the receptacle.</p> + +<p class="ctr"><img src="images/4-fig2.png" width="310" height="161" alt="Fig. 2" title=""> +<br clear="all" />FIG. 2</p> + +<p>To use the apparatus, open the stop cock D in the +pipe C, leading to one of the receptacles B, whereupon, +owing to the lower pressure in the cylinder B, the +liquid carbon dioxide expands and rises to the top of +the cylinder A and forces the liquid carbon dioxide into +the cylinder B, the same as the superior steam of a +boiler forces the water of the boiler out when the same +is tapped below the surface of the liquid. Now upon +opening the tap H, this superior gas forces out the +mixture of water and liquid carbon dioxide, which +suddenly expanding causes portions of the globules of +liquefied gas to be frozen, and these, being protected +by a rapidly evaporating portion of the liquefied gas, +are thrown on the fire in solid particles. At the same +time the water is blown into a spray, which is more +or less frozen. The fire is thus rapidly extinguished by +the vaporization of the carbon dioxide and water spray.</p> + +<hr /> + +<a name="tech2"></a><h2>SMOKELESS GUNPOWDER.</h2> + +<h3>By HUDSON MAXIM.</h3> + +<p>During the last forty years leading chemists have +continued to experiment with a view to the production +of a gunpowder which should be smokeless. But not +until the last few years has any considerable degree of +success been attained.</p> + +<p>To be smokeless, a gunpowder must yield only gaseous +products of combustion. None of the so-called +smokeless powders are entirely smokeless, although +some of them are very nearly so.</p> + +<p>The smoke of common black gunpowder is largely +due to minute particles of solid matter which float in +the air. About one-half of the total products of combustion +of black gunpowder of ordinary composition +consists of potassium carbonate in a finely divided condition +and of potassium sulphate, which is produced +chiefly by the burning in the air of potassium sulphide, +another production of combustion, as on the outrushing +gases it is borne into the air in a fine state of +division.</p> + +<p>Another cause for the smoke of gunpowder is the +formation of small liquid vesicles which condense from +some of the products of combustion thrown into the +air in a state of vapor, in the same manner as vesicles +of aqueous vapor form in the air on the escape of highly +heated steam from the whistle of a locomotive.</p> + +<p>Broadly speaking, an explosive compound is one +which contains, within itself, all the elements necessary +for its complete combustion, and whose +heated gaseous products occupy vastly more space +than the original compound. Such compound usually +consists of oxygen, associated with other elements, for +which it has great affinity, and from which it is held +from more intimate union, or direct chemical combination, +under normal conditions, by being in combination +as well with other elements for which it has less +affinity, but which it readily gives up for the stronger +affinities when explosion takes place, the other elements +either combining with one another to form new +compounds or being set free in an uncombined state.</p> + +<p>An explosive is said to detonate when the above +changes take place instantaneously, the action being +transmitted with the speed of electricity by a sort of +molecular rhythm from molecule to molecule throughout +the entire substance of the compound.</p> + +<p>An explosive is said to explode when the above + +changes do not occur instantaneously throughout the +whole substance, but whose combustion takes place +from the surface inward of the particles or grains of +which it is composed, thus requiring some definite +lapse of time.</p> + +<p>The elements of an explosive compound may be associated +chemically as in nitro-glycerine and gun-cotton, +which are chemical compounds, being the results of definite +reactions. Or, an explosive may be a mere mechanical +mixture of different substances comprising the +necessary elements, as is ordinary black gunpowder, +which is a compound of charcoal, sulphur and saltpeter, +the saltpeter supplying the necessary oxygen.</p> + +<p>No gunpowder can be smokeless in which saltpeter +or any oxygen-bearing salt having a metallic base is +employed, for when the salt gives up its oxygen, the +base combines with other elements to produce a sulphate, +a carbonate, or other salt, which, being solid, +produces smoke. Therefore, to be smokeless, a gunpowder +must contain no other elements than oxygen, +hydrogen, nitrogen, and carbon, and in such proportions +that the products of combustion shall be +wholly gaseous. The nitric ethers--gun-cotton and +nitro-glycerine--constitute such explosive compounds. +These substances were formerly thought to be nitro-substitution +compounds, but are now known to belong +to the compound ethers of nitric acid.</p> + +<p>Gun-cotton, discovered by Schonbein, in 1845, has +since been looked upon as the most promising material +for a smokeless gunpowder, it being a very powerful +explosive and burning with practically no smoke. To-day, +gun-cotton, in some form or other, constitutes the +base of substantially all of the smokeless powders with +which have been attained any considerable degree of +success.</p> + +<p>Gun-cotton alone and in its fibrous state has been +found to be too quick, or violent, for propulsive purposes, +such as use in firearms; as under such conditions +of confinement it is very likely to detonate and +burst the gun. However, if gun-cotton be dissolved in +a suitable solvent, which is capable of being evaporated +out, such as acetone, or acetate of ethyl, which +are very volatile, it becomes, when thus dissolved and +dried, a very hard, horn-like, amorphous substance, +which may be used for a smokeless gunpowder. But +this substance taken alone is very difficult to mould or +granulate, and the loss of expensive solvents must +necessarily be quite considerable.</p> + +<p>When gun-cotton is reduced to a collodial solid, as +above, and used as a smokeless gunpowder, the grains +must be made comparatively small to insure prompt +and certain ignition, and consequently the pressures +developed in the gun are apt to be too great when +charges sufficiently large are used to give desired velocities.</p> + +<p>If, however, a compound be made of gun-cotton and +nitro-glycerine, in about equal parts, by means of +a volatile solvent or combining agent, such as one of +the before mentioned, and the solvent evaporated out, +we obtain practically a new substance and one which, +as regards its explosive nature, is quite unlike either of +its two constituents taken alone. The nitro-glycerine, +furthermore, being itself a solvent of gun-cotton, much +less of the volatile ether is necessary to render the compound +of an amorphous character. Being quite plastic +this substance may be wrought or moulded into any +desired size or form of grain.</p> + +<p>This simple compound of nitro-glycerine and gun-cotton, +or with some slight modifications, has been +found, when properly granulated, to be the most +smokeless powder that has yet been discovered or invented. +If pure chemicals are employed in the manufacture, +and the gun-cotton and nitro-glycerine be +made of the highest nitration and best quality, we +have a smokeless powder which will possess the following +desirable qualities:</p> + +<p>1st. It is absolutely smokeless, that is, its products +of combustion are entirely gaseous.</p> + +<p>2d. Its products of combustion are in no way deleterious +or unpleasant.</p> + +<p>3d. It is perfectly safe to manufacture, handle and +transport. There is no more danger of its exploding +accidentally than there would be of an explosion of +shavings or sawdust; for, unless well confined and set +off with a strong primer, it will not explode at all. In +the open its combustion is so slow as to in no way resemble +or partake of the nature of an explosion.</p> + +<p>4th. It is perfectly stable, and will keep any length +of time absolutely without undergoing any change +whatever, under all conditions of temperature or exposure +to which gunpowder would ever be subjected.</p> + +<p>5th. It is not hygroscopic, and may be soaked in water +without being at all affected by it.</p> + +<p>6th. It will not corrode the cartridge case.</p> + +<p>7th. It will not foul the gun.</p> + +<p>8th. It is sure of ignition with a good primer, and +may be made to burn as slowly as desired by varying +the character and size of the grains. Indeed, it may +be made to burn so slowly as to fail of complete combustion +before the bullet leaves the gun, and after firing +several rounds, partly burned pieces of the powder +may be picked up in front of the gun.</p> + +<p>9th. In a shoulder arm, a velocity of 2,000 feet per +second may be imparted to the bullet with this powder, +and with a pressure in the chamber of the gun of +not more than fifteen English tons. This is, of course, +when the gun, cartridge case, primer, and projectile +are adapted to the use of smokeless powder, and the +granulation of the powder is adapted to them.</p> + +<p>If what I have here claimed for the above smokeless +powder be true, it would appear that it may be taken +as really an ideal smokeless powder. Why, then, has +it not already been universally adopted? Surely such +a powder is just what every government is seeking. In +reply to this, let me say that, in order for the above +compound to be an effective and successful smokeless +powder, with the manifestation of the many desirable +qualities which I have recited, a great many other conditions +are necessary, some of which I will mention. +To arrive at the knowledge that this compound would +constitute the best smokeless powder has required a +great deal of experimenting. It was first thought that +gun-cotton colloid, without any nitro-glycerine, that is, +gun-cotton dissolved and dried, would burn more slowly, +keep better, and give better ballistics than it would +if combined with nitro-glycerine. It was also thought +that gun-cotton of a high degree of nitration when +made into colloidal form would even then burn too +quickly to be suitable for use in firearms. Consequently, +the first experiments were with low grade + +gun-cotton, what is called collodion cotton, such as is +employed in the manufacture of celluloid. But, as +this would not explode without the addition of some +oxygen-bearing element, various oxygen-bearing salts +were combined with it, such as nitrate of potassium, +nitrate of ammonia, nitrate of baryta, etc. Also a +great many of the first smokeless powders were made +of low grade gun-cotton combined with nitro-glycerine +in varying proportions. These powders would often +give very good results when first made; but low grade +gun-cotton or di-nitro-cellulose, as it is called, is a very +unstable compound, and these powders, after giving +very promising results, were found to be constantly +undergoing change, sooner or later resulting in complete +decomposition.</p> + +<p>When nitro-glycerine was first combined with gun-cotton +in small quantities, camphor was often added, +to lessen the rapidity of combustion which the nitro-glycerine +was supposed to impart and also to render +the compound more plastic, and to tend to prevent the +decomposition of the low grade gun-cotton. But +camphor being volatile, would, by its evaporation, +cause the powder to constantly change in character. +Castor oil has been found to be a better diluent, as +this will not evaporate.</p> + +<p>As all of the smokeless powders made of a low grade +gun-cotton were found to deteriorate and spoil, experiments +were made with gun-cotton of the highest degree +of nitration, both alone and in combination with +nitro-glycerine. These experiments were first conducted +in England by private parties and by the British government, +when it was found that high grade gun-cotton +would give excellent results if made into a colloidal +solid and used alone, or in combination with certain +other constituents. With a view to saving the large +quantity of solvents necessary to reduce the gun-cotton, +and to get a more prompt and certain ignition +with a larger grain, experiments were cautiously made +by the admixture of varying proportions of nitro-glycerine +to the gun-cotton when dissolved, or rather +along with other solvents in the process of dissolving +it.</p> + +<p>It was soon found that nitro-glycerine added in quantities, +even equal in weight to the gun-cotton itself, did +not materially increase the rapidity of the explosion +of the compound. And it was also found that high +grade gun-cotton, when combined with nitro-glycerine, +gave very much better results than low grade gun-cotton.</p> + +<p>I have spoken here of high and low grade gun-cotton, +when in fact the word gun-cotton should be applied +only to the highest nitro-compound of cellulose. +The word gun cotton has always been rather loosely +used. Pyroxyline would be a better word, as this applies +to all grades. When cotton fiber is soaked in a +large excess of a mixture of the strongest nitric and +sulphuric acids, gun-cotton proper, or that of the +highest grade, is produced. When weaker acids are +used, lower grades of nitro-cellulose are formed.</p> + +<p>The first mentioned or highest grade gun-cotton, +when thoroughly freed from its acids, has always +proved to be a perfectly stable compound. The lower +grades have always been found to be unstable and subject +to spontaneous decomposition. Nitro-glycerine +has also been erroneously thought to be a very unstable +compound. But experiments have proved that, +when made pure, it is perfectly stable.</p> + +<p>Having now explained how the knowledge came to +be arrived at that the aforementioned compound of +highest grade nitro-glycerine and highest grade gun-cotton +would constitute the best basis for a smokeless +powder, I will now mention a few of the other conditions +necessary to success with its use, without assuming +that smokeless powder has yet passed its experimental +stage, and is beyond further improvement. +Nevertheless, such is the compound which has come to +stay as the basis of all smokeless powders; and any +smokeless powder, if a successful one, may be counted +upon as being made of this compound of gun-cotton +and nitro-glycerine, or of a colloid of gun-cotton, either +alone or combined with diluents, oxygen-bearing +salts, or inert matter. The fact that smokeless powder +may still be said to be in somewhat of an experimental +stage is not to admit that it is not a success. Firearms, +cartridge cases, and projectiles are also still in an experimental +stage, for they are constantly being improved; +yet their use has been a great success for a good +many years.</p> + +<p>The question of success of a smokeless powder does +not rest alone with the powder itself. The gun, the +cartridge case, primer, and bullet have been as much +the subjects of experiments in adapting them to the +use of smokeless powder as has the smokeless powder +in being adapted to them. To impart a velocity of +2,000 feet per second to a rifle ball, with corresponding +long range and accuracy of flight, has been a question +as much of improvement in rifles and projectiles as +in the powder. To give a velocity of 2,000 feet per +second to a bullet, requires a pressure of at least 15 +English tons in the chamber of a gun. This would be +a dangerous pressure in an old-fashioned shoulder +arm; while a bullet made only of lead would strip on +striking the rifling and pass right through the barrel +of the gun without taking any rotary motion whatever. +It might at first seem that the powder is the only +thing to be considered; but high ballistics can only be +obtained when everything else is adapted to its use.</p> + +<p>The projectile, the cartridge case, the fulminating +cap, and the gun have had to be all built up together, +and a very large amount of experimenting has been +necessary to determine what would constitute the +best projectile, best cartridge case, best fulminating +cap, and what should be the character of the rifling +and the quality and temper of the steel of the gun +barrel.</p> + +<p>It has been necessary first to conduct experiments to +test the smokeless powders for velocities and pressures, +and then with the powders test various kinds of +projectiles and guns. In order to obtain the high ballistics +which have been secured, it has been found +necessary to cover the bullet with something harder +than lead and to rifle the gun in a special manner.</p> + +<p>The French, who were the first to definitely adopt +smokeless powder, were the first also to make a rifle, +projectile, cartridge case and primer suited to its use.</p> + +<p>To obtain long range with a small long bullet such +as is now used, it should rotate at a very high speed. +It is well known to artillerists that a projectile of four +or more calibers in length has to be rotated at a much +higher speed than one of half that length, in order to + +keep the projectile stiff in the air, and to prevent it +from ending over in its flight. To communicate this +very high rotary movement to the bullet in the instant +of time during which it is passing through the barrel, +the rifling of the gun has to exert an enormous torsion +on the bullet. Lead, no matter how hardened, is not +sufficiently strong, as it will not only strip and pass +straight through the gun without taking any rotary +movement whatever, but under such very high pressures +it behaves like wax, and is thrown from the gun +in a distorted mass.</p> + +<p>The French cover their bullets with German silver, +a substance made of nickel, zinc and copper; and in +order to put as little strain upon the rifling and projectile +as possible, the rifling of the gun is made with an +increasing twist, and has no sharp edges. The French +rifle is made very strong at the breech and is of tempered +steel throughout. In this way the French have +made smokeless powder a success--a smokeless powder +made substantially of a character such as I have +herein described. With smokeless powder, the French +rifle imparts a muzzle velocity of 2,000 feet per second +to the bullet, with a range of about 2,400 meters.</p> + +<p>If smokeless powder be divided into sufficiently +small grains to be ignited by an ordinary fulminating +cap, it would burn too quickly, thereby causing the +pressure to mount too high, and without giving the +desired velocity. Consequently very large and strong +fulminating caps have to be employed. Smokeless +powder is not ignited in the same manner as black +powder. Something besides ignition is necessary. +Black powder simply requires to be set on fire; while +a smokeless powder, on the contrary, not only requires +that it be set on fire, but that a certain degree +of pressure be set up inside of the cartridge case. For +instance, if a primer of a certain size should be found +to operate perfectly well, giving prompt ignition in the +cartridge case of a rifle of small caliber, it would be +found that the same primer would not ignite a charge +of the same powder if loaded into a gun of one inch +caliber. In the latter case a few grains only lying near +the primer would be ignited, and these would soon +become extinguished by sudden release of pressure +bringing about a cooling effect due to expansion of +the gases. In small cartridges a large fulminating cap +is all that is required, but in large cartridges it is +necessary to resort to additional means of ignition.</p> + +<p>In France, where experiments were conducted with +a 37 millimeter Maxim gun, it was found to be impracticable +to use a fulminating cap sufficiently large to +ignite the powder and cause it to burn. Therefore, a +small ignition charge of black powder was employed, +it being put in a capsule or bag and placed next the +primer. On firing at the rate of 300 rounds per minute, +the black powder, though small in quantity, produced +a cloud of smoke through which it was quite +impossible to see. The inventor of the gun then prepared +for the French some wafers of pyroxyline canvas, +which were placed next to the primer, securing +thereby prompt ignition without the production of +any smoke.</p> + +<p>Smokeless powder, made as I have described, cannot +be detonated by a fulminating cap of any size or by +any means whatever. A large charge of fulminate of +mercury placed inside the cartridge case next the +primer will not detonate the powder, it serving only +to ignite it and cause it to explode. But even this +would not cause the powder to explode except it be +confined behind a projectile, that sufficient pressure +may be run up to make it burn in its own gases.</p> + +<p>Some curious experiments with smokeless powder +may be tried with a shot gun. If the fulminating cap +be large, the powder fine, the wads numerous and +hard and the charge of shot heavy, all being well +rammed down, and the paper case well spun over the +last pasteboard wad, a charge of smokeless powder +about equal in weight to one-half of what would be +employed of black powder would give about the same +results as black powder. But if the charge of shot be +omitted, the primer will only ignite the powder, and +there will be set up sufficient pressure merely to throw +the wads about half way up the barrel of the gun, when +the powder will go out. Now if this same charge of +powder be collected and reloaded into a new cartridge +case and well confined behind wads and a charge of +shot, as above explained, it will all burn, giving the +same results as black powder.</p> + +<p>Attempts have been made to use this powder in pistols +and revolvers, but here it has proved a failure, as +the pressure is not great enough to cause the powder +to be consumed, unless it be in the form of very fine +grains or dust, in which case the pressure mounts too +high. However, this might be overcome to a degree +by making the powder porous. The chemical conditions +of the powder might be the same, but the physical +conditions must be different. A powder suitable +for shot guns and pistols would not be suitable for +rifles.</p> + +<p>One not familiar with the characteristics of smokeless +powder would be almost certain to fail in his first +attempt to fire it. Many persons have been convinced +by their first experiments that this powder would not +burn at all in a gun, any more than so much sand.</p> + +<p>Smokeless powder is consumed with a rapidity +which accords with the conditions of its confinement. +Therefore, the bullets which have been experimented +with by different governments have been the cause of +much of the varying pressures attributed to the smokeless +powders.</p> + +<p>The Austrians use the Mannlicher steel jacketed bullet. +The steel casing or jacket is first tinned on the inside +and then the lead is cast in, thus melting the tin and +adhering firmly to the jacket. This projectile sets up +enormous friction in the barrel of the gun when used +with smokeless powder; as the smokeless powder +leaves the gun barrel perfectly clean and the two steel +surfaces being in absolute contact cause tremendous +friction; and as the coefficient of friction varies with +every shot, the pressure in the gun constantly varies +greatly.</p> + +<p>The German silver covered bullet used by the French +has the disadvantage that when firing rapidly the +chamber of the barrel becomes nickel plated and great +friction is caused, mounting up the pressures and causing +the muzzle velocities to fall off.</p> + +<p>The Austrians, in order to prevent their steel cased +bullets from rusting and to lessen the friction in the +barrel of the gun, cover them with a heavy lubricant, +which gives the cartridges an unsightly appearance +and causes them to gather dust and sand. + +The French employ a lubricant at the base of the +projectile, with a small copper disk between the same +and the powder.</p> + +<p>Col. A.R. Buffington, commander of the National +Armory at Springfield, Mass., has made a steel covered +projectile which he prevents from rusting by blackening +by a niter process. Several grooves are pressed +in the base of the bullet which carry a lubricant, and +when the bullet is inserted in the cartridge case the +grooves are covered by it. Furthermore, these grooves +prevent the lead filling from bursting through the steel +casing, leaving the latter in the barrel, as often occurs +with the Austrian and French projectiles when using +smokeless powder.</p> + +<p>A new projectile has lately come out, the invention +of Captain Edward Palliser, of the British army. This +bullet consists of a jacket made of very soft Swedish +wrought iron, coated with zinc and filled with lead, the +lead being pressed into this jacket. The bullet is corrugated +at its base, after the manner of the one made +by Colonel Buffington. This projectile has been experimented +with very extensively by the British government, +and at the works of the Maxim-Nordenfelt +Guns and Ammunition Company, in England. The +zinc coating of the bullet is too soft to stick to the barrel +of the gun, and also in a measure acts as a lubricant. +This projectile has given better results than any other +that has been experimented with. The great velocities +and the most uniform pressures by the use of smokeless +powder have been attained with this Palliser bullet.</p> + + +<h3>NOISELESSNESS.</h3> + +<p>A great many stories have been told about the noiselessness +of smokeless powder. But there is no such +thing as a noiseless gunpowder. The report of a gun +charged with smokeless powder is very sharp, and is +as loud as when black powder is used, yet the volume +of sound is much less, so that the report cannot be +heard at so great a distance.</p> + +<p>The report of a gun using smokeless powder is a +sound of much higher pitch than when black powder +is used, and consequently cannot be heard at so great +a distance as the lower notes given by black powder.</p> + +<p>As smokeless powder exerts a much greater pressure +than common black powder when burned in a gun, +one would naturally think that the recoil of the barrel +would be greater, owing to the greater pressure exerted +by the smokeless powder on the base of the cartridge +case and the breech mechanism. However, such +is not the fact; for the barrel actually recoils very much +less when smokeless powder is used. This is due to +the suddenness with which the pressure is exerted by +smokeless powder, it acting more like a very sharp +blow on the metal, whereby more of the energy is converted +into heat instead of being spent in overcoming +the inertia of the barrel to give recoil. Similarly when +smokeless powder is fired in a gun, the displacement +of the air is so sudden that the sound waves do not +possess the same amplitude of recoil or vibration as is +given by black powder.</p> + +<hr /> + +<a name="elec1"></a><h2>THE CONSTRUCTION AND MAINTENANCE OF +UNDERGROUND CIRCUITS.</h2> + +<h3>By S.B. FOWLER.</h3> + +<p>The numerous disastrous storms of the last winter +have brought out very vividly the advantages of having +all wires placed underground, and many inquiries +have been addressed to the companies operating underground +circuits as to their success. It is not probable +that all of the answers to these inquiries have +been of the most favorable character. To many central +station managers an underground system means +frequent break-downs and interruptions of service, +with, perhaps, slow and expensive repairs, which bring +in their turn numerous complaints, loss of customers, +and reduced profits. In many installations burn-outs +both underground and in the station are frequent, +with the natural result that the operating of circuits +underground is not there considered an unqualified +success. The writer has in mind two very different +experiences with underground cables. Several +miles of cable were bought by a certain company, +carefully laid, and up to to-day not a single burn-out +or interruption of service can be attributed to failure +of cables; at about the same time another company +bought about an equal amount of the same kind of cable, +and in a comparatively short time the current had +to be shut off the lines and the whole installation repaired +and parts of it replaced. Both of these experiences +have been repeated many times and will be +again, although it is simply a distinction between a +good cable properly laid and a good cable ruined by +careless and incompetent workmanship.</p> + +<p>Every failure can be traced to poor work in the original +installation or to the use of a cheap cable, both +causes being due, generally, to that false economy +which looks for too quick returns. A poorly insulated +line wire and a poorly insulated cable are two very +different things. However, it is a fact that by the use +of a good cable it is not difficult to construct an underground +system for light, power, telegraph or telephone +uses that will be superior to overhead lines in +its service and in cost of maintenance. The ideal underground +system must have as a starting point a system +of subways admitting of the easy drawing in and +out of cables and affording means of making subsidiary +connections readily and with the minimum of expense +and interruption of service. This is practically +accomplished by a subway consisting of lines of pipe +terminating at convenient intervals, say at street intersections, +in manholes, for convenience in jointing +and in running out house connections. These pipes, +or ducts, as they are called, should be for two kinds of +service; the lower or deeper laid lines for the main or +trunk circuits, and a second series of ducts laid nearer +the surface, running into service boxes placed near +together for lines to "house to house" connections. +In some cities where it is allowed to run overhead lines, +the plan of running but one service connection in a +block is followed, all customers in the block being supplied +from a line run over the housetops or strung on +the rear walls.</p> + +<p>This makes unnecessary all subsidiary ducts except a +short one from the manhole to the nearest building in +the block, and effects a considerable saving in pipe, +service boxes, cables and labor. The manholes should +have their walls built up of brick, the floors should be + +of concrete, and there should be an inside lid which +can be fastened down and the manhole thus made +water-tight.</p> + +<p>For ducts wood, iron or cement lined pipe may be +used. To preserve the wood it is generally treated +with creosote, which, in contact with the lead cover of +the cable, sets up a chemical action, resulting in the +destruction of the lead. Wood offers but little protection +for the cable, as it is too easily damaged and broken +through in the frequent street openings made by +companies operating lines of pipe in the streets, and +as one of the main purposes of a subway is that of a +protection to cables, wooden ducts have little to recommend +them except their cheapness.</p> + +<p>Iron pipes are either laid in trenches filled in with +earth or are laid in cement. Iron pipe will of course +rust out in time, and if absolute permanence in construction +is desired, should be laid in cement, for after +the pipe rusts out, the duct of cement is still left. +However, if we are going to the expense of laying in +cement, it would be much preferable to use cement +lined pipe, which is not only cheaper than iron pipe, +but makes the most perfect cable conduit, as it affords +a perfectly smooth surface to draw the cable over and +give a good duct edge.</p> + +<p>It is not necessary, however, in small installations +of cable, especially where additional connections will +not be of frequent occurrence, to go to the expense +of subways, for cable may be safely laid in the ground +in trenches filled in with earth, or can be inclosed in a +plain wooden box or a wooden box filled with pitch.</p> + +<p>There are, of course, many localities where, if the +cable is laid in contact with the earth, a chemical +action would take place which might result in the destruction +of the cable.</p> + +<p>Underground cables are of the following classes: 1. +Rubber insulated cables, insulated with rubber or +other homogeneous material. 2. Fibrous cables, so +called from the conductors being covered with some +fibrous material, as cotton or paper, which is saturated +with the insulating material, paraffine, resin oil, or +some special compound. Under this latter head is +also included the dry core paper cables.</p> + +<p>The first thing to do is to get the cable drawn into the +ducts, and on the proper accomplishment of this depends +to a great extent the success or failure of the whole installation. +Probably the ducts have been wired when +the subway was constructed, but if not a wire must be +run through as a means of pulling in the draw rope. +There are several kinds of apparatus for getting a +wire through a duct--rods, flexible tapes, mechanical +"creepers," etc.; but probably the best is the sectional +rod. This simply consists of three or four foot lengths +of hard wood rods, having metal tips that screw into +each other. A rod is placed in a duct at a manhole, +one screwed to that, both are pushed forward, another +one added and pushed forward, and so on until they +extend the entire length of the duct. Then the wire +is attached and the rods are pulled out and detached +one at a time and with the last rod the wire is through. +At least No. 14 galvanized iron or steel wire should be +used, for any smaller size cannot be used a second time, +as a rule. In starting to pull in the draw rope a wire +brush should be attached to the wire and to this again +the rope, and when the brush arrives at the distant +end of the duct it very likely will bring with it a miscellaneous +collection of material which for the good of +the cable had better be in the manhole than in the +duct.</p> + +<p>The reel or drum carrying the cable should be +mounted on wheels or jacks and placed on the same +side of the manhole as the duct into which the cable +is to be drawn, and must always be so placed that the +cable will run off the top of the reel.</p> + +<p>There are several methods of attaching the draw +rope to the cable. As simple and strong a method as +any is to punch two of these holes through the cable, +lead and all, and attach the rope by means of an iron +wire--some of the draw wire will do--run through +these holes. Depending on the length and weight of +cable to be pulled it can be drawn either by hand or +by a multiplying winch. The rope should run through +a block fastened in the manhole in such a position +that the rope shall have a good straightaway lead from +the mouth of the duct.</p> + +<p>The strain on the cable should be perfectly uniform +and steady; if the power is applied by a series of jerks +either the lead covering may be pulled apart or some of +the conductors broken. At the reel there must always +be a large enough number of men to turn it and keep +the cable from rubbing on anything, and in the manhole +one or more men to see that the cable feeds into +the duct straight and to guide it if necessary. If the +ducts are of iron and are not perfectly smooth at the +ends, these should be made so with a file, and in addition +a protector of some sort should be placed in the +mouths of the duct, both above and below the cable. +Six inches of lead pipe, split lengthwise and bent over +at one end to prevent being drawn into the duct with +the cable, makes a very good protector. The cable +should be reeled off the drum just fast enough to prevent +any of the power used in pulling the cable through +the duct being utilized in unreeling it. If this latter +is allowed to occur the cable will be bent too short and +the lead covering buckled or broken, and also the cable +may be jammed against the upper edge of the duct +and perhaps cut through.</p> + +<p>If the reel is allowed to turn faster than the cable is +drawn in, the first three or four turns on the reel will +slacken up, and the lead covering may either be dented +or cut through by scraping on the ground. If the +cable end when pulled through up to the block is not +long enough to bend around the hole more than half +way, the rope should be unfastened from its end, a +length of rope with a well frayed out end should be run +through the block, and by fastening to the cable close +to the duct, with a series of half hitches, as much slack +as necessary can be pulled in. If this is properly +manipulated there need not be a scratch on the cable, +but unless great care is taken the lead may be pressed +up into ridges and the core itself damaged.</p> + +<p>Immediately after the cable is drawn in, if the joint +is not to be at once made, the open end or ends should +be cut off and the cable soldered up, as most cables are +very susceptible to moisture and readily absorb water +even from the atmosphere. Where practicable it is +always a good plan to pull the cable through as many +manholes as possible without cutting the cable; for +the joint is, especially in telephone or telegraph cables, +the weak point. To do this the rope should be pulled + +through the proper duct in the next section without +unfastening it from the cable; the winch should be +moved to the next manhole, and pulling through then +done as before. There should always be a man in +every hole through which the cable is running to see +that it does not bind anywhere and to keep protectors +around the cable.</p> + +<p>It is not advisable to pull more than one cable into a +duct, and never advisable to pull a cable into a duct +containing another cable, but if two or more cables +have to go into the same duct, they should always be +drawn in together. Lead covered cables and those +with no lead on the outside should never be pulled into +the same duct, for if they bind anywhere the soft +cable will suffer where two lead covered cables would +get through all right. Some manufacturers are now +putting on their cables a tape or braid covering, which +saves the lead many bad bruises and cuts, and is a +valuable addition to a cable at very little additional +expense.</p> + +<p>Practically all electric light and power cables are +either single or double conductors, and the jointing of +these is comparatively a simple matter, although requiring +considerable care. The lead is cut back from +each end about four or five inches, and the conductors +bared of insulation for two or three inches. The bare +conductors should be thoroughly tinned by dipping in +the metal pot or pouring the melted solder over them. +A sperm candle is better than resin or acid for any +part of the operations where solder is used. A lead +sleeve is here slipped back over the cable, out of the +way, and the ends of the conductors brought together +in a copper sleeve which is then sweated to a firm joint. +This part must be as good a piece of work mechanically +as electrically. The bare splice is then wrapped +tightly with cotton or silk tape to a thickness slightly +greater than that of the insulation of the cable, and is +thoroughly saturated with the insulating compound +until all moisture previously absorbed by the tape is +driven off.</p> + +<p>The lead sleeve is then brought over the splice and +wiped to the cable. The joint is then filled with the +insulating compound poured through holes in the top +of the sleeve; these holes are then closed and the joint +is complete, and there is no reason why, in light and +power cables, that joint should not be as perfect as +any other part of the cable. When the cable ends are +prepared for jointing they should be hung up in such +a position that they are in the same plane, both horizontal +and vertically, and firmly secured there, so that +when the lead sleeve is wiped on the conductor may +be in its exact center, and great care must be taken +not to move the cables again until the sleeve is filled +and the insulation sufficiently cooled to hold the conductor +in position.</p> + +<p>It is also very important to see that there are no sharp +points on the conductors themselves, on the copper +sleeve, on the edges of the lead covering or on the lead +sleeve. All these should be made perfectly smooth, for +points facilitate disruptive discharges. Branch joints +had better be made as T-joints rather than as Y-joints, +for they are better electrically and mechanically, although +they occupy more room in the manholes. They +are of course made in the same way as straight joints, +a lead T-sleeve being used, however. For multiple +arc circuits copper T-sleeves and for series circuits +copper L-sleeves are used.</p> + +<p>Telephone and telegraph cables are made of any required +gauge of wire and with from 1 to 150 conductors +in a cable. In jointing these the splices are never +soldered, the conductors being joined either with a +twist joint or with the so-called Western Union splice. +Each splice is covered with a cotton or silk sleeve or a +wrapping of tape, the latter being preferable, although +considerably increasing the time necessary for making +the joint. Great care must be taken that no ends of +wire are left sticking up, for they will surely work +their way through the tape and grounds, and crosses +will be the result. The wires should always be joined +layer to layer and each splice very tightly taped in +order to get as much insulating compound around each +splice as possible in the limited space. The splices +should be "broken" as much as possible, so as to avoid +having adjoining splices coming over each other. After +the joint has been saturated with insulating compound +the wires should have an outside wrapping of tape to +keep them in shape, and then the sleeve is wiped on +and filled. If the insulation resistance of the jointed +telegraph or telephone cable is a quarter of what the +cable tested in the factory, it may be considered that +an exceptionally good piece of work has been done. I +have spoken more particularly of fibrous lead covered +cables, as the handling of them includes practically +every step of the work on any other kind of underground +cable. In insulating dry core paper cables a +paper sleeve is slipped over the splice, and in rubber +cables the splice is wrapped with rubber tape; all +other details are the same for these as for the fibrous +cable.</p> + +<p>In the laying of light and power cables every joint, +as made, should be tested for insulation with a Thomson +galvanometer, as the insulation must necessarily be +very high, and if one joint or section of cable is any +weaker than another it may be very important in the +future to know it. All tests must be made after the +joint has cooled, for while hot its insulation resistance +will be very low.</p> + +<p>Tests for copper resistance should also be made to +determine if the splices are electrically perfect; an imperfect +splice may cause considerable trouble. In telegraph +and telephone cables the conductors should be +of very soft copper, for in stripping the conductor of +insulation it is very easy to nick the wire, and if of +hard drawn copper open wires will be the result.</p> + +<p>All work should be frequently tested for continuity +with telephones, magnetos, or small portable galvanometers. +It is only necessary to ground the conductors +at one end and try each wire at the other end. For +this sort of work a telephone receiver used with one +cell of some dry battery is most convenient, and has +the additional advantage of affording a means of communication +while testing, and is by far the best thing +for identifying and tagging conductors.</p> + +<p>These cables should be frequently tested during the +progress of the work for grounds and crosses with a +Thomson instrument, and when the cable is complete, +a careful series of tests of the capacity, insulation resistance, +and copper resistance of each wire should be +made and the exact condition of the cable determined +before it is put in service, and thereafter an intelligent + +oversight of the condition of the circuits can thus +be more readily maintained.</p> + +<p>Where a company has extensive underground service, +a regular cable gang should be in its employ, for quick +and safe handling of cables demands the employment +of men accustomed to the work. If the cable +has been properly laid and tests show it to be in good +condition before current is turned on, almost the only +trouble to be anticipated will be due to mechanical +injury. Disruptive discharge, puncturing the lead, +may occur; but the small chance of its occurring can +be greatly lessened by the use of some kind of "cable +protector," which will provide for the spark an artificial +path of less resistance than the dielectric of the +condenser, which the cable in fact becomes.</p> + +<p>If a fault suddenly develops on a circuit, the chances +are it will be found in a manhole, and an inspection +of the cable in the manhole will generally reveal the +trouble without resorting to locating with a Wheatstone +bridge. The cable is often cut through at the +edge of the duct, or damaged by something falling on +it, or by some one "walking all over it." To guard +against these, the ducts should always be fitted with +protectors both above and below the cable. The +cables should never be left across the manholes, for +they then answer the purpose of a ladder, but should +be bent, around the walls of the hole and securely +fastened with lead straps, that they may not be moved +and the lead gradually worn through.</p> + +<p>In telegraph cables, when one or two conductors +"go," it will probably be useless to look for trouble +except with instruments; but if several wires are +"lost" at once it will probably be found to be caused +by mechanical injury, which can be located by inspection. +If it is ever necessary to loop out conductors, +a joint can be readily opened and the conductors +wanted picked out and connected into the branch +cable and the joint again closed without disturbing the +working wires. In doing this a split sleeve must be +used, and the only additional precaution to be taken +is in filling the sleeve to have the insulating compound +not hot enough to melt the solder and open up the +split in the sleeve. In cutting in service on light +and power cables it is entirely practicable to do so +without interruption of service on multiple arc circuits, +even those of very high voltage; but they require +great precaution and involve considerable risk +to the jointer, and where possible the circuit to which +the connection is to be made should previously be cut +dead. Where the voltage is not dangerous to human +life, almost any service connection can be made without +interruption of service.</p> + +<p>I have only indicated a very few of the operations +that may be found necessary, and the probable causes +of troubles that may be encountered in the operating +of underground circuits, believing that the different +problems that arise can, with a little experience, be +successfully met by any one who has a fair knowledge +of the original construction of cable lines.--<i>Electrical +World</i>.</p> + +<hr /> + +<a name="eng1"></a><h2>RAILROADS TO THE CLOUDS.</h2> + +<p>If George Stephenson, when he placed the first locomotive +on the track and guaranteed it a speed of six +miles an hour, could have foreseen that in less than +eighty years the successors of his rude machine would +be climbing the sides of mountain ranges, piercing +gorges hitherto deemed inaccessible, crossing ravines +on bridges higher than the dome of St. Paul's, and +traversing the bowels of the earth by means of tunnels, +no doubt his big blue eyes would have stood out +with wonder and amazement. But he foresaw nothing +of the kind; the only problem present in his mind was +how to get goods from the seaports in western England +to London as easily and cheaply as possible, and to do +this he substituted for horses, which had for 150 years +been drawing cars along wooden or iron tracks, the +wonderful machine which has revolutionized the +freight and passenger traffic of the world.</p> + +<p>It was, indeed, impossible for any one to foresee the +triumphs of engineering which have accompanied the +advances in transportation. To the engineer of the +present day there are no impossibilities. The engineer +is a wizard at whose command space and matter +are annihilated. The highest mountain, the deepest +valley, has no terrors for him. He can bridge the +latter and encircle or tunnel the former. The only requisites +which he demands are that something in his +line be needed, and that the money is forthcoming to +defray the expense, and the thing will be done. But +the railroad he is asked to construct must be necessary, +and the necessity must be plainly shown, or no funds +will be advanced; and although the theory does not +invariably hold good, especially when a craze for railroad +building is raging, as a rule no expense for the +construction of a road will be incurred without a prospect +of remuneration.</p> + +<p>Hence the need of railroad communication has caused +lines to be constructed through districts where only a +few years ago the thing would have been deemed impossible. +The Pacific roads of this country were a necessity +long before their construction, and in the face +of difficulties almost insuperable were carried to successful +completion. So, also, of the railroads in the +Andes of South America. The famous road from +Callao through the heart of Peru is one of the highest +mountain roads in the world, as well as of the most +difficult construction. The grades are often of 300 +feet and more to the mile, and when the mountains +were reached so great were the difficulties the engineers +were forced to confront that in some places laborers +were lowered from cliffs by ropes in order that, with +toil and difficulty, they might carve a foothold in order +to begin the cutting for the roadway.</p> + +<p>In some sections tunnels are more numerous than +open cuts, and so far as the road has gone sixty-one +tunnels, great and small, have been constructed, aggregating +over 20,000 feet in length. The road attains +a height of 15,000 feet above the level of the sea, and +at the highest point of the track is about as high as +the topmost peak of Mont Blanc. It pierces the range +above it by a tunnel 3,847 feet long. The stern necessities +of business compelled the construction of this +road, otherwise it never would have been begun.</p> + +<p>The tunnels of the Andes, however, do not bear +comparison with the tunnels, bridges, and snow sheds +of the Union Pacific, nor do even these compare with +the vast undertakings in the Alps--three great tunnels +of nine to eleven miles in length, which have been prepared + +for the transit of travelers and freight. The requirements +of business necessitated the piercing of the +Alps, and as soon as the necessity was shown, funds in +abundance were forthcoming for the enterprise.</p> + +<p>But tunneling a mountain is a different thing from +climbing it. Many years ago the attention of inventors +was directed to the practicability of constructing a +railroad up the side of a mountain on grades which, to +an ordinary engine, were quite impossible. The improvements +in locomotives twenty-five and thirty years +ago rendered them capable of climbing grades which, +in the early days of railroad engineering, were deemed +out of the question. The improvements proved a serious +stumbling block in the way of the inventors, who +found that an ordinary locomotive was able to climb +a much steeper grade than was commonly supposed. +The first railroads were laid almost level, but it was +soon discovered that a grade of a few feet to the mile +was no impediment to progress, and gradually the +grade was steepened.</p> + +<p>The inventors of mountain railroad transportation +might have been discouraged by this discovery, but it +is a characteristic of an inventor that he is not set +back by opposition, which, in fact, only serves to +stimulate his zeal. The projectors of inclined roads +and mountain engines kept steadily on, and in France, +Germany, England, and the United States many experimental +roads were constructed, each of a few hundred +yards in length, and locomotive models were +built and put in motion to the amazement of the general +public, who jeered alike at the contrivances and +the contrivers, deeming the former impracticable and +the latter crazy.</p> + +<p>But the idea of building a road up the side of a hill +was not to be dismissed. There was money in it for +the successful man, so the cranky inventors kept on at +work in spite of the jeers of the rabble and the discouragements +of capitalists loath to invest their money +in an uncertain scheme. To the energy and perseverance +of railroad inventors the success of the mountain +railroad is due, as also is the construction of the various +mountain roads, of which the road up Mt. Washington, +finished in 1868, was the first, and the road +up Pike's Peak, completed the other day, was the +latest.</p> + +<p>Of all the mountain roads which have been constructed +since the one up Mt. Washington was finished, +the best known is that which ascends the world-famous +Rigi. With the exception of Mont Blanc, Rigi is, perhaps, +the best known of any peak in the Alps, though +it is by no means the highest, its summit being but +5,905 feet above the level of the sea. Although scarcely +more than a third of the height of some other mountains +in the Alps, it seems much higher because of its +isolated position. Standing as it does between lakes +Lucerne, Zug, and Lowertz, it commands a series of +fine views in every direction, and he who looks from +the summit of Rigi, if he does no other traveling in +Switzerland, can gain a fair idea of the Swiss mountain +scenery. Many of the most noted peaks are in sight, +and from the Rigi can be seen the three lakes beneath, +the villages which here and there dot the shores, and, +further on, the mighty Alps, with their glaciers and +eternal snows.</p> + +<p>Many years ago a hotel was built on the summit of +the Rigi for the benefit of the tourists who daily +flocked to this remarkable peak to enjoy the benefit of +its wonderful scenery. The mountain is densely +wooded save where the trees have been cut away to +clear the land for pastures. The ease of its ascent by +the six or eight mule paths which had been made, the +gradual and almost regular slope, and the throngs of +travelers who resorted to it, made it a favorable place +for an experiment, and to Rigi went the engineers in +order to ascertain the practicability of such a road. +The credit of the designs is due to a German engineer +named Regenbach, who, about the year 1861, designed +the idea of a mountain road, and drew up plans not +only for the bed but also for the engine and cars. The +scheme dragged. Capitalists were slow to invest their +money in what they deemed a wild and impracticable +undertaking, and even the owners of the land on +the Rigi were reluctant for such an experiment to be +tried. But Regenbach persevered, and toward the close +of the decade the inhabitants of Vitznau, at the base +of the Rigi, were astonished to see gangs of laborers +begin the work of making a clearing through the +forests on the mountain slope. They inquired what it +meant, and were told that a road up the Rigi was to be +made. The Vitznauers were delighted, for they had no +roads, and there was not a wheeled vehicle in the +town, nor a highway by which it could be brought +thither. The idea of a railroad in their desolate +mountain region, and, above all, a railroad up the Rigi, +never entered their heads, and a report which some +time after obtained currency in the town, that the +laborers were beginning the construction of a railroad, +was greeted with a shout of derision.</p> + +<p>Nevertheless, that was the beginning of the Rigi +line, and in May, 1871, the road was opened for traffic. +It begins at Vitznau, on Lake Lucerne, and extends to +the border of the canton and almost to the top of the +mountain. It is 19,000 feet long, and during that distance +rises 4,000 feet at an average grade of 1 foot in 4. +Though steep, it is by no means so much so as the Mt. +Washington road, which rises 5,285 feet above the sea, +at an average of 1 foot in 3. There are, however, +stretches of the Rigi road at which the grade is about +1 foot in 2½, which is believed to be the steepest in the +world.</p> + +<p>The Rigi road has several special features aside +from its terrific slopes which entitle it to be considered +a triumph of the engineer's skill. About midway +up the mountains the builders came to a solid +mass of rock, which presented a barrier that to a surface +road was impassable. They determined to tunnel +it, and, after an enormous expenditure of labor, +finished an inclined tunnel 225 feet in length, of the +same gradient as the road. A gorge in the side of the +mountain where a small stream, the Schnurtobel, had +cut itself a passage also hindered their way, and was +crossed by a bridge of lattice girder work in three +spans, each 85 feet long. The entire roadbed, from beginning +to end, was cut in the solid rock. A channel +was chiseled out to admit the central beam, which +contains the cogs fitting the driving wheel of the locomotive. +The engine is in the rear of the train, and +presents the exceedingly curious feature of a boiler +greatly inclined, in order that at the steeper gradients +it may remain almost perpendicular. The coal and + +water are contained in boxes over the driving wheels, +so that all the weight of the engine is really concentrated +on the cogs--a precaution to prevent their +slipping. The cost of the road, including three of +these strangely constructed locomotives, three passenger +coaches, and three open wagons, was $260,000, and +it is a good paying investment. The fare demanded +for the trip up the mountains is 5 francs, while half +that sum is required for the downward passage, and +the road is annually traversed by from 30,000 to 50,000 +passengers.</p> + +<p>Curious sensations are produced by a ride up this remarkable +line. The seats of the cars are inclined like +the boiler of the locomotive, and so long as the cars +are on a level the seats tilt at an angle which renders +it almost impossible to use them. But when the start +is made the frightful tilt places the body in an upright +position, and, with the engine in the rear, the train +starts up the hill with an easy, gliding motion, passing +up the ascent, somewhat steeper than the roof of a +house, without the slightest apparent effort. But if the +going up excites tremor, much more peculiar are the +feelings aroused on the down grade. The trip begins +with a gentle descent, and all at once the traveler +looking ahead sees the road apparently come an end. +On a nearer approach he is undeceived and observes +before him a long decline which appears too steep +even to walk down. Involuntarily he catches at the +seats, expecting a great acceleration of speed. Very +nervous are his feelings as the train approaches this +terrible slope, but on coming to the incline the engine +dips and goes on not a whit faster than before and not +more rapidly on the down than on the up grade. +Many people are made sick by the sensation of falling +experienced on the down run. Some faint, and a few +years ago one traveler, supposed to be afflicted with +heart disease, died of fright when the train was going +over the Schnurtobel bridge. The danger is really +very slight, there not having been a serious accident +since the road was opened. The attendants are watchful, +the brakes are strong, but even with all these +safeguards, men of the steadiest nerves cannot help +wondering what would become of them in case anything +went wrong.</p> + +<p>Bold as was the project of a railroad on the Rigi, a +still bolder scheme was broached ten years later, when +a daring genius proposed a railroad up Mt. Vesuvius. +A railroad up the side of an ordinary mountain seemed +hazardous enough, but to build a line on the slope of a +volcano, which in its eruption had buried cities, and +every few years was subject to a violent spasm, seemed +as hazardous as to trust the rails of an ordinary line +to the rotten river ice in spring time. The proposal +was not, however, so impracticable as it looked. +While the summit of Vesuvius changes from time to +time from the frequent eruptions, and varies in height +and in the size of the crater, the general slope and contour +of the mountain are about the same to-day as +when Vesuvius, a wooded hill, with a valley and lake +in the center of its quiescent crater, served as the +stronghold of Spartacus and his rebel gladiators. There +have been scores of eruptions since that in which Herculaneum +and Pompeii were overthrown, but the sides +of the mountain have never been seriously disturbed.</p> + +<p>A road on Vesuvius gave promise of being a good +speculation. Naples and the other resorts of the +neighborhood annually attracted many thousands of +visitors, and a considerable number of these every +year ascended the volcano, even when forced to contend +with all the difficulties of the way. Many, however, +desiring to ascend, but being unable or unwilling to +walk up, a chair service was established--a peculiar +chair being slung on poles and borne by porters. In +course of time the chair service proved to be inadequate +for the numbers who desired to make the ascent, +and the time was deemed fit for the establishment +of more speedy communication.</p> + +<p>Notwithstanding the necessity, the proposal to establish +a railroad met with general derision, but the +scheme was soon shown to be perfectly practicable, and +a beginning was made in 1879. The road is what is +known as a cable road, there being a single sleeper +with three rails, one on the top which really bore the +weight, and one on each side near the bottom, which +supported the wheels, which coming out from the axle +at a sharp angle, prevented the vehicle from being +overturned. The road covers the last 4,000 feet of the +ascent, and the power house is at the bottom, a steel +cable running up, passing round a wheel at the top +and returning to the engine in the power house. The +ascent to the lower terminus of the road is made on +mules or donkeys; then, in a comfortable car, the traveler +is carried to a point not far from the crater. The +car is a combined grip and a passenger car, similar in +some points to the grip car of the present day, while +the seats of the passenger portion are inclined as in +the cars on the Rigi road. But the angle of the road +being from thirty-three to forty-five degrees, makes +both ascent and descent seem fearfully perilous. Every +precaution, however, is taken to insure the safety +of passengers; each car is provided with several strong +and independent brakes, and thus far no accident +worth recording has occurred. The road was opened +in June, 1880. Although there have been several considerable +eruptions since that date, none of them did +any damage to the line but what was repaired in a few +hours.</p> + +<p>The fashion thus set will, no doubt, be followed in +many other quarters. Wherever there is sufficient travel +to pay working expenses and a profit on a steep +grade mountain road it will probably be built. Already +there is talk of a road on Mont Blanc, of another up +the Yungfrau, and several have been projected in the +Schwartz and Hartz mountains. A route on Ben Nevis, +in Scotland, is already surveyed, and it is said surveys +have also been made up Snowden, with a view to +the establishment of a road to the summit of the highest +Welsh peak. Sufficient travel is all that is necessary, +and when that is guaranteed, whenever a mountain +possesses sufficient interest to induce people to +make its ascent in considerable numbers, means +of transportation, safe and speedy, will soon be +provided. The modern engineer is able, willing and +ready to build a road to the top of Mt. Everest in the +Himalayas if he is paid for doing so.--<i>St. Louis Globe-Democrat.</i></p> + +<hr /> + +<p>To clean hair brushes, wash with weak solution of +washing soda, rinse out all the soda, and expose to +sun.</p> + +<hr /> + + + +<a name="mar1"></a><h2>THE MARCEAU.</h2> + +<p class="ctr"><a href="./images/8-ship.png"><img src="images/8-ship_th.jpg " width="600" height="402" alt="THE FRENCH ARMORED TURRET SHIP MARCEAU" title=""></a><br clear="all" /> +THE FRENCH ARMORED TURRET SHIP MARCEAU</p> + +<p>The Marceau, the last ironclad completed and added +to the French navy, was put in commission at +Toulon in April last, and has lately left that town to +join the French squadron of the north at Brest. The +original designs of this ship were prepared by M. +Huin, of the French Department of Naval Construction, +but since the laying down of the keel in the +year 1882 they have been very considerably modified, +and many improvements have been introduced.</p> + +<p>Both ship and engines were constructed by the celebrated +French firm, the Société des Forges et Chantiers +de la Mediterranée, the former at their shipyard in +La Seyne and the latter at their engine works in Marseilles. +The ship was five years in construction on the +stocks, was launched in May, 1887, and not having +been put in commission until the present year, was +thus nearly nine years in construction. She is a barbette +belted ship of somewhat similar design to the +French ironclads Magenta, now being completed at +the Toulon arsenal, and the Neptune, in construction +at Brest.</p> + +<p>The hull is constructed partly of steel and partly of +iron, and has the principal dimensions as follows. +Length, 330 ft. at the water line; beam, 66 ft. outside +the armor; draught, 27 ft. 6 in. aft.; displacement, +10,430 English or 10,600 French tons. The engines are +two in number, one driving each propeller; they are +of the vertical compound type, and on the speed trials +developed 11,300 indicated horse power under forced +and 5,500 indicated horse power under natural +draught, the former giving a speed of 16.2 knots per +hour with 90 revolutions per minute. The boilers are +eight in number, of the cylindrical marine type, and +work at a pressure of 85.3 lb. per square inch. During +the trials the steering powers of the ship were +found to be excellent, but the bow wave is said, by one +critic, to have been very great.</p> + +<p>The ship is completely belted with Creusot steel armor, +which varies in thickness from 9 in. forward to +17¾ in. midships. In addition to this belt the ship is +protected by an armored deck of 3½ in., while the barbette +gun towers are protected with 15¾ in. steel armor +with a hood of 2½ in. to protect the men against machine +gun fire. As a further means of insuring the life +of the ship in combat and also against accidents at sea, +the Marceau is divided into 102 water-tight compartments +and is fitted with torpedo defense netting. +There are two masts, each carrying double military +tops; and a conning tower is mounted on each mast, +from either of which the ship may be worked in time +of action, and both of which are in telegraphic communication +with the engine rooms and magazines. +Provision is made for carrying 600 tons of coal, which, +at a speed of 10 knots, should be sufficient to supply +the boilers for a voyage of 4,000 miles.</p> + +<p>The armament of the Marceau is good for the tonnage +of the ship and consists principally of four guns +of 34 centimeters (13.39 in.) of the French 1884 model, +having a weight of 52 tons, a length of 28½ calibers, +and being able to pierce 30 in. of iron armor at the muzzle. +The projectiles weigh 924 lb., and are fired with +a charge of 387 lb. of powder. The muzzle velocity has +been calculated to be 1,968 ft. per second. The guns +are entirely of steel and are mounted on Canet carriages +in four barbette towers, one forward, one aft, +and one on each side amidships. On the firing trials +both the guns and all the Canet machinery, for working + +the guns and hoisting the ammunition, gave very +great satisfaction to all present at the time. In addition +to the above four heavy guns there are, in the +broadside battery, sixteen guns of 14 centimeters +(5.51 in.), eight on each side, and a gun of equal caliber +is mounted right forward on the same deck. The +armament is completed by a large number of Hotchkiss +quick-firing and revolver guns and four torpedo +tubes, one forward, one aft, and one on each side.</p> + +<p>The crew of the Marceau has been fixed at 600 men, +and the cost is stated to have been about $3,750,000.--<i>Engineering</i>.</p> + +<hr /> + +<h3>[Continued from SUPPLEMENT, No. 820, page 13097.]</h3> + +<a name="mar2"></a><h2>A REVIEW OF MARINE ENGINEERING DURING +THE PAST DECADE.<a name="FNanchor_1"></a><a href="#Footnote_1"><sup>1</sup></a></h2> + +<h3>By Mr. ALFRED BLECHYNDEN, of Barrow-in-Furness</h3> + + +<p><i>Steam Pipes</i>.--The failures of copper steam pipes on +board the Elbe, Lahn, and other vessels have drawn +serious attention both to the material and to the modes +of construction of the pipes. The want of elastic +strength in copper is an important element in the +matter; and the three following remedies have been +proposed, while still retaining copper as the material. +First, in view of the fact that in the operation of brazing +the copper may be seriously injured, to use solid +drawn tubes. This appears fairly to meet the main +dangers incidental to brazing; but as solid drawn +pipes of over 7 inches diameter are difficult to procure, +it hardly meets the case sufficiently. Secondly, to use +electrically deposited tubes. At first much was promised +in this direction; but up to the present time it +can hardly be regarded as more than in the experimental +stage. Thirdly, to use the ordinary brazed or +solid drawn tubes, and to re-enforce them by serving +with steel cord or steel or copper wire. This has been +tried, and found to answer perfectly. For economical +reasons, as well as for insuring the minimum of torsion +to the material during manufacture, it is important +to make as few bends as possible; but in practice +much less difficulty has been experienced in serving +bent pipes in a machine than would have been +expected. Discarding copper, it has been proposed to +substitute steel or iron. In the early days of the +higher pressures, Mr. Alexander Taylor adopted +wrought iron for steam pipes. One fitted in the +Claremont in February, 1882, was recently removed +from the vessel for experimental purposes, and was +reported upon by Mr. Magnus Sandison in a paper +read before the Northeast Coast Institution of Engineers +and Shipbuilders.<a name="FNanchor_2"></a><a href="#Footnote_2"><sup>2</sup></a> The following is a summary +of the facts. The pipe was 5 inches external diameter, +and 0.375 inch thick. It was lap welded in the works +of Messrs. A. & J. Stewart. The flanges were screwed +on and brazed externally. The pipe was not lagged +or protected in any manner. After eight and a half +years' service the metal measured where cut 0.32 and +0.375 inch in thickness, showing that the wasting during +that time had been very slight. The interior surface +of the tube exhibited no signs of pitting or corrosion. +It was covered by a thin crust of black oxide, +the maximum thickness of which did not exceed 1/32 +inch. Where the deposit was thickest it was curiously +striated by the action of the steam. On the scale being +removed, the original bloom on the surface of the +metal was exposed. It would thus appear that the +danger from corrosion of iron steam pipes is not borne +out in their actual use; and hence so much of the way +is cleared for a stronger and more reliable material +than copper. So far the source of danger seems to be +in the weld, which would be inadmissible in larger +pipes; but there is no reason why these should not be +lapped and riveted. There seems, however, a more +promising way out of the difficulty in the Mannesmann +steel tubes which are now being "spun" out +of solid bars, so as to form weldless tubes.</p> + +<p class="ctr">TABLE I.--TENSILE STRENGTH OF GUN METAL AT HIGH TEMPERATURES.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gun Metal Strength"> +<colgroup><col align="left"><col span="4" align="right"></colgroup> +<tr><th>Composition of gun metal.</th><th>Temperature of oil bath</th><th>Tensile strength per square inch.</th><th>Elastic limit per square inch.</th><th>Elongation in length of 2 inches</th></tr> +<tr><td align="right">Per cent.</td><td>Fahr.</td><td>Tons</td><td>Tons</td><td>Per cent. </td></tr> +<tr><th rowspan="2" align="justify">Copper 87 <br />Tin 8<br />Zinc 3½<br />Lead 1½</th> +<td>50°</td><td>12.34</td><td>8.38</td><td>14.64</td></tr> +<tr><td>400°</td><td>10.83</td><td>6.30</td><td>11.79</td></tr> +<tr><th rowspan="2">Copper 87<br />Tin 8<br />Zinc 5</th> +<td>50°</td><td>13.86</td><td>8.33</td><td>20.30</td></tr> +<tr><td>458°</td><td>10.70</td><td>7.43</td><td>12.42</td></tr> +</table> + + +<p>Cast steel has been freely used by the writer for +bends, junction pieces, etc., of steam pipes, as well as +for steam valve chests; and except for the fact that +steel makers' promises of delivery are generally better +than their performance, the result has thus far been +satisfactory in all respects. These were adopted because +there existed some doubt as to the strength of +gun metal under a high temperature; and as the data +respecting its strength appeared of a doubtful character, +a series of careful tests were made to determine +the tensile strength of gun metal when at atmospheric +and higher temperatures. The test bars were all 0.75 +in diameter, or 0.4417 square inch sectional area; and +those tested at the higher temperatures were broken +while immersed in a bath of oil at the temperature here +stated, each line being the mean of four experiments. +The result of these experiments was to give somewhat +greater faith in gun metal as a material to be used +under a higher temperature; but as steel is much +stronger, it is probably the most advisable material +to use, when the time necessary to procure it can be +allowed.</p> + +<p><i>Feed Heating</i>.--With the double object of obviating +strain on the boiler through the introduction of the +feed water at a low temperature, and also of securing +a greater economy of fuel, the principle of previously +heating the feed water by auxiliary means has received +considerable attention, and the ingenious method +introduced by Mr. James Weir has been widely +adopted. It is founded on the fact that, if the +feed water as it is drawn from the hot well be raised +in temperature by the heat of a portion of steam introduced +into it from one of the steam receivers, +the decrease of the coal necessary to generate steam +from the water of the higher temperature bears a +greater ratio to the coal required without feed heating +than the power which would be developed in the +cylinder by that portion of steam would bear to the + +whole power developed when passing all the steam +through all the cylinders. The temperature of the +feed is of course limited by the temperature of the +steam in the receiver from which the supply for heating +is drawn. Supposing, for example, a triple expansion +engine were working under the following conditions +without feed heating: Boiler pressure, 150 lb.;--indicated +horse power in high pressure cylinder +398, in intermediate and low pressure cylinders +together 790, total, 1,188; and temperature of hot well +100° Fahr. Then with feed heating the same engine +might work as follows: The feed might be heated to +220° Fahr., and the percentage of steam from the first +receiver required to heat it would be 12.2 per cent.; +the indicated horse power in the high pressure cylinder +would be as before 398, and in the intermediate +and low pressure cylinders it would be 12.2 per cent, +less than before, or 694, and the total would be 1,092, +or 92 per cent. of the power developed without feed +heating. Meanwhile the heat to be added to each +pound of the feed water at 220° Fahr. for converting it +into steam would be 1,005 units against 1,125 units with +feed at 100° Fahr., equivalent to an expenditure of +only 89.4 per cent. of the heat required without feed +heating. Hence the expenditure of heat in relation to +power would be 89.4 + 92.0 = 97.2 per cent., equivalent to +a heat economy of 2.8 per cent. If the steam for heating +can be taken from the low pressure receiver, the +economy is about doubled. Other feed heaters, more +or less upon the same principle, have been introduced. +Also others which heat the feed in a series of pipes +within the boiler, so that it is introduced into the +water in the boiler practically at boiling temperature; +this is economical, however, only in the sense that +wear and tear of the boiler is saved; in principle the +plan does not involve economy of fuel.</p> + +<p><i>Auxiliary Supply of Fresh Water</i>.--Intimately associated +with the feed is the means adopted for making +up the losses of fresh water due to leakage of steam +from safety valves, glands, joints, etc., and of water +discharged from the air pumps. A few years ago this +loss was regularly made up from the sea, with the result +that the water in the boilers was gradually increased +in density; whence followed deposit on the +internal surfaces, and consequent loss of efficiency, and +danger of accident through overheating the plates. +With the higher pressures now adopted, the danger +arising from overheating is much more serious, and the +necessity is absolute of maintaining the heating surfaces +free from deposit. This can be done only by +filling the boiler with fresh water in the first instance, +and maintaining it in that condition. To do this two +methods are adopted, either separately or in conjunction. +Either a reserve supply of fresh water is carried +in tanks or the supplementary feed is distilled from +sea water by special apparatus provided for the purpose. +In the construction of the distilling or evaporating +apparatus advantage has been taken of two +important physical facts, namely, that, if water be +heated to a temperature higher than that corresponding +with the pressure on its surface, evaporation will +take place; and that the passage of heat from steam +at one side of a plate to water at the other is very +rapid. In practice the distillation is effected by passing +steam, say from the first receiver, through a nest +of tubes inside a still or evaporator, of which the steam +space is connected either with the second receiver or +with the condenser. The temperature of the steam +inside the tubes being higher than that of the steam +either in the second receiver or in the condenser, the +result is that the water inside the still is evaporated, +and passes with the rest of the steam into the condenser, +where it is condensed, and serves to make up +the loss. This plan localizes the trouble of deposit, +and frees it from its dangerous character, because an +evaporator cannot become overheated like a boiler, +even though it be neglected until it salts up solid; and +if the same precautions are taken in working the +evaporator which used to be adopted with low +pressure boilers when they were fed with salt water, +no serious trouble should result. When the tubes +do become incrusted with deposit, they can be +either withdrawn or exposed, as the apparatus is +generally so arranged; and they can then be cleaned.</p> + +<p><i>Screw Propeller</i>.--In Mr. Marshall's paper of 1881 it +was said that "the screw propeller is still to a great extent +an unsolved problem." This was at the time a +fairly true remark. It was true the problem had been +made the subject of general theoretical investigation +by various eminent mathematicians, notably by Professor +Rankine and Mr. William Froude, and of special +experimental investigation by various engineers. As +examples of the latter may be mentioned the +extended series of investigations in the French +vessel Pelican, and the series made by Mr. +Isherwood on a steam launch about 1874. These +experiments, however, such as they were, did little to +bring out general facts and to reduce the subject to a +practical analysis. Since the date of Mr. Marshall's paper, +the literature on this subject has grown rapidly, +and, has been almost entirely of a practical character. +The screw has been made the subject of most +careful experiments. One of the earliest extensive +series of experiments was made under the writer's +direction in 1881, with a large number of models, +the primary object being to determine what value there +was in a few of the various twists which inventive ingenuity +can give to a screw blade. The results led the +experimenters to the conclusion that in free water such +twists and curves are valueless as serving to augment +efficiency. The experiments were then carried further +with a view to determine quantitative moduli for the +resistance of screws with different ratios of pitch to +diameter, or "pitch ratios," and afterward with different +ratios of surface to the area of the circle described +by the tips of the blades, or "surface ratios." As these +results have to some extent been analyzed and published, +no further reference need be made to them now.</p> + +<p>In 1886, Mr. R.E. Froude published in the Transactions +of the Institution of Naval Architects the deductions +drawn from an extensive series of trials made +with four models of similar form and equal diameter, +but having different pitch ratios. Mr. S.W. Barnaby +has published some of the results of experiments made +under the direction of Mr. J.I. Thornycroft; and in +his paper read before the Institution of Civil Engineers +in 1890 he has also put Mr. R.E. Froude's results into +a shape more suitable for comparison with practice. +Nor ought Mr. G.A. Calvert's carefully planned experiments +to pass unnoticed, of which an account was + +given in the Transactions of the Institution of Naval +Architects in 1887. These experiments were made on +rectangular bodies with sections of propeller blade +form, moved through the water at various velocities in +straight lines, in directions oblique to their plane +faces; and from their results an estimate was formed +of the resistance of a screw.</p> + +<p>One of the most important results deduced from experiments +on model screws is that they appear to have +practically equal efficiencies throughout a wide range +both in pitch ratio and in surface ratio; so that great +latitude is left to the designer in regard to the form of +the propeller. Another important feature is that, although +these experiments are not a direct guide to the +selection of the most efficient propeller for a particular +ship, they supply the means of analyzing the performances +of screws fitted to vessels, and of thus indirectly +determining what are likely to be the best dimensions +of screw for a vessel of a class whose results are known. +Thus a great advance has been made on the old method +of trial upon the ship itself, which was the origin of +almost every conceivable erroneous view respecting +the screw propeller. The fact was lost sight of that +any modification in form, dimensions, or proportions +referred only to that particular combination of ship +and propeller, or to one similar thereto; so something +like chaos was the result. This, however, need not be +the case much longer.</p> + +<p>In regard to the materials used for propellers, steel +has been largely adopted for both solid and loose-bladed +screws; but unless protected in some way, the +tips of the blades are apt to corrode rapidly and become +unserviceable. One of the stronger kinds of +bronze is often judiciously employed for the blades, in +conjunction with a steel boss. Where the first extra +expense can be afforded, bronze seems the preferable +material; the castings are of a reliable character, and +the metal does not rapidly corrode; the bronze blades +can therefore with safety be made lighter than steel +blades, which favors their springing and accommodating +themselves more readily to the various speeds of +the different parts of the wake. This might be expected +to result in some slight increase of efficiency; +of which, however, the writer has never had the opportunity +of satisfactorily determining the exact extent. +Instances can be brought forward where bronze blades +have been substituted for steel or iron with markedly +improved results; but in cases of this kind which the +writer has had the opportunity of analyzing, the whole +improvement might be accounted for by the modified +proportions of the screw when in working condition. +In other words, both experiment and practical working +alike go to show that, although cast iron and steel +blades as usually proportioned are sufficiently stiff to +retain their form while at work, bronze blades, being +made much lighter, are not; and the result is that the +measured or set pitch is less than that which the +blades assume while at work. Some facts relative to +this subject have already been given in a recent paper +by the author.</p> + +<p><i>Twin Screws</i>.--The great question of twin screw propulsion +has been put to the test upon a large scale in +the mercantile marine, or rather in what would usually +be termed the passenger service. While engineers, +however, are prepared to admit its advantages so far +as greater security from total breakdown is concerned, +there is by no means thorough agreement as to +whether single or twin screws have the greater propulsive +efficiency. What is required to form a sound +judgment upon the whole question is a series of examples +of twin and single screw vessels, each of which is +known to be fitted with the most suitable propeller for +the type of vessel and speed; and until this information +is available, little can be said upon the subject with +any certainty. So far the following large passenger +steamers, particulars of which are given in table II., +have been fitted with twin screws. It appears t be a +current opinion that the twin screw arrangement necessitates +a greater weight of machinery. This is not +necessarily so, however; on the contrary, the opportunity +is offered for reducing the weight of all that part +of the machinery of which the weight relatively to +power is inversely proportional to the revolutions for a +given power. This can be reduced in the proportion of +1 to the square root of 2, that is 71 per cent. of its weight in the single +screw engine; for since approximately the same total +disk area is required in both cases with similar proportioned +propellers, the twins will work at a greater +speed of revolution than the single screw. From a commercial +point of view there ought to be little disagreement +as to the advantage of twin screws, so long as the +loss of space incurred by the necessity for double tunnels +is not important; and for the larger passenger +vessels now built for ocean service the disadvantage +should not be great. Besides their superiority in the +matter of immunity from total breakdown, and in +greatly diminished weight of machinery, they also offer +the opportunity of reducing to some extent the cost of +machinery. A slightly greater engine room staff is +necessary; but this seems of little importance compared +with the foregoing advantages.</p> + +<p class="ctr">TABLE II.--PASSENGER STEAMERS FITTED WITH +TWIN SCREWS.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Twin screw passenger stemeaers"> +<colgroup><col align="left" width="25%"><col span="2" align="center" width="10%"><col align="center" width="15%"><col span="2" align="right" width="10%"><col align="right" width="15%"></colgroup> +<tr><td>Vessels.</td><td>Length between perpen- diculars.</td><td>Beam.</td><td colspan="2">Cylinders two sets in all cases.</td><td>Boiler pressure per square inch.</td><td>Indicated horsepower.</td></tr> +<tr><td> </td><td>Feet.</td><td>Feet.</td><td>Diameters.<br />Inches.</td><td>Stroke.<br />Inches.</td><td>Lb.</td><td> </td></tr> +<tr><td>City of Paris.<br />City of New York.</td><td>525</td><td>63¼</td><td> 45, 71, 113</td><td>60</td><td>150</td><td>20,000 </td></tr> +<tr><td>Teutonic.<br /> Majestic.</td><td>565</td><td>58</td><td>43, 68, 110</td><td>60</td><td>180</td><td>18,000 </td></tr> +<tr><td>Normannia.</td><td>500</td><td>57½</td><td> 40, 67, 106</td><td>66</td><td>160</td><td>11,500 </td></tr> +<tr><td>Columbia.</td><td>463½</td><td>55½</td><td> 41, 66, 101</td><td>66</td><td>160</td><td>12,500 </td></tr> +<tr><td>Empress of India.<br />Empress of Japan.<br />Empress of China.</td><td>440</td><td>51</td><td>32, 51, 82</td><td>54</td><td>160</td><td>10,125</td></tr> +<tr><td>Orel.</td><td>415</td><td>48</td><td>34, 54, 85</td><td>51</td><td>160</td><td>10,000 </td></tr> +</table> + +<p><i>Weight of Machinery Relatively to Power</i>.--It is interesting +to compare the weight of machinery relatively + +to the power developed; for this comparison has +sometimes been adopted as the standard of excellence +in design, in respect of economy in the use of material. +The principle, however, on which this has generally +been done is open to some objections. It has been usual +to compare the weight directly with the indicated +horse-power, and to express the comparison in pounds +per horse-power. So long as the machinery thus compared +is for vessels of the same class and working at +about the same speed of revolution, no great fault can +be found; but as speed of revolution is a great factor +in the development of power, and as it is often dependent +on circumstances altogether external to the engine +and concerning rather the speed of the ship, the engines +fitted to high speed ships will thus generally +appear to greater advantage than is their due. Leaving +the condenser out of the question, the weight of an +engine would be much better referred to cylinder +capacity and working pressures, where these are materially +different, than directly to the indicated power. +The advantages of saving weight of machinery, so long +as it can be done with efficiency, are well known and +acknowledged. If weight is to be reduced, it must be +done by care in design, not by reduction of strength, +because safety and saving of repairs are much more +important than the mere capability of carrying a +few tons more of paying load. It must also be +done with economy; but this is a matter which generally +settles itself aright, as no shipowner will pay more +for a saving in weight than will bring in a remunerative +interest on his outlay. In his paper on the weight +of machinery in the mercantile marine,<a name="FNanchor_3"></a><a href="#Footnote_3"><sup>3</sup></a> Mr. William +Boyd discussed this question at some length, and proposed +to attain the end of reducing the weight of machinery +by the legitimate method of augmenting the +speed of revolution and so developing the required +power with smaller engines. This method, while promising, +is limited by the efficiency of the screw, but may +be adopted with advantage so long as the increase in +speed of revolution involves no such change in the +screw as to reduce its efficiency as a propeller. But +when the point is reached beyond which a further +change involves loss of propelling efficiency, it is time +to stop; and the writer ventures to say that in many +cargo vessels now at work the limit has been reached, +while in many others it has certainly been passed.</p> + +<p><i>Economy of Fuel</i>.--Coming to the highly important +question of economy of fuel, the average consumption +of coal per indicated horse-power is 1.522 lb. per hour. +The average working pressure is 158.5 lb. per square +inch. Comparing this working pressure with 77.4 lb. in +1881, a superior economy of 19 per cent. might be expected +now, on account of the higher pressure, or +taking the 1.828 lb. of coal per hour per indicated +horse-power in 1881, the present performance under +similar conditions should be 1.48 lb. per hour per indicated +horse-power. It appears that the working +pressures have been increased twice in the last ten +years, and nearly three times in the last nineteen. The +coal consumptions have been reduced 16.7 per cent. in +the last ten years and 27.9 per cent. in the last nineteen. +The revolutions per minute have increased in the +ratios of 100, 105, 114; and the piston speeds as 100, 124, +140. Although it is quite possible that the further investigations +of the Research Committee on Marine +Engine Trials may show that the present actual consumption +of coal per indicated horse-power is understated, +yet it is hardly probable that the relative +results will be affected thereby.</p> + +<p><i>Dimensions</i>.--In the matter of the power put into +individual vessels, considerable strides have been +made. In 1881, probably the greatest power which has +been put into one vessel was in the case of the Arizona, +whose machinery indicated about 6,360 horse-power. +The following table gives an idea of the dimensions +and power of the larger machinery in the later +passenger vessels:</p> + +<p class="ctr">TABLE III.--DIMENSIONS AND POWER OF MACHINERY +IN LATER PASSENGER VESSELS.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Later Passenger Vessels"> +<colgroup><col align="left"><col align="left" width="25%"><col align="center"><col span="2" align="right"></colgroup> +<tr><td>Year.</td><td>Name of vessel. </td><td>Diameters of cylinders<br />Inches.</td><td>Length of Stroke.<br />Inches.</td><td>Indicated horsepower</td></tr> +<tr><td>1881</td><td>Alaska</td><td>68, 100, 100</td><td>72</td><td>10,686</td></tr> +<tr><td>1881</td><td>City of Rome</td><td>46, 86; 46, 86; 46, 86</td><td>72</td><td>11,800</td></tr> +<tr><td>1881</td><td>Servia</td><td>72, 100, 100</td><td>78</td><td>10,300</td></tr> +<tr><td>1881</td><td>Livadia yacht</td><td>60, 78, 78; 60, 78,78; 60, 78, 78</td><td>39</td><td>12,500</td></tr> +<tr><td>1883</td><td>Oregon</td><td>70, 104, 104</td><td>72</td><td>13,300</td></tr> +<tr><td>1884<br />1884</td><td>Umbria<br />Etruria</td><td>71, 105, 105</td><td>72</td><td>14,320</td></tr> +<tr><td>1888<br />1889</td><td>City of New York<br /> City of Paris</td><td>45, 71, 113; 45, 71, 113</td><td>60</td><td>20,000 about</td></tr> +<tr><td>1889<br />1889</td><td>Majestic<br />Teutonic</td><td>43, 68, 110; 43, 68, 110</td><td>60</td><td>18,000</td></tr> +</table> + + +<p>In war vessels the increase has been equally marked. +In 1881 the maximum power seems to have been in the +Inflexible, namely, 8,485 indicated horse-power. The +following will give an idea of the recent advance made: +Howe (Admiral class), 11,600 indicated horse-power; +Italia and Lepanto, 19,000 indicated horse-power; Re +Umberto, 19,000 indicated horse-power; Blake and +Blenheim (building), 18,000 indicated horse-power; Sardegna +(building), 22,800 indicated horse-power. It is +thus evident that there are vessels at work to-day +having about three times the maximum power of any +before 1881.</p> + +<p><i>General Conclusions</i>.--The progress made during the +last ten years having been sketched out, however +roughly, the general conclusions may be stated briefly +as follows: First, the working pressure has been about +doubled. Second, the increase of working pressure and +other improvements have brought with them their +equivalent in economy of coal, which is about 20 per +cent. Third, marked progress has been made in the +direction of dimension, more than twice the power +having been put into individual vessels. Fourth, substantial +advance has been made in the scientific principles +of engineering. It only remains for the writer to +thank the various friends who have so kindly furnished +him with data for some of the tables which have been +given; and to express the hope that the next ten years +may be marked by such progress as has been witnessed +in the past. But it must be remembered that, if +future progress be equal in merit or ratio, it may well +be less in quantity, because advance becomes more difficult +of achievement as perfection is more nearly approached.</p> + +<a name="Footnote_1"></a><a href="#FNanchor_1">[1]</a><div class="note">Paper read before the Institution of Mechanical Engineers, July 28, +1891.</div> + +<a name="Footnote_2"></a><a href="#FNanchor_2">[2]</a><div class="note">Transactions Northeast Coast Institution of Engineers and Shipbuilders, +vol. 7, 1890-91, p. 179.</div> + +<a name="Footnote_3"></a><a href="#FNanchor_3">[3]</a><div class="note">Transactions Northeast Coast Institution of Engineers and Shipbuilders, +vol. 6, 1889-90, p. 253.</div> + +<hr /> + +<a name="misc1"></a><h2>THE LITTLE HOUSE</h2> + +<h3>By M.M.</h3> + + +<p>One of the highest medical authorities is credited +with the statement that "nine-tenths of the diseases +that afflict humanity are caused by neglect to answer +the calls of Nature."</p> + +<p>This state of affairs is generally admitted, but is +usually attributed to individual indolence. That, +doubtless, has a great deal to do with it, but should +not part of the blame be laid upon the often unpleasant +environments, which make us shrink as from the +performance of a painful duty?</p> + +<p>In social life, unless from absolute necessity or charity, +people of refined habits do not call on those whose +surroundings shock their sense of decency; but when +they go to pay the calls of Nature, they are often compelled +to visit her in the meanest and most offensive +of abodes; built for her by men's hands; for Nature +herself makes no such mistakes in conducting her +operations. She does not always surround herself +with the pomp and pride of life, but she invariably +hedges herself in with the thousand decencies and the +pomp of privacy.</p> + +<p>But what do we often do? We build what is sometimes +aptly termed "an out-house," because it is placed +so that the delicate minded among its frequenters may +be made keenly alive to the fact that they can be +plainly seen by every passer-by and by every idle +neighbor on the lookout. This tiny building is seldom +weatherproof; In consequence, keen cold winds from +above, below, and all around find ready entrance, chill +the uncovered person, frequently check the motions, +and make the strong as well as the weak, the young as +well as the old, very sorry indeed that they are so often +uselessly obliged to answer the calls of Nature. It is +true, the floor is sometimes carpeted with snow, but +the feet feel that to be but cold comfort, though the +door may enjoy rattling its broken hasp and creaking +its loose hinges.</p> + +<p>How often, too, are the nose and the eye offended by +disregard of the Mosaic injunction, found in the +twelfth, thirteenth, and fourteenth verses of the +twenty-third chapter of Deuteronomy! Of course this +injunction was addressed to a people who had been +debased by slavery, but who were being trained to fit +them for their high calling as the chosen of God; but +is not some such sanitary regulation needed in these +times, when a natural office is often made so offensive +to us by its environments that it is difficult for us to +believe that "God made man a little lower than the +angels," or that the human body is the temple of the +Holy Ghost?</p> + +<p>Dwellers in the aristocratic regions of a well drained +city, whose wealth enables them to surround themselves +with all devices tending to a refined seclusion, +may doubt all this, but sanitary inspectors who have +made a round of domiciliary visits in the suburbs, or +the older, neglected parts of a large city, of to any part +of a country town or village, will readily affirm as to its +general truth.</p> + +<p>This unpardonable neglect of one of the minor decencies +by the mass of the people seems to be caused +partly by a feeling of false shame, and partly by an +idea that it is expensive and troublesome to make any +change that will improve their sanitary condition or +dignify their daily lives.</p> + +<p>The Rev. Henry Moule, of Fordington Vicarage, +Dorsetshire, England, was one of the first to turn his +attention to this matter. With the threefold object of +improving the sanitary condition of his people, refining +their habits, and enriching their gardens, he invented +what he called the "dry earth closet."</p> + +<p>"It is based on the power of clay and the decomposed +organic matter found in the soil to absorb and retain +all offensive odors and all fertilizing matters; and it +consists, essentially, of a mechanical contrivance (attached +to the ordinary seat) for measuring out and +discharging into the vault or pan below a sufficient +quantity of sifted dry earth to entirely cover the solid +ordure and to absorb the urine.</p> + +<p>"The discharge of earth is effected by an ordinary +pull-up, similar to that used in the water closet, or (in +the self-acting apparatus) by the rising of the seat +when the weight of the person is removed.</p> + +<p>"The vault or pan under the seat is so arranged that +the accumulation can be removed at pleasure.</p> + +<p>"From the moment when the earth is discharged +and the evacuation covered, all offensive exhalation +entirely ceases. Under certain circumstances there +may be, at times, a slight odor as of guano mixed with +earth, but this is so trifling and so local that a commode +arranged on this plan may, without the least +annoyance, be kept in use in any room."</p> + +<p>The "dry earth closet" of the philanthropic clergyman +was found to work well, and was acceptable to +his parishioners. One reason why it was so was because +dry earth was ready to hand, or could be easily +procured in a country district where labor was cheap. +But where labor was dear and dry earth scarce, those +who had to pay for the carting of the earth and the +removal of the deodorized increment found it both +expensive and troublesome.</p> + +<p>But a modification of this dry earth closet, the joint +contrivance of an English church clergyman and his +brother, "the doctor," residents of a Canadian country +town, who had heard of Moule's invention, is a +good substitute, and is within the reach of all. This +will be briefly described.</p> + +<p>The vault was dug as for an ordinary closet, about +fifteen feet deep, and a rough wooden shell fitted in. +About four feet below the surface of this wooden shell +a stout wide ledge was firmly fastened all around. +Upon this ledge a substantially made wooden box was +placed, just as we place a well fitting tray into our +trunks. About three feet of the back of the wooden +shell was then taken out, leaving the back of the box +exposed. From the center of the back of the box a +square was cut out and a trap door fitted in and hasped +down.</p> + +<p>The tiny building, on which pains, paint, and inventive +genius had not been spared to make it snug, +comfortable, well lighted and well ventilated, was +placed securely on this vault.</p> + +<p>After stones had been embedded in the earth at the +back of the vault, to keep it from falling upon the trap + +door, two or three heavy planks were laid across the +hollow close to the closet. These were first covered +with a barrowful of earth and then with a heap of +brushwood.</p> + +<p>Within the closet, in the left hand corner, a tall +wooden box was placed, about two-thirds full of dry, +well sifted wood ashes. The box also contained a +small long-handled fire shovel. When about six inches +of the ashes had been strewn into the vault the closet +was ready for use. No; not quite; for squares of suitable +paper had to be cut, looped together with twine, +and hung within convenient reaching distance of the +right hand; also a little to the left of this pad of paper, +and above the range of sight when seated, a ten pound +paper bag of the toughest texture had to be hung by a +loop on a nail driven into the corner.</p> + +<p>At first the rector thought that his guests would be +"quick-witted enough to understand the arrangement," +but when he found that the majority of them +were, as the Scotch say, "dull in the uptak," he had +to think of some plan to enforce his rules and regulations. +As by-word-of-mouth instructions would have +been rather embarrassing to both sides, he tacked up +explicit written orders, which must have provoked +many a smile. Above the bin of sifted ashes he nailed +a card which instructed "Those who use this closet +must strew two shovelfuls of ashes into the vault." +Above the pad of clean paper he tacked the thrifty +proverb: "Waste not, want not;" and above the +paper bag he suspended a card bearing this warning: +"All refuse paper must be put into this bag; not a +scrap of clean or unclean paper must be thrown into +the vault."</p> + +<p>This had the desired effect. Some complacently +united to humor their host's whim, as they called it, +and others, immediately recognizing its utility and +decency, took notes with a view to modifying their +own closet arrangements.</p> + +<p>Sarah, the maid of all work, caused a good deal of +amusement in the family circle by writing her instructions +in blue pencil on the front of the ash bin. These +were: "Strew two shuffefuls of ashes into the volt, but +don't spill two shuffefuls onto the floor. By order of +the Gurl who has to sweap up." This order was emphatically +approved of by those fastidious ones who +didn't have to "sweep up."</p> + +<p>This closet opened off the woodshed, and besides being +snugly weatherproof in itself, was sheltered on one +side by the shed and on another by a high board fence. +The other two sides were screened from observation by +lattice work, outside of which evergreens were planted +to give added seclusion and shade. A ventilator in the +roof and two sunny little windows, screened at will +from within by tiny Venetian shutters, gave ample +light and currents of fresh air. For winter use, the +rector's wife and daughters made "hooked" mats for +floor and for foot support. These were hung up every +night in the shed to air and put back first thing in the +morning. For the greater protection and comfort of +invalids, an old-fashioned foot warmer, with a handle +like a basket, was always at hand ready to be filled +with live coals and carried out.</p> + +<p>The little place was always kept as exquisitely clean +as the dainty, old-fashioned drawing room, and so +vigilant was the overseeing care bestowed on every detail, +that the most delicate and acute sense of smell +could not detect the slightest abiding unpleasant odor. +The paper bag was frequently changed, and every +night the accumulated contents were burned; out of +doors in the summer, and in the kitchen stove--after a +strong draught had been secured--in the winter.</p> + +<p>At stated times the deodorized mass of solid increment--in +which there was not or ought not to have +been any refuse paper to add useless bulk--was spaded, +through the trap door, out of the box in the upper +part of the vault, into a wheelbarrow, thrown upon +the garden soil, and thoroughly incorporated with it. +In this cleansing out process there was little to offend, +so well had the ashes done their concealing deodorizing +work.</p> + +<p>In using this modified form of Moule's invention, it +is not necessary to dig a deep vault. The rector, given +to forecasting, thought that some day his property +might be bought by those who preferred the old style, +but his brother, the doctor, not troubling about what +might be, simply fitted his well made, four feet deep +box, with its trap door, into a smoothly dug hole that +exactly held it, and set the closet over it. In all other +respects it was a model of his brother's.</p> + +<p>This last is within the reach of all, even those who +live in other people's houses; for, when they find +themselves in possession of an unspeakably foul closet, +they can cover up the old vault and set the well +cleaned, repaired, fumigated closet upon a vault +fashioned after the doctor's plan. A stout drygoods +box, which can be bought for a trifle, answers well for +this purpose, after a little "tinkering" to form a trap +door.</p> + +<p>Of course, dry earth is by far the best deodorizer +and absorbent, but when it cannot be easily and +cheaply procured, well sifted wood or coal ashes--wood +preferred--is a good substitute. The ashes must be +kept dry. If they are not, they lose their absorbing, +deodorizing powers. They must also be well sifted. If +they are not, the cinders add a useless and very heavy +bulk to the increment.</p> + +<p>An ash sifter can be made by knocking the bottom +out of a shallow box, studding the edge all round with +tacks, and using them to cross and recross with odd +lengths of stovepipe wire to form a sieve.--<i>The Sanitarian</i>.</p> + +<hr /> +<a name="med1"></a><h2>THE HYGIENIC TREATMENT OF OBESITY.<a name="FNm1_anc_1"></a><a href="#FNm1_1"><sup>1</sup></a></h2> + +<h3>By Dr. Paul Cheron.</h3> + + +<p>In order to properly regulate the regimen of the +obese, it is first necessary to determine the source of +the superfluous adipose of the organism, since either +the albuminoids or the hydrocarbons may furnish fat.</p> + +<p>Alimentary fat becomes fixed in the tissues, as has +been proved by Lebede, who fed dogs, emaciated by +long fast, with meat wholly deprived of fat, and substituted +for the latter linseed oil, when he was able to +recover the oil in each instance from the animal; +parallel experiments with mutton fat, <i>in lieu</i> of oil, +afforded like results.</p> + +<p>Hoffman also deprived dogs of fat for a month, causing +them to lose as high as twenty-two pounds weight, + +then began nourishing with bacon fat with but little +lean; the quantity of fat formed in five days, in the +dog that lost twenty-two pounds, was more than three +pounds, which could have been derived only from the +bacon fat.</p> + +<p>It has been stated, however, that alimentary fat +seems to preserve from destruction the fat of the organism +which arises from other sources. Be this as it may, +it is a fact that the pre-existence of fat furthers the +accumulation of more adipose; or in other words, fat +induces fattening!</p> + +<p>That adipose may be formed through the transformation +of albuminous matters (meat) is an extremely +important corollary, one established beyond cavil by +Pettinkofer and Voit, in an indirect way, by first +estimating the nitrogen and carbon ingested, and +second the amount eliminated. Giving a dog meat +that was wholly deprived of fat, they found it impossible +to recover more than a portion of the contained carbon; +hence some must necessarily have been utilized in the +organism, and this would be possible only by the transformation +of the carbon into fat! It goes without +saying, however, that the amount of adipose thus +deposited is meager.</p> + +<p>Other facts also plead in favor of the transformation +of a portion of albumen into fat within the economy, +notably the changing of a portion of dead organism +into what is known as "cadaveric fat," and the very +rapid fatty degeneration of organs that supervenes +upon certain forms of poisoning, as by phosphorus.</p> + +<p>The carbohydrates, or more properly speaking +hydrocarbons, are regarded by all physiologists as +specially capable of producing fat, and numerous alimentary +experiments have been undertaken to prove +this point. Chaniewski, Meissl, and Munk obtained +results that evidenced, apparently, sugar and starch +provide more fat than do the albuminoids. Voit, however, +disapproves this, maintaining the greater part of +the hydrocarbons is burned (furnishes fuel for the +immediate evolution of force), and that fat cannot be +stored up unless a due proportion of albuminoids is +also administered. He believes the hydrocarbons exert +a direct influence only; being more oxidizable than +fats, they guard the latter from oxidation. This protective +role of the hydrocarbons applies also to the +albuminoids.</p> + +<p>We may believe, then, that the three great classes of +aliment yield fat, in some degree; that alimentary fat +may be fixed in the tissues; and that hydrocarbons +favor the deposition of adipose either directly or indirectly.</p> + +<p>It is well understood that fat may disappear with +great rapidity under certain conditions; many maladies +are accompanied by speedy emaciation; therefore, +as fat never passes into the secretions, at least not in +appreciable quantities, it probably undergoes transformation, +perhaps by oxidation or a form of fermentation, +the final results of which are, directly or +indirectly, water and cadaveric acid. It is certain +the process of oxidation favors the destruction of +adipose, and that everything which inhibits such +destruction tends to fat accumulation.</p> + +<p>Since the earliest period of history, there seems to +have been an anxiety to secure some regimen of general +application that would reduce or combat obesity. +Thus Hippocrates says:</p> + +<p>Fat people, and all those who would become lean, +should perform laborious tasks while fasting, and eat +while still breathless from fatigue, without rest, and +after having drunk diluted wine not very cold. Their +meats should be prepared with sesamum, with sweets, +and other similar substances, and these dishes should +be free from fat.</p> + +<p>In this manner one will be satiated through eating +less.</p> + +<p>But, besides, one should take only one meal; take +no bath; sleep on a hard bed; and walk as much as +may be.</p> + +<p>How much has medical science gained in this direction +during the interval of more than two thousand +years? Let us see:</p> + +<p>First among moderns to seek to establish on a scientific +basis a regimen for the obese, was Dancel, who +forbade fats, starchy foods, etc., prescribed soups and +aqueous aliment, and reduced the quantity of beverage +to the lowest possible limit; at the same time he employed +frequent and profuse purgation.</p> + +<p>This regimen, which permits, at most, but seven to +twelve ounces of fluid at each repast, is somewhat +difficult to follow, though it may be obtained, gradually, +with ease. Dr. Constantine Paul records a case +in which this regimen, gradually induced, and followed +for ten years, rewarded the patient with "moderate +flesh and most excellent health."</p> + +<p>In Great Britain, a mode of treatment instituted in +one Banting, by Dr. Harvey, whereby the former was +decreased in weight forty pounds, has obtained somewhat +wide celebrity; and what is more remarkable, it +is known as "Bantingism," taking its name from the +patient instead of the physician who originated it. +The dietary is as follows:</p> + +<p><i>Breakfast</i>.--Five to six ounces of lean meat, broiled +fish, or smoked bacon--veal and pork interdicted; a +cup of tea or coffee without milk or sugar; one ounce +of toast or dry biscuit (crackers).</p> + +<p><i>Dinner</i>.--Five or six ounces of lean meat or fish--excluding +eel, salmon, and herring; a small quantity of +vegetables, but no potatoes, parsnips, carrots, beets, +peas, or beans; one ounce of toast, fruit, or fowl; two +glasses of red wine--beer, champagne, and port forbidden.</p> + +<p><i>Tea</i>.--Two or three ounces of fruit; one kind of +pastry; one cup of tea.</p> + +<p><i>Supper</i>.--Three or four ounces of lean beef or fish; +one or two glasses of red wine.</p> + +<p><i>At bed-time.</i>--Grog without sugar (whisky and water, +or rum and water), and one or two glasses of sherry or +Bordeaux.</p> + +<p>"Bantingism," to be effective, must be most closely +followed, when, unfortunately also, it proves extremely +debilitating; it is suitable only for sturdy, hard +riding gluttons of the Squire Western type. The +patient rapidly loses strength as well as flesh, and +speedily acquires an unconquerable repugnance to the +dietary. Further, from a strictly physiological point +of view, the quantity of meat is greatly in excess, while +with the cessation of the regimen, the fat quickly reappears.</p> + +<p>Next Ebstein formulated a dietary that is certainly +much better tolerated than that of Harvey and Banting, + +and yields as good, or even better, results. He +allows patients to take a definite quantity--two to two +and a half ounces-of fat daily, in the form of bacon +or butter which, theoretically at least, offers several +advantages: It diminishes the sensations of hunger +and thirst, and plays a special role with respect to the +albuminoids; the latter may thus be assimilated by +the economy without being resolved into fat, and thus +the adipose of the organism at this period is drawn +upon without subsequent renewal. The following is +the outline:</p> + +<p><i>Breakfast</i>.--At 6 a.m. in summer; 7:30 in winter:--Eight +ounces of black tea without either milk or sugar; +two ounces of white bread or toast, with a copious layer +of butter.</p> + +<p><i>Dinner</i>.--2 p.m.:--A modicum of beef marrow soup; +four ounces of meat, preferably of fatty character; +moderate quantity of vegetable, especially the legumines, +but no potatoes or anything containing starch; +raw fruits in season, and cooked fruits (stewed, without +sugar); two or three glasses of light wine as a +beverage, and after eating, a cup of black tea without +sugar.</p> + +<p><i>Supper</i>.--7:30 p m.:--An egg, bit of fat roast, ham, +or bacon; a slice of white bread well buttered; a large +cup of black tea without milk or sugar; from time to +time, cheese and fresh fruits.</p> + +<p>Germain See suggests as a modification of this regimen, +the abundant use of beverage, the addition of +gelatins, and at times small doses of potassium iodide +in twenty cases he claims constant and relatively +prompt results.</p> + +<p>Whatever may be urged for Ebstein's system--and it +has afforded most excellent results to Unna and to +Lube, as well as its author--it certainly exposes the +patient to the terrors of dyspepsia, when the routine +must needs be interrupted or modified; hence it is not +always to be depended upon. As between dyspepsia +and obesity, there are few, I fancy, who would not +prefer the latter.</p> + +<p>Another "system" that has acquired no little celebrity, +and which has for its aim the reduction as far +as possible of alimentary hydrocarbons while permitting +a certain proportion of fat, is that, of Denneth, +which necessarily follows somewhat closely the lines +laid down by Ebstein.</p> + +<p>Oertels' treatment, somewhat widely known, and not +without due measure of fame, is based upon a series of +measures having as object the withdrawal from both +circulation and the economy at large, as much of the +fluids as possible. It is especially adapted for the relief +of those obese who are suffering fatty degeneration of +the heart. The <i>menu</i> is as follows:</p> + +<p><i>Breakfast</i>.--Pour to five ounces of tea or coffee with +a little milk; two to two and a half ounces bread.</p> + +<p><i>Dinner</i>.--Three or four ounces of roast or boiled +meat, or moderately fat food; fish, slightly fat; salad +and vegetables at pleasure; one and a half ounces of +bread (in certain cases as much as three ounces of farinaceous +food may be permitted); three to six ounces of +fruit; at times a little pastry for dessert.--In summer, +if fruit is not obtainable, six to eight ounces of light +wine may be allowed.</p> + +<p><i>Tea</i>,--A cupful (four to five ounces) of tea or coffee, +with a trifle of milk, as at breakfast; one and three-fourths +ounces of bread; and exceptionally (and at +most) six ounces of water.</p> + +<p><i>Supper</i>.--One to two soft boiled eggs; four or five +ounces of meat; one and three fourths ounces of bread; +a trifle of cheese, salad, or fruit; six to eight ounces of +light wine diluted with an eighth volume of water. +The quantity of beverage may be slightly augmented +at each meal if necessary, especially if there is no morbid +heart trouble.</p> + +<p>Schwenninger (Bismarck's physician), who opened a +large sanitarium near Berlin a few years since for the +treatment of the obese, employs Oertel's treatment, +modified in that an abundance of beverage is permitted, +provided it is not indulged in at meals; it is forbidden +until two hours after eating.</p> + +<p>Both Oertel's and Schwenninger's methods have procured +grave dyspepsias, and fatal albuminurias as well, +according to Meyer and Rosenfield. It has been +charged the allowance of beverage upon which Schwenninger +lays so much stress in the treatment at his sanitarium +has a pecuniary basis, in other words a commission +upon the sale of wines.<a name="FNm1_anc_2"></a><a href="#FNm1_2"><sup>2</sup></a></p> + + +<p>Thus, it will be observed that while some forbid +beverage, others rather insist upon its employment in +greater or less quantities. Under such circumstances, +it would seem but rational, before undertaking to +relieve obesity, to establish its exact nature, and also +the role taken by fluids in the phenomena of nutrition.</p> + +<p>Physiologists generally admit water facilitates nutritive +exchanges, which is explained by the elimination +of a large quantity of urine; the experiments of Genth +and Robin in this direction appear conclusive.</p> + +<p>Bischoff, Voit, and Hermann have shown that water +increases, not alone the elimination of urine, but also +of sodium chloride, phosphoric acid, etc. Grigoriantz +observed augmentation of disintegration when the +quantity of beverage exceeded forty-six to eighty +ounces ("1,400 to 2,400 cubic centimeters") per diem. +Oppenheim, Fraenkel, and Debove, while believing +water has but little influence upon the exchanges, admit +it certainly need not diminish the latter; and Debove +and Flament, after administering water in quantities +varying from two to eight pints per diem, concluded +that urine was diminished below the former +figure, while above the latter it increased somewhat, +being dependent upon the amount ingested. It was on +the strength of the foregoing that Lallemand declared +water to have no influence upon the exchanges.</p> + +<p>The results claimed by Oppenheim, Debove, <i>et al.</i> +were immediately challenged--and it is now generally +admitted, not without some justice--by Germain See. +It seems certain, to say the least, that water taken during +the repast does tend to augment the quantity and +facilitate the elimination of urine. Abundance of beverage, +moreover, presents other advantages, in that it +facilitates digestion by reason of its diluent action, a +fact well worth bearing in mind when treating the +obese who are possessed of gouty diathesis, and whose +kidneys are accordingly encumbered with uric and +oxalic acids. The foregoing presents the ground upon +which Germain See permits an abundance of beverage; +but he also expresses strong reservation as regards beer + +and alcohol, either of which (more especially the former) +tends to the production of adipose. In his opinion, +the only beverage of the alcoholic class that is at all +permissible, and then only for cases suffering from fatty +heart, is a little <i>liqueur</i> or diluted wine. Coffee and +tea he commends highly, and recommends the ingestion +of large quantities at high temperature, both during +the repasts and their intervals. Coffee in large doses +is undoubtedly a means of de-nutrition, and so, too, in +no less extent, is tea; both act vigorously owing to the +contained alkaloids, though, to be sure, they sometimes, +at first, tend to insomnia and palpitation, to +which no attention need be paid, however. The treatment +outlined by See is:</p> + +<p>1. A physiological regimen comprising four to five +ounces of nitrogenous principles as derived from eight +to ten ounces animal muscle and albuminates; three +to six ounces of fat; eight to ten ounces of hydrocarbons +as yielded by ten to twelve ounces of sugar or +starch food.</p> + +<p>These proportions to be modified in such manner +that the musculo-albuminates shall not sensibly exceed +the normal ratio, for meat in excess itself furnishes +fat during transformation. The fatty substances +of easy digestion may, without inconvenience, be utilized +in doses of two to three ounces. The hydrocarbons +should be reduced to a minimum. As for the herbaceous +elements, they contain nothing nutritive.</p> + +<p>2. Beverage, far from being suppressed, should be +augmented, in order to facilitate stomachal digestion +and promote general nutrition, though alcoholic liquids +must be inhibited; likewise mineral waters, except, +perhaps, for occasional use. Both should be replaced +by infusions of coffee or tea, taken as hot as can be +drank.</p> + +<p>Henrich Kisch insists that any method which promises +rapid and marked decrease of adipose must, <i>per se</i>, +be objectionable, even if not positively injurious, since +it tends to provoke general troubles of nutrition. He +suggests that first the fats and hydrocarbons be reduced +as little as possible; that a moderate mixed +regimen is required, containing a preponderance of +albumen, small quantities of hydrocarbons and gelatinous +matters, with but very little fat. Certain fatty +meats, however, should be generally interdicted, such +as pork sausage, smoked beef tongue, goose breast, +smoked ham, fat salmon, and herring in any form. +Eggs, however, may be partaken of in moderation, +giving preference to the albumen over the yelk. Farinaceous +foods, in the main, should be rejected, even +bread being allowed only in small quantities, and then +preferably in the form of toast. Cheese likewise contains +too much fat; and mushrooms are so rich in hydrocarbons +that they should be rejected. Condiments, +water, vegetable acids (vinegars excepted) may be permitted; +especially pernicious is vinegar where there is +any tendency to gout or gravel. All fatty beverages--<i>bouillon</i>, +unskimmed milk, chocolate, or cacao--and +all alcoholics, are hurtful; breakfast tea is undoubtedly +the best beverage, but, after a little, is advantageously +replaced by light white wine diluted with water.</p> + +<p>Kisch believes in a free and abundant use of water +by the obese, especially where there is a tendency to +plethora, since this fluid facilitates oxidation as the +result of absorption; thus he advocates the inhibition +of large quantities of cold water by all, save those presenting +evidence of cardiac insufficiency. In short, +his regimen is based upon the administration of a +large quantity of albumen, like that of Harvey-Banting.</p> + +<p>E. Munk recommends an almost identical dietary, +save that he prefers great moderation in fluids employed +as beverage.</p> + +<p>M. Robin has sought to harmonize the opposing +views regarding fluids, and therefore declares obesity +arises from two distinct sources: 1. Augmentation of +assimilation. 2. Reduced disassimilation. In the former, +he insists water must be interdicted, while in the +latter it may be allowed <i>ad libitum</i>.</p> + +<p>Again, in order to recognize the exact variety of +obesity, he divides his patients into three classes, each +recognizable by the volume of urea excreted. In the +first there is an increase above normal; in the second +the volume of urea is stationary; in the third decreased, +increased, or stationary.</p> + +<p>When the urea is stationary, which is most frequently +the case, it is necessary to calculate the coefficient of +oxidation; that is, the relation existing between the +solid matters of the urine and the urea. The elevation +of the coefficient is <i>prima facie</i> evidence the obesity +is due to excess of assimilation, while depression of +the coefficient indicates default of assimilation. In the +first case, water and liquids must be denied as far as +possible, the same as if there was no augmentation of +urea; in the second, the same as if there was diminution +of urea, the patients may be permitted to imbibe +fluids at pleasure.</p> + +<p>For the obese from default of disassimilation, Robin +recommends a regimen of green vegetables and bread +chiefly--the latter in small quantities, however, and +fluids as may be desired. By this means, on one occasion, +he was able in the course of one month to diminish +the weight of a female patient by twelve and a half +pounds, her measurement around the waist at the same +time decreasing 5.2 inches and across the stomach 4.8 +inches.</p> + +<p>M. De St. Germain achieved good results by combining +judicious exercise with moderate alimentation, +excluding wine and bread.</p> + +<p>M. Dujardin Beaumetz, who professes to have given +most close and careful study and attention to regimen +for the obese, outlines the following, provided there +is no evidence of fatty degeneration of heart.</p> + +<p><i>Breakfast</i> (at 8 a. m.)--Three-fourths of an ounce of +bread "<i>en flute</i>"--that is abounding with crust; one +and a half ounces of cold meat, ham or beef, six ounces +weak black tea, <i>sans</i> sugar.</p> + +<p><i>Lunch</i> (at 1 p.m.)--An ounce and a half to two ounces +of bread, or a <i>ragout</i>, or two eggs; three ounces green +vegetables; one-half ounce of cheese; fruits at discretion.</p> + +<p><i>Dinner</i> (at 7 p.m.)--An ounce and a half to two +ounces of bread; three to four ounces of meat, or +<i>ragout</i>; ditto of green vegetables, salad, half an ounce +of cheese, fruit <i>ad libitum</i>.</p> + +<p>At meal times the patient may take only a "glass and +a half" of liquid--approximately ten ounces--though +a greater amount may be permitted if he abstains during +the intervals.</p> + +<p>Special alimentary regimen, however, does not constitute + +the sole treatment of obesity. Concurrently +must be employed a number of practical adjuvants +which are oftentimes of the utmost assistance. For +one thing, exercise is indispensable; all authorities +agree on this point. The exercise taken in the gymnasium +is one of the best, notably the "wall exercise," +which is more particularly suited to those afflicted +with pendulous and protuberant abdomens as the result +of feebleness of the hypogastric muscles, to accumulation +of fat under the skin and in the omentum, +and to dilation of the stomach and intestines. In the +"wall exercise," the patient stands erect against an +absolutely straight and plumb wall, lifts his hands +(carrying a weight) straight over the head, and causes +them to describe a semicircle forward. Zantz particularly +insists upon arm and leg exercise for the obese, +especially the former, since with the same amount of +effort a larger amount of oxygen is consumed than is +possible by the latter.</p> + +<p>However, of whatever character, the exercise should +be continued to the point of fatigue or dyspn#oelig;a--three +thousand movements daily, gradually increased to +twenty-five thousand, if the system can bear it; and +under such conditions, not only is there consumption +of hydrocarbons, but there is provided a veritable +greed for air that augments waste. The experiments +of Oertel indicate that loss of weight due to fatiguing +exercise arises more particularly from dehydration, +which is made good by absorption of the fluids employed +as beverage; the fluids are claimed by Germain +See to act as accelerants of oxidation.</p> + +<p>During exercise there is obviously more abundant +absorption of oxygen, and consequently greater elimination +of carbonic acid, and as a consequence (as +shown by researches of Voit), the reserve fat of the +economy is attacked and diminished; in intense labor +there is an average hourly consumption of about 8.2 +percent. of fat. Further physical activity is useful in +exercising the voluntary muscles, and thus opposing +the invasion by interstitial fat of the muscle fibrils. +Extreme exercise also, to a certain degree, exerts a +favorable influence on the cardiac muscle, augmenting +both its nutrition and its capacity for labor. With the +anæmic obese, however, it is necessary to be most circumspect +in prescribing forced exercise; also with the +elderly obese possessed of enfeebled or fatty heart.</p> + +<p>Hydrotherapy, especially in the form of cold douches, +particularly when combined with massage, is often of +considerable value in relieving obesity; the method of +Harmman, of St. Germain, which has in many instances +induced rapid loss of adipose, is of this class. +Tepid saline baths and vapor baths have many advocates, +and may afford material aid when the heart and +circulation do not inhibit their employment. Hot baths +elevate the temperature of the body and increase the +organic exchanges, hence, as Bert and Reynard have +pointed out, tend to the elimination of oxygen and carbonic +acid; but when employed, the patient should be +introduced while the temperature is below 130° F., +when it may be gradually raised in the course of thirty +or forty minutes to 140° F.</p> + +<p>It has already been intimated, the chief feature of +the treatment of obesity is acceleration of the exchanges; +and this is in the main true, though it must +also be borne in mind that, while there are obese who +excrete little urea and have a depressed central nervous +temperature, many may be azoturic, and besides +eliminate phosphate in excess, when an oxidating +treatment will not only fail, but prove positively injurious.</p> + +<p>The bile throws out fat, therefore, to accelerate +nutritive oxidations, the liver and nervous system +must be acted upon, <i>i.e.</i>, stimulated. Everything +that tends to diminish the activity of the former, or +depress the latter, must be avoided. Hence intellectual +labor should be encouraged, or in lieu thereof, travel +advised. Exercise should be taken chiefly while fasting; +the limits of sleep confined to strict necessity, and +<i>siestas</i> after meals and during the day strictly forbidden; +the skin stimulated by hydro-therapeutic +measures, including massage under cold affusions, during +warm salt baths, etc.</p> + +<p>To increase the activity of the liver, salicylate of +soda may often be advantageously administered for its +cholagogue effect; or resort may be had to saline purgatives +such as are afforded by the springs of Marienbad, +Kissengen, Homburg, Carlsbad, Brides, Hunyadi, +or Chatel-Guyon; and it is somewhat remarkable +that while undergoing a course of these waters, there +is often no appreciable change in weight or obesity, +though the decrease becomes most marked almost immediately +upon cessation of treatment.</p> + +<p>Everything tending to increased or fuller respiration +is to be encouraged, for the fats are thus supplied with +oxygen, hastening their disintegration and consumption.</p> + +<p>Direct medicinal treatment presents no very wide +scope. Bouchard imagines lime water may be useful +by accelerating nutrition, but this is problematical, +since fat in emulsion or in droplets does not burn. +Nevertheless, alkalies in general, alkaline carbonates, +liquor potassa, soaps, etc., aid in rendering fat more +soluble, and consequently more susceptible to attack. +The alkaline waters, however, are much less active in +obesity than the saline mineral waters, unless, as sometimes +happens, there is a complication of diabetes and +obesity.</p> + +<p>Purgatives are always more or less useful, and often +required to be renewed with all the regularity of +habit. Then too, the iodides, especially iodide of +sodium or potassium, as recommended by M. Germain +See, frequently prove of excellent service by +aiding elimination and facilitating the mutations.</p> + +<p>According to Kisch, the cold mineral waters containing +an abundance of sulphate of soda, like Hunyadi +and Marienbad, are to be preferred to the hot +mineral waters, such as Carlsbad, because of their lesser +irritant action on the vascular system, and because +they strongly excite diuresis through their low +temperature and contained carbonic acid; Carlsbad +deserves preference only when obesity is combined with +uric acid calculi, or with diabetes. For very anæmic +persons, however, the weak alkaline and saline waters +should be selected; or they should confine themselves +to chalybeate waters containing an excess of sulphate +of soda. Water containing sulphate of soda is also indicated +as a beverage where there are troubles of the +circulatory apparatus; it is contraindicated only in accentuated +arterio-sclerosis.</p> + +<p>As a matter of fact, I find the suggestion of M. + +Dujardin-Beaumetz, that the obese should be divided +into two groups, a most practical one, for some are +strong and vigorous--great eaters, perhaps even gluttons--while +others, on the contrary, are feeble and +debilitated, with flesh soft and flaccid; and upon the +former may be imposed all the rigors of the reducing +system, while the latter must be dealt with more carefully.</p> + +<p>In general, it must be noted, the regimen prescribed +for the obese is insufficient, as the following table prepared +by M.C. Paul abundantly proves:</p> + + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Regimen For Obese"> +<colgroup><col align="left"><col span="3" align="center"></colgroup> +<tr><td align="center">Author.</td><td>Albuminous Matters.</td><td>Fatty Matters.</td><td>Hydrocarbons.</td></tr> +<tr><td>Voit.</td><td>118</td><td>40</td><td>150</td></tr> +<tr><td>Harvey-Banting.</td><td>170</td><td>10</td><td>80</td></tr> +<tr><td>Ebstein.</td><td>100</td><td>85</td><td>50</td></tr> +<tr><td>Oertel.</td><td>155-179</td><td>25-41</td><td>70-110</td></tr> +<tr><td>Kisch (plethoric).</td><td>160</td><td>10</td><td>80</td></tr> +<tr><td>Kisch (anæmic).</td><td>200</td><td>12</td><td>100</td></tr> +<tr><td>Normal ration.</td><td>124</td><td>55</td><td>455</td></tr> +</table> + +<p>There is, therefore, as Dujardin-Beaumetz asserts, +autophagia in the obese, and all these varieties of treatment +have but one end, viz.: Reduction of the daily +ration. But the quantity of nourishment should not +be too greatly curtailed, for, manifestly, if the fat disappears +the more surely, the muscles (rich in albumen) +undergo too rapid modification. It is progressive action +that should always be sought.</p> + +<p>The quantity of aliment may be reduced either by +imposing an always uniform regimen, which soon begets +anorexia and disgust, or by withholding from the +food a considerable quantity of fat, or, finally, by forbidding +beverage during meals. Emaciation is obtained +readily enough in either way, and demands +only the constant exercise of will power on the part of +the patient; but unhappily, severe regimen cannot +always be prescribed. When the obese patient has +passed the age of forty; when the heart suffers from +degeneration; or when the heart is anæmic--in all, +rigorous treatment will serve to still further enfeeble +the central organ of circulation, and tend to precipitate +accidents that, by all means, are to be avoided. +In such cases, by <i>not</i> treating the obesity, the days of +the patient will be prolonged. In degeneration of the +heart, however, the method of Ebstein may be tried; +and when there is renal calculi and gouty diathesis, +that of Germain See may prove satisfactory.</p> + +<h3>Paris, France.</h3> + +<a name="FNm1_1"></a><a href="#FNm1_anc_1">[1]</a><div class="note"> +Translated by Mr. Jos. Helfman, Detroit, Mich.</div> + +<a name="FNm1_2"></a><a href="#FNm1_anc_2">[2]</a><div class="note">The sanitarium is owned by a stock company, Schwenninger being +merely Medical Director.--ED.</div> + +<hr /> + + + +<a name="misc2"></a><h2>STILT WALKING.</h2> + +<p class="ctr"><a href="./images/12-stilt.png"><img src="images/12-stilt_th.jpg " width="256" height="391" alt="THE FRENCH ARMORED TURRET SHIP MARCEAU" title=""></a> +<br clear="all" />SYLVAIN DORNON, THE STILT WALKER OF LANDES.</p> + +<p>Sylvain Dornon, the stilt walker of Landes, started +from Paris on the 12th of last March for Moscow, +and reached the end of his journey at the end of a fifty-eight +days' walk. This long journey upon stilts constitutes +a genuine curiosity, not only to the Russians, +to whom this sort of locomotion is unknown, but also +to many Frenchmen.</p> + +<p>Walking on stilts, in fact, which was common twenty +years ago in certain parts of France, is gradually tending +to become a thing of the past. In the wastes of +Gascony it was formerly a means of locomotion adapted +to the nature of the country. The waste lands +were then great level plains covered with stunted bushes +and dry heath. Moreover, on account of the permeability +of the subsoil, all the declivities were transformed +into marshes after the slightest fall of rain.</p> + +<p>There were no roads of any kind, and the population, +relying upon sheep raising for a living, was much +scattered. It was evidently in order to be able to +move around under these very peculiar conditions +that the shepherds devised and adopted stilts. The +stilts of Landes are called, in the language of the +country, <i>tchangues</i>, which signifies "big legs," and +those who use them are called <i>tchanguès</i>. The stilts +are pieces of wood about five feet in length, provided +with a shoulder and strap to support the foot. The +upper part of the wood is flattened and rests against +the leg, where it is held by a strong strap. The lower +part, that which rests upon the earth, is enlarged and +is sometimes strengthened with a sheep's bone. The +Landese shepherd is provided with a staff which he +uses for numerous purposes, such as a point of support +for getting on to the stilts and as a crook for directing +his flocks. Again, being provided with a board, the +staff constitutes a comfortable seat adapted to the +height of the stilts. Resting in this manner, the shepherd +seems to be upon a gigantic tripod. When he +stops he knits or he spins with the distaff thrust in his +girdle. His usual costume consists of a sort of jacket +without sleeves, made of sheep skin, of canvas gaiters, +and of a drugget cloak. His head gear consists of a +beret or a large hat. This accouterment was formerly +completed by a gun to defend the flock against wolves, +and a stove for preparing meals.</p> + +<p>The aspect of the Landeses is doubtless most picturesque, +but their poverty is extreme. They are generally +spare and sickly, they are poorly fed and are +preyed upon by fever. Mounted on their stilts, the +shepherds of Landes drive their flocks across the wastes, +going through bushes, brush and pools of water, and +traversing marshes with safety, without having to seek +roads or beaten footpaths. Moreover, this elevation +permits them to easily watch their sheep, which are +often scattered over a wide surface. In the morning +the shepherd, in order to get on his stilts, mounts by a +ladder or seats himself upon the sill of a window, or else +climbs upon the mantel of a large chimney. Even in a +flat country, being seated upon the ground, and having +fixed his stilts, he easily rises with the aid of his staff. +To persons accustomed to walking on foot, it is evident +that locomotion upon stilts would be somewhat +appalling.</p> + +<p>One may judge by what results from the fall of a +pedestrian what danger may result from a fall from a +pair of stilts. But the shepherds of Landes, accustomed +from their childhood to this sort of exercise, acquire +an extraordinary freedom and skill therein. The +<i>tchanguè</i> knows very well how to preserve his equilibrium; +he walks with great strides, stands upright, +runs with agility, or executes a few feats of true acrobatism, +such as picking up a pebble from the ground, +plucking a flower, simulating a fall and quickly rising, +running on one foot, etc.</p> + +<p>The speed that the stilt walkers attain is easily explained. +Although the angle of the legs at every step + +is less than that of ordinary walking with the feet on +the ground, the sides prolonged by the stilts are five +or six feet apart at the base. It will be seen that with +steps of such a length, distances must be rapidly +covered.</p> + +<p>When, in 1808, the Empress Josephine went to +Bayonne to rejoin Napoleon I, who resided there by +reason of the affairs of Spain, the municipality sent an +escort of young Landese stilt walkers to meet her. On +the return, these followed the carriages with the greatest +facility, although the horses went at a full trot.</p> + +<p>During the stay of the empress, the shepherds, +mounted upon their stilts, much amused the ladies of +the court, who took delight in making them race, or +in throwing money upon the ground and seeing several +of them go for it at once, the result being a scramble +and a skillful and cunning onset, often accompanied +with falls.</p> + +<p>Up to recent years scarcely any merry-makings occurred +in the villages of Gascony that were not accompanied +with stilt races. The prizes usually consisted +of a gun, a sheep, a cock, etc. The young people vied +with each other in speed and agility, and plucky young +girls often took part in the contests.</p> + +<p>Some of the municipalities of the environs of Bayonne +and Biarritz still organize stilt races, at the period of +the influx of travelers; but the latter claim that the +stiltsmen thus presented are not genuine Landese shepherds, +but simple supernumeraries recruited at hazard, +and in most cases from among strolling acrobats. The +stilt walkers of Landes not only attain a great speed, +but are capable of traveling long distances without appreciable +fatigue.</p> + +<p>Formerly, on the market days at Bayonne and Bordeaux, +long files of peasants were seen coming in on +stilts, and, although they were loaded with bags and +baskets, they came from the villages situated at 10, 15, +or 20 leagues distance. To-day the sight of a stilt +walker is a curiosity almost as great at Bordeaux as at +Paris. The peasant of Landes now comes to the city +in a wagon or even by railway.--<i>La Nature</i>.</p> + +<hr /> +<a name="misc3"></a><h2>REMAINS OF A ROMAN VILLA IN +ENGLAND.</h2> + +<p>A correspondent of the <i>Lincolnshire Chronicle</i> +writes: For some weeks past, remains of a Roman villa +have been exposed to view by Mr. Ramsden's miners in +Greetwell Fields. From, the extent of the tesselated +pavements laid bare there is hardly any doubt +that in the Greetwell Fields, in centuries long gone +by, there stood a Roman mansion, which for magnitude +was perhaps unrivaled in England. Six years +ago I drew attention to it. The digging for iron ore +soon after this was brought to a standstill by the company, +which at the time was working the mines, ceasing +their operations. Then the property came into +other hands, and since then more extensive basement +floors of the villa have from time to time been laid +bare, and from tentative explorations which have +been just made, still more floors remain to be uncovered +which may be of a most interesting and instructive +character. What a pity it is that the inhabitants +of Lincoln have not made an effort to preserve these +precious relics of the grandeur of the Roman occupation, +an occupation to which England owes so much. +From the Romans the people of this country inherit +the sturdy self-reliance and perseverance in action +which have helped to make England what it is, and +from the Romans too, in a great degree, does England +also inherit her colonizing instincts, which impel her +people to cover the waste places of the world with colonies. +If the Roman remains which have been so abundantly +discovered of late years in Lincoln and its vicinity + +had been collected and laid out for exhibition, they +would have formed a most interesting collection of antiquities +worthy of the town, and well worth showing to +visitors who now annually make Lincoln a visitation. +Although these relics of a remote age are being dug +up and are being destroyed, it is not the fault of Mr. +Ramsden, for he not only preserved them as long as he +conveniently could, but he also had the soil removed +from over them, and had them thoroughly washed, in +order that people might have an opportunity of seeing +their extent and beauty. One of these patches of pavement +extended 48 yards northward from what might +be called the main building, which had previously +been broken up. This strip was 13 ft. in breadth, and +down its center ran an intricate pattern worked in blue +tesseræ. The pattern is much used in these days in +fabrics and works of art, and is, I think, called the +Grecian or Roman key pattern. On each side of this +ran alternately broad ribbons of white and narrower +ribbons of red tesseræ. There is also another strip of +pavement to the south of the preceding patch, which +has been laid bare to the extent of 27 yards. This +patch is about 10 ft. in breadth, and its western portion +is cut up in neat patterns, which show that they +formed the floors of rooms. From the eastern extremity +of these floors evidently another long strip of 48 or +50 yards still remains to be uncovered. Doubtless +there are other remains beneath the ground which will +be laid bare as the work of mining goes on. All +these floors were not deeper than from 18 to 30 inches +below the surface of the soil. The bones of animals +and other relics have been found in the covering soil +and have been turned up by the miners from +time to time. The pavement is all worked out with +cubes, varying in size from an inch and a half to two +inches square, each piece being placed in position +with most careful exactness. The strip which extends +48 yards and is 13 ft. wide runs due north and south. +There is a second patch, running east and west, and +this is 27 ft. long by 10 ft. wide, while a third is 27 ft. +long by 11 ft. wide, this also running in a northern +direction. To the north of this latter piece, and separated +only by about two feet (about the width of a +wall, which very possibly was the original division), +there is a strip of tesseræ 16 ft. wide, which had been +laid bare 40 yards. It was thought probable that at +the end of the last named strip still another patch +would be found. Mr. Ramsden, the manager of the +Ironstone Works, is keeping a plan of the whole of the +pavement, which he is coloring in exact imitation of +the original work. This, when completed, will be +most interesting, and he will be quite willing to show +it to any one desirous of inspecting the same. Many +persons have paid a visit to the spot where the discoveries +have been made, and surprise is invariably +expressed at the magnitude and beautiful symmetry +of the work.</p> + +<p>Several interesting fragments of Roman work have +been brought to light in the course of excavations that +are being made for building purposes at Twyford, near +Winchester. About a month ago, a paved way, composed +entirely of small red tiles, six feet in width and +extending probably a considerable distance (a length +of 14 ft. was uncovered), was found while digging on +the site for flints. The more recent excavations are +20 ft. west of this passage, and there is now to be seen, +in a very perfect state of preservation, an oven or kiln +with three openings. Five yards away from this is a +chamber about eight feet square, paved with tiles, and +the sides coated with a reddish plaster. On one side is +a ledge 15 in. from the ground, extending the whole +length of the chamber; on the floor is a sunk channel +with an opening at the end for the water to escape. +This chamber evidently represents the bath. Portions +of the dividing walls of the different chambers have + +also been discovered, together with various bones, +teeth, horns and ornaments, but very few coins. It is +probable that an alteration in the plans of the house +which was about to be built on the spot will be made +so as to preserve all the more interesting features of +these remains in the basement. These discoveries +were made at a depth of only two or three feet from +the surface of the ground, and are within about a +quarter of a mile of other Roman remains which were +similarly brought to light a few months ago.</p> + +<hr /> +<h3>[Continued from SUPPLEMENT, No. 830, page 13110.]</h3> + + +<a name="misc4"></a><h2>GUM ARABIC AND ITS MODERN SUBSTITUTES.<a name="FNms4_anc_1"></a><a href="#FNms4_1"><sup>1</sup></a></h2> + +<h3>By Dr. S. RIDEAL and W.E. YOULE.</h3> + +<p>Subjoined is a table giving the absolute viscosity +of various gums. A comparison of the uncorrected +viscosities with the corrected shows the great importance +of Slotte's correction for dextrins and inferior +gum arabics; in other words, for solutions of low viscosity, +while it will be observed to have little influence +upon the uncorrected η obtained for the Ghatti gums +and the best samples of gum arabic.</p> + +<p class="ctr">TABLE OF ABSOLUTE VISCOSITIES OF 10 PER CENT. GUM +AND DEXTRIN SOLUTIONS.</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gum Viscosity"> +<colgroup><col align="left"><col span="3" align="right"></colgroup> +<tr><td align="center">Sample.</td><td>η Uncorrected.</td><td>η Corrected.</td><td>Z Water = 100.</td></tr> +<tr><td>Gum arabic</td><td>0.1876</td><td>0.1856</td><td>1,233</td></tr> +<tr><td>Cape gum</td><td>0.1575</td><td>0.1555</td><td>1,029</td></tr> +<tr><td>Indian gum</td><td>0.0540</td><td>0.0470</td><td>311</td></tr> +<tr><td>Eastern gum</td><td>0.0689</td><td>0.0639</td><td>417</td></tr> +<tr><td>Gum arabic</td><td>0.0550</td><td>0.0480</td><td>317</td></tr> +<tr><td>Senegal</td><td>0.0494</td><td>0.0410</td><td>271</td></tr> +<tr><td>Senegal</td><td>0.0468</td><td>0.0380</td><td>251</td></tr> +<tr><td>Senegal</td><td>0.0627</td><td>0.0557</td><td>364</td></tr> +<tr><td>Gum arabic</td><td>0.0511</td><td>0.0430</td><td>285</td></tr> +<tr><td>Water</td><td>0.0149</td><td>0.0124</td><td>100</td></tr> +<tr><td>Ghatti</td><td>0.2903</td><td>0.2880</td><td>2,322</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.0903</td><td>0.0828</td><td>688</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1391</td><td>0.1350</td><td>1,089</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1795</td><td>0.1760</td><td>1,420</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1527</td><td>0.1485</td><td>1,198</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1139</td><td>0.1083</td><td>873</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1419</td><td>0.1369</td><td>1,104</td></tr> +<tr><td>Dextrin</td><td>0.0398</td><td>0.0255</td><td>169</td></tr> +<tr><td>Dextrin</td><td>0.0341</td><td>0.0196</td><td>129</td></tr> +<tr><td>Dextrin</td><td>0.0455</td><td>0.0380</td><td>306</td></tr> +<tr><td>Gum substitute</td><td>0.0318</td><td>0.0224</td><td>180</td></tr> +<tr><td>Gum substitute</td><td>0.0318</td><td>0.0224</td><td>180</td></tr> +<tr><td>Amrad</td><td>0.0793</td><td>0.0708</td><td>570</td></tr> +<tr><td>Australian</td><td>0.0378</td><td>0.0283</td><td>228</td></tr> +<tr><td>Australian</td><td>0.0365</td><td>0.0268</td><td>216</td></tr> +<tr><td>Brazilian</td><td>0.0668</td><td>0.0627</td><td>506</td></tr> +<tr><td>Brazilian</td><td>0.0516</td><td>0.0445</td><td>359</td></tr> +<tr><td>Ghatti</td><td>0.3636</td><td>0.3621</td><td>2,920</td></tr> +</table> + + +<p>In the column for η corrected the differences due to +the use of different instruments are of course eliminated. +The absolute viscosity of water at 15° C. determined +in four different instruments is shown below. +Poiseuille's value for water being 0.0122.</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Instrument Differences"> +<colgroup><col align="left"><col span="4" align="right"> +<tr><td align="center">Instrument.</td><td>1.</td><td>2.</td><td>3.</td><td>4.</td></tr> +<tr><td>η corrtd. of water.</td><td>0.0109</td><td>0.01185</td><td>0.0124</td><td>0.0120 </td></tr> +<tr><td>K<sub>1</sub> value.</td><td>0.000000898</td><td>0.000000863</td><td>0.000000932</td><td>0.00000052 </td></tr> +<tr><td>K<sub>2</sub> value.</td><td>0.235</td><td>0.2175</td><td>0.226</td><td>0.0204 </td></tr> +</table> + +<p>The above values for various gums and dextrins were +obtained at a constant temperature of 15° C. and are +compared with water at that temperature. It is of the +utmost importance that the temperature of the water +surrounding the bulbs should be adjusted for each series +of experiments to the temperature at which the absolute +viscosity of the water was determined. As far as +we have ascertained, in gum solutions there is a steady +diminution in viscosity with increase of temperature +until a certain temperature is reached, beyond which +increase of heat does not markedly influence the viscosity, +and it is possible that above this "critical +point," as we may term it, the gum solutions once more +begin to increase in viscosity. The temperature at +which the viscosity becomes stationary varies somewhat +with different gums, but broadly speaking it lies +between 60° C. and 90° C., no gums showing any marked +decrease in viscosity between 80° C. and 90° C.</p> + +<p>The experiments we have made in this direction were +conducted as follows. The 300 c.c. bottle containing +the gum was placed in a capacious beaker full of hot +water, and the viscosity instrument was also surrounded +with water at the same temperature. Thermometers +were suspended both in the beaker and the outer +jar. The viscosity at the highest temperature obtained, +about 90° C., was then taken and repeated for +every fall of 4° C. till the water reached the temperature +of the air.</p> + +<p>The values so obtained gradually diminished with +the increase of temperature. From the η values obtained +the Z values were calculated, using water at 15° C. +as a standard. From the Z values thus obtained +taken as the ordinate, and the temperature of each +experiment as the abscissa, curves were plotted out +embodying the results, examples of which are given +below. The curves yielded by three gums 2, 7, and 8 +changed between 90° C and 100° C., while gum sample +4 has a curve bending between 60° C. and 70° C. Experimentally + +this increase of viscosity of the latter gum +above 60° C. was confirmed, but the critical point of the +other solutions tried approaches too nearly to the boiling +point of water for experiments to be conducted +with accuracy, as the temperature of the bulbs diminishes +sensibly while the experiment is being made.</p> + +<p>If viscosity values have been determined it is possible +to calculate the remaining or intermediate values +for Z at any particular temperature from the general +equation--Zt = A + Bt + Ct²</p> + +<p>As an example of the mode of calculation we may +quote the following. A gum gave the following values +for Z at the temperature stated:</p> + +<blockquote><p>Gum. 50° C. Z<sub>50°</sub> = 228</p> + +<p>Gum. 30° C. Z<sub>30°</sub> = 339</p> + +<p>Gum. 20° C. Z<sub>20°</sub> = 412</p> +</blockquote> + +<p>from which the constants--</p> + +<blockquote><p>A = 592.99 B = -10.2153 C = 0.0583</p></blockquote> + +<p>can be obtained, and thus the value of Z<sub>t°</sub> for any required +temperature. The numbers calculated for gums +all point to a diminution in viscosity up to a certain +point, and then a gradual increase. A comparison of +some of the figures actually obtained in some of these +experiments, compared with the calculated figures for +the same temperature, shows their general agreement.</p> + +<p class="ctr"> <img src="./images/13-gr1.png" height="320" width="306" alt=""> +<br clear="all" /> Curves showing viscosity change with temperature +for three typical gums. A--Arabic VII. B--Senegal +VIII. C--Ghatti 15.</p> + +<p class="ctr">EFFECT OF TEMPERATURE UPON VISCOSITY--GUM VII.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gum VII"> +<colgroup><col align="center"><col span="3" align="right"></colgroup> +<tr><td>Temperature. ºC.</td><td align="center"> η</td><td>Z found.</td><td>Z calculated.</td></tr> +<tr><td>50</td><td>0.0283</td><td>228</td><td>228.00</td></tr> +<tr><td>45</td><td>0.0305</td><td>246</td><td>246.55</td></tr> +<tr><td>42</td><td>0.0352</td><td>284</td><td>266.75</td></tr> +<tr><td>38</td><td>0.0368</td><td>297</td><td>289.00</td></tr> +<tr><td>34</td><td>0.0410</td><td>330</td><td>313.06</td></tr> +<tr><td>30</td><td>0.0419</td><td>339</td><td>339.00</td></tr> +<tr><td>26</td><td>0.0445</td><td>359</td><td>367.80</td></tr> +<tr><td>22</td><td>0.0492</td><td>398</td><td>396.47</td></tr> +<tr><td>20</td><td>0.0511</td><td>412</td><td>412.00</td></tr> +<tr><td>18</td><td>0.0531</td><td>428</td><td>428.00</td></tr> +</table> + + +<p class="ctr">EFFECT OF TEMPERATURE UPON VISCOSITY.--GUM VIII.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gum VIII"> +<colgroup><col align="center"><col span="3" align="right"></colgroup> +<tr><td>Temperature. ºC.</td><td align="center"> η</td><td>Z found.</td><td>Z calculated.</td></tr> +<tr><td>50</td><td>0.0430</td><td>347</td><td>347</td></tr> +<tr><td>46</td><td>0.0475</td><td>383</td><td>371.14</td></tr> +<tr><td>42</td><td>0.0502</td><td>405</td><td>397.09</td></tr> +<tr><td>38</td><td>0.0510</td><td>411</td><td>424.73</td></tr> +<tr><td>34</td><td>0.0575</td><td>463</td><td>454.06</td></tr> +<tr><td>30</td><td>0.0602</td><td>485</td><td>485</td></tr> +<tr><td>26</td><td>0.0637</td><td>513</td><td>517.82</td></tr> +<tr><td>22</td><td>0.0667</td><td>538</td><td>552.25</td></tr> +<tr><td>20</td><td>0.0707</td><td>570</td><td>570</td></tr> +<tr><td>18</td><td>0.0755</td><td>609</td><td>583.07</td></tr> +</table> + +<p>The constants for the first gum are those given in +the preceding column, while for the latter they were--</p> + +<blockquote><p>A = 771.9: B = -11.15: C = 0.053</p></blockquote> + +<p>As will be observed, the effect of heat appears to be +the same upon the two typical gum arabics quoted +above, an increase of temperature from 18° C. to 50° C. +decreasing the viscosity by nearly one half in both +cases, and the same seems to be true of most gum arabics. +Roughly also the same holds good for Ghattis, +as the following numbers show:</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Heat Effect on Gums"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">Gum.</td><td>Z at 18° C.</td><td>Z at 50° C.</td></tr> +<tr><td>Gum arabic.</td><td>1016</td><td>579</td></tr> +<tr><td>Gum arabic.</td><td>428</td><td>228</td></tr> +<tr><td>Gum arabic.</td><td>609</td><td>347</td></tr> +<tr><td>Gum arabic.</td><td>581</td><td>258</td></tr> +<tr><td>Ghatti.</td><td>572</td><td>306</td></tr> +<tr><td>Ghatti.</td><td>782</td><td>418</td></tr> +</table> + + +<p>The following table shows the effect of heat upon +the viscosity of a typical Ghatti:</p> + +<p class="ctr">GHATTI GUM NO. 15.--VISCOSITY.</p> +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Ghatti 15 Viscosity"> +<colgroup><col align="center"><col span="2" align="right"></colgroup> +<tr><td>Temperature. <br/>°C.</td><td>η</td><td>Z.</td></tr> +<tr><td>50</td><td>0.0517</td><td>418 </td></tr> +<tr><td>46</td><td>0.0581</td><td>468 </td></tr> +<tr><td>42</td><td>0.0628</td><td>506 </td></tr> +<tr><td>38</td><td>0.0726</td><td>585 </td></tr> +<tr><td>34</td><td>0.0788</td><td>635 </td></tr> +<tr><td>30</td><td>0.0857</td><td>691 </td></tr> +<tr><td>26</td><td>0.0889</td><td>717 </td></tr> +<tr><td>22</td><td>0.0919</td><td>741 </td></tr> +<tr><td>20</td><td>0.0946</td><td>763 </td></tr> +<tr><td>18</td><td>0.0964</td><td>777 </td></tr> +</table> + + +<p>There is therefore no essential difference in the behavior +of a Ghatti and a gum arabic on heating. Some +interesting results, however, were obtained by heating +gums, both Ghattis and arabics, at a fixed temperature +for the same time, cooling, and then after making the +solutions up to the original volume taking their viscosities +at the ordinary temperature. The effect of heating +for two hours to 60° C., 80° C., or 100° C. was a small +permanent alteration in viscosity of the solution, and +it would therefore seem desirable that gum solutions +should be made up cold to get the maximum results. +The following numbers illustrate this change, viz.:</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Effect of Heating"> +<colgroup><col align="left"><col span="4" align="right"></colgroup> +<tr><td> </td><td> </td><td colspan="3" align="center">After heating to</td></tr> +<tr><td>Gum Arabic<br /> 10 Per Cent.</td><td>Without heat.</td><td>60°C.</td><td>80°C.</td><td>100°C. </td></tr> +<tr><td>Z at 18°C</td><td>570</td><td>468</td><td>470</td><td>517</td></tr> +<tr><td>Z at 30°C</td><td>485</td><td>400</td><td>422</td><td>439</td></tr> +<tr><td>Z at 50°C</td><td>347</td><td>287</td><td>258</td><td>301</td></tr> +<tr><td>Ghatti gum No. 15,<br /> 5 per cent.<br /> Z at 18°C.</td><td>1,104</td><td>780</td><td>660</td><td>758</td></tr> +</table> + +<p>The variation of viscosity with strength of solution +was also studied with one or two typical gums. A 10 +per cent. is invariably more than twice as viscous as a +5 per cent. solution. The following curve was obtained +from one of the Ghattis. Similar results were +shown by other gums.</p> + +<p class="ctr"><img src="./images/13-gr2.png" height="396" width="399" alt="Variation of Viscosity With Dilution"> +<br clear="all" />Variation of Viscosity, with Dilution. +Ghatti No. 888.</p> + +<p>It would seem, therefore, that strong solutions, say of +50 per cent. strength, would be more alike in viscosity +than solutions of 5 per cent. strength of the same +gums. In other words, the viscosity of a gum solution +should be taken as nearly as possible to the strength +it is used at, to obtain an exact quantitative idea of its +gumming value.</p> + +<p>The observation of this fact was one of the circumstances +which decided us to use 5 per cent. solutions +for the determination of Ghatti gum viscosities, the +ratio between the 5 per cent. and 10 per cent. solutions +of gum arabics being roughly the same as that between +the respective weights required for gumming solutions +of equal value.</p> + +<p>From observation of the general nature of the solutions +of Ghatti gums, and from the fact that when +allowed to stand portions of the apparently insoluble +matter passed into solution, the hypothesis suggested +itself that metarabin was soluble in arabin, +although insoluble in cold water. If this hypothesis +were correct, it would explain the apparent anomaly +of Ghattis giving solutions of higher viscosity than +gum arabics, although they leave insoluble matter +behind. The increase in viscosity would be due to +the thickening of the arabic acid by the metarabin. +Moreover, the solutions yielded by various Ghattis +leaving insoluble matter behind would <i>be all of the +same kind</i>, viz., a saturated solution of metarabin in +arabin more or less diluted by water. Still further, if +the insoluble residue of a Ghatti be the residual metarabin +over and above that required to saturate the +arabin, then it will be possible to dissolve this by the +addition of more arabin in the form of ordinary gum +arabic. In order to see if this were the case the following +experiments were performed. Equal parts of a +Ghatti and of a gum arabic were ground up together +and dissolved in water. The resulting solution was +<i>clear</i>. It was diluted until of 10 per cent. strength, +and its viscosity then taken:</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="50-50 Ghatti-Gum"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td> </td><td colspan="2" align="center">Contains 50 per Cent. Ghatti.</td></tr> +<tr><td>A. Pressure 200 mm</td><td>η</td><td>Z</td></tr> +<tr><td>Temperature 15° C</td><td>0.2517</td><td>2,030</td></tr> +</table> + +<p>The viscosity of this solution therefore was considerably +greater than the mean viscosity of the 10 per cent. +solutions of the Ghatti and the gum arabic, viz., +(0.288 + 0.0636)/2 = 0.1758 for the calculated η. Hence it is +evident that the increase in viscosity is due to the +solution of the metarabin.</p> + +<p>Next a solution was made from a mixture of 70 per +cent. Ghatti and 30 per cent. gum arabic. This was +also clear and gave a considerably higher viscosity than +the previous solution.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="70-30 Ghatti-Gum"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td> </td><td colspan="2" align="center">Contains 70 per Cent. Ghatti.</td></tr> +<tr><td>B. Pressure 200 mm</td><td>η</td><td>Z.</td></tr> +<tr><td>Temperature 15° C</td><td>0.3177</td><td>2,562</td></tr> +</table> + + +<p>It will be obvious that the increase of viscosity over +the previous solution in this case must be due to the +smaller amount of the thin gum arabic which is present, +<i>i.e.</i>, in the first case there is more gum arabic than +is required to dissolve the whole of the insoluble metarabin. +Further experiments showed that this is also +true of the second mixture, as the viscosities of the +following mixtures illustrate:</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="High Concentrations of Ghatti"> +<colgroup><col align="left"><col span="2" align="right"> +<tr><td align="center">Strength of Solution.</td><td align="center">η</td><td>Z.</td></tr> +<tr><td>C. 80 per cent. Ghatti.</td><td>0.3642</td><td>2,937 </td></tr> +<tr><td>D. 75 per cent. Ghatti.</td><td>0.33095</td><td>2,669 </td></tr> +<tr><td>E. 77.5 per cent. Ghatti.</td><td>0.4860</td><td>3,819 </td></tr> +</table> + + +<p>This last solution E we called for convenience the +"maximum viscosity" solution, as we believe it to be a +10 per cent. solution containing arabin very nearly +saturated with metarabin. As will be observed, its +viscosity differs widely from those of solutions C and +D, between which it lies in percentage of Ghatti. The +first named solution C contains <i>too little</i> of gum arabic +to dissolve the whole of the metarabin. Consequently +there is a residue left undissolved, which of course diminishes +its viscosity. The second solution D is too +low in viscosity, as it still contains too much of the +weak gum arabic, and as will be seen further on, a +very slight change in the proportions increases or decreases +the viscosity enormously.</p> + +<p>We next tried a series of similar experiments with a +Ghatti containing far less insoluble residue and which +consequently would require less gum arabic to produce +a perfect solution. Mixtures were made in the following +proportions, viz.:</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="13.3% Ghatti"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">----</td><td colspan="2" align="center">13.3 per Cent. Ghatti.</td></tr> +<tr><td>F. Pressure 200 mm</td><td>η</td><td>Z.</td></tr> +<tr><td>Temperature 15° C</td><td> 0.0976</td><td>787</td></tr> +</table> +<br /><br /> +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="86.6% Ghatti"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">----</td><td colspan="2" align="center">86.6 per Cent. Ghatti.</td></tr> +<tr><td>G. Pressure 200 mm</td><td>η</td><td>Z.</td></tr> +<tr><td>Temperature 15° C</td><td> 0.4336</td><td> 3,497</td></tr> +</table> + + +<p>This latter solution is approaching fairly closely to +our "maximum viscosity" with the previous Ghatti, +and probably a very slight decrease in the amount of +gum arabic would bring about the required increase in +viscosity.</p> + +<p>When these experiments were first commenced we +were still under the impression, which several months' +experience of working with gums had produced, namely, +that the Ghattis were quite distinct in their properties +to ordinary gum arabics. But the new hypothesis, +and the experiments undertaken to confirm it, +showed clearly that if the viscosity of a gum solution +depends on the ratio of metarabin to arabin, then +there is no absolute line of demarkation between a +Ghatti and a gum arabic. In other words, there is a +constant gradation between gum arabic and Ghattis, +down to such gums as cherry gum, consisting wholly +of metarabin and quite insoluble in water. Therefore +those gum arabics which are low in viscosity consist +of nearly pure arabin, while as the viscosity increases +so does the amount of metarabin, until we come to +Ghattis which contain more metarabin than their arabin +can hold in solution, when their viscosity goes +down again.</p> + +<p>From these observations it would follow, that by +taking a gum of less viscosity than the gum arabic previously +used to dissolve the Ghatti, less of it would be +required to do the same work. We confirmed this suggestion +experimentally by taking another gum arabic +of viscosity 0.0557 at 15° C. A mixture containing +93.3 per cent. of this Ghatti and 6.7 per cent. of our +thinnest gum arabic gave a clear solution which had +the highest viscocity we have yet obtained for a 10 per +cent. solution.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Highest Viscosity"> +<colgroup><col align="left"><col span="2" align="center"></colgroup> +<tr><td>H. Pressure 200 mm.<br />Temperature 15° C.</td><td>η<br /> 0.5525</td><td> Z.<br />4,456 </td></tr> +</table> + + +<p>This gum arabic may be regarded as nearly pure arabin +(as calcium and potassium, etc., salt). By diluting +the new "maximum viscosity" solution, therefore, with +the 10 per cent. solution of the gum arabic in fixed proportions +we obtain a series of viscosities which are +shown in the following curve.</p> + +<p class="ctr"><img src="./images/14-gr1.png" height="397" width="353" alt="Ghatti Viscosity Curve"> +<br clear="all" />Curve Showing Influence of Ghatti +upon Viscosity.</p> + +<p>Besides obtaining this curve for change in viscosity +from maximum amount of metarabin to no metarabin +at all, we also traced the decrease in viscosity of the +"maximum" solution by dilution with water. The +following numbers were thus obtained, and plotted +out into a curve.</p> + +<p>Having obtained this curve, we are now in a position +to follow up the hypothesis by calculating the surplus +amount of insoluble matter in a Ghatti. For, let it be +conceded that the solution of any Ghatti leaving an insoluble +residue is a mixture of arabin and metarabin in +the same ratio as our "maximum" solution, only more +diluted with water, then from the found viscosity we +obtain a point on the curve for dilution, which gives +the percentage of dissolved matter.</p> + +<p>Now to show the use of this: The Z value for a 10 per +cent. solution of the second Ghatti at 15° C. is 2,940. +This corresponds on the curve to 8.4 dissolved matter. +10-8.4 = 1.6 grammes in 10 grammes, which is insoluble.</p> + + +<p class="ctr">CHANGE OF VISCOSITY WITH DILUTION--"MAXIMUM" +SOLUTION. 15° C. TEMPERATURE.</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Viscosity Changes With Dilution"> +<colgroup><col span="3" align="right"></colgroup> +<tr><td align="center">Percentage.</td><td align="center">η</td><td align="center">Z.</td></tr> +<tr><td>10</td><td>0.55250</td><td>4,456</td></tr> +<tr><td>9</td><td>0.42850</td><td>3,456</td></tr> +<tr><td>8</td><td>0.35120</td><td>2,832</td></tr> +<tr><td>7</td><td>0.27660</td><td>2,230</td></tr> +<tr><td>6</td><td>0.22290</td><td>1,797</td></tr> +<tr><td>5</td><td>0.16810</td><td>1,355</td></tr> +<tr><td>4</td><td>0.11842</td><td>955</td></tr> +<tr><td>3</td><td>0.08020</td><td>647</td></tr> +<tr><td>2</td><td>0.06190</td><td>499</td></tr> +<tr><td>1</td><td>0.03610</td><td>291</td></tr> +</table> + + +<p class="ctr"><img src="./images/14-gr2.png" height="402" width="396" alt="Variation in Viscosity on Dilution(Maximum)"> +<br clear="all" /> Curve of Variation in Viscosity on Dilution +of the "Maximum" Solution.</p> + +<p>We have already shown that a "maximum" viscosity +solution of this gum is formed when 6.7 per cent, of thin +gum arabic is added to it, and therefore 6.7 parts of a +thin gum arabic are required to bring 16 parts of metarabin +into solution. A convenient rule, therefore, in +order to obtain complete solution of a Ghatti gum is +to add half the weight in thin gum of the insoluble +metarabin found from the viscosity determination. +But the portion of the gum which dissolved is made +up in a similar manner (being a diluted "maximum" +solution).</p> + +<p>Therefore the 84 per cent. of soluble matter contains +58 parts of metarabin, and the total metarabin in this +gum is 58 + 16 = 74 per cent, on the dry gum.</p> + +<p>With these solutions of high viscosity some other +work was done which may be of interest. The temperature +curves of the mixtures marked E, G, and F +were obtained between 60° C. and 15° C. The two former +curves showed a direction practically parallel to +that at the 10 per cent. solutions, and as they were approaching +to the "maximum" solution, this is what +one would expect. Mr. S. Skinner, of Cambridge, was +also good enough to determine the electrical resistances +of these solutions and the Ghattis and gum arabics employed +in their preparation. The electrical resistance +of these gum solutions steadily diminishes as the temperature +increases, and the curve is similar to those +obtained for rate of change with temperature. Although +the curves run in, roughly, the same direction, +there does not appear to be any exact ratio between +the viscosities of two gums say at 15° C. and their electrical +resistances at the same temperature; hence it +would not seem possible to substitute a determination +of the electrical resistance for the viscosity determination. +The results appear to be greatly influenced by the +amount of mineral matter present, gums with the +greatest ash giving lower resistances.</p> + +<p>Experiments were conducted with two Ghattis and +two gum arabics, besides the mixtures marked E, F, +and H. Comparison of the electrical resistances with +the viscosities at 15° C. shows the absence of any fixed +ratio between them.</p> + + +<table align='center' border='1' cellpadding='2' cellspacing='0' summary=''> +<colgroup><col align="left"><col span="3" align="right"></colgroup> +<tr><td>Gum or Mixture.</td><td>°C.</td><td>Ohms Resistance.</td><td>Z Viscosity at 15° C.</td></tr> +<tr><td>Ghatti, 1</td><td>10</td><td>5,667</td><td>1,490</td></tr> +<tr><td>Ghatti, 2</td><td>15</td><td>2,220</td><td>2,940</td></tr> +<tr><td>Arabic 1</td><td>15</td><td>1,350</td><td>605</td></tr> +<tr><td>Arabic 2</td><td>10</td><td>2,021</td><td>449</td></tr> +<tr><td>Mixture F</td><td>15</td><td>1,930</td><td>787</td></tr> +<tr><td>Mixture E</td><td>11.3</td><td>2,058</td><td>3,919</td></tr> +</table> + +<p>While performing these experiments, an attempt +was made to obtain an "ash-free" gum, in order to +compare its viscosity with that of the same gum in +its natural state. A gum low in ash was dissolved in +water, and the solution poured on to a dialyzer, and +sufficient hydrochloric acid added to convert the salts +into chlorides. When the dialyzed gum solution ceased +to contain any trace of chlorides, it was made up to +a 10 per cent. solution, and its viscosity determined +under 100 mm. pressure, giving the following results +at 15° C.:</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Ash-free Gum"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">--------</td><td align="center">η</td><td align="center">Z</td></tr> +<tr><td>Natural gum</td><td>0.05570</td><td>449</td></tr> +<tr><td>"Ash-free" gum</td><td>0.05431</td><td>438</td></tr> +</table> + +<p>Thus showing that the viscosity of pure arabin is almost +identical with that of its salts in gum.</p> + +<p>The yield of furfuraldehyde by the breaking down +of arabin and metarabin was thought possibly to be +of some value in differentiating the natural gums from +one another, but we have not succeeded in obtaining +results of much value. 0.2 gramme of a gum were +heated with 100 c.c. of 15 per cent. sulphuric acid for +about 2½ hours in an Erlenmeyer flask with a reflux +condenser. After this period of time, further treating +did not increase the amount of furfuraldehyde produced. +The acid liquid, which was generally yellow in +color, was then cooled and neutralized with strong +caustic soda. The neutral or very faintly alkaline solution +was then distilled almost to dryness, when practically +the whole of the furfuraldehyde comes over. +The color produced by the gum distillate with +aniline acetate can now be compared with that +obtained from some standard substance treated +similarly. The body we have taken as a standard +is the distillate from the same weight of cane sugar. +The tint obtained with the standard was then compared +with that yielded by the gum distillate from which +the respective ratios of furfuraldehyde are obtained. +The following table shows some of these results:</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Yield of Furfuraldehyde"> +<colgroup><col align="left"><col span="2" align="center"></colgroup> +<tr><td>Substance.</td><td>Comparative<br /> Yield of <br />Furfuraldehyde.</td><td>Amount of<br /> Glucose Produced.</td></tr> +<tr><td>Cane sugar</td><td>1.00</td><td>..</td></tr> +<tr><td>Starch</td><td>0.50</td><td>..</td></tr> +<tr><td>Gum arabic</td><td>1.33</td><td>34.72</td></tr> +<tr><td>Gum arabic</td><td>1.20</td><td>43.65</td></tr> +<tr><td>Ghatti, 1</td><td>1.00</td><td>26.78</td></tr> +<tr><td>Ghatti, 2</td><td>1.33</td><td>22.86</td></tr> +<tr><td>Metarabin</td><td>1.75</td><td>..</td></tr> +</table> + + +<p>The amount of reducing sugar calculated as glucose is +also appended. This was estimated in the residue left +in the flask after distillation by Fehling's solution in +the usual way. The yields of furfuraldehyde would +appear to have no definite relation to the other chemical +data about a gum, such as the potash and baryta +absorptions or the sugar produced on inversion.</p> + +<p>The action of gum solutions upon polarized light is +interesting, especially in view of the fact that arabin is +itself strongly lævo-rotatory α<sub>D</sub> = -99°, while certain +gums are distinctly dextro-rotatory. Hence it is evident +that some other body besides arabin is present in +the gum. We have determined the rotatory power of +a number of gum solutions, the results of which are +subjoined. On first commencing the experiments we +experienced great difficulty from the nature of the +solutions. Most of them are distinctly yellow in color +and almost opaque to light, even in dilute solutions +such as 5 percent. We found it necessary first to bleach +the gums by a special process; 5 grammes of gum are +dissolved in about 40 c.c. of lukewarm water, then a +drop of potassium permanganate is added, and the +solution is heated on a water bath with constant stirring +until the permanganate is decomposed and the +solution becomes brown. A drop of sodium hydrogen +sulphate is now added to destroy excess of permanganate. +At the same time the solution becomes perfectly +colorless.</p> + +<p>It can now be cooled down and made up to 100 c.c., +yielding a 5 per cent. solution of which the rotatory +power can be taken with ease. Using a 20 mm. tube +and white light the above numbers were obtained.</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Rotatory values of Gums"> +<colgroup><col align="left"><col align="center"><col align="right"></colgroup> +<tr><td>Gum or Dextrin.</td><td>Solution used.<br /> Per Cent.</td><td align="center">α<sub>D</sub></td></tr> +<tr><td>Aden, 1</td><td>5</td><td>- 33.8</td></tr> +<tr><td>Cape, 2</td><td>5</td><td>+ 28.6</td></tr> +<tr><td>Indian, 3</td><td>5</td><td>+ 66.2</td></tr> +<tr><td>Eastern, 4</td><td>5</td><td>- 26.0</td></tr> +<tr><td>Eastern, 5</td><td>5</td><td>- 30.6</td></tr> +<tr><td>Senegal, 6</td><td>5</td><td>- 17.6</td></tr> +<tr><td>Senegal, 7</td><td>5</td><td>- 18.4</td></tr> +<tr><td>Senegal, 8</td><td>2½</td><td>- 19.6</td></tr> +<tr><td>Senegal, 9</td><td>5</td><td>- 38.2</td></tr> +<tr><td>Senegal, 10</td><td>5</td><td>- 25.8</td></tr> +<tr><td>Amrad</td><td>2½</td><td>+ 57.6</td></tr> +<tr><td>Australian, 1</td><td>5</td><td>- 28.2</td></tr> +<tr><td>Australian, 2</td><td>5</td><td>- 26.4</td></tr> +<tr><td>Brazilian, 1</td><td>2½</td><td>- 36.8</td></tr> +<tr><td>Brazilian, 2</td><td>2½</td><td>+ 21.0</td></tr> +<tr><td>Dextrin, 1</td><td>5</td><td>+148.0</td></tr> +<tr><td>Dextrin, 2</td><td>5</td><td>+133.2</td></tr> +<tr><td>Ghatti, 1</td><td>5</td><td>- 39.2</td></tr> +<tr><td>Ghatti, 2</td><td>5</td><td>- 80.4</td></tr> +</table> + + +<p>These numbers do not show any marked connection +between the viscosity, etc., of a gum and its specific +rotatory power.</p> + +<p>When gum arabic solution is treated with alcohol +the gum is precipitated entirely if a large excess of +spirit be used. With a view to seeing if the precipitate +yielded by the partial precipitation of a gum solution +was identical in properties to the original gum, we examined +several such precipitates from various gums to +ascertain their rotatory power. We found in each case +that the specific rotatory power of the alcohol precipitate +redissolved in water was not the same as that of +the original gum. In other words these gums contained +at least two bodies of different rotatory powers, of which +one is more soluble in alcohol than the other. O'Sullivan +obtained similar results with pure arabin. +The experiments were conducted in the following +manner:</p> + +<p>(a.) Five grammes of a dextro-rotatory gum (No. 3 in +table) were dissolved in 20 c.c. of water. To the solution +was added 90 c.c. of 95 per cent. alcohol. The +white precipitate which formed was thrown on to +a tared filter and washed with 30 c.c. more alcohol. +The total filtrate therefore was 140 c.c. The precipitate +was dried and weighed = 2.794 grammes or 55.88 +per cent. of the total gum. The precipitate was then +redissolved in water, bleached as before and diluted +to a 5 per cent. solution. This was then examined +in the polarimeter. Readings gave the value α<sub>D</sub> = ++58.4°. The previous rotatory power of the gum was ++66°. Now the alcohol was driven off from the filtrate, +which, allowing for the 11.95 per cent. of water in the +gum, should contain 32.17 per cent. of gum. The alcohol-free +liquid was then diluted to a known volume + +(for 5 per cent, solution), and α<sub>J</sub> found to be + 57.7°. +This experiment was then repeated again, using 5 +grammes of No. 3, when 3.5805 grammes of precipitate +were obtained, using the same volumes of alcohol and +water. The precipitate gave α<sub>J</sub> = +57.4°; the filtrate +treated as before, only the percentage of gum dissolved +being directly determined instead of being calculated +by difference, gave α<sub>J</sub> = + 52.5°.</p> + +<p>(b.) Another gum (No. 9) with α<sub>J</sub> = -38.2° and containing +13.86 per cent, of moisture, gave 2.3315 grms. of +precipitate when similarly treated. The precipitate +gave when redissolved in water α<sub>J</sub> = -20.8°. The +filtrate containing 39.5 per cent, real gum gave α<sub>J</sub> = +-67.5°, so that the least lævo-rotatory gum. was precipitated +by the alcohol.</p> + +<p>The Ghattis apparently are all lævo-rotatory, and +give much less alcoholic precipitates than the gum +arabic. The precipitation moreover was in the opposite +direction, that is, the most lævo-rotatory gum was +thrown down by the alcohol. The appended table +shows the nature of the precipitates and the respective +amounts from two Ghattis and two gum arabics. It +will be observed that the angle of rotation in three of +the cases is decidedly less both for precipitate and filtrate +than for the original solution:</p> + +<p class="ctr">SPECIFIC ROTATORY POWERS OF GUMS.</p> + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Specific Rotatory values of Gums"> +<colgroup><col span="2" align="left"><col align="left"><col span="5" align="right"></colgroup> +<tr><td colspan="2" align="center">Gum used.</td><td align="center">Weight Gum Waken. <br />Grms.</td><td align="center">Weight Alcohol Precipitate.</td><td align="center">Weight Gum Filtrate.</td><td align="center">α<sub>J</sub> Original Gum.</td><td align="center">α<sub>J</sub> Alcohol Precipitate.</td><td align="center">α<sub>J</sub> Filtrate.</td></tr> +<tr><td>3</td><td><i>a</i><br /><i>b</i></td><td>5<br />5</td><td>2.7940<br/>3.5805</td><td>1.9415<br /> 0.8910</td><td>+ 66.2</td><td> + 58.4<br /> + 57.4</td><td> + 53.7<br /> - 52.5</td></tr> +<tr><td>9</td><td><i>a</i><br /><i>b</i></td><td>5<br />4.9620</td><td>2.3315<br/>2.3310</td><td>2.3736<br />2.4180</td><td> - 38.2 </td><td>- 20.8 <br />- 19.4</td><td> - 67.5<br /> - 63.4 </td></tr> +<tr><td>Ghatti:</td><td><i>a</i><br /><i>b</i></td><td>3.4900<br />3.2450</td><td>0.3925<br />0.4605</td><td>2.7920<br />2.8385</td><td>-140.8</td><td> -104.2 <br /> -106.0</td><td>- 76.0<br /> - 72.4</td></tr> +<tr><td>Ghatti</td><td><i>a</i><br /><i>b</i></td><td>2.2550<br />2.6635 </td><td>0.2900<br />0.2845 </td><td>1.8078<br />2.3360 </td><td>-147.05</td><td> -106.04<br /> -102.04</td><td>+ 68.0<br />- 66.2 </td></tr> +</table> + +<p>The hygrometric nature of a gum or dextrin is a +point of considerable importance when the material is +to be used for adhesive purposes. The apparatus +which we finally adopted after many trials for testing +this property consists simply of a tinplate box about 1 +ft. square, with two holes of 2 in. diameter bored in +opposite sides. Through these holes is passed a piece +of wide glass tubing 18 in. long. This is fitted with +India rubber corks at each end, one single and the other +double bored. Through the double bored cork goes a +glass tube to a Woulffe's bottle containing warm water. +A thermometer is passed into the interior of the tube +by the second hole. The other stopper is connected +by glass tubing to a pump, and thus draws warm air +laden with moisture through the tube. Papers gummed +with the gums or dextrins, etc., to be tested are placed +in the tube and the warm moist air passed over them +for varying periods, and their proneness to become +sticky noted from time to time. By this means the +gums can be classified in the order in which they succumbed +to the combined influences of heat and moisture. +We find that in resisting such influences any +natural gum is better than a dextrin or a gum substitute +containing dextrin or gelatin. The Ghattis are +especially good in withstanding climatic changes.</p> + +<p>Dextrins containing much starch are less hygroscopic +than those which are nearly free from it, as the same +conditions which promote the complete conversion of +the starch into dextrin also favor the production of +sugars, and it is to these sugars probably that commercial +dextrin owes its hygroscopic nature. We have +been in part able to confirm these results by a series of +tests of the same gums in India, but have not yet obtained +information as to their behavior in the early +part of the year.</p> + +<p>The fermentation of natural gum solutions is accompanied +by a decrease in the viscosity of the liquid and +the separation of a portion of the gum in lumps. Apparently +those gums which contain most sugar, as +indicated by their reduction of Fehling's solution, are +the most susceptible to this change. Oxalic acid is +formed by the fermentation, which by combination +with the lime present renders the fermenting liquid +turbid, and also some volatile acid, probably acetic.</p> + +<p>We have made some experiments with a gum which +readily fermented--in a week--as to the respective +value of various antiseptics in retarding the fermentation. +Portions of the gum solutions were mixed with +small quantities of menthol, thymol, salol, and saccharin +in alkaline solution, also with boric acid, sodium +phosphate, and potash alum in aqueous solution. +Within a week a growth appeared in a portion to +which no antiseptic had been added; the others remained +clear. After over five months the solutions +were again examined, when the following results were +observed:</p> + + +<table align='center' border="1" cellpadding="4" cellspacing="0" summary="Gum Fermentation"> +<colgroup><col span="2" align="left"></colgroup> +<tr><td align="center">Antiseptics.</td><td align="center"> Solution after Five Months.</td> +<tr><td> Menthol in KOH</td><td> Some growth at bottom, upper layer clear.</td></tr> +<tr><td> Thymol in KOH</td><td> Growth at top, gum white and opaque.</td></tr> +<tr><td> Salol in KOH</td><td> Growth at top, gum black and opaque</td></tr> +<tr><td> Saccharin in KOH</td><td> White growth at top.</td></tr> +<tr><td> Boric acid</td><td> Remained clear; did not smell.</td></tr> +<tr><td> Sodium phosphate</td><td> Slight growth at top.</td></tr> +<tr><td> Potash alum</td><td> Slight growth at top.</td></tr> +</table> + + + +<p>The solution to which no antiseptic had been added +was of course quite putrid, and gave the reactions for +acetic acid.</p> + +<p>In the earlier part of this paper we have given a +short account of the chief characteristics of the more +important gum substitutes. The following additional +notes may be of interest.</p> + +<p>The ashes of most gum substitutes, consisting chiefly +of dextrin, are characterized by the high percentage of +chlorides they contain, due no doubt to the use of + +hydrochloric acid in their preparation. The soluble +constituents of the ash consist of neutral alkaline salts, +but as a rule no alkaline carbonates, and it is thus +possible to demonstrate the absence of any natural +gum in such a compound. We have seldom noticed +the presence of any sulphates in such ashes, but when +sulphurous or sulphuric acids have been used in the +starch conversion it will be found in small quantities.</p> + +<p>We have already pointed out that the potash absorption +value of a gum is low and that dextrins give high +numbers, but the latter vary very considerably, and as +the starch and sugar present also influence the potash +absorption value, it does not give information of much +service. The following table shows the kind of results +obtained:</p> + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Starch Absorbed"> +<colgroup><col align="left"><col span="3" align="right"></colgroup> +<tr><td>Sample.</td><td>KOH absorbed.</td><td>Starch.<br />Per Cent.</td><td>Real Gum.<br />Per Cent.</td></tr> +<tr><td>Dextrin, 1</td><td>25.40</td><td>1.99</td><td>..</td></tr> +<tr><td>Dextrin, 2</td><td>19.70</td><td>13.13</td><td>..</td></tr> +<tr><td>Dextrin, 3</td><td>7.57</td><td>24.72</td><td>..</td></tr> +<tr><td>Artificial gum, 1</td><td>19.70</td><td>10.98</td><td>9.00</td></tr> +<tr><td>Artificial gum, 2</td><td>13.70</td><td>8.05</td><td>23.50</td></tr> +<tr><td>Starch</td><td>9.43</td><td>100.00</td><td>None</td></tr> +</table> + + +<p>The baryta absorptions seem to be chiefly due to the +quantity of starch present in the composition:</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Starch Present"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td>Sample.</td><td>Starch.<br />Per Cent.</td><td>BaO absorbed.<br />Per Cent.</td></tr> +<tr><td>Dextrin, 1</td><td>1.99</td><td>1.75</td></tr> +<tr><td>Dextrin, 2</td><td>13.13</td><td>3.53</td></tr> +<tr><td>Dextrin, 3</td><td>24.72</td><td>5.64</td></tr> +<tr><td>Starch</td><td>100.00</td><td>23.61</td></tr> +</table> + +<p>The viscosity of a dextrin or artificial gum is determined +in exactly the same way as a natural gum, using +10 per cent. solutions. It would probably be an improvement +to use 10 per cent. solutions for many of the +dextrins, as they are when low in starch extremely +thin.</p> + +<p>The hygroscopic nature of dextrins renders them +unsuitable for foreign work, but when the quantity of +starch is appreciable, better results are obtainable. A +large percentage of unaltered starch is usually accompanied +with a small percentage of sugar, and no doubt +this is the explanation of this fact. An admixture +containing natural gum of course behaved better than +when no such gum is present. Bodies like "arabol" +made up with water and containing gelatin are very +hygroscopic when dry, although as sold they lose water +on exposure to the air. Gum substitutes consisting +entirely of some form of gelatin with water, like fish +glue, are also somewhat hygroscopic when dried. The +behavior of these artificial gums and dextrins on +exposure to a warm moist atmosphere can be determined +in the same apparatus as described for gums.</p> + +<p>The process we have adopted for estimating the glucose +starch and dextrin in commercial gum substitutes +is based on C. Hanofsky's method for the assay of +brewers' dextrins (this Journal, 8, 561). A weighed +quantity of the dextrin is dissolved in cold water, +filtered from any insoluble starch, and then the glucose +determined directly in the clear filtrate by Fehling's +solution. The real dextrin is determined by inverting +a portion of the filtered liquid with HCl, and then +determining its reducing power. The starch is estimated +by inverting a portion of the solid dextrin, and +determining the glucose formed by Fehling. After +deducting the amounts due to the original glucose and +the inverted dextrin present, the residue is calculated +as starch. A determination of the acidity of the solution +is also made with decinormal soda, and results +returned in number of c. c. alkali required to neutralize +100 grammes of the dextrin. Results we have obtained +using this method are embodied in the following table:</p> + +<p class="ctr">ANALYSIS OF GUM SUBSTITUTES</p> + + +<table align='center' border='1' cellpadding='2' cellspacing='0' summary=''> +<colgroup><col span="8" align="right"></colgroup> +<tr><td> No.</td><td> Glucose.</td><td> Dextrin.</td><td> Starch.</td><td> Moisture.</td><td> Gum, &c.</td><td> Ash.</td><td> Acidity.<br />c.c. </td></tr> +<tr><td> 1</td><td> 8.92</td><td> 81.57</td><td> 1.99</td><td> 10.12</td><td> None</td><td> 0.207</td><td>57.3</td></tr> +<tr><td> 2</td><td> 7.19</td><td> 71.46</td><td> 13.13</td><td> 10.40</td><td> None</td><td> 0.120</td><td> 44.8</td></tr> +<tr><td> 3</td><td> 1.29</td><td> 69.42</td><td> 24.72</td><td> 4.17</td><td> 1.12</td><td> 0.280</td><td> 5.22</td></tr> +<tr><td> 4</td><td> 8.40</td><td> 60.98</td><td> 10.98</td><td> 10.09</td><td> 9.02</td><td> 0.530</td><td> 20.0</td></tr> +<tr><td> 5</td><td> 10.60</td><td> 44.98</td><td> 8.05</td><td> 12.20</td><td> 23.57</td><td> 0.600</td><td> 52.0</td></tr> +<tr><td> 6</td><td> 14.80</td><td> 11.57</td><td> 36.46</td><td> 34.87</td><td> 1.89</td><td> 0.580</td><td> 8.0</td></tr> +<tr><td> 7</td><td> 8.00</td><td> 29.61</td><td> 26.78</td><td> 33.98</td><td> 0.88</td><td> 0.750</td><td> 88.0</td></tr> +<tr><td> 8</td><td> 2.29</td><td> 52.38</td><td> 37.65</td><td> None</td><td> 7.335</td><td> 0.315</td><td> 9.6</td></tr> +</table> + +<p>In those cases in which the substitute is made by +admixture with gelatin or liquid glue the quantity of +other organic matter obtained can be checked by a +Kjeldahl determination of the total nitrogen. If a +natural gum is added, it will be partially converted +into sugar when the filtered liquid is inverted, and so +make the dextrin determination slightly too high.</p> + +<a name="FNms4_1"></a><a href="#FNms4_anc_1">[1]</a><div class="note">A paper read before the Society of Chemical Industry, London, 1891. +From the Journal</div> + +<hr /> + + +<a name="phys2"></a><h2>MR. CAILLETET'S CRYOGEN.</h2> + + +<p>The "cryogen," a new apparatus constructed by +Mr. E. Ducretet, from instructions given by Mr. Cailletet, +is designed for effecting a fall of temperature of +from 70° to 80° C. below zero, through the expansion of +liquid carbonic acid.</p> + +<p>The apparatus consists of two concentric vessels having +an annular space between them of a few centimeters. +A worm, S, is placed in the internal vessel R. +All this is of nickel plated copper. The worm, S carries, +at Ro', an expansion cock and ends, at O in the +annular space, R'. A very strong tube is fixed to the + +cock, Ro', and to the ajutage, A'. It receives the tube, +Tu, which, at the time of an experiment, is coupled +with the cylinder of carbonic acid, CO². A tubulure, +D, usually closed by a plug, Bo, communicates with +the inner receptacle, R. This is capable of serving in +certain experiments in condensation. The table, Ta, +of the tripod receives the various vessels or bottles for +the condensed products.</p> + +<p>The entire apparatus is placed in a box, B, lined +with silk waste and provided with a cover, C, of the +same structure. Apertures, Th, Ro, and T", allow of +the passage of a key for acting upon the cock, Ro', as +well as of thermometers and stirrers if they are necessary.</p> + +<p>When it is desired to operate, the internal vessel, R, +is filled with alcohol (3 quarts for the ordinary model). +This serves as a refrigerant bath for the experiments to +be made. The worm, S, having been put in communication +with the carbonic acid cylinder, CO², the cock, +Ro, of the latter is turned full on. The cock of the +worm, which is closed, is opened slightly. The vaporization +and expansion of the liquid carbonic acid cause +it to congeal in the form of snow, which distributes itself +and circulates in the worm, S, and then in R. The +flakes thus coming in contact with the metallic sides +of S rapidly return to the gaseous state and produce +an energetic refrigeration. At the lower part of the +annular space, R', are placed fragments of sponge impregnated +with alcohol. The snow that has traversed +the worm without vaporizing reaches R'. and dissolves +in this alcohol, and the refrigeration that results therefrom +completes the lowering of the temperature. The +gas finally escapes at O, and then through the bent +tube, T'. </p> + +<p class="ctr"><a href="./images/15-cry.png"><img src="./images/15-cry_th.jpg" alt="" height="360" width="389"></a> +<br clear="all" />CAILLETET'S CRYOGEN.</p> + +<p>The apparatus may be constructed with an inverse +circulation, the carbonic acid then entering the annular +vessel, R, directly, and afterward the worm, S, +whence it escapes to the exterior of the apparatus. +The expansion cock sometimes becomes obstructed by +the solidification of the snow. It will then suffice to +wait until the circulation becomes re-established of itself. +It may be brought about by giving the cock, Ro', +a few turns with the wooden handled key that serves +to maneuver the latter. It is not necessary to have +a large discharge of carbonic acid, and consequently +the expansion cock needs to be opened but a little +bit. A few minutes suffice to reduce the temperature + of the alcohol bath to 70°, with an output of +about from 4½ to 5½ lb. of liquid carbonic acid. +When the circulation is arrested, the apparatus thus +surrounded by its isolating protective jackets becomes +heated again with extreme slowness. In one experiment, +it was observed that at the end of nine hours the +temperature of the alcohol had risen but from 70° to +22°. On injecting a very small quantity of liquid carbonic +acid from time to time, a sensibly constant and +extremely low temperature may be maintained indefinitely.--<i>Le +Genie Civil</i>.</p> + +<hr /> + + + + +<a name="tech3"></a><h2>METHOD OF PRODUCING ALCOHOL.</h2> + + +<p>In carrying out my improved process in and with +the apparatus employed in ordinary commercial distilleries, +says Mr. Alfred Springer, of Cincinnati, O.. I preferably +employ separate vats or tubs for the nitric acid +solution and the material to be treated, and a convenient +arrangement is to locate the nitric acid tub directly +under the grain tub, so that one may discharge into +the other. In the upper vat is placed the farinaceous +material, preferably ground, thoroughly steeped in +three times its weight of water, and, where whole +grain is used, preferably "cooked" in the ordinary +manner. The vat into which the dilute acid is placed +is an ordinary cooking tub of suitable material to resist +the acid, provided with closed steam coils and also +nozzles for the discharge of steam into the contained +mass. Into this vat is placed for each one hundred +parts of the grain to be treated one part of commercial +nitric acid diluted with fifty parts of water and +brought to a state of ebullition and agitation by the +steam coils and the discharge through the nozzles, the +latter being regulated so that the gain by condensation +of steam approximately equals the loss by evaporation. +The farinaceous contents of the upper vat are allowed +to flow slowly into the nitric acid solution while +the ebullition and agitation of the mass is continued. +This condition is then maintained for six to eight +hours, after which the mass is allowed to stand for one +day or until the saccharification becomes complete. +The conversion can be followed by the "iodine test" +for intermediary dextrins and the "alcohol test" for +dextrin. After the saccharification is complete I may +partially or wholly neutralize the nitric acid, preferably +with potassium or Ammonium carbonate, preferably +employing only one-half the amount necessary + +to neutralize the original quantity of nitric acid used, +so that the mass now ready to undergo fermentation +has an acid reaction. The purpose in view here is to +keep the peptones in solution also, because an acid +medium is best adapted to the propagation of the +yeast cells. It is not absolutely necessary to even partially +neutralize the nitric acid, but it is preferable. +Yeast is now added, and the remaining processes are +similar to those generally employed in distilleries, excepting +that just prior to distillation potassium carbonate +sufficient to neutralize the remaining nitric +acid is added, in order to avoid corrosion of the still +and correct the acid reaction of the slop.</p> + +<p>As a variant of the process I sometimes add to the +usual amount of nitric acid an additional one one-hundredth +part of phosphoric acid on account of its beneficial +nutritive powers--that is to say, to one hundred +parts of grain one part of nitric acid and one one-hundredth +part of phosphoric acid.</p> + +<p>While my improved process is based on the well-known +converting power of acids on starch, I am not +aware that it has ever been applied in the manner and +for the purposes I have described. For example, sulphuric +and hydrochloric, also sulphuric and nitric, +acids have been employed in the manufacture of +glucose; but in every such case the resulting products +were not capable of superseding those obtained by the +existing methods of saccharification used in distilleries. +In my process, on the other hand, the product is +so capable. Not only may malted grain be entirely +omitted, but more fermentable products are formed and +the products of fermentation are purer. The saccharification +being more complete, there are less intermediary +and nonfermentable dextrins, and the yield +of spirits is therefore increased. Malted grain being +omitted or used in reduced quantity, there is less lactic +acid and few or foreign ferments to contaminate the +fermenting mass; also, the formation of higher alcohols +than the ethyl alcohol is almost totally suppressed. +Consequently the final yield of spirits is purer in quality +and requires little or no further purification. Also, +further, the nitrates themselves acting as nutrients to +the yeast cells, these become more active and require +less nutrition to be taken from the grain.</p> + +<hr /> + + + + +<a name="pho1"></a><h2>SPECTROSCOPIC DETERMINATION OF THE +SENSITIVENESS OF DRY PLATES.</h2> + + +<p>After describing other methods of determining the +sensitiveness of plates, Mr. Gf. F. Williams, in the <i>Br. +Jour, of Photo</i>., thus explains his plan. I will now explain +the method I adopt to ascertain the relative +sensitiveness of plates to daylight. Procure a small +direct vision pocket spectroscope, having adjustable +slit and sliding focus. To the front of any ordinary +camera that will extend to sixteen or eighteen inches, +fit a temporary front of soft pine half an inch thick, +and in the center of this bore neatly with a center bit +a hole of such diameter as will take the eye end of the +spectroscope; unscrew the eyehole, and push the tube +into the hole in wood, bushing the hole, if necessary, +with a strip of black velvet glued in to make a tight +fit. By fixing the smaller tube in the front of camera +we can focus by sliding the outer tube thereon; if we +fix the larger tube in the front, we should have to focus +inside the camera, obviously most inconvenient in +practice. Place the front carrying the spectroscope +<i>in situ</i> in the camera, and rack the latter out to its +full extent; point the camera toward a bright sky, or +the sun itself, if you can, while you endeavor to get a +good focus. The spectrum will be seen on the ground +glass, probably equal in dimensions to that of a quarter +plate. Proceed to focus by sliding the outer tube +to and fro until the colors are quite clear and distinct, +and at same time screw down the slit until the Fraunhofer +lines appear. By using the direct rays of the +sun, and focusing carefully, and adjusting the slit to +the correct width, the lines can be got fairly sharply. +Slide your front so that the spectrum falls on the +ground glass in just such a position as a quarter plate +glass would occupy when in the dark slide, and arrange +matters so that the red comes to your left, and +the violet to the right, and invariably adopt that plan. +It is advisable to include the double H lines in the violet +on the right hand edge of your plate. They afford +an unerring point from which you can calculate backward, +finding Gr, F, E, etc., by their relative positions +to the violet lines. Otherwise you may be mistaken as +to what portion of the spectrum you are really photographing. +The red should just be seen along the left +edge of the quarter plate. When all is arranged thus, +you utilize three-fourths of your plate with the spectrum, +with just a little clear glass at each end. Before +disturbing the arrangement of, the apparatus, it is desirable +to scratch a mark on the sliding tube, and +make a memorandum of the position of all the parts, so +that they may be taken away and replaced exactly +and thus save time in future.</p> + +<p>To take a photograph of the spectrum, put a quarter +plate in the dark slide and place in camera; point the +camera toward a bright sky, or white cloud, near the +sun--not at the sun, as there is considerable difficulty +in keeping the direct rays exactly in the axis of the +spectroscope--draw the shutter, and give, say, sixty +seconds. On development, you will probably obtain +a good spectrum at the first trial. The duration of +exposure must, of course, depend upon the brightness +of the day; but if the experiments are to have relative +values, the period of exposure must be distinctly noted, +and comparisons made for a normal exposure of sixty +seconds, ninety seconds, two minutes or more, just according +to whatever object one has in view in making +the experiments. With a given exposure the results will +vary with the light and the width of the slit, as well as +being influenced by the character of the instrument +itself. Further, all such experiments should be made +with a normal developer, and development continued +for a definite time. The only exception to this rule +would be in the event of wishing to ascertain the utmost +that could be got out of a plate, but, under ordinary +circumstances, the developer ought never to vary, +nor yet the duration of development. To try the effect +of various developers, or varying time in development, +a departure must be made of such a nature as would +operate to bring out upon each plate, or piece of a +plate, the utmost it would develop short of fog, against +which caution must be adopted in all spectrum experiments.</p> + +<p>On development, say for one, two, or three minutes, +wash off and fix. You will recognize the H violet lines +and the others to the left, and this experiment shows +what is the sensitiveness of this particular plate to the +various regions of the spectrum with this particular +apparatus, and with a normal exposure and development. +So far, this teaches very little; it merely indicates +that this particular plate is sensitive or insensitive +to certain rays of colored light. To make this +teaching of any value, we must institute comparisons. +Accordingly, instead of simply exposing one plate, +suppose we cut a strip from two, three, four, or even +half a dozen different plates, and arrange them side +by side, horizontally, in the dark slide, so that the +spectrum falls upon the whole when they are placed +in the camera and exposed. There is really no difficulty +in cutting strips a quarter of an inch wide, the +lengthway of a quarter plate. Lay the gelatine plate +film up, and hold a straight edge on it firmly, so that +when we use a suitable diamond we can plow through +the film and cut a strip which will break off easily between +the thumb and finger. A quarter plate can +thus be cut up into strips to yield about a dozen comparative +experiments. When cut and snapped off, +mark each with pencil with such a distinguishing mark +as shall be clearly seen after fixing. The cut up strips +can be kept in the maker's plate box.</p> + +<hr /> + +<p>The deep down underground electric railway in +London has so far proved an unprofitable concern for +its stockholders. It is 3½ miles long, touches some of +the greatest points of traffic, but somehow or other +people won't patronize it. The total receipts for the +last six months were a little under $100,000, and they +only carried seventeen persons per train mile. On this +road the passengers are carried on elevators up and +down from the street level to the cars. The poor +results so far make the stockholders sick of the project +of extending the road.</p> + +<hr /> + + +<h3>A New Catalogue of Value</h3> + +<p>Contained in Scientific American Supplement +during the past ten years, sent <i>free of charge</i> to any +address. MUNN & CO., 361 Broadway, New York.</p> + +<hr /> + +<h3>THE SCIENTIFIC AMERICAN</h3> + +<h2>Architects and Builders Edition</h2> + +<p class="ctr"><b>$2.50 a Year. 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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 821, Sep. 26, 1891 + +Author: Various + +Release Date: October 5, 2004 [EBook #13640] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Victoria Woosley, Don Kretz, Juliet Sutherland and the +PG Distributed Proofreaders Team + + + + + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 821 + + + + +NEW YORK, September 26, 1891 + +Scientific American Supplement. Vol. XXXII, No. 821. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + * * * * * + + + + +TABLE OF CONTENTS. + + +I. Architectural.--The New Labor Exchange in Paris.--With + views of the interior and exterior of the building + +II. Electrical.--The Construction and Maintenance of Underground + Circuits.--By S.B. FOWLER.--A comprehensive article, + discussing at length the various devices for protecting underground + circuits, methods _of_ inserting the cables, etc. + +III. Engineering.--Railroads to the Clouds.--Sketches of a number + of mountain railroads + +IV. Marine Engineering.--The French Armored Turret Ship + the Marceau.--1 engraving.--A full description of the vessel, giving + dimensions and cost + + A Review of Marine Engineering during the Past Decade.--A + paper read before the Institution of Mechanical Engineers by Mr. + Alfred Blechynben, of Barrow-in-Furness.--This paper, which + is continued from Supplement No. 820, treats on steam pipes, + feed water heating, twin screws, etc. + +V. Miscellaneous.--The Little House.--An article giving various + hints about the arrangement and management of small + dwellings, with special view to the best sanitary arrangements + + Stilt Walking.--A sketch, with engraving, of Sylvain Dornon, + the stilt walker of Landes + + Remains of a Roman Villa in England + + Gum Arabic and its Modern Substitutes.--A continuation of a + paper by Dr. S. Rideal and W.E. Youle.--With 26 tables + + A New Method of Extinguishing Fires.--Invented by George + Dickson and David A. Jones, of Toronto, Canada.--Apparatus designed + to utilize a mixture of water and liquefied carbonic acid + +VI. Medicine and Hygiene.--The Hygienic Treatment of + Obesity.--By Dr. Paul Chebon.--Methods of eating, drinking, + and exercising for the purpose of reducing fat.--An extended + article, giving valuable information to people troubled with too + much flesh + +VII. Photography.--Spectroscopic Determination of the Sensitiveness + of Dry Plates.--A full description of the new plan of + Mr. G.F. WILLIAMS, for determining the sensitiveness of dry + plates by the use of a small direct vision pocket spectroscope + +VIII. Physics.--A Physical Laboratory Indicator.--By J.W. + MOORE, of Lafayette College.--1 engraving.--This is a modification + of the old peg board adapted to use in the laboratory.--It indicates + the names of the members of the class, contains a full + list of the experiments to be performed, refers the student + to the book and page where information in reference to experiments + or apparatus may be found, it shows what experiments + are to be performed by each student at a given time, etc. + + Cailletet's Cryogen.--A description, with one engraving, of Mr. + Cailletet's new apparatus for producing temperatures from 70 + degrees to 80 degrees C., below zero, through the expansion of + liquid carbonic acid + +IX. Technology.--The Manufacture of Roll Tar Paper.--An extended + article containing a historical sketch and full information + as to the materials used and the methods of manufacture + + Smokeless Gunpowder.--By Hudson Maxim.--A comprehensive + article on the manufacture and use of smokeless gunpowder, + giving a sketch of its history, and describing the methods of + manufacture and its characteristics + + Method of Producing Alcohol.--A description of an improved + process for making alcohol.--Invented by Mr. Alfred Springer, + of Cincinnati, Ohio + + * * * * * + + + + + +[Illustration: INTERIOR OF THE NEW LABOR EXCHANGE, PARIS.] + +[Illustration: NEW LABOR EXCHANGE, PARIS.] + +THE NEW LABOR EXCHANGE, PARIS. + + +The new Labor Exchange is soon to be inaugurated. We give herewith a +view of the entrance facade of the meeting hall. The buildings, which +are the work of Mr Bouvard, architect, of the city of Paris, are +comprised within the block of houses whose sharp angle forms upon +Place de la Republique, the intersection of Boulevard Magenta and +Bondy street. One of the entrances of the Exchange is on a level with +this street. The three others are on Chateau d'Eau street, where the +facade of the edifice extends for a length of one hundred feet. From +the facade and above the balcony that projects from the first story, +stand out in bold relief three heads surrounded by foliage and fruit +that dominate the three entrance doors. These sculptures represent the +Republic between Labor and Peace. The windows of the upper stories are +set within nine rows of columns, from between the capitals of which +stand out the names of the manufacturers, inventors, and statesmen +that have sprung from the laboring classes. Upon the same line, at the +two extremities of the facade, two modillions, traversed through their +center by palms, bear the devices "Labor" and "Peace." Above, there is +a dial surmounted by a shield bearing the device of the city of Paris. + +The central door of the ground floor opens upon a large vestibule, +around which are arranged symmetrically the post, telegraph, +telephone, and intelligence offices, etc. Beyond the vestibule there +is a gallery that leads to the central court, upon the site of which +has been erected the grand assembly hall. This latter, which measures +20 meters in length, 22 in width, and 6 in height, is lighted by a +glazed ceiling, and contains ten rows of benches. These latter contain +900 seats, arranged in the form of circular steps, radiating around +the president's platform, which is one meter in height. A special +combination will permit of increasing the number of seats reserved for +the labor associations on occasions of grand reunions to 1,200. The +oak doors forming the lateral bays of the hall will open upon the two +large assembly rooms and the three waiting rooms constructed around +the faces of the large hall. In the assembly rooms forming one with +the central hall will take place the deliberations of the syndic +chambers. The walls of the hall will, ere long, receive decorative +paintings.--_L'Illustration._ + + * * * * * + + + + +MANUFACTURE OF ROLL TAR PAPER. + + +Roofing paper was first used in Scandinavia early as the last century, +the invention being accredited to Faxa, an official of the Swedish +Admiralty. The first tar and gravel roofs in Sweden were very +defective. The impregnation of the paper with a water-proofing liquid +had not been thought of, and the roofs were constructed by laying over +the rafters a boarding, upon which the unsaturated paper, the sides of +which lapped over the other, was fastened with short tacks. The +surface of the paper was next coated with heated pine tar to make it +waterproof. The thin layer of tar was soon destroyed by the weather, +so that the paper, swelled by the absorption of rain water, lost its +cohesiveness and was soon destroyed by the elements. This imperfect +method of roof covering found no great favor and was but seldom +employed. + +In Germany the architect Gilly was first to become interested in tar +paper roofing, and recommended it in his architecture for the country. +Nevertheless the new style of roof covering was but little employed, +and was finally abandoned during the first year of the 19th century. +It was revived again in 1840, when people began to take a renewed +interest in tar paper roofs, the method of manufacturing an +impermeable paper being already so far perfected that the squares of +paper were dipped in tar until thoroughly saturated. The roof +constructed of these waterproof paper sheets proved itself to be a +durable covering, being unimpenetrable to atmospheric precipitations, +and soon several factories commenced manufacturing the paper. The +product was improved continually and its method of manufacture +perfected. The good qualities of tar paper roofs being recognized by +the public, they were gradually adopted. The costly pine tar was soon +replaced by the cheaper coal tar. Square sheets of paper were made at +first; they were dipped sufficiently long in ordinary heated coal tar, +until perfectly saturated. The excess of tar was then permitted to +drip off, and the sheets were dried in the air. The improvement of +passing them through rollers to get rid of the surplus tar was +reserved for a future time, when an enterprising manufacturer +commenced to make endless tar paper in place of sheets. Special +apparatus were constructed to impregnate these rolls with tar; they +were imperfect at first, but gradually improved to a high degree. Much +progress was also made in the construction of the roofs, and several +methods of covering were devised. The defects caused by the old method +of nailing the tar paper direct upon the roof boarding were corrected; +the consequence of this method was that the paper was apt to tear, +caused by the unequal expansion of the roofing boards and paper, and +this soon led to the idea of making the latter independent of the +former by nailing the sides of the paper upon strips running parallel +with the gable. The use of endless tar paper proved to be an essential +advantage, because the number of seams as well as places where it had +to be nailed to the roof boarding was largely decreased. The +manufacture of tar paper has remained at about the same stage and no +essential improvements have been made up to the present. As partial +improvement may be mentioned the preparation of tar, especially since +the introduction of the tar distillery, and the manufacture of special +roof lacquers, which have been used for coating in place of the coal +tar. As an essential progress in the tar paper roofing may be +mentioned the invention of the double tar paper roof, and the wood +cement roof, which is regarded as an offshoot. + +The tar paper industry has, within the last forty years, assumed great +dimensions, and the preferences for this roofing are gaining ground +daily. In view of the small weight of the covering material, the wood +construction of the roof can be much lighter, and the building is +therefore less strained by the weight of the roof than one with the +other kind, so that the outer walls need not be as heavy. Considering +the price, the paper roof is not only cheaper than other fireproof +roofs, but its light weight makes it possible for the whole building +to be constructed lighter and cheaper. The durability of the tar paper +roof is satisfactory, if carefully made of good material; the double +tar paper roof, the gravel double roof, and the wood cement roof are +distinguished by their great durability. + +These roofs may be used for all kinds of buildings, and not only are +factories, storehouses, and country buildings covered with it, but +also many dwellings. The most stylish residences and villas are at +present being inclosed with the more durable kinds; the double roof, +the gravel double roof, and the wood cement roof. For factory +buildings, which are constantly shaken by the vibrations of the +machinery, the tar paper roof is preferable to any other. + +In order to ascertain to what degree tar paper roofs would resist +fire, experiments were instituted at the instigation of some of the +larger manufacturers of roofing paper, in the presence of experts, +architects, and others, embracing the most severe tests, and it was +fully proved that the tar paper roof is as fireproof as any other. +These experiments were made in two different ways; first, the +readiness of ignition of the tar paper roof by a spark or flame from +the outside was considered, and, second, it was tested in how far it +would resist a fire in the interior of the building. In the former +case, it was ascertained that a bright, intense fire could be kept +burning upon the roof for some time, without igniting the woodwork of +the roof, but heat from above caused some of the more volatile +constituents of the tar to be expelled, whereby small flames appeared +upon the surface within the limits of the fire; the roofing paper was +not completely destroyed. There always remained a cohesive substance, +although it was charred and friable, which by reason of its bad +conductivity of heat protected the roof boarding to such an extent +that it was "browned" only by the developed tar vapors. A fire was +next started within a building covered with a tar paper roof; the +flame touched the roof boarding, which partly commenced to char and +smoulder, but the bright burning of the wood was prevented by the +air-tight condition of the roof; the fire gases could not escape from +the building. The smoke collecting under the roof prevented the +entrance of fresh air, in consequence of which the want of oxygen +smothered the fire. The roofing paper remained unchanged. By making +openings in the sides of the building so that the fire gases could +escape, the wood part of the roof was consumed, but the roofing paper +itself was only charred and did not burn. After removing the fire in +contact with the paper, this ceased burning at once and evinced no +disposition whatever to spread. In large conflagrations, also, the tar +paper roofs behaved in identically a similar manner. Many instances +have occurred where the tar paper roof prevented the fire from +spreading inside the building, and developing with sufficient +intensity to work injury. + +As it is of interest to the roofer to know the manner of making the +material he uses, we give in the following a short description of the +manufacture of roofing paper. At first, when square sheets were used +exclusively, the raw paper consisted of ordinary dipped or formed +sheets. The materials used in its manufacture were common woolen rags +and other material. In order to prepare the pulp from the rags it is +necessary to cut them so small that the fabric is entirely dissolved +and converted into short fibers. The rags are for this purpose first +cut into pieces, which are again reduced by special machines. The rags +are cut in a rag cutting machine, which was formerly constructed +similar to a feed cutter; later on, more complicated machines of +various constructions were employed. It is not our task to describe +the various kinds, but we remain content with the general remark that +they are all based on the principles of causing revolving knives to +operate upon the rags. The careful cleansing of the cut rags, +necessary for the manufacture of paper, is not required for roofing +paper. It is sufficient to rinse away the sand and other solid +extraneous matter. The further reduction of the cut rags was formerly +performed in a stamp mill, which is no longer employed, the pulp mill +or rag engine being universally used. + +The construction of this engine may be described as follows: A box or +trough of wood, iron, or stone is by a partition divided into two +parts which are connected at their ends. At one side upon the bottom +of the box lies an oakwood block, called the back fall. In a hollow of +this back fall is sunk the so-called plate, furnished with a number of +sharp steel cutters or knives, lying alongside of each other. A roller +of solid oakwood, the circumference of which is also furnished with +sharp steel cutters or knives, is fastened upon a shaft and revolves +within the hollow. The journal bearings of the shaft are let into and +fastened in movable wooden carriers. The carriers of the bearings may +be raised and lowered by turning suitable thumbscrews, whereby the +distance between the roller and the back fall is increased or +decreased. The whole is above covered with a dome, the so-called case, +to prevent the throwing out of the mass under the operation of +grinding. The roller is revolved with a velocity of from 100 to 150 +revolutions per minute, whereby the rags are sucked in between the +roller and the back fall and cut and torn between the knives. At the +beginning of the operation, the distance between the roller and the +back fall is made as great as possible, the intention being less to +cut the rags than to wash them thoroughly. The dirty water is then +drawn off and replaced by clean, and the space of the grinding +apparatus is lessened gradually, so as to cut the rags between the +knives. The mass is constantly kept in motion and each piece of rag +passes repeatedly between the knives. The case protects the mass from +being thrown out by the centrifugal force. The work of beating the +rags is ended in a few hours, and the ensuing thin paste is drawn off +into the pulp chest, this being a square box lined with lead. + +From the pulp chest it passes to the form of the paper machine. This +form consists of an endless fine web of brass wire, which revolves +around rollers. The upper part of this form rests upon a number of +hollow copper rollers, whereby a level place is formed. The form +revolves uniformly around the two end rollers, and has at the same +time a vibratory motion, by which the pulp running upon the form is +spread out uniformly and conducted along, more flowing on as the +latter progresses. The water escapes rapidly through the close wire +web. In order to limit the form on the sides two endless leather +straps revolve around the rollers on each side, which touch with their +lower parts the form on both sides and confine the fluid within a +proper breadth. The thickness of the pulp is regulated at the head of +the form by a brass rule standing at a certain height; its function is +to level the pulp and distribute it at a certain thickness. The +continually moving pulp layer assumes greater consistency the nearer +it approaches to the dandy roll. This is a cylinder covered with brass +wire, and is for the purpose of compressing the paper, after it has +left the form, and free it from a great part of the water, which +escapes into a box. The paper is now freed of a good deal of the +fluid, and assumes a consistency with which it is enabled to leave the +form, which now commences to return underneath the paper, passing on +to an endless felt, which revolves around rollers and delivers it to +two iron rolls. The paper passes through a second pair of iron +rollers, the interiors of which are heated by steam. These rollers +cause the last of the water to be evaporated, so that it can then be +rolled upon reels. A special arrangement shaves the edges to the exact +size required. + +The paper is made in different thicknesses and designated by numbers +to the size and weight. + +Waste paper, bookbinders' shavings, etc., can be used for making the +paper. As much wool as possible should be employed, because the wool +fiber has a greater resistance than vegetable fiber to the effects of +the temperature. By wool fiber is understood the horny substance +resembling hair, with the difference that the former has no marrowy +tissue. The covering pellicle of the wool fiber consists of flat, +mostly elongated leaves, with more or less corners, lying over each +other like scales, which makes the surface of the fiber rough; this +condition, together with the inclination of curling, renders it +capable of felting readily. Pure wool consists of a horny substance, +containing both nitrogen and sulphur, and dissolves in a potash +solution. In a clean condition, the wool contains from 0.3 to 0.5 per +cent. of ash. It is very hygroscopical, and under ordinary +circumstances it contains from 13 to 16 per cent. humidity, in dry air +from 7 to 11 per cent., which can be entirely expelled at a +temperature of from 226 to 230 degrees Fahrenheit. Wool when ignited +does not burn with a bright flame, as vegetable fiber does, but +consumes with a feeble smouldering glow, soon extinguishes, spreading +a disagreeable pungent vapor, as of burning horn. By placing a test +tube with a solution of five parts caustic potash in 100 parts water, +a mixture of vegetable fibers and wool fibers, the latter dissolve if +the fluid is brought to boiling above an alcohol flame, while the +cotton and linen fibers remain intact. + +The solubility of the woolen fibers in potash lye is a ready means of +ascertaining the percentage of wool fiber in the paper. An exhaustive +analysis of the latter can be performed in the following manner: A +known quantity of the paper is slowly dried in a drying apparatus at +temperature of 230 deg. Fahrenheit, until a sample weighed on a scale +remains constant. The loss of weight indicates the degree of humidity. +To determine the ash percentage, the sample is placed in a platinum +crucible, and held over a lamp until all the organic matter is burned +out and the ash has assumed a light color. The cold ash is then +moistened with a carbonate of ammonia solution, and the crucible again +exposed until it is dark red; the weight of the ash is then taken. To +determine the percentage of wool, a sample of the paper is dried at +230 deg. Fahrenheit and weighed, boiled in a porcelain dish in potash lye +12 deg. B. strong, and frequently stirred with a glass rod. The wool fiber +soon dissolves in the potash lye, while the vegetable fiber remains +unaltered. The pulpy mass resulting is placed upon a filter, dried at +212 deg. Fahrenheit, and after the potash lye has dripped off, the +residue, consisting of vegetable fiber and earthy ash ingredients, is +washed until the water ceases to dissolve anything. The residue dried +at 212 deg. Fahrenheit is weighed with a filter, after which that of the +latter is deducted. The loss of weight experienced is essentially +equal to the loss of the wool fiber. If the filtrate is saturated with +hydrochloric acid, the dissolved wool fiber separates again, and after +having been collected upon a weighed filter, it may be weighed and the +quantity ascertained. + +The weight of the mineral substances in the raw paper is ascertained +by analyzing the ash in a manner similar to that above described. The +several constituents of the ash and the mineral added to the raw paper +are ascertained as follows: Sufficient of the paper is calcined in the +manner described; a known quantity of the ash is weighed and thrown +into a small porcelain dish containing a little distilled water and an +excess of chemically pure hydrochloric acid. In this solution are +dissolved the carbonates, carbonate of lime, carbonate of magnesia, a +little of sulphate of alumina, as well as metallic oxides, while +silicate of magnesia, silicic acid, sulphate of lime (gypsum) remain +undissolved. The substance is heated until the water and excess of +free hydrochloric acid have been driven off; it is then moistened with +a little hydrochloric acid, diluted with distilled water and heated. +The undissolved residue is by filtering separated from the dissolved, +the filter washed with distilled water, and the wash water added to +the filtrate. The undissolved residue is dried, and after the filter +has also been burned in due manner and the ash added, the weight is +ascertained. It consists of clay, sand, silicic acid and gypsum. + +The filtrate is then poured into a cylinder capable of holding 100 +cubic centimeters, and furnished with a scale; sufficient distilled +water is then added until the well-shaken fluid measures precisely 100 +cubic centimeters. By means of this measuring instrument, the filtrate +is then divided into two equal portions. One of these parts is in a +beaker glass over-saturated with chemically pure chloride of ammonia, +whereby any iron of oxide present and a little dissolved alumina fall +down as deposit. The precipitate is separated by filtering, washed, +dried at 212 deg. Fahrenheit and weighed. To the filtrate is then added a +solution of oxalate of ammonia until a white precipitate of oxalate of +lime is formed. This precipitate is separated by filtering, washed, +dried and when separated from the filter, is collected upon dark +satinized paper; the filter itself is burned and the ash added to the +oxalate of lime. This oxalate of lime is then heated to a dark red +heat in a platinum crucible with lid until the oxalate of lime is +converted into carbonate of lime. By the addition of a few drops of +carbonate of ammonia solution and another slight heating of the +crucible, also the caustic lime produced in the filter ash by heating, +is reconverted into carbonate of lime, and after cooling in the +exsiccator, the whole contents of the crucible is weighed as +carbonate of lime, after deducting the known quantity of filter ash. + +Any magnesia present in the filtrate of the oxalate of lime is by the +addition of a solution of phosphate of soda separated as phosphate of +ammonia and magnesia, after having stood twenty-four hours. The +precipitate is filtered off, washed with water to which a little +chloride of ammonia is added, dried, and after calcining the fiber and +adding the filter ash, glow heated in the crucible. The glowed +substance is weighed after cooling, and is pyrophosphate of magnesia, +from which the magnesia or carbonate of magnesia is calculated +stoichiometrically. All the ascertained sums must be multiplied by 2, +if they are to correspond to the analyzed and weighed quantity of ash. + +The second half of the filtrate is used for determining the small +quantity of sulphate of lime still contained in the hydrochlorate +solution. By adding chloride of barium solution the sulphuric acid is +bound to the barytes and sulphate of baryta separates as white +precipitate. This is separated by filtering, washed, dried and weighed +in the customary manner. From the weight of the sulphate of baryta is +then computed the weight of sulphate of lime, which has passed over +into solution. The ascertained sum is also to be multiplied with 2. + +The manufacture of roll tar paper from the roll paper was at first +found to be difficult, as it was impossible to submerge a surface +larger than from ten to fifteen square yards, rolled up, in the tar, +because more would have required too large a pan. Besides this, the +paper tears easily, when it is in the hot tar. All kinds of +experiments were tried, in order to impregnate the surface of the +paper without employing too large a pan. + +The following method was tried at first: The roll paper was cut into +lengths of ten yards, which were rolled up loosely, so that a certain +space was left between the different coils. These loose rolls, of +course, occupied much space and could be put into the tar only in a +standing position, because in a horizontal one the several coils would +have pressed together again. The loose roll was therefore slipped over +a vertical iron rod fastened into a circular perforated wooden foot. +The upper end of this iron rod ended in a ring, in which the hook of a +chain or rope could be fastened. With the aid of a windlass the roll +was raised or lowered. When placed in the pan with boiling tar, it was +left there until thoroughly saturated. It was then taken out, placed +upon a table, and the excess of tar allowed to drip off into a vessel +underneath. After partially drying, the roll was spread out in open +air, occasionally turned, until sufficiently dried, when it was rolled +up again. + +In order to neutralize the smeary, sticky condition of the surface and +avoid the disagreeable drying in open air, the experiment of strewing +sand on the sticky places was tried next. The weight of the paper was +largely increased by the sand, and appeared considerably thicker. For +this reason the method of sanding the paper was at once universally +adopted. To dispense with the process of permitting the surplus tar to +drip off, means were devised by which it was taken off by scrapers, or +by pressing through rollers. The scrapers, two sharp edged rods +fastened across the pan, were then so placed that the paper was drawn +through them. The excess of tar adhering to its surface was thereby +scraped off and ran back into the pan. + +This work, however, was performed better and to more satisfaction by a +pair of rollers fastened to the pan. These performed a double duty; +thoroughly removed the tar from the surface and by reason of their +pressure they caused a more perfect incorporation of the tar with the +fibers of the paper. Finally, different factories employed different +methods of manufacture, one of which was to cut the rolls into +definite lengths of about ten yards; these were then rerolled very +loosely and immersed in the hot tar until sufficiently saturated. The +paper was then passed through the roller, much pressure exerted, and +then loosely rolled up again. Being tarred once, it was then laid into +a second pan with hot tar, reeled out after a time, strewn with sand, +and rolled up again. Another method was to cut clothes lines into +lengths of about fifteen yards, and at a distance of two inches have +knots tied in them. The paper was cut in lengths of ten or fifteen +yards, three pieces of the knotted clothes line were then rolled +between the loose coils of paper, which was then submerged in the tar, +which on account of the knots could penetrate the paper. The paper was +next sanded by permitting its lower surface to pass over dry sand in a +box standing on the floor. A workman rolled off the paper, and with +his hand he strews sand on the upper surface. The rolling taking place +on the edge of a table, by means of a crank, the excess of sand +dropped off. + +It is said by this method two workmen, one of which tends to the +rolling and sanding, the other turning the crank, could turn out +eighty rolls per day. This method is still in use. It is useless to +describe the many antiquated methods in vogue in smaller factories, +and it can truthfully be said that nearly all of them are out of date. +It appears to be the fact of almost all inventions that when reduced +to practical use, the arrangements, apparatus, and working methods +employed are generally of the most complicated nature, and time and +experience only will simplify them. This has been also the case with +the methods in the roofing paper industry, which are at present +gradually being reduced to a practical basis. The method gradually +adopted has been described in the preceding. The pan is of a certain +length, whereby it becomes possible to saturate the paper by slowly +drawing it through the heated tar. This is the chief feature. The work +is much simplified thereby and the workmen need not dip their hands +into the tar or soil them with it. The work of impregnating has become +much cleaner and easier, while at the same time the tar can be heated +to a much higher temperature. The pan is generally filled with +distilled coal tar, and the heating is regulated in such a manner that +the temperature of the impregnating mass is raised far beyond 212 deg. +Fahrenheit. This accelerates the penetration, which takes place more +quickly as the degree of heat is raised, which may be almost up to the +boiling point of the tar, as at this degree the paper is not destroyed +by the heat. In order to prevent the evaporation of the volatile +ingredients of the tar, the pan is covered with a sheet iron cover, +with a slot at the place where the paper enters into the impregnating +mass and another at the place where it issues. The tar is always kept +at the same level, by occasional additions. + +The roll of paper is mounted upon a shaft at the back end of the pan, +and by suitable arrangement of guide rollers it unwinds slowly, passes +into the tar in which it is kept submerged. The guide rollers can be +raised so that when a new roller is set up they can be raised out of +the tar. The end of the paper is then slipped underneath them above +the surface of the tar, when having passed through the squeezing +rollers, it is fastened to the beaming roller, and the guide rollers +are submerged again. A workman slowly turns the crank of the beaming +roller. + +This motion draws the paper slowly through the fluid, the roll at the +back end unwinding. The speed with which the squeezing rollers are +turned is regulated in such a manner that the paper remains +sufficiently long underneath the fluid to be thoroughly impregnated +with it. The workmen quickly learn by experience how fast to turn the +crank. The hotter the tar, the more rapid the saturation; the high +degree of heat expels the air and evaporates the hygroscopic fluid in +the pores of the paper. The strong heating of the tar causes another +advantage connected with this method. The surface of the paper as it +issues from the squeezing rollers is still very hot, and a part of the +volatile oils evaporate very quickly at this high temperature. The +surface is thereby at once dried to a certain degree and at the same +time receives a handsome luster, as if it had been coated with a black +lacquer. The paper is sanded in a very simple manner without the use +of mechanical apparatus; as it is being wrapped into a coil, it passes +with its lower surface over a layer of sand, while the workman who +tends to rolling up strews the inside with sand. The lower surface is +coated very equally. Care only being necessary that the sand lies +smooth and even at all times. When the workman has rolled up ten or +fifteen yards, he cuts it across with a knife and straightedge, so +that the paper is cut at right angles with its sides. + +There are three different sorts of roofing paper, according to the +impregnating fluid used in its manufacture. The ordinary tar paper is +that saturated with clear cold tar. This contains the greatest amount +of fluid ingredients and is very raggy in a fresh condition. It is +easy to see that the volatile hydrocarbons evaporate in a short time, +and when expelled, the paper becomes stiffer and apparently drier. +This drying, or the volatilization of the hydrocarbons, causes pores +between the fibers of the paper. These pores are highly injurious to +it, as they facilitate a process of decomposition which will ruin it +in a short time. + +Roofing paper can be called good only when it is essentially made from +woolen rags, and contains either very few or no earthy additions. It +is beyond doubt that the durability of a roofing paper increases with +the quality of wool fiber it contains--vegetable fibers and earthy +additions cause a direct injury. Reprehensible altogether is any +combination with lime, either in form of a carbonate or sulphate, +because the lime enters into chemical combination with the +decomposition products of the tar. + +The general nature of gravel is too well known to require description. +The grains of quartz sand are either sharp cornered or else rounded +pieces of stone of quartz, occasionally mixed with grains of other +amorphous pieces of silica--such as horn stone, silicious slate, +carnelian, etc.; again, with lustrous pieces of mica, or red and white +pieces of feldspar. The gravel used for a tar paper roof must be of a +special nature and be prepared for the purpose. The size of its grains +must not exceed a certain standard--say, the size of a pea. When found +in the gravel bank, it is frequently mixed with clay, etc., and it +cannot be used in this condition for a roof, but must be washed. The +utensils necessary for this purpose are of so simple and suggestive a +nature that they need not be described. Slag is being successfully +used in place of the gravel. It is easily reduced to suitable size, by +letting the red hot mass, as it runs from the furnace, run into a +vessel with water. The sudden chilling of the slag causes it to burst +into fragments of a sharp cornered structure. It is next passed +through a sieve, and the suitably sized gravel makes an excellent +material, as it gives a clean appearance to the roof. + +The thinking mind can easily go one step further and imagine that, +since the tar contains a number of volatile hydrocarbons, it might be +made more adaptable for impregnation by paper by distilling it, as by +this process the fluid would lose its tendency to evaporate and the +percentage of resinous substances increase. Singular to say, there was +a prejudice against the employment of distilled tar, entertained by +builders and people who had no knowledge of chemistry. Increasing +intelligence and altered business circumstances, however, brought +about the almost universal employment of distilled tar, and every +large factory uses it at present. The roofing paper prepared with +distilled tar is perhaps most suitably called asphaltum paper, as this +has been used in its manufacture. It possesses properties superior to +the ordinary tar paper, one of which is that immediately after its +manufacture, as soon as cold, it is dry and ready for shipment; nor +does it require to be kept in store for a length of time, and it has +also a good, firm body, being as flexible and tough as leather. It is +very durable upon the roof, and remains flexible for a long time. It +is true that asphaltum papers will always in a fresh state contain a +small percentage of volatile ingredients, which after a while make it +hard and friable upon the roof; but, by reason of its greater +percentage of resinous components, it will always preserve a superior +degree of durability and become far less porous. One hundred parts by +weight absorb 140 or 150 parts by weight of coal tar. A factory which +distilled a good standard tar for roofing paper recovered, besides +benzole and naphtha, also about ten per cent. of creosote oil, used +for one hundred parts raw paper, 176.4 partially distilled tar. +Experiments on a larger as well as a smaller scale reduced this +quantity to an average of 141.5 parts for one hundred parts raw paper. +The weight of sanded paper is very variable, as it depends altogether +upon the size of the sand grains. It may be stated generally that the +weight of the sand is as large as that of the tarred paper. + +The kinds of roofing paper saturated with other additions besides coal +tar form a separate class, in order to neutralize the defects inherent +in coal tar. These additions were originally for the purpose of +thickening the paper and making it stiffer and drier. The most +ordinary and cheapest thickener was the coal pitch. Although the +resinous substances are increased thereby, still the light tar oils +remain to evaporate, and the paper prepared with such a substance +readily becomes hard and brittle. A better addition is the natural +asphaltum, because it resists better the destroying influence of the +decomposition process, and also, to a certain degree, protects the +coal tar in which it is dissolved. The addition of natural asphaltum +doubtless caused the name of "asphaltum roofing paper." Resin, +sulphur, wood tar and other substances were also used as additions; +each manufacturer kept his method secret, however, and simply pointed +out by high sounding title in what manner his paper was composed. In +most cases, however, this appellation was applied to the ordinary tar +paper; the impregnating substance was mixed only with coal pitch, or +else a roofing paper saturated with distilled tar. The costly +additions, by the use of which a high grade of roofing paper can +doubtless be produced, largely increased its price, and on account of +the constant fall of prices of the article, its use became rather one +of those things "more honored in the breach than in the observance," +and was dispensed with whenever practicable. The crude paper is the +foundation of the roofing paper. The qualities of a good, +unadulterated paper have already been stated. At times, the crude +paper contains too many earthy ingredients which impair the cohesion +of the felted fibrous substance, and which especially the carbonate of +lime is very injurious, as it readily effects the decomposition of the +coal tar. The percentage of wool, upon which the durability of the +paper depends very largely, is very small in some of the paper found +in the market. In place of woolen rags, cheap substitutes have been +used, such as waste, which contains vegetable fibers. Since this +cannot resist the decomposition process for any length of time, it is +evident that the roofing paper which contains a noticeable quantity of +vegetable fibers cannot be very durable. To judge from the endeavors +made to improve the coal tar, it may be concluded that this material +does not fully comply with its function of making the roofing paper +perfectly and durably waterproof. The coal tar, be it either crude or +distilled, is not a perfect impregnating material, and the roofing +paper, saturated with it, possesses several defects. Let us in the +following try to ascertain their shortcomings, and then express our +idea in what manner the roofing paper may be improved. It was +previously mentioned that every tar roofing paper will, after a +greater or smaller lapse of time, assume a dry, porous, friable +condition, caused by the volatilization of a part of the constituents +of the tar. This alteration is materially assisted by the oxygen of +the air, which causes the latter to become resinous and exerts a +chemical influence upon them. By the volatilization of the lighter tar +oils, pores are generated between the fibers of the roofing paper, +into which the air and humidity penetrate. In consequence of the +greatly enlarged surface, not only the solid ingredients of the tar, +which still remain unaltered, are exposed to the action of the oxygen, +but also the fibers of the roofing paper are exposed to decomposition. +How destructive the alternating influence of the oxygen and the +atmospheric precipitations are for the roofing paper will be shown by +the following results of tests. It will have been observed that the +rain water running from an old paper roof, especially after dry +weather, has a yellowish, sometimes a brown yellow color. The +supposition that this colored rain water might contain decomposition +products of the roofing paper readily prompted itself, and it has been +collected and analyzed at different seasons of the year. After a +period of several weeks of fair weather during the summer, rain fell, +and the sample of water running from a roof was caught and evaporated; +the residue when dried weighed 1.68 grammes. It was of a brownish +black color, fusible in heat and readily soluble, with a yellow brown +color in water. The dark brown substance readily dissolved in ammonia, +alcohol, dilute acid, hydrochloric acid, sulphuric acid, and +decomposed in nitric acid, but did not dissolve in benzine or fat oil. +After several days' rain during the summer, a quantity of the water +was caught, evaporated, and the residue dried. Its characteristics +were similar to those above mentioned. By an experiment instituted in +water under conditions similar to the first mentioned, the dry brown +substance weighed 71 grammes. It possessed the same characteristics. +In the solution effected with water containing some aqua ammonia of +the brown substance, a white precipitate of oxalate of lime occurred +when an oxalate of ammonia solution was added, but the brown substance +remained in solution. A further precipitation of oxalate of lime was +produced by a solution of oxalic acid, but the brown organic substance +remained in solution. This organic substance being liberated from the +lime was evaporated, and left a dry, resinous, fusible brownish black +substance, which also dissolved readily in water. It will be seen from +these trials that the substance obtained from the rain water running +from a paper roof is a combination of an organic acid with lime, which +readily dissolves in water, and that also the free organic acid +combined with the lime dissolves easily in water. + +The question concerning the origin of this organic substance or its +combination with lime can only be answered in one way, viz., that it +must have been washed by the rain water out of the paper. But since +such a solid substance, easily soluble in water, is contained neither +in the fresh roofing paper nor in the coal tar, the only deduction is +that it must have arisen by the decomposition of the tar, in +consequence of the operation of the oxygen. The lime comes from the +coating substance of the roof, for which tar mixed with coal pitch was +used. The latter was fused with carbonate of lime. These analyses +furthermore show that the formation of the organic acid easily soluble +in water depends upon the season; and that a larger quantity of it is +generated in warm, sunny weather than in cold, without sunshine. This +peculiarity of the solid, resinous constituents of the coal tar, to be +by the operation of the atmospheric oxygen altered into such products +that are readily soluble in water, makes the tar very unsuitable as a +saturative substance for a roofing paper. How rapidly a paper roof can +be ruined by the generation of this injurious organic acid will be +seen from the following calculation: Let us suppose that an average +of 132 gallons of rain water falls upon ten square feet roof surface +per year, and that the arithmetical mean 0.932 of the largest (1.680) +and smallest number (0.184) be the quantity of the soluble brown +substance which on an average is dissolved in one quart of rain water; +hence from ten square feet of roof surface are rinsed away with the +rain water per year 466 grammes of the soluble decomposition products +of the tar. The oxidation process will not always occur as intensely +as by a paper roof, ten years old and painted two years ago, which +instigated above described experiment. As long as the roofing paper is +fresh and less porous, especially if the occurring pores are filled +and closed again by repeated coatings, oxidation will take place far +less rapidly. Besides this, the protective coating applied to the roof +surface is exposed most to this oxidation process. Even by assuming +this constantly progressive destructive action of the oxygen on the +roofing paper to be much less than above stated, we can readily +imagine that it must be quite large. If it is desired to produce a +material free of faults, it is first of all indispensable that +unobjectionable raw material be procured. Coal tar was formerly used +almost exclusively for the coating of a roof. It was heated and +applied hot upon the surface. In order to avoid the running off of the +thinly fluid mass, the freshly coated surface was strewn with sand. +The most volatile portion of the tar evaporated soon, whereby the +coating became thicker and finally dried. The bad properties of the +coal tar, pointed out elsewhere, made it very unsuitable even for this +purpose, and experiments were instituted to compound mixtures, by +adding other ingredients to the tar, that should more fully comply +with its function. It may be said in general that the coating masses +for roofs can be divided into two classes: either as lacquers or as +cements. To the former may be classed those of a fairly thinly fluid +consistency, and which contain volatile oils in such quantities that +they will dry quickly. Cements are those of a thickly fluid +consistency, and are rendered thus fluid by heating. It is not +necessary that the coating applied should harden quickly, as it +assumes soon after its application a firmness sufficient to prevent it +from running off the roof. Coal tar is to be classed among lacquers. +If it has been liberated by distillation from the volatile oils, it is +made better suited for the purpose than the ordinary kind. The mass +contains much more asphaltum, and after drying, which takes place +soon, it leaves a far thicker layer upon the roof surface, while the +pores, which had formed in the roofing paper consequent on drying, are +better filled up. Nevertheless, the distilled tar also has retained +the property of drying with time into a hard, vitreous mass, and +ultimately to be destroyed by decomposition.--_The Roofer_. + + * * * * * + + + + +A PHYSICAL LABORATORY INDICATOR. + + +The difficulties attending the management of a physical laboratory are +much greater than those of a chemical one. The cause of this lies in the +fact that in the latter the apparatus is less complicated and the pieces +less varied. Any contrivance that will reduce the labor and worry +connected with the running of a laboratory is valuable. + +A physical laboratory may be arranged in several ways. The apparatus may +be kept in a store room and such as is needed may be given to the +student each day and removed after the experiments are performed; or the +apparatus for each experiment or system of experiments may be kept in a +fixed place in the laboratory ready for assembling; for certain +experiments the apparatus may be kept in a fixed place in the laboratory +and permanently arranged for service. + +Each student may have his own desk and apparatus or he may be required +to pass from desk to desk. The latter method is preferable. + +When a store room is used the services of a man are required to +distribute and afterward to collect. If the apparatus is permanently +distributed, a large room is necessary, but the labor of collecting and +distributing is done away with. + +There are certain general experiments intended to show the use of +measuring instruments which all students must perform. To illustrate the +use of the indicator I have selected an elementary class, although the +instrument is equally applicable to all classes of experiments. + +Having selected a suitable room, tables may be placed against the walls +between the windows and at other convenient places. Shallow closets are +built upon these tables against the wall; they have glass doors and are +fitted with shelves properly spaced. A large number of light wooden +boxes are prepared, numbered from one up to the limit of the storage +capacity of the closets. A number corresponding to that upon the box is +placed upon the shelf, so that each one after removal may be returned to +its proper place without difficulty. On the front of the box is a label +upon which is written the experiment to be performed or the name of the +apparatus whose use is to be learned, references to various books, which +may be found in the laboratory library, and the apparatus necessary for +the experiment, which ought to be found in the box. If any parts of the +apparatus are too large to be placed in the box, the label indicates by +a number where it may be found in the storage case. + +It is evident that, instead of the above arrangement, all the boxes can +be stacked in piles in a general store room. The described arrangement +is preferable, as it prevents confusion in collecting and distributing +apparatus when the class is large. + +_The Indicator_ (see figure).--Some device is evidently desirable to +direct the work of a laboratory with the least trouble and friction +possible. I have found that the old fashioned "peg board," formerly used +in schools to record the demerits of scholars, modified as in the +following description, leaves nothing to be desired. + +The requirements of such an instrument are these: It must show the names +of the members of the class; it must contain a full list of the +experiments to be performed; it must refer the student to the book and +page where information in reference to the experiments or apparatus may +be found; it must show what experiments are to be performed by each +student at a given time; it must give information as to the place in the +laboratory where the apparatus is deposited; it must show to the +instructor what experiments have been performed by each student; it must +prevent the assignment of the same experiment to two students; it must +enable the instructor to assign the same experiment to two or more +students; it must form a complete record of what has been done, what +work is incomplete, and what experiments have not yet been assigned; it +must also be so arranged that new experiments or sets of experiments may +be exhibited. + + +------+---+---+---+---+---+---+---+---+ + | | A | B | C | D | E | F | G | H | + +------+---+---+---+---+---+---+---+---+ + | 1 | * o o * o o o o | + | 2 | * o * * o o o o | + | 3 | + * * * o o o o | + | 4 | + o * * o o o o | + | 5 | o + * * * * o o | + | 6 | o + * * o * o o | + | 7 | o o + * o o o o | + | 8 | o o o + * o o o | + | 9 | o o o * + o o o | + | 10 | o o o o o + o o | + | 11 | o o o * o o + * | + | 12 | o o * * o + + + | + | 13 | o o * o o o o o | + | 14 | o o * o o o o o | + | 15 | o o + o o o o o | + | 16 | o o + + * o o * | + +--------------------------------------+ + + A, B, C, etc., are cards upon which are the names of students. 1, + 2, 3, etc., are cards like the one described in the article. The + small circles (o) represent unassigned experiments. The black + circles (*) (slate nails) represent work done. The caudate circles + (+) (brass nail) represent work assigned. + +The indicator consists of a plank of any convenient length and breadth. +The front surface is divided into squares of such size that the pegs may +be introduced and withdrawn with ease. At each corner of the squares +holes are bored into which nails may be placed. There is a blank border +at the top and another on the left side. At the top of each vertical +column of holes is placed a card holder. This is made of light tin +turned up on the long edges--which are vertical--and tacked to the +board. Opposite each horizontal row of holes is a similar tin card +holder, but of greater length, and having its length horizontal. The +holders at the top of the board contain cards upon which the names of +the class are written. + +Cards, like the following, are prepared for the horizontal holders. + +-------------------------------------------------------------- +Stewart & Gee 229 +Physical Manip. 85 Intensity of Gravity--Borda's Method 39 +Glazebrook & Shaw 132 +-------------------------------------------------------------- + +These cards are numbered from one to any desired number and are arranged +in the holders consecutively. + +Two kinds of nails are provided to fit the holes in the board: An +ordinary slate nail and a common picture frame nail with a brass head. +The latter indicates work to be done, the former work done. + +To prepare the board for service, brass headed nails are placed opposite +each experiment, and below the names, care being taken not to have more +than one nail in the same horizontal row, unless it is intended that two +persons or more are to work upon the same experiment. + +There will be no conflict when the brass nails occupy diagonal lines. If +they do not, a glance will show the fact. + +After an experiment has been performed and a report made upon the usual +blank, the brass nail is removed and a slate nail put in its place. + +The board will show by the slate nails what work has been done by each +student, by the brass nails what is yet to be done, and by the empty +holes, experiments which have been omitted or are yet to be assigned. A +slate nail opposite an experiment card indicates that that experiment +may now be assigned to another person. + +It is evident that the schedule for a whole term may be arranged in a +few minutes and that the daily changes require very little time. + +The board is hung in a convenient place. The student as he enters the +laboratory looks for his name on the upper cards and under it for the +first brass nail in the vertical column: to the left he finds the +experiment card. On the left hand end of the slip he sees the book +references, on the right hand end a number--39 in the sample card given +above. Knowing the number, he proceeds to a desk and finds a box +numbered in the same manner. He removes the box from the closet. On the +label of the box is a list of all the apparatus necessary, which he will +find in the box; the label also contains the book references. He +performs the experiment, fills up a blank which he gives to the +instructor, puts all the materials back in the box, replaces the box in +its proper place in the closet and proceeds with the next experiment. +With this indicator there is no difficulty in managing fifty students or +more. + +Comparatively little apparatus need be duplicated. Where apparatus is +fixed against a wall a number may be tacked upon the wall and a card +containing the information desired. The procedure is then the same as +with the boxes. The cards on the board being removable, other ones may +be inserted containing information in reference to other boxes having +the same number but containing different materials. There can be no +successful tampering with the board, for the record of experiments +performed is upon the blanks which the students turn in and also in the +individual note books which are written up and given to the instructor +for daily examination. + +Lafayette College. J.W. MOORE. + + * * * * * + + + + +NEW METHOD OF EXTINGUISHING FIRES + + +This is by George Dickson, of Toronto, Canada, and David Alanson Jones. + +A mixture of water and liquefied carbon dioxide upon being discharged +through pipes at high pressure causes the rapid expansion of the gas and +converts the mixture into spray more or less frozen, and portions of the +liquid carbon dioxide are frozen, owing to its rapid expansion, and are +thus thrown upon the fire in a solid state, where said frozen carbon +dioxide in its further expansion not only acts to put out the fire, but +cools the surface upon which it falls, and thus tends to prevent +reignition. + +A represents a receptacle sufficiently strong to stand a pressure of not +less than a thousand pounds to the square inch. + +B B water receptacles. + +[Illustration: Fig. 1] + +In the drawings we have shown two receptacles B and only one receptacle +A; but we do not wish to confine ourselves to any particular number, nor +do we wish to confine ourselves to the horizontal position in which the +receptacles are shown. + +C is a pipe leading from the receptacle A to a point at or near the +bottom of the receptacle B. + +F is a pipe through which the mixture of water and liquefied gas from +the receptacle B is forced by the expansion of said liquefied gas, the +said pipe taking the mixture of water and liquefied gas from the bottom +of the receptacle. + +[Illustration: Fig. 2] + +To use the apparatus, open the stop cock D in the pipe C, leading to one +of the receptacles B, whereupon, owing to the lower pressure in the +cylinder B, the liquid carbon dioxide expands and rises to the top of +the cylinder A and forces the liquid carbon dioxide into the cylinder B, +the same as the superior steam of a boiler forces the water of the +boiler out when the same is tapped below the surface of the liquid. Now +upon opening the tap H, this superior gas forces out the mixture of +water and liquid carbon dioxide, which suddenly expanding causes +portions of the globules of liquefied gas to be frozen, and these, being +protected by a rapidly evaporating portion of the liquefied gas, are +thrown on the fire in solid particles. At the same time the water is +blown into a spray, which is more or less frozen. The fire is thus +rapidly extinguished by the vaporization of the carbon dioxide and water +spray. + + * * * * * + + + + +SMOKELESS GUNPOWDER. + +BY HUDSON MAXIM. + + +During the last forty years leading chemists have continued to +experiment with a view to the production of a gunpowder which should be +smokeless. But not until the last few years has any considerable degree +of success been attained. + +To be smokeless, a gunpowder must yield only gaseous products of +combustion. None of the so-called smokeless powders are entirely +smokeless, although some of them are very nearly so. + +The smoke of common black gunpowder is largely due to minute particles +of solid matter which float in the air. About one-half of the total +products of combustion of black gunpowder of ordinary composition +consists of potassium carbonate in a finely divided condition and of +potassium sulphate, which is produced chiefly by the burning in the air +of potassium sulphide, another production of combustion, as on the +outrushing gases it is borne into the air in a fine state of division. + +Another cause for the smoke of gunpowder is the formation of small +liquid vesicles which condense from some of the products of combustion +thrown into the air in a state of vapor, in the same manner as vesicles +of aqueous vapor form in the air on the escape of highly heated steam +from the whistle of a locomotive. + +Broadly speaking, an explosive compound is one which contains, within +itself, all the elements necessary for its complete combustion, and +whose heated gaseous products occupy vastly more space than the original +compound. Such compound usually consists of oxygen, associated with +other elements, for which it has great affinity, and from which it is +held from more intimate union, or direct chemical combination, under +normal conditions, by being in combination as well with other elements +for which it has less affinity, but which it readily gives up for the +stronger affinities when explosion takes place, the other elements +either combining with one another to form new compounds or being set +free in an uncombined state. + +An explosive is said to detonate when the above changes take place +instantaneously, the action being transmitted with the speed of +electricity by a sort of molecular rhythm from molecule to molecule +throughout the entire substance of the compound. + +An explosive is said to explode when the above changes do not occur +instantaneously throughout the whole substance, but whose combustion +takes place from the surface inward of the particles or grains of which +it is composed, thus requiring some definite lapse of time. + +The elements of an explosive compound may be associated chemically as in +nitro-glycerine and gun-cotton, which are chemical compounds, being the +results of definite reactions. Or, an explosive may be a mere mechanical +mixture of different substances comprising the necessary elements, as is +ordinary black gunpowder, which is a compound of charcoal, sulphur and +saltpeter, the saltpeter supplying the necessary oxygen. + +No gunpowder can be smokeless in which saltpeter or any oxygen-bearing +salt having a metallic base is employed, for when the salt gives up its +oxygen, the base combines with other elements to produce a sulphate, a +carbonate, or other salt, which, being solid, produces smoke. Therefore, +to be smokeless, a gunpowder must contain no other elements than oxygen, +hydrogen, nitrogen, and carbon, and in such proportions that the +products of combustion shall be wholly gaseous. The nitric +ethers--gun-cotton and nitro-glycerine--constitute such explosive +compounds. These substances were formerly thought to be +nitro-substitution compounds, but are now known to belong to the +compound ethers of nitric acid. + +Gun-cotton, discovered by Schonbein, in 1845, has since been looked upon +as the most promising material for a smokeless gunpowder, it being a +very powerful explosive and burning with practically no smoke. To-day, +gun-cotton, in some form or other, constitutes the base of substantially +all of the smokeless powders with which have been attained any +considerable degree of success. + +Gun-cotton alone and in its fibrous state has been found to be too +quick, or violent, for propulsive purposes, such as use in firearms; as +under such conditions of confinement it is very likely to detonate and +burst the gun. However, if gun-cotton be dissolved in a suitable +solvent, which is capable of being evaporated out, such as acetone, or +acetate of ethyl, which are very volatile, it becomes, when thus +dissolved and dried, a very hard, horn-like, amorphous substance, which +may be used for a smokeless gunpowder. But this substance taken alone is +very difficult to mould or granulate, and the loss of expensive solvents +must necessarily be quite considerable. + +When gun-cotton is reduced to a collodial solid, as above, and used as a +smokeless gunpowder, the grains must be made comparatively small to +insure prompt and certain ignition, and consequently the pressures +developed in the gun are apt to be too great when charges sufficiently +large are used to give desired velocities. + +If, however, a compound be made of gun-cotton and nitro-glycerine, in +about equal parts, by means of a volatile solvent or combining agent, +such as one of the before mentioned, and the solvent evaporated out, we +obtain practically a new substance and one which, as regards its +explosive nature, is quite unlike either of its two constituents taken +alone. The nitro-glycerine, furthermore, being itself a solvent of +gun-cotton, much less of the volatile ether is necessary to render the +compound of an amorphous character. Being quite plastic this substance +may be wrought or moulded into any desired size or form of grain. + +This simple compound of nitro-glycerine and gun-cotton, or with some +slight modifications, has been found, when properly granulated, to be +the most smokeless powder that has yet been discovered or invented. If +pure chemicals are employed in the manufacture, and the gun-cotton and +nitro-glycerine be made of the highest nitration and best quality, we +have a smokeless powder which will possess the following desirable +qualities: + +1st. It is absolutely smokeless, that is, its products of combustion are +entirely gaseous. + +2d. Its products of combustion are in no way deleterious or unpleasant. + +3d. It is perfectly safe to manufacture, handle and transport. There is +no more danger of its exploding accidentally than there would be of an +explosion of shavings or sawdust; for, unless well confined and set off +with a strong primer, it will not explode at all. In the open its +combustion is so slow as to in no way resemble or partake of the nature +of an explosion. + +4th. It is perfectly stable, and will keep any length of time absolutely +without undergoing any change whatever, under all conditions of +temperature or exposure to which gunpowder would ever be subjected. + +5th. It is not hygroscopic, and may be soaked in water without being at +all affected by it. + +6th. It will not corrode the cartridge case. + +7th. It will not foul the gun. + +8th. It is sure of ignition with a good primer, and may be made to burn +as slowly as desired by varying the character and size of the grains. +Indeed, it may be made to burn so slowly as to fail of complete +combustion before the bullet leaves the gun, and after firing several +rounds, partly burned pieces of the powder may be picked up in front of +the gun. + +9th. In a shoulder arm, a velocity of 2,000 feet per second may be +imparted to the bullet with this powder, and with a pressure in the +chamber of the gun of not more than fifteen English tons. This is, of +course, when the gun, cartridge case, primer, and projectile are adapted +to the use of smokeless powder, and the granulation of the powder is +adapted to them. + +If what I have here claimed for the above smokeless powder be true, it +would appear that it may be taken as really an ideal smokeless powder. +Why, then, has it not already been universally adopted? Surely such a +powder is just what every government is seeking. In reply to this, let +me say that, in order for the above compound to be an effective and +successful smokeless powder, with the manifestation of the many +desirable qualities which I have recited, a great many other conditions +are necessary, some of which I will mention. To arrive at the knowledge +that this compound would constitute the best smokeless powder has +required a great deal of experimenting. It was first thought that +gun-cotton colloid, without any nitro-glycerine, that is, gun-cotton +dissolved and dried, would burn more slowly, keep better, and give +better ballistics than it would if combined with nitro-glycerine. It was +also thought that gun-cotton of a high degree of nitration when made +into colloidal form would even then burn too quickly to be suitable for +use in firearms. Consequently, the first experiments were with low grade +gun-cotton, what is called collodion cotton, such as is employed in the +manufacture of celluloid. But, as this would not explode without the +addition of some oxygen-bearing element, various oxygen-bearing salts +were combined with it, such as nitrate of potassium, nitrate of ammonia, +nitrate of baryta, etc. Also a great many of the first smokeless powders +were made of low grade gun-cotton combined with nitro-glycerine in +varying proportions. These powders would often give very good results +when first made; but low grade gun-cotton or di-nitro-cellulose, as it +is called, is a very unstable compound, and these powders, after giving +very promising results, were found to be constantly undergoing change, +sooner or later resulting in complete decomposition. + +When nitro-glycerine was first combined with gun-cotton in small +quantities, camphor was often added, to lessen the rapidity of +combustion which the nitro-glycerine was supposed to impart and also to +render the compound more plastic, and to tend to prevent the +decomposition of the low grade gun-cotton. But camphor being volatile, +would, by its evaporation, cause the powder to constantly change in +character. Castor oil has been found to be a better diluent, as this +will not evaporate. + +As all of the smokeless powders made of a low grade gun-cotton were +found to deteriorate and spoil, experiments were made with gun-cotton of +the highest degree of nitration, both alone and in combination with +nitro-glycerine. These experiments were first conducted in England by +private parties and by the British government, when it was found that +high grade gun-cotton would give excellent results if made into a +colloidal solid and used alone, or in combination with certain other +constituents. With a view to saving the large quantity of solvents +necessary to reduce the gun-cotton, and to get a more prompt and certain +ignition with a larger grain, experiments were cautiously made by the +admixture of varying proportions of nitro-glycerine to the gun-cotton +when dissolved, or rather along with other solvents in the process of +dissolving it. + +It was soon found that nitro-glycerine added in quantities, even equal +in weight to the gun-cotton itself, did not materially increase the +rapidity of the explosion of the compound. And it was also found that +high grade gun-cotton, when combined with nitro-glycerine, gave very +much better results than low grade gun-cotton. + +I have spoken here of high and low grade gun-cotton, when in fact the +word gun-cotton should be applied only to the highest nitro-compound of +cellulose. The word gun cotton has always been rather loosely used. +Pyroxyline would be a better word, as this applies to all grades. When +cotton fiber is soaked in a large excess of a mixture of the strongest +nitric and sulphuric acids, gun-cotton proper, or that of the highest +grade, is produced. When weaker acids are used, lower grades of +nitro-cellulose are formed. + +The first mentioned or highest grade gun-cotton, when thoroughly freed +from its acids, has always proved to be a perfectly stable compound. The +lower grades have always been found to be unstable and subject to +spontaneous decomposition. Nitro-glycerine has also been erroneously +thought to be a very unstable compound. But experiments have proved +that, when made pure, it is perfectly stable. + +Having now explained how the knowledge came to be arrived at that the +aforementioned compound of highest grade nitro-glycerine and highest +grade gun-cotton would constitute the best basis for a smokeless powder, +I will now mention a few of the other conditions necessary to success +with its use, without assuming that smokeless powder has yet passed its +experimental stage, and is beyond further improvement. Nevertheless, +such is the compound which has come to stay as the basis of all +smokeless powders; and any smokeless powder, if a successful one, may be +counted upon as being made of this compound of gun-cotton and +nitro-glycerine, or of a colloid of gun-cotton, either alone or combined +with diluents, oxygen-bearing salts, or inert matter. The fact that +smokeless powder may still be said to be in somewhat of an experimental +stage is not to admit that it is not a success. Firearms, cartridge +cases, and projectiles are also still in an experimental stage, for they +are constantly being improved; yet their use has been a great success +for a good many years. + +The question of success of a smokeless powder does not rest alone with +the powder itself. The gun, the cartridge case, primer, and bullet have +been as much the subjects of experiments in adapting them to the use of +smokeless powder as has the smokeless powder in being adapted to them. +To impart a velocity of 2,000 feet per second to a rifle ball, with +corresponding long range and accuracy of flight, has been a question as +much of improvement in rifles and projectiles as in the powder. To give +a velocity of 2,000 feet per second to a bullet, requires a pressure of +at least 15 English tons in the chamber of a gun. This would be a +dangerous pressure in an old-fashioned shoulder arm; while a bullet made +only of lead would strip on striking the rifling and pass right through +the barrel of the gun without taking any rotary motion whatever. It +might at first seem that the powder is the only thing to be considered; +but high ballistics can only be obtained when everything else is adapted +to its use. + +The projectile, the cartridge case, the fulminating cap, and the gun +have had to be all built up together, and a very large amount of +experimenting has been necessary to determine what would constitute the +best projectile, best cartridge case, best fulminating cap, and what +should be the character of the rifling and the quality and temper of the +steel of the gun barrel. + +It has been necessary first to conduct experiments to test the smokeless +powders for velocities and pressures, and then with the powders test +various kinds of projectiles and guns. In order to obtain the high +ballistics which have been secured, it has been found necessary to cover +the bullet with something harder than lead and to rifle the gun in a +special manner. + +The French, who were the first to definitely adopt smokeless powder, +were the first also to make a rifle, projectile, cartridge case and +primer suited to its use. + +To obtain long range with a small long bullet such as is now used, it +should rotate at a very high speed. It is well known to artillerists +that a projectile of four or more calibers in length has to be rotated +at a much higher speed than one of half that length, in order to keep +the projectile stiff in the air, and to prevent it from ending over in +its flight. To communicate this very high rotary movement to the bullet +in the instant of time during which it is passing through the barrel, +the rifling of the gun has to exert an enormous torsion on the bullet. +Lead, no matter how hardened, is not sufficiently strong, as it will not +only strip and pass straight through the gun without taking any rotary +movement whatever, but under such very high pressures it behaves like +wax, and is thrown from the gun in a distorted mass. + +The French cover their bullets with German silver, a substance made of +nickel, zinc and copper; and in order to put as little strain upon the +rifling and projectile as possible, the rifling of the gun is made with +an increasing twist, and has no sharp edges. The French rifle is made +very strong at the breech and is of tempered steel throughout. In this +way the French have made smokeless powder a success--a smokeless powder +made substantially of a character such as I have herein described. With +smokeless powder, the French rifle imparts a muzzle velocity of 2,000 +feet per second to the bullet, with a range of about 2,400 meters. + +If smokeless powder be divided into sufficiently small grains to be +ignited by an ordinary fulminating cap, it would burn too quickly, +thereby causing the pressure to mount too high, and without giving the +desired velocity. Consequently very large and strong fulminating caps +have to be employed. Smokeless powder is not ignited in the same manner +as black powder. Something besides ignition is necessary. Black powder +simply requires to be set on fire; while a smokeless powder, on the +contrary, not only requires that it be set on fire, but that a certain +degree of pressure be set up inside of the cartridge case. For instance, +if a primer of a certain size should be found to operate perfectly well, +giving prompt ignition in the cartridge case of a rifle of small +caliber, it would be found that the same primer would not ignite a +charge of the same powder if loaded into a gun of one inch caliber. In +the latter case a few grains only lying near the primer would be +ignited, and these would soon become extinguished by sudden release of +pressure bringing about a cooling effect due to expansion of the gases. +In small cartridges a large fulminating cap is all that is required, but +in large cartridges it is necessary to resort to additional means of +ignition. + +In France, where experiments were conducted with a 37 millimeter Maxim +gun, it was found to be impracticable to use a fulminating cap +sufficiently large to ignite the powder and cause it to burn. Therefore, +a small ignition charge of black powder was employed, it being put in a +capsule or bag and placed next the primer. On firing at the rate of 300 +rounds per minute, the black powder, though small in quantity, produced +a cloud of smoke through which it was quite impossible to see. The +inventor of the gun then prepared for the French some wafers of +pyroxyline canvas, which were placed next to the primer, securing +thereby prompt ignition without the production of any smoke. + +Smokeless powder, made as I have described, cannot be detonated by a +fulminating cap of any size or by any means whatever. A large charge of +fulminate of mercury placed inside the cartridge case next the primer +will not detonate the powder, it serving only to ignite it and cause it +to explode. But even this would not cause the powder to explode except +it be confined behind a projectile, that sufficient pressure may be run +up to make it burn in its own gases. + +Some curious experiments with smokeless powder may be tried with a shot +gun. If the fulminating cap be large, the powder fine, the wads numerous +and hard and the charge of shot heavy, all being well rammed down, and +the paper case well spun over the last pasteboard wad, a charge of +smokeless powder about equal in weight to one-half of what would be +employed of black powder would give about the same results as black +powder. But if the charge of shot be omitted, the primer will only +ignite the powder, and there will be set up sufficient pressure merely +to throw the wads about half way up the barrel of the gun, when the +powder will go out. Now if this same charge of powder be collected and +reloaded into a new cartridge case and well confined behind wads and a +charge of shot, as above explained, it will all burn, giving the same +results as black powder. + +Attempts have been made to use this powder in pistols and revolvers, but +here it has proved a failure, as the pressure is not great enough to +cause the powder to be consumed, unless it be in the form of very fine +grains or dust, in which case the pressure mounts too high. However, +this might be overcome to a degree by making the powder porous. The +chemical conditions of the powder might be the same, but the physical +conditions must be different. A powder suitable for shot guns and +pistols would not be suitable for rifles. + +One not familiar with the characteristics of smokeless powder would be +almost certain to fail in his first attempt to fire it. Many persons +have been convinced by their first experiments that this powder would +not burn at all in a gun, any more than so much sand. + +Smokeless powder is consumed with a rapidity which accords with the +conditions of its confinement. Therefore, the bullets which have been +experimented with by different governments have been the cause of much +of the varying pressures attributed to the smokeless powders. + +The Austrians use the Mannlicher steel jacketed bullet. The steel casing +or jacket is first tinned on the inside and then the lead is cast in, +thus melting the tin and adhering firmly to the jacket. This projectile +sets up enormous friction in the barrel of the gun when used with +smokeless powder; as the smokeless powder leaves the gun barrel +perfectly clean and the two steel surfaces being in absolute contact +cause tremendous friction; and as the coefficient of friction varies +with every shot, the pressure in the gun constantly varies greatly. + +The German silver covered bullet used by the French has the disadvantage +that when firing rapidly the chamber of the barrel becomes nickel plated +and great friction is caused, mounting up the pressures and causing the +muzzle velocities to fall off. + +The Austrians, in order to prevent their steel cased bullets from +rusting and to lessen the friction in the barrel of the gun, cover them +with a heavy lubricant, which gives the cartridges an unsightly +appearance and causes them to gather dust and sand. The French employ a +lubricant at the base of the projectile, with a small copper disk +between the same and the powder. + +Col. A.R. Buffington, commander of the National Armory at Springfield, +Mass., has made a steel covered projectile which he prevents from +rusting by blackening by a niter process. Several grooves are pressed in +the base of the bullet which carry a lubricant, and when the bullet is +inserted in the cartridge case the grooves are covered by it. +Furthermore, these grooves prevent the lead filling from bursting +through the steel casing, leaving the latter in the barrel, as often +occurs with the Austrian and French projectiles when using smokeless +powder. + +A new projectile has lately come out, the invention of Captain Edward +Palliser, of the British army. This bullet consists of a jacket made of +very soft Swedish wrought iron, coated with zinc and filled with lead, +the lead being pressed into this jacket. The bullet is corrugated at its +base, after the manner of the one made by Colonel Buffington. This +projectile has been experimented with very extensively by the British +government, and at the works of the Maxim-Nordenfelt Guns and Ammunition +Company, in England. The zinc coating of the bullet is too soft to stick +to the barrel of the gun, and also in a measure acts as a lubricant. +This projectile has given better results than any other that has been +experimented with. The great velocities and the most uniform pressures +by the use of smokeless powder have been attained with this Palliser +bullet. + + +NOISELESSNESS. + +A great many stories have been told about the noiselessness of smokeless +powder. But there is no such thing as a noiseless gunpowder. The report +of a gun charged with smokeless powder is very sharp, and is as loud as +when black powder is used, yet the volume of sound is much less, so that +the report cannot be heard at so great a distance. + +The report of a gun using smokeless powder is a sound of much higher +pitch than when black powder is used, and consequently cannot be heard +at so great a distance as the lower notes given by black powder. + +As smokeless powder exerts a much greater pressure than common black +powder when burned in a gun, one would naturally think that the recoil +of the barrel would be greater, owing to the greater pressure exerted by +the smokeless powder on the base of the cartridge case and the breech +mechanism. However, such is not the fact; for the barrel actually +recoils very much less when smokeless powder is used. This is due to the +suddenness with which the pressure is exerted by smokeless powder, it +acting more like a very sharp blow on the metal, whereby more of the +energy is converted into heat instead of being spent in overcoming the +inertia of the barrel to give recoil. Similarly when smokeless powder is +fired in a gun, the displacement of the air is so sudden that the sound +waves do not possess the same amplitude of recoil or vibration as is +given by black powder. + + * * * * * + + + + +THE CONSTRUCTION AND MAINTENANCE OF UNDERGROUND CIRCUITS. + +BY S.B. FOWLER. + + +The numerous disastrous storms of the last winter have brought out very +vividly the advantages of having all wires placed underground, and many +inquiries have been addressed to the companies operating underground +circuits as to their success. It is not probable that all of the answers +to these inquiries have been of the most favorable character. To many +central station managers an underground system means frequent +break-downs and interruptions of service, with, perhaps, slow and +expensive repairs, which bring in their turn numerous complaints, loss +of customers, and reduced profits. In many installations burn-outs both +underground and in the station are frequent, with the natural result +that the operating of circuits underground is not there considered an +unqualified success. The writer has in mind two very different +experiences with underground cables. Several miles of cable were bought +by a certain company, carefully laid, and up to to-day not a single +burn-out or interruption of service can be attributed to failure of +cables; at about the same time another company bought about an equal +amount of the same kind of cable, and in a comparatively short time the +current had to be shut off the lines and the whole installation repaired +and parts of it replaced. Both of these experiences have been repeated +many times and will be again, although it is simply a distinction +between a good cable properly laid and a good cable ruined by careless +and incompetent workmanship. + +Every failure can be traced to poor work in the original installation or +to the use of a cheap cable, both causes being due, generally, to that +false economy which looks for too quick returns. A poorly insulated line +wire and a poorly insulated cable are two very different things. +However, it is a fact that by the use of a good cable it is not +difficult to construct an underground system for light, power, telegraph +or telephone uses that will be superior to overhead lines in its service +and in cost of maintenance. The ideal underground system must have as a +starting point a system of subways admitting of the easy drawing in and +out of cables and affording means of making subsidiary connections +readily and with the minimum of expense and interruption of service. +This is practically accomplished by a subway consisting of lines of pipe +terminating at convenient intervals, say at street intersections, in +manholes, for convenience in jointing and in running out house +connections. These pipes, or ducts, as they are called, should be for +two kinds of service; the lower or deeper laid lines for the main or +trunk circuits, and a second series of ducts laid nearer the surface, +running into service boxes placed near together for lines to "house to +house" connections. In some cities where it is allowed to run overhead +lines, the plan of running but one service connection in a block is +followed, all customers in the block being supplied from a line run over +the housetops or strung on the rear walls. + +This makes unnecessary all subsidiary ducts except a short one from the +manhole to the nearest building in the block, and effects a considerable +saving in pipe, service boxes, cables and labor. The manholes should +have their walls built up of brick, the floors should be of concrete, +and there should be an inside lid which can be fastened down and the +manhole thus made water-tight. + +For ducts wood, iron or cement lined pipe may be used. To preserve the +wood it is generally treated with creosote, which, in contact with the +lead cover of the cable, sets up a chemical action, resulting in the +destruction of the lead. Wood offers but little protection for the +cable, as it is too easily damaged and broken through in the frequent +street openings made by companies operating lines of pipe in the +streets, and as one of the main purposes of a subway is that of a +protection to cables, wooden ducts have little to recommend them except +their cheapness. + +Iron pipes are either laid in trenches filled in with earth or are laid +in cement. Iron pipe will of course rust out in time, and if absolute +permanence in construction is desired, should be laid in cement, for +after the pipe rusts out, the duct of cement is still left. However, if +we are going to the expense of laying in cement, it would be much +preferable to use cement lined pipe, which is not only cheaper than iron +pipe, but makes the most perfect cable conduit, as it affords a +perfectly smooth surface to draw the cable over and give a good duct +edge. + +It is not necessary, however, in small installations of cable, +especially where additional connections will not be of frequent +occurrence, to go to the expense of subways, for cable may be safely +laid in the ground in trenches filled in with earth, or can be inclosed +in a plain wooden box or a wooden box filled with pitch. + +There are, of course, many localities where, if the cable is laid in +contact with the earth, a chemical action would take place which might +result in the destruction of the cable. + +Underground cables are of the following classes: 1. Rubber insulated +cables, insulated with rubber or other homogeneous material. 2. Fibrous +cables, so called from the conductors being covered with some fibrous +material, as cotton or paper, which is saturated with the insulating +material, paraffine, resin oil, or some special compound. Under this +latter head is also included the dry core paper cables. + +The first thing to do is to get the cable drawn into the ducts, and on +the proper accomplishment of this depends to a great extent the success +or failure of the whole installation. Probably the ducts have been wired +when the subway was constructed, but if not a wire must be run through +as a means of pulling in the draw rope. There are several kinds of +apparatus for getting a wire through a duct--rods, flexible tapes, +mechanical "creepers," etc.; but probably the best is the sectional rod. +This simply consists of three or four foot lengths of hard wood rods, +having metal tips that screw into each other. A rod is placed in a duct +at a manhole, one screwed to that, both are pushed forward, another one +added and pushed forward, and so on until they extend the entire length +of the duct. Then the wire is attached and the rods are pulled out and +detached one at a time and with the last rod the wire is through. At +least No. 14 galvanized iron or steel wire should be used, for any +smaller size cannot be used a second time, as a rule. In starting to +pull in the draw rope a wire brush should be attached to the wire and to +this again the rope, and when the brush arrives at the distant end of +the duct it very likely will bring with it a miscellaneous collection of +material which for the good of the cable had better be in the manhole +than in the duct. + +The reel or drum carrying the cable should be mounted on wheels or jacks +and placed on the same side of the manhole as the duct into which the +cable is to be drawn, and must always be so placed that the cable will +run off the top of the reel. + +There are several methods of attaching the draw rope to the cable. As +simple and strong a method as any is to punch two of these holes through +the cable, lead and all, and attach the rope by means of an iron +wire--some of the draw wire will do--run through these holes. Depending +on the length and weight of cable to be pulled it can be drawn either by +hand or by a multiplying winch. The rope should run through a block +fastened in the manhole in such a position that the rope shall have a +good straightaway lead from the mouth of the duct. + +The strain on the cable should be perfectly uniform and steady; if the +power is applied by a series of jerks either the lead covering may be +pulled apart or some of the conductors broken. At the reel there must +always be a large enough number of men to turn it and keep the cable +from rubbing on anything, and in the manhole one or more men to see that +the cable feeds into the duct straight and to guide it if necessary. If +the ducts are of iron and are not perfectly smooth at the ends, these +should be made so with a file, and in addition a protector of some sort +should be placed in the mouths of the duct, both above and below the +cable. Six inches of lead pipe, split lengthwise and bent over at one +end to prevent being drawn into the duct with the cable, makes a very +good protector. The cable should be reeled off the drum just fast enough +to prevent any of the power used in pulling the cable through the duct +being utilized in unreeling it. If this latter is allowed to occur the +cable will be bent too short and the lead covering buckled or broken, +and also the cable may be jammed against the upper edge of the duct and +perhaps cut through. + +If the reel is allowed to turn faster than the cable is drawn in, the +first three or four turns on the reel will slacken up, and the lead +covering may either be dented or cut through by scraping on the ground. +If the cable end when pulled through up to the block is not long enough +to bend around the hole more than half way, the rope should be +unfastened from its end, a length of rope with a well frayed out end +should be run through the block, and by fastening to the cable close to +the duct, with a series of half hitches, as much slack as necessary can +be pulled in. If this is properly manipulated there need not be a +scratch on the cable, but unless great care is taken the lead may be +pressed up into ridges and the core itself damaged. + +Immediately after the cable is drawn in, if the joint is not to be at +once made, the open end or ends should be cut off and the cable soldered +up, as most cables are very susceptible to moisture and readily absorb +water even from the atmosphere. Where practicable it is always a good +plan to pull the cable through as many manholes as possible without +cutting the cable; for the joint is, especially in telephone or +telegraph cables, the weak point. To do this the rope should be pulled +through the proper duct in the next section without unfastening it from +the cable; the winch should be moved to the next manhole, and pulling +through then done as before. There should always be a man in every hole +through which the cable is running to see that it does not bind anywhere +and to keep protectors around the cable. + +It is not advisable to pull more than one cable into a duct, and never +advisable to pull a cable into a duct containing another cable, but if +two or more cables have to go into the same duct, they should always be +drawn in together. Lead covered cables and those with no lead on the +outside should never be pulled into the same duct, for if they bind +anywhere the soft cable will suffer where two lead covered cables would +get through all right. Some manufacturers are now putting on their +cables a tape or braid covering, which saves the lead many bad bruises +and cuts, and is a valuable addition to a cable at very little +additional expense. + +Practically all electric light and power cables are either single or +double conductors, and the jointing of these is comparatively a simple +matter, although requiring considerable care. The lead is cut back from +each end about four or five inches, and the conductors bared of +insulation for two or three inches. The bare conductors should be +thoroughly tinned by dipping in the metal pot or pouring the melted +solder over them. A sperm candle is better than resin or acid for any +part of the operations where solder is used. A lead sleeve is here +slipped back over the cable, out of the way, and the ends of the +conductors brought together in a copper sleeve which is then sweated to +a firm joint. This part must be as good a piece of work mechanically as +electrically. The bare splice is then wrapped tightly with cotton or +silk tape to a thickness slightly greater than that of the insulation of +the cable, and is thoroughly saturated with the insulating compound +until all moisture previously absorbed by the tape is driven off. + +The lead sleeve is then brought over the splice and wiped to the cable. +The joint is then filled with the insulating compound poured through +holes in the top of the sleeve; these holes are then closed and the +joint is complete, and there is no reason why, in light and power +cables, that joint should not be as perfect as any other part of the +cable. When the cable ends are prepared for jointing they should be hung +up in such a position that they are in the same plane, both horizontal +and vertically, and firmly secured there, so that when the lead sleeve +is wiped on the conductor may be in its exact center, and great care +must be taken not to move the cables again until the sleeve is filled +and the insulation sufficiently cooled to hold the conductor in +position. + +It is also very important to see that there are no sharp points on the +conductors themselves, on the copper sleeve, on the edges of the lead +covering or on the lead sleeve. All these should be made perfectly +smooth, for points facilitate disruptive discharges. Branch joints had +better be made as T-joints rather than as Y-joints, for they are better +electrically and mechanically, although they occupy more room in the +manholes. They are of course made in the same way as straight joints, a +lead T-sleeve being used, however. For multiple arc circuits copper +T-sleeves and for series circuits copper L-sleeves are used. + +Telephone and telegraph cables are made of any required gauge of wire +and with from 1 to 150 conductors in a cable. In jointing these the +splices are never soldered, the conductors being joined either with a +twist joint or with the so-called Western Union splice. Each splice is +covered with a cotton or silk sleeve or a wrapping of tape, the latter +being preferable, although considerably increasing the time necessary +for making the joint. Great care must be taken that no ends of wire are +left sticking up, for they will surely work their way through the tape +and grounds, and crosses will be the result. The wires should always be +joined layer to layer and each splice very tightly taped in order to get +as much insulating compound around each splice as possible in the +limited space. The splices should be "broken" as much as possible, so as +to avoid having adjoining splices coming over each other. After the +joint has been saturated with insulating compound the wires should have +an outside wrapping of tape to keep them in shape, and then the sleeve +is wiped on and filled. If the insulation resistance of the jointed +telegraph or telephone cable is a quarter of what the cable tested in +the factory, it may be considered that an exceptionally good piece of +work has been done. I have spoken more particularly of fibrous lead +covered cables, as the handling of them includes practically every step +of the work on any other kind of underground cable. In insulating dry +core paper cables a paper sleeve is slipped over the splice, and in +rubber cables the splice is wrapped with rubber tape; all other details +are the same for these as for the fibrous cable. + +In the laying of light and power cables every joint, as made, should be +tested for insulation with a Thomson galvanometer, as the insulation +must necessarily be very high, and if one joint or section of cable is +any weaker than another it may be very important in the future to know +it. All tests must be made after the joint has cooled, for while hot its +insulation resistance will be very low. + +Tests for copper resistance should also be made to determine if the +splices are electrically perfect; an imperfect splice may cause +considerable trouble. In telegraph and telephone cables the conductors +should be of very soft copper, for in stripping the conductor of +insulation it is very easy to nick the wire, and if of hard drawn copper +open wires will be the result. + +All work should be frequently tested for continuity with telephones, +magnetos, or small portable galvanometers. It is only necessary to +ground the conductors at one end and try each wire at the other end. For +this sort of work a telephone receiver used with one cell of some dry +battery is most convenient, and has the additional advantage of +affording a means of communication while testing, and is by far the best +thing for identifying and tagging conductors. + +These cables should be frequently tested during the progress of the work +for grounds and crosses with a Thomson instrument, and when the cable is +complete, a careful series of tests of the capacity, insulation +resistance, and copper resistance of each wire should be made and the +exact condition of the cable determined before it is put in service, and +thereafter an intelligent oversight of the condition of the circuits +can thus be more readily maintained. + +Where a company has extensive underground service, a regular cable gang +should be in its employ, for quick and safe handling of cables demands +the employment of men accustomed to the work. If the cable has been +properly laid and tests show it to be in good condition before current +is turned on, almost the only trouble to be anticipated will be due to +mechanical injury. Disruptive discharge, puncturing the lead, may occur; +but the small chance of its occurring can be greatly lessened by the use +of some kind of "cable protector," which will provide for the spark an +artificial path of less resistance than the dielectric of the condenser, +which the cable in fact becomes. + +If a fault suddenly develops on a circuit, the chances are it will be +found in a manhole, and an inspection of the cable in the manhole will +generally reveal the trouble without resorting to locating with a +Wheatstone bridge. The cable is often cut through at the edge of the +duct, or damaged by something falling on it, or by some one "walking all +over it." To guard against these, the ducts should always be fitted with +protectors both above and below the cable. The cables should never be +left across the manholes, for they then answer the purpose of a ladder, +but should be bent, around the walls of the hole and securely fastened +with lead straps, that they may not be moved and the lead gradually worn +through. + +In telegraph cables, when one or two conductors "go," it will probably +be useless to look for trouble except with instruments; but if several +wires are "lost" at once it will probably be found to be caused by +mechanical injury, which can be located by inspection. If it is ever +necessary to loop out conductors, a joint can be readily opened and the +conductors wanted picked out and connected into the branch cable and the +joint again closed without disturbing the working wires. In doing this a +split sleeve must be used, and the only additional precaution to be +taken is in filling the sleeve to have the insulating compound not hot +enough to melt the solder and open up the split in the sleeve. In +cutting in service on light and power cables it is entirely practicable +to do so without interruption of service on multiple arc circuits, even +those of very high voltage; but they require great precaution and +involve considerable risk to the jointer, and where possible the circuit +to which the connection is to be made should previously be cut dead. +Where the voltage is not dangerous to human life, almost any service +connection can be made without interruption of service. + +I have only indicated a very few of the operations that may be found +necessary, and the probable causes of troubles that may be encountered +in the operating of underground circuits, believing that the different +problems that arise can, with a little experience, be successfully met +by any one who has a fair knowledge of the original construction of +cable lines.--_Electrical World_. + + * * * * * + + + + +RAILROADS TO THE CLOUDS. + + +If George Stephenson, when he placed the first locomotive on the track +and guaranteed it a speed of six miles an hour, could have foreseen that +in less than eighty years the successors of his rude machine would be +climbing the sides of mountain ranges, piercing gorges hitherto deemed +inaccessible, crossing ravines on bridges higher than the dome of St. +Paul's, and traversing the bowels of the earth by means of tunnels, no +doubt his big blue eyes would have stood out with wonder and amazement. +But he foresaw nothing of the kind; the only problem present in his mind +was how to get goods from the seaports in western England to London as +easily and cheaply as possible, and to do this he substituted for +horses, which had for 150 years been drawing cars along wooden or iron +tracks, the wonderful machine which has revolutionized the freight and +passenger traffic of the world. + +It was, indeed, impossible for any one to foresee the triumphs of +engineering which have accompanied the advances in transportation. To +the engineer of the present day there are no impossibilities. The +engineer is a wizard at whose command space and matter are annihilated. +The highest mountain, the deepest valley, has no terrors for him. He can +bridge the latter and encircle or tunnel the former. The only requisites +which he demands are that something in his line be needed, and that the +money is forthcoming to defray the expense, and the thing will be done. +But the railroad he is asked to construct must be necessary, and the +necessity must be plainly shown, or no funds will be advanced; and +although the theory does not invariably hold good, especially when a +craze for railroad building is raging, as a rule no expense for the +construction of a road will be incurred without a prospect of +remuneration. + +Hence the need of railroad communication has caused lines to be +constructed through districts where only a few years ago the thing would +have been deemed impossible. The Pacific roads of this country were a +necessity long before their construction, and in the face of +difficulties almost insuperable were carried to successful completion. +So, also, of the railroads in the Andes of South America. The famous +road from Callao through the heart of Peru is one of the highest +mountain roads in the world, as well as of the most difficult +construction. The grades are often of 300 feet and more to the mile, and +when the mountains were reached so great were the difficulties the +engineers were forced to confront that in some places laborers were +lowered from cliffs by ropes in order that, with toil and difficulty, +they might carve a foothold in order to begin the cutting for the +roadway. + +In some sections tunnels are more numerous than open cuts, and so far as +the road has gone sixty-one tunnels, great and small, have been +constructed, aggregating over 20,000 feet in length. The road attains a +height of 15,000 feet above the level of the sea, and at the highest +point of the track is about as high as the topmost peak of Mont Blanc. +It pierces the range above it by a tunnel 3,847 feet long. The stern +necessities of business compelled the construction of this road, +otherwise it never would have been begun. + +The tunnels of the Andes, however, do not bear comparison with the +tunnels, bridges, and snow sheds of the Union Pacific, nor do even these +compare with the vast undertakings in the Alps--three great tunnels of +nine to eleven miles in length, which have been prepared for the +transit of travelers and freight. The requirements of business +necessitated the piercing of the Alps, and as soon as the necessity was +shown, funds in abundance were forthcoming for the enterprise. + +But tunneling a mountain is a different thing from climbing it. Many +years ago the attention of inventors was directed to the practicability +of constructing a railroad up the side of a mountain on grades which, to +an ordinary engine, were quite impossible. The improvements in +locomotives twenty-five and thirty years ago rendered them capable of +climbing grades which, in the early days of railroad engineering, were +deemed out of the question. The improvements proved a serious stumbling +block in the way of the inventors, who found that an ordinary locomotive +was able to climb a much steeper grade than was commonly supposed. The +first railroads were laid almost level, but it was soon discovered that +a grade of a few feet to the mile was no impediment to progress, and +gradually the grade was steepened. + +The inventors of mountain railroad transportation might have been +discouraged by this discovery, but it is a characteristic of an inventor +that he is not set back by opposition, which, in fact, only serves to +stimulate his zeal. The projectors of inclined roads and mountain +engines kept steadily on, and in France, Germany, England, and the +United States many experimental roads were constructed, each of a few +hundred yards in length, and locomotive models were built and put in +motion to the amazement of the general public, who jeered alike at the +contrivances and the contrivers, deeming the former impracticable and +the latter crazy. + +But the idea of building a road up the side of a hill was not to be +dismissed. There was money in it for the successful man, so the cranky +inventors kept on at work in spite of the jeers of the rabble and the +discouragements of capitalists loath to invest their money in an +uncertain scheme. To the energy and perseverance of railroad inventors +the success of the mountain railroad is due, as also is the construction +of the various mountain roads, of which the road up Mt. Washington, +finished in 1868, was the first, and the road up Pike's Peak, completed +the other day, was the latest. + +Of all the mountain roads which have been constructed since the one up +Mt. Washington was finished, the best known is that which ascends the +world-famous Rigi. With the exception of Mont Blanc, Rigi is, perhaps, +the best known of any peak in the Alps, though it is by no means the +highest, its summit being but 5,905 feet above the level of the sea. +Although scarcely more than a third of the height of some other +mountains in the Alps, it seems much higher because of its isolated +position. Standing as it does between lakes Lucerne, Zug, and Lowertz, +it commands a series of fine views in every direction, and he who looks +from the summit of Rigi, if he does no other traveling in Switzerland, +can gain a fair idea of the Swiss mountain scenery. Many of the most +noted peaks are in sight, and from the Rigi can be seen the three lakes +beneath, the villages which here and there dot the shores, and, further +on, the mighty Alps, with their glaciers and eternal snows. + +Many years ago a hotel was built on the summit of the Rigi for the +benefit of the tourists who daily flocked to this remarkable peak to +enjoy the benefit of its wonderful scenery. The mountain is densely +wooded save where the trees have been cut away to clear the land for +pastures. The ease of its ascent by the six or eight mule paths which +had been made, the gradual and almost regular slope, and the throngs of +travelers who resorted to it, made it a favorable place for an +experiment, and to Rigi went the engineers in order to ascertain the +practicability of such a road. The credit of the designs is due to a +German engineer named Regenbach, who, about the year 1861, designed the +idea of a mountain road, and drew up plans not only for the bed but also +for the engine and cars. The scheme dragged. Capitalists were slow to +invest their money in what they deemed a wild and impracticable +undertaking, and even the owners of the land on the Rigi were reluctant +for such an experiment to be tried. But Regenbach persevered, and toward +the close of the decade the inhabitants of Vitznau, at the base of the +Rigi, were astonished to see gangs of laborers begin the work of making +a clearing through the forests on the mountain slope. They inquired what +it meant, and were told that a road up the Rigi was to be made. The +Vitznauers were delighted, for they had no roads, and there was not a +wheeled vehicle in the town, nor a highway by which it could be brought +thither. The idea of a railroad in their desolate mountain region, and, +above all, a railroad up the Rigi, never entered their heads, and a +report which some time after obtained currency in the town, that the +laborers were beginning the construction of a railroad, was greeted with +a shout of derision. + +Nevertheless, that was the beginning of the Rigi line, and in May, 1871, +the road was opened for traffic. It begins at Vitznau, on Lake Lucerne, +and extends to the border of the canton and almost to the top of the +mountain. It is 19,000 feet long, and during that distance rises 4,000 +feet at an average grade of 1 foot in 4. Though steep, it is by no means +so much so as the Mt. Washington road, which rises 5,285 feet above the +sea, at an average of 1 foot in 3. There are, however, stretches of the +Rigi road at which the grade is about 1 foot in 21/2, which is believed to +be the steepest in the world. + +The Rigi road has several special features aside from its terrific +slopes which entitle it to be considered a triumph of the engineer's +skill. About midway up the mountains the builders came to a solid mass +of rock, which presented a barrier that to a surface road was +impassable. They determined to tunnel it, and, after an enormous +expenditure of labor, finished an inclined tunnel 225 feet in length, of +the same gradient as the road. A gorge in the side of the mountain where +a small stream, the Schnurtobel, had cut itself a passage also hindered +their way, and was crossed by a bridge of lattice girder work in three +spans, each 85 feet long. The entire roadbed, from beginning to end, was +cut in the solid rock. A channel was chiseled out to admit the central +beam, which contains the cogs fitting the driving wheel of the +locomotive. The engine is in the rear of the train, and presents the +exceedingly curious feature of a boiler greatly inclined, in order that +at the steeper gradients it may remain almost perpendicular. The coal +and water are contained in boxes over the driving wheels, so that all +the weight of the engine is really concentrated on the cogs--a +precaution to prevent their slipping. The cost of the road, including +three of these strangely constructed locomotives, three passenger +coaches, and three open wagons, was $260,000, and it is a good paying +investment. The fare demanded for the trip up the mountains is 5 francs, +while half that sum is required for the downward passage, and the road +is annually traversed by from 30,000 to 50,000 passengers. + +Curious sensations are produced by a ride up this remarkable line. The +seats of the cars are inclined like the boiler of the locomotive, and so +long as the cars are on a level the seats tilt at an angle which renders +it almost impossible to use them. But when the start is made the +frightful tilt places the body in an upright position, and, with the +engine in the rear, the train starts up the hill with an easy, gliding +motion, passing up the ascent, somewhat steeper than the roof of a +house, without the slightest apparent effort. But if the going up +excites tremor, much more peculiar are the feelings aroused on the down +grade. The trip begins with a gentle descent, and all at once the +traveler looking ahead sees the road apparently come an end. On a nearer +approach he is undeceived and observes before him a long decline which +appears too steep even to walk down. Involuntarily he catches at the +seats, expecting a great acceleration of speed. Very nervous are his +feelings as the train approaches this terrible slope, but on coming to +the incline the engine dips and goes on not a whit faster than before +and not more rapidly on the down than on the up grade. Many people are +made sick by the sensation of falling experienced on the down run. Some +faint, and a few years ago one traveler, supposed to be afflicted with +heart disease, died of fright when the train was going over the +Schnurtobel bridge. The danger is really very slight, there not having +been a serious accident since the road was opened. The attendants are +watchful, the brakes are strong, but even with all these safeguards, men +of the steadiest nerves cannot help wondering what would become of them +in case anything went wrong. + +Bold as was the project of a railroad on the Rigi, a still bolder scheme +was broached ten years later, when a daring genius proposed a railroad +up Mt. Vesuvius. A railroad up the side of an ordinary mountain seemed +hazardous enough, but to build a line on the slope of a volcano, which +in its eruption had buried cities, and every few years was subject to a +violent spasm, seemed as hazardous as to trust the rails of an ordinary +line to the rotten river ice in spring time. The proposal was not, +however, so impracticable as it looked. While the summit of Vesuvius +changes from time to time from the frequent eruptions, and varies in +height and in the size of the crater, the general slope and contour of +the mountain are about the same to-day as when Vesuvius, a wooded hill, +with a valley and lake in the center of its quiescent crater, served as +the stronghold of Spartacus and his rebel gladiators. There have been +scores of eruptions since that in which Herculaneum and Pompeii were +overthrown, but the sides of the mountain have never been seriously +disturbed. + +A road on Vesuvius gave promise of being a good speculation. Naples and +the other resorts of the neighborhood annually attracted many thousands +of visitors, and a considerable number of these every year ascended the +volcano, even when forced to contend with all the difficulties of the +way. Many, however, desiring to ascend, but being unable or unwilling to +walk up, a chair service was established--a peculiar chair being slung +on poles and borne by porters. In course of time the chair service +proved to be inadequate for the numbers who desired to make the ascent, +and the time was deemed fit for the establishment of more speedy +communication. + +Notwithstanding the necessity, the proposal to establish a railroad met +with general derision, but the scheme was soon shown to be perfectly +practicable, and a beginning was made in 1879. The road is what is known +as a cable road, there being a single sleeper with three rails, one on +the top which really bore the weight, and one on each side near the +bottom, which supported the wheels, which coming out from the axle at a +sharp angle, prevented the vehicle from being overturned. The road +covers the last 4,000 feet of the ascent, and the power house is at the +bottom, a steel cable running up, passing round a wheel at the top and +returning to the engine in the power house. The ascent to the lower +terminus of the road is made on mules or donkeys; then, in a comfortable +car, the traveler is carried to a point not far from the crater. The car +is a combined grip and a passenger car, similar in some points to the +grip car of the present day, while the seats of the passenger portion +are inclined as in the cars on the Rigi road. But the angle of the road +being from thirty-three to forty-five degrees, makes both ascent and +descent seem fearfully perilous. Every precaution, however, is taken to +insure the safety of passengers; each car is provided with several +strong and independent brakes, and thus far no accident worth recording +has occurred. The road was opened in June, 1880. Although there have +been several considerable eruptions since that date, none of them did +any damage to the line but what was repaired in a few hours. + +The fashion thus set will, no doubt, be followed in many other quarters. +Wherever there is sufficient travel to pay working expenses and a profit +on a steep grade mountain road it will probably be built. Already there +is talk of a road on Mont Blanc, of another up the Yungfrau, and several +have been projected in the Schwartz and Hartz mountains. A route on Ben +Nevis, in Scotland, is already surveyed, and it is said surveys have +also been made up Snowden, with a view to the establishment of a road to +the summit of the highest Welsh peak. Sufficient travel is all that is +necessary, and when that is guaranteed, whenever a mountain possesses +sufficient interest to induce people to make its ascent in considerable +numbers, means of transportation, safe and speedy, will soon be +provided. The modern engineer is able, willing and ready to build a road +to the top of Mt. Everest in the Himalayas if he is paid for doing +so.--_St. Louis Globe-Democrat._ + + * * * * * + +To clean hair brushes, wash with weak solution of washing soda, rinse +out all the soda, and expose to sun. + + * * * * * + + + + +THE MARCEAU. + + +[Illustration: THE FRENCH ARMORED TURRET SHIP MARCEAU] + +The Marceau, the last ironclad completed and added to the French navy, +was put in commission at Toulon in April last, and has lately left that +town to join the French squadron of the north at Brest. The original +designs of this ship were prepared by M. Huin, of the French Department +of Naval Construction, but since the laying down of the keel in the year +1882 they have been very considerably modified, and many improvements +have been introduced. + +Both ship and engines were constructed by the celebrated French firm, +the Societe des Forges et Chantiers de la Mediterranee, the former at +their shipyard in La Seyne and the latter at their engine works in +Marseilles. The ship was five years in construction on the stocks, was +launched in May, 1887, and not having been put in commission until the +present year, was thus nearly nine years in construction. She is a +barbette belted ship of somewhat similar design to the French ironclads +Magenta, now being completed at the Toulon arsenal, and the Neptune, in +construction at Brest. + +The hull is constructed partly of steel and partly of iron, and has the +principal dimensions as follows. Length, 330 ft. at the water line; +beam, 66 ft. outside the armor; draught, 27 ft. 6 in. aft.; +displacement, 10,430 English or 10,600 French tons. The engines are two +in number, one driving each propeller; they are of the vertical compound +type, and on the speed trials developed 11,300 indicated horse power +under forced and 5,500 indicated horse power under natural draught, the +former giving a speed of 16.2 knots per hour with 90 revolutions per +minute. The boilers are eight in number, of the cylindrical marine type, +and work at a pressure of 85.3 lb. per square inch. During the trials +the steering powers of the ship were found to be excellent, but the bow +wave is said, by one critic, to have been very great. + +The ship is completely belted with Creusot steel armor, which varies in +thickness from 9 in. forward to 173/4 in. midships. In addition to this +belt the ship is protected by an armored deck of 31/2 in., while the +barbette gun towers are protected with 153/4 in. steel armor with a hood +of 21/2 in. to protect the men against machine gun fire. As a further +means of insuring the life of the ship in combat and also against +accidents at sea, the Marceau is divided into 102 water-tight +compartments and is fitted with torpedo defense netting. There are two +masts, each carrying double military tops; and a conning tower is +mounted on each mast, from either of which the ship may be worked in +time of action, and both of which are in telegraphic communication with +the engine rooms and magazines. Provision is made for carrying 600 tons +of coal, which, at a speed of 10 knots, should be sufficient to supply +the boilers for a voyage of 4,000 miles. + +The armament of the Marceau is good for the tonnage of the ship and +consists principally of four guns of 34 centimeters (13.39 in.) of the +French 1884 model, having a weight of 52 tons, a length of 281/2 calibers, +and being able to pierce 30 in. of iron armor at the muzzle. The +projectiles weigh 924 lb., and are fired with a charge of 387 lb. of +powder. The muzzle velocity has been calculated to be 1,968 ft. per +second. The guns are entirely of steel and are mounted on Canet +carriages in four barbette towers, one forward, one aft, and one on each +side amidships. On the firing trials both the guns and all the Canet +machinery, for working the guns and hoisting the ammunition, gave very +great satisfaction to all present at the time. In addition to the above +four heavy guns there are, in the broadside battery, sixteen guns of 14 +centimeters (5.51 in.), eight on each side, and a gun of equal caliber +is mounted right forward on the same deck. The armament is completed by +a large number of Hotchkiss quick-firing and revolver guns and four +torpedo tubes, one forward, one aft, and one on each side. + +The crew of the Marceau has been fixed at 600 men, and the cost is +stated to have been about $3,750,000.--_Engineering_. + + * * * * * + +[Continued from SUPPLEMENT, No. 820, page 13097.] + + + + +A REVIEW OF MARINE ENGINEERING DURING THE PAST DECADE.[1] + +[Footnote 1: Paper read before the Institution of Mechanical Engineers, +July 28, 1891.] + +BY MR. ALFRED BLECHYNDEN, OF BARROW-IN-FURNESS + + +_Steam Pipes_.--The failures of copper steam pipes on board the Elbe, +Lahn, and other vessels have drawn serious attention both to the +material and to the modes of construction of the pipes. The want of +elastic strength in copper is an important element in the matter; and +the three following remedies have been proposed, while still retaining +copper as the material. First, in view of the fact that in the operation +of brazing the copper may be seriously injured, to use solid drawn +tubes. This appears fairly to meet the main dangers incidental to +brazing; but as solid drawn pipes of over 7 inches diameter are +difficult to procure, it hardly meets the case sufficiently. Secondly, +to use electrically deposited tubes. At first much was promised in this +direction; but up to the present time it can hardly be regarded as more +than in the experimental stage. Thirdly, to use the ordinary brazed or +solid drawn tubes, and to re-enforce them by serving with steel cord or +steel or copper wire. This has been tried, and found to answer +perfectly. For economical reasons, as well as for insuring the minimum +of torsion to the material during manufacture, it is important to make +as few bends as possible; but in practice much less difficulty has been +experienced in serving bent pipes in a machine than would have been +expected. Discarding copper, it has been proposed to substitute steel or +iron. In the early days of the higher pressures, Mr. Alexander Taylor +adopted wrought iron for steam pipes. One fitted in the Claremont in +February, 1882, was recently removed from the vessel for experimental +purposes, and was reported upon by Mr. Magnus Sandison in a paper read +before the Northeast Coast Institution of Engineers and Shipbuilders.[2] +The following is a summary of the facts. The pipe was 5 inches external +diameter, and 0.375 inch thick. It was lap welded in the works of +Messrs. A. & J. Stewart. The flanges were screwed on and brazed +externally. The pipe was not lagged or protected in any manner. After +eight and a half years' service the metal measured where cut 0.32 and +0.375 inch in thickness, showing that the wasting during that time had +been very slight. The interior surface of the tube exhibited no signs of +pitting or corrosion. It was covered by a thin crust of black oxide, the +maximum thickness of which did not exceed 1/32 inch. Where the deposit +was thickest it was curiously striated by the action of the steam. On +the scale being removed, the original bloom on the surface of the metal +was exposed. It would thus appear that the danger from corrosion of iron +steam pipes is not borne out in their actual use; and hence so much of +the way is cleared for a stronger and more reliable material than +copper. So far the source of danger seems to be in the weld, which would +be inadmissible in larger pipes; but there is no reason why these should +not be lapped and riveted. There seems, however, a more promising way +out of the difficulty in the Mannesmann steel tubes which are now being +"spun" out of solid bars, so as to form weldless tubes. + +[Footnote 2: Transactions Northeast Coast Institution of Engineers and +Shipbuilders, vol. 7, 1890-91, p. 179.] + +TABLE I.--TENSILE STRENGTH OF GUN METAL AT HIGH TEMPERATURES. + +--------------+------------+-------------+-------------+------------+ + | | | | | + Composition |Temperature | Tensile | Elastic | Elongation | + of | of oil | strength | limit | in | + gun metal. | bath. | per square | per square | length of | + | | inch. | inch. | 2 inches | +--------------+------------+-------------+-------------+------------+ + Per cent. | Fahr. | Tons | Tons | Per cent. | + Copper 87 /| 50 deg. | 12.34 | 8.38 | 14.64 | + Tin 8 / | | | | | + Zinc 31/2 \ | | | | | + Lead 11/2 \| 400 deg. | 10.83 | 6.30 | 11.79 | +--------------+------------+-------------+-------------+------------+ + Copper 87 /| 50 deg. | 13.86 | 8.33 | 20.30 | + Tin 8 { | | | | | + Zinc 5 \| 458 deg. | 10.70 | 7.43 | 12.42 | +--------------+------------+-------------+-------------+------------+ + +Cast steel has been freely used by the writer for bends, junction +pieces, etc., of steam pipes, as well as for steam valve chests; and +except for the fact that steel makers' promises of delivery are +generally better than their performance, the result has thus far been +satisfactory in all respects. These were adopted because there existed +some doubt as to the strength of gun metal under a high temperature; and +as the data respecting its strength appeared of a doubtful character, a +series of careful tests were made to determine the tensile strength of +gun metal when at atmospheric and higher temperatures. The test bars +were all 0.75 in diameter, or 0.4417 square inch sectional area; and +those tested at the higher temperatures were broken while immersed in a +bath of oil at the temperature here stated, each line being the mean of +four experiments. The result of these experiments was to give somewhat +greater faith in gun metal as a material to be used under a higher +temperature; but as steel is much stronger, it is probably the most +advisable material to use, when the time necessary to procure it can be +allowed. + +_Feed Heating_.--With the double object of obviating strain on the +boiler through the introduction of the feed water at a low temperature, +and also of securing a greater economy of fuel, the principle of +previously heating the feed water by auxiliary means has received +considerable attention, and the ingenious method introduced by Mr. James +Weir has been widely adopted. It is founded on the fact that, if the +feed water as it is drawn from the hot well be raised in temperature by +the heat of a portion of steam introduced into it from one of the steam +receivers, the decrease of the coal necessary to generate steam from the +water of the higher temperature bears a greater ratio to the coal +required without feed heating than the power which would be developed in +the cylinder by that portion of steam would bear to the whole power +developed when passing all the steam through all the cylinders. The +temperature of the feed is of course limited by the temperature of the +steam in the receiver from which the supply for heating is drawn. +Supposing, for example, a triple expansion engine were working under the +following conditions without feed heating: Boiler pressure, 150 +lb.;--indicated horse power in high pressure cylinder 398, in +intermediate and low pressure cylinders together 790, total, 1,188; and +temperature of hot well 100 deg. Fahr. Then with feed heating the same +engine might work as follows: The feed might be heated to 220 deg. Fahr., +and the percentage of steam from the first receiver required to heat it +would be 12.2 per cent.; the indicated horse power in the high pressure +cylinder would be as before 398, and in the intermediate and low +pressure cylinders it would be 12.2 per cent, less than before, or 694, +and the total would be 1,092, or 92 per cent. of the power developed +without feed heating. Meanwhile the heat to be added to each pound of +the feed water at 220 deg. Fahr. for converting it into steam would be 1,005 +units against 1,125 units with feed at 100 deg. Fahr., equivalent to an +expenditure of only 89.4 per cent. of the heat required without feed +heating. Hence the expenditure of heat in relation to power would be +89.4 + 92.0 = 97.2 per cent., equivalent to a heat economy of 2.8 per +cent. If the steam for heating can be taken from the low pressure +receiver, the economy is about doubled. Other feed heaters, more or less +upon the same principle, have been introduced. Also others which heat +the feed in a series of pipes within the boiler, so that it is +introduced into the water in the boiler practically at boiling +temperature; this is economical, however, only in the sense that wear +and tear of the boiler is saved; in principle the plan does not involve +economy of fuel. + +_Auxiliary Supply of Fresh Water_.--Intimately associated with the feed +is the means adopted for making up the losses of fresh water due to +leakage of steam from safety valves, glands, joints, etc., and of water +discharged from the air pumps. A few years ago this loss was regularly +made up from the sea, with the result that the water in the boilers was +gradually increased in density; whence followed deposit on the internal +surfaces, and consequent loss of efficiency, and danger of accident +through overheating the plates. With the higher pressures now adopted, +the danger arising from overheating is much more serious, and the +necessity is absolute of maintaining the heating surfaces free from +deposit. This can be done only by filling the boiler with fresh water in +the first instance, and maintaining it in that condition. To do this two +methods are adopted, either separately or in conjunction. Either a +reserve supply of fresh water is carried in tanks or the supplementary +feed is distilled from sea water by special apparatus provided for the +purpose. In the construction of the distilling or evaporating apparatus +advantage has been taken of two important physical facts, namely, that, +if water be heated to a temperature higher than that corresponding with +the pressure on its surface, evaporation will take place; and that the +passage of heat from steam at one side of a plate to water at the other +is very rapid. In practice the distillation is effected by passing +steam, say from the first receiver, through a nest of tubes inside a +still or evaporator, of which the steam space is connected either with +the second receiver or with the condenser. The temperature of the steam +inside the tubes being higher than that of the steam either in the +second receiver or in the condenser, the result is that the water inside +the still is evaporated, and passes with the rest of the steam into the +condenser, where it is condensed, and serves to make up the loss. This +plan localizes the trouble of deposit, and frees it from its dangerous +character, because an evaporator cannot become overheated like a boiler, +even though it be neglected until it salts up solid; and if the same +precautions are taken in working the evaporator which used to be adopted +with low pressure boilers when they were fed with salt water, no serious +trouble should result. When the tubes do become incrusted with deposit, +they can be either withdrawn or exposed, as the apparatus is generally +so arranged; and they can then be cleaned. + +_Screw Propeller_.--In Mr. Marshall's paper of 1881 it was said that +"the screw propeller is still to a great extent an unsolved problem." +This was at the time a fairly true remark. It was true the problem had +been made the subject of general theoretical investigation by various +eminent mathematicians, notably by Professor Rankine and Mr. William +Froude, and of special experimental investigation by various engineers. +As examples of the latter may be mentioned the extended series of +investigations in the French vessel Pelican, and the series made by Mr. +Isherwood on a steam launch about 1874. These experiments, however, such +as they were, did little to bring out general facts and to reduce the +subject to a practical analysis. Since the date of Mr. Marshall's paper, +the literature on this subject has grown rapidly, and, has been almost +entirely of a practical character. The screw has been made the subject +of most careful experiments. One of the earliest extensive series of +experiments was made under the writer's direction in 1881, with a large +number of models, the primary object being to determine what value there +was in a few of the various twists which inventive ingenuity can give to +a screw blade. The results led the experimenters to the conclusion that +in free water such twists and curves are valueless as serving to augment +efficiency. The experiments were then carried further with a view to +determine quantitative moduli for the resistance of screws with +different ratios of pitch to diameter, or "pitch ratios," and afterward +with different ratios of surface to the area of the circle described by +the tips of the blades, or "surface ratios." As these results have to +some extent been analyzed and published, no further reference need be +made to them now. + +In 1886, Mr. R.E. Froude published in the Transactions of the +Institution of Naval Architects the deductions drawn from an extensive +series of trials made with four models of similar form and equal +diameter, but having different pitch ratios. Mr. S.W. Barnaby has +published some of the results of experiments made under the direction of +Mr. J.I. Thornycroft; and in his paper read before the Institution of +Civil Engineers in 1890 he has also put Mr. R.E. Froude's results into a +shape more suitable for comparison with practice. Nor ought Mr. G.A. +Calvert's carefully planned experiments to pass unnoticed, of which an +account was given in the Transactions of the Institution of Naval +Architects in 1887. These experiments were made on rectangular bodies +with sections of propeller blade form, moved through the water at +various velocities in straight lines, in directions oblique to their +plane faces; and from their results an estimate was formed of the +resistance of a screw. + +One of the most important results deduced from experiments on model +screws is that they appear to have practically equal efficiencies +throughout a wide range both in pitch ratio and in surface ratio; so +that great latitude is left to the designer in regard to the form of the +propeller. Another important feature is that, although these experiments +are not a direct guide to the selection of the most efficient propeller +for a particular ship, they supply the means of analyzing the +performances of screws fitted to vessels, and of thus indirectly +determining what are likely to be the best dimensions of screw for a +vessel of a class whose results are known. Thus a great advance has been +made on the old method of trial upon the ship itself, which was the +origin of almost every conceivable erroneous view respecting the screw +propeller. The fact was lost sight of that any modification in form, +dimensions, or proportions referred only to that particular combination +of ship and propeller, or to one similar thereto; so something like +chaos was the result. This, however, need not be the case much longer. + +In regard to the materials used for propellers, steel has been largely +adopted for both solid and loose-bladed screws; but unless protected in +some way, the tips of the blades are apt to corrode rapidly and become +unserviceable. One of the stronger kinds of bronze is often judiciously +employed for the blades, in conjunction with a steel boss. Where the +first extra expense can be afforded, bronze seems the preferable +material; the castings are of a reliable character, and the metal does +not rapidly corrode; the bronze blades can therefore with safety be made +lighter than steel blades, which favors their springing and +accommodating themselves more readily to the various speeds of the +different parts of the wake. This might be expected to result in some +slight increase of efficiency; of which, however, the writer has never +had the opportunity of satisfactorily determining the exact extent. +Instances can be brought forward where bronze blades have been +substituted for steel or iron with markedly improved results; but in +cases of this kind which the writer has had the opportunity of +analyzing, the whole improvement might be accounted for by the modified +proportions of the screw when in working condition. In other words, both +experiment and practical working alike go to show that, although cast +iron and steel blades as usually proportioned are sufficiently stiff to +retain their form while at work, bronze blades, being made much lighter, +are not; and the result is that the measured or set pitch is less than +that which the blades assume while at work. Some facts relative to this +subject have already been given in a recent paper by the author. + +_Twin Screws_.--The great question of twin screw propulsion has been put +to the test upon a large scale in the mercantile marine, or rather in +what would usually be termed the passenger service. While engineers, +however, are prepared to admit its advantages so far as greater security +from total breakdown is concerned, there is by no means thorough +agreement as to whether single or twin screws have the greater +propulsive efficiency. What is required to form a sound judgment upon +the whole question is a series of examples of twin and single screw +vessels, each of which is known to be fitted with the most suitable +propeller for the type of vessel and speed; and until this information +is available, little can be said upon the subject with any certainty. So +far the following large passenger steamers, particulars of which are +given in table II., have been fitted with twin screws. It appears t be a +current opinion that the twin screw arrangement necessitates a greater +weight of machinery. This is not necessarily so, however; on the +contrary, the opportunity is offered for reducing the weight of all that +part of the machinery of which the weight relatively to power is +inversely proportional to the revolutions for a given power. This can be +reduced in the proportion of 1 to the square root of 2, that is 71 per +cent. of its weight in the single screw engine; for since approximately +the same total disk area is required in both cases with similar +proportioned propellers, the twins will work at a greater speed of +revolution than the single screw. From a commercial point of view there +ought to be little disagreement as to the advantage of twin screws, so +long as the loss of space incurred by the necessity for double tunnels +is not important; and for the larger passenger vessels now built for +ocean service the disadvantage should not be great. Besides their +superiority in the matter of immunity from total breakdown, and in +greatly diminished weight of machinery, they also offer the opportunity +of reducing to some extent the cost of machinery. A slightly greater +engine room staff is necessary; but this seems of little importance +compared with the foregoing advantages. + +TABLE II.--PASSENGER STEAMERS FITTED WITH TWIN SCREWS. + +-----------------+-----------+-----+-----------+-------+--------+-------+ + | Length | | Cylinders, | Boiler |Indi- | + | between | | two sets in all |pressure|cated | + Vessels. | perpen- |Beam.| cases. | per |horse- | + | diculars. | |-----------+-------| square |power. | + | | |Diameters. |Stroke.| inch. | | +-----------------+-----------+-----+-----------+-------+--------+-------+ + | Feet. |Feet.| Inches. |Inches.| Lb. | | +City of Paris. |\ | | | | | | + | } 525 | 631/4 |45, 71, 113| 60 | 150 |20,000 | +City of New York.|/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Teutonic. |\ | | | | | | + | } 565 | 58 |43, 68, 110| 60 | 180 |18,000 | +Majestic. |/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Normannia. | 500 | 571/2 |40, 67, 106| 66 | 160 |11,500 | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Columbia. | 4631/2 | 551/2 |41, 66, 101| 66 | 160 |12,500 | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Empress of India.|\ | | | | | | +Empress of Japan.| } 440 | 51 |32, 51, 82 | 54 | 160 |10,125 | +Empress of China.|/ | | | | | | +-----------------+-----------+-----+-----------+-------+--------+-------+ +Orel. | 415 | 48 |34, 54, 85 | 51 | 160 |10,000 | +-----------------+-----------+-----+-----------+-------+--------+-------+ + +_Weight of Machinery Relatively to Power_.--It is interesting to compare +the weight of machinery relatively to the power developed; for this +comparison has sometimes been adopted as the standard of excellence in +design, in respect of economy in the use of material. The principle, +however, on which this has generally been done is open to some +objections. It has been usual to compare the weight directly with the +indicated horse-power, and to express the comparison in pounds per +horse-power. So long as the machinery thus compared is for vessels of +the same class and working at about the same speed of revolution, no +great fault can be found; but as speed of revolution is a great factor +in the development of power, and as it is often dependent on +circumstances altogether external to the engine and concerning rather +the speed of the ship, the engines fitted to high speed ships will thus +generally appear to greater advantage than is their due. Leaving the +condenser out of the question, the weight of an engine would be much +better referred to cylinder capacity and working pressures, where these +are materially different, than directly to the indicated power. The +advantages of saving weight of machinery, so long as it can be done with +efficiency, are well known and acknowledged. If weight is to be reduced, +it must be done by care in design, not by reduction of strength, because +safety and saving of repairs are much more important than the mere +capability of carrying a few tons more of paying load. It must also be +done with economy; but this is a matter which generally settles itself +aright, as no shipowner will pay more for a saving in weight than will +bring in a remunerative interest on his outlay. In his paper on the +weight of machinery in the mercantile marine,[3] Mr. William Boyd +discussed this question at some length, and proposed to attain the end +of reducing the weight of machinery by the legitimate method of +augmenting the speed of revolution and so developing the required power +with smaller engines. This method, while promising, is limited by the +efficiency of the screw, but may be adopted with advantage so long as +the increase in speed of revolution involves no such change in the screw +as to reduce its efficiency as a propeller. But when the point is +reached beyond which a further change involves loss of propelling +efficiency, it is time to stop; and the writer ventures to say that in +many cargo vessels now at work the limit has been reached, while in many +others it has certainly been passed. + +[Footnote 3: Transactions Northeast Coast Institution of Engineers and +Shipbuilders, vol. 6, 1889-90, p. 253.] + +_Economy of Fuel_.--Coming to the highly important question of economy +of fuel, the average consumption of coal per indicated horse-power is +1.522 lb. per hour. The average working pressure is 158.5 lb. per square +inch. Comparing this working pressure with 77.4 lb. in 1881, a superior +economy of 19 per cent. might be expected now, on account of the higher +pressure, or taking the 1.828 lb. of coal per hour per indicated +horse-power in 1881, the present performance under similar conditions +should be 1.48 lb. per hour per indicated horse-power. It appears that +the working pressures have been increased twice in the last ten years, +and nearly three times in the last nineteen. The coal consumptions have +been reduced 16.7 per cent. in the last ten years and 27.9 per cent. in +the last nineteen. The revolutions per minute have increased in the +ratios of 100, 105, 114; and the piston speeds as 100, 124, 140. +Although it is quite possible that the further investigations of the +Research Committee on Marine Engine Trials may show that the present +actual consumption of coal per indicated horse-power is understated, yet +it is hardly probable that the relative results will be affected +thereby. + +_Dimensions_.--In the matter of the power put into individual vessels, +considerable strides have been made. In 1881, probably the greatest +power which has been put into one vessel was in the case of the Arizona, +whose machinery indicated about 6,360 horse-power. The following table +gives an idea of the dimensions and power of the larger machinery in the +later passenger vessels: + +TABLE III.--DIMENSIONS AND POWER OF MACHINERY IN LATER PASSENGER +VESSELS. + +-----+----------------+-----------------------+-------+-----------+ + | | |Length | | +Year.| Name of vessel.| Diameters of | of |Indicated | + | | cylinders. |Stroke.|horsepower.| +-----+----------------+-----------------------+-------+-----------+ + | | Inches. |Inches.| | +1881 |Alaska | 68, 100, 100 | 72 | 10,686 | +-----+----------------+-----------------------+-------+-----------+ +1881 |City of Rome | 46, 86; 46, 86; 46, 86| 72 | 11,800 | +-----+----------------+-----------------------+-------+-----------+ +1881 |Servia | 72, 100, 100 | 78 | 10,300 | +-----+----------------+-----------------------+-------+-----------+ +1881 |Livadia yacht | 60, 78, 78; 60, 78, \| 39 | 12,500 | + | | 78; 60, 78, 78 /| | | +-----+----------------+-----------------------+-------+-----------+ +1883 |Oregon | 70, 104, 104 | 72 | 13,300 | +-----+----------------+-----------------------+-------+-----------+ +1884 |Umbria |\ 71, 105, 105 | 72 | 14,320 | +1884 |Etruria |/ | | | +-----+----------------+-----------------------+-------+-----------+ +1888 |City of New York|\ 45, 71, 113; \| 60 | 20,000 | +1889 |City of Paris |/ 45, 71, 113 /| | about | +-----+----------------+-----------------------+-------+-----------+ +1889 |Majestic |\ 43, 68, 110; \| 60 | 18,000 | +1889 |Teutonic |/ 43, 68, 110 /| | | +-----+----------------+-----------------------+-------+-----------+ + +In war vessels the increase has been equally marked. In 1881 the maximum +power seems to have been in the Inflexible, namely, 8,485 indicated +horse-power. The following will give an idea of the recent advance made: +Howe (Admiral class), 11,600 indicated horse-power; Italia and Lepanto, +19,000 indicated horse-power; Re Umberto, 19,000 indicated horse-power; +Blake and Blenheim (building), 18,000 indicated horse-power; Sardegna +(building), 22,800 indicated horse-power. It is thus evident that there +are vessels at work to-day having about three times the maximum power of +any before 1881. + +_General Conclusions_.--The progress made during the last ten years +having been sketched out, however roughly, the general conclusions may +be stated briefly as follows: First, the working pressure has been about +doubled. Second, the increase of working pressure and other improvements +have brought with them their equivalent in economy of coal, which is +about 20 per cent. Third, marked progress has been made in the direction +of dimension, more than twice the power having been put into individual +vessels. Fourth, substantial advance has been made in the scientific +principles of engineering. It only remains for the writer to thank the +various friends who have so kindly furnished him with data for some of +the tables which have been given; and to express the hope that the next +ten years may be marked by such progress as has been witnessed in the +past. But it must be remembered that, if future progress be equal in +merit or ratio, it may well be less in quantity, because advance becomes +more difficult of achievement as perfection is more nearly approached. + + * * * * * + + + + +THE LITTLE HOUSE. + +BY M.M. + + +One of the highest medical authorities is credited with the statement +that "nine-tenths of the diseases that afflict humanity are caused by +neglect to answer the calls of Nature." + +This state of affairs is generally admitted, but is usually attributed +to individual indolence. That, doubtless, has a great deal to do with +it, but should not part of the blame be laid upon the often unpleasant +environments, which make us shrink as from the performance of a painful +duty? + +In social life, unless from absolute necessity or charity, people of +refined habits do not call on those whose surroundings shock their sense +of decency; but when they go to pay the calls of Nature, they are often +compelled to visit her in the meanest and most offensive of abodes; +built for her by men's hands; for Nature herself makes no such mistakes +in conducting her operations. She does not always surround herself with +the pomp and pride of life, but she invariably hedges herself in with +the thousand decencies and the pomp of privacy. + +But what do we often do? We build what is sometimes aptly termed "an +out-house," because it is placed so that the delicate minded among its +frequenters may be made keenly alive to the fact that they can be +plainly seen by every passer-by and by every idle neighbor on the +lookout. This tiny building is seldom weatherproof; In consequence, keen +cold winds from above, below, and all around find ready entrance, chill +the uncovered person, frequently check the motions, and make the strong +as well as the weak, the young as well as the old, very sorry indeed +that they are so often uselessly obliged to answer the calls of Nature. +It is true, the floor is sometimes carpeted with snow, but the feet feel +that to be but cold comfort, though the door may enjoy rattling its +broken hasp and creaking its loose hinges. + +How often, too, are the nose and the eye offended by disregard of the +Mosaic injunction, found in the twelfth, thirteenth, and fourteenth +verses of the twenty-third chapter of Deuteronomy! Of course this +injunction was addressed to a people who had been debased by slavery, +but who were being trained to fit them for their high calling as the +chosen of God; but is not some such sanitary regulation needed in these +times, when a natural office is often made so offensive to us by its +environments that it is difficult for us to believe that "God made man a +little lower than the angels," or that the human body is the temple of +the Holy Ghost? + +Dwellers in the aristocratic regions of a well drained city, whose +wealth enables them to surround themselves with all devices tending to a +refined seclusion, may doubt all this, but sanitary inspectors who have +made a round of domiciliary visits in the suburbs, or the older, +neglected parts of a large city, of to any part of a country town or +village, will readily affirm as to its general truth. + +This unpardonable neglect of one of the minor decencies by the mass of +the people seems to be caused partly by a feeling of false shame, and +partly by an idea that it is expensive and troublesome to make any +change that will improve their sanitary condition or dignify their daily +lives. + +The Rev. Henry Moule, of Fordington Vicarage, Dorsetshire, England, was +one of the first to turn his attention to this matter. With the +threefold object of improving the sanitary condition of his people, +refining their habits, and enriching their gardens, he invented what he +called the "dry earth closet." + +"It is based on the power of clay and the decomposed organic matter +found in the soil to absorb and retain all offensive odors and all +fertilizing matters; and it consists, essentially, of a mechanical +contrivance (attached to the ordinary seat) for measuring out and +discharging into the vault or pan below a sufficient quantity of sifted +dry earth to entirely cover the solid ordure and to absorb the urine. + +"The discharge of earth is effected by an ordinary pull-up, similar to +that used in the water closet, or (in the self-acting apparatus) by the +rising of the seat when the weight of the person is removed. + +"The vault or pan under the seat is so arranged that the accumulation +can be removed at pleasure. + +"From the moment when the earth is discharged and the evacuation +covered, all offensive exhalation entirely ceases. Under certain +circumstances there may be, at times, a slight odor as of guano mixed +with earth, but this is so trifling and so local that a commode arranged +on this plan may, without the least annoyance, be kept in use in any +room." + +The "dry earth closet" of the philanthropic clergyman was found to work +well, and was acceptable to his parishioners. One reason why it was so +was because dry earth was ready to hand, or could be easily procured in +a country district where labor was cheap. But where labor was dear and +dry earth scarce, those who had to pay for the carting of the earth and +the removal of the deodorized increment found it both expensive and +troublesome. + +But a modification of this dry earth closet, the joint contrivance of an +English church clergyman and his brother, "the doctor," residents of a +Canadian country town, who had heard of Moule's invention, is a good +substitute, and is within the reach of all. This will be briefly +described. + +The vault was dug as for an ordinary closet, about fifteen feet deep, +and a rough wooden shell fitted in. About four feet below the surface of +this wooden shell a stout wide ledge was firmly fastened all around. +Upon this ledge a substantially made wooden box was placed, just as we +place a well fitting tray into our trunks. About three feet of the back +of the wooden shell was then taken out, leaving the back of the box +exposed. From the center of the back of the box a square was cut out and +a trap door fitted in and hasped down. + +The tiny building, on which pains, paint, and inventive genius had not +been spared to make it snug, comfortable, well lighted and well +ventilated, was placed securely on this vault. + +After stones had been embedded in the earth at the back of the vault, to +keep it from falling upon the trap door, two or three heavy planks were +laid across the hollow close to the closet. These were first covered +with a barrowful of earth and then with a heap of brushwood. + +Within the closet, in the left hand corner, a tall wooden box was +placed, about two-thirds full of dry, well sifted wood ashes. The box +also contained a small long-handled fire shovel. When about six inches +of the ashes had been strewn into the vault the closet was ready for +use. No; not quite; for squares of suitable paper had to be cut, looped +together with twine, and hung within convenient reaching distance of the +right hand; also a little to the left of this pad of paper, and above +the range of sight when seated, a ten pound paper bag of the toughest +texture had to be hung by a loop on a nail driven into the corner. + +At first the rector thought that his guests would be "quick-witted +enough to understand the arrangement," but when he found that the +majority of them were, as the Scotch say, "dull in the uptak," he had to +think of some plan to enforce his rules and regulations. As +by-word-of-mouth instructions would have been rather embarrassing to +both sides, he tacked up explicit written orders, which must have +provoked many a smile. Above the bin of sifted ashes he nailed a card +which instructed "Those who use this closet must strew two shovelfuls of +ashes into the vault." Above the pad of clean paper he tacked the +thrifty proverb: "Waste not, want not;" and above the paper bag he +suspended a card bearing this warning: "All refuse paper must be put +into this bag; not a scrap of clean or unclean paper must be thrown into +the vault." + +This had the desired effect. Some complacently united to humor their +host's whim, as they called it, and others, immediately recognizing its +utility and decency, took notes with a view to modifying their own +closet arrangements. + +Sarah, the maid of all work, caused a good deal of amusement in the +family circle by writing her instructions in blue pencil on the front of +the ash bin. These were: "Strew two shuffefuls of ashes into the volt, +but don't spill two shuffefuls onto the floor. By order of the Gurl who +has to sweap up." This order was emphatically approved of by those +fastidious ones who didn't have to "sweep up." + +This closet opened off the woodshed, and besides being snugly +weatherproof in itself, was sheltered on one side by the shed and on +another by a high board fence. The other two sides were screened from +observation by lattice work, outside of which evergreens were planted to +give added seclusion and shade. A ventilator in the roof and two sunny +little windows, screened at will from within by tiny Venetian shutters, +gave ample light and currents of fresh air. For winter use, the rector's +wife and daughters made "hooked" mats for floor and for foot support. +These were hung up every night in the shed to air and put back first +thing in the morning. For the greater protection and comfort of +invalids, an old-fashioned foot warmer, with a handle like a basket, was +always at hand ready to be filled with live coals and carried out. + +The little place was always kept as exquisitely clean as the dainty, +old-fashioned drawing room, and so vigilant was the overseeing care +bestowed on every detail, that the most delicate and acute sense of +smell could not detect the slightest abiding unpleasant odor. The paper +bag was frequently changed, and every night the accumulated contents +were burned; out of doors in the summer, and in the kitchen stove--after +a strong draught had been secured--in the winter. + +At stated times the deodorized mass of solid increment--in which there +was not or ought not to have been any refuse paper to add useless +bulk--was spaded, through the trap door, out of the box in the upper +part of the vault, into a wheelbarrow, thrown upon the garden soil, and +thoroughly incorporated with it. In this cleansing out process there was +little to offend, so well had the ashes done their concealing +deodorizing work. + +In using this modified form of Moule's invention, it is not necessary to +dig a deep vault. The rector, given to forecasting, thought that some +day his property might be bought by those who preferred the old style, +but his brother, the doctor, not troubling about what might be, simply +fitted his well made, four feet deep box, with its trap door, into a +smoothly dug hole that exactly held it, and set the closet over it. In +all other respects it was a model of his brother's. + +This last is within the reach of all, even those who live in other +people's houses; for, when they find themselves in possession of an +unspeakably foul closet, they can cover up the old vault and set the +well cleaned, repaired, fumigated closet upon a vault fashioned after +the doctor's plan. A stout drygoods box, which can be bought for a +trifle, answers well for this purpose, after a little "tinkering" to +form a trap door. + +Of course, dry earth is by far the best deodorizer and absorbent, but +when it cannot be easily and cheaply procured, well sifted wood or coal +ashes--wood preferred--is a good substitute. The ashes must be kept dry. +If they are not, they lose their absorbing, deodorizing powers. They +must also be well sifted. If they are not, the cinders add a useless and +very heavy bulk to the increment. + +An ash sifter can be made by knocking the bottom out of a shallow box, +studding the edge all round with tacks, and using them to cross and +recross with odd lengths of stovepipe wire to form a sieve.--_The +Sanitarian_. + + * * * * * + + + + +THE HYGIENIC TREATMENT OF OBESITY.[1] + +[Footnote 1: Translated by Mr. Jos. Helfman, Detroit, Mich.] + +BY DR. PAUL CHERON. + + +In order to properly regulate the regimen of the obese, it is first +necessary to determine the source of the superfluous adipose of the +organism, since either the albuminoids or the hydrocarbons may furnish +fat. + +Alimentary fat becomes fixed in the tissues, as has been proved by +Lebede, who fed dogs, emaciated by long fast, with meat wholly deprived +of fat, and substituted for the latter linseed oil, when he was able to +recover the oil in each instance from the animal; parallel experiments +with mutton fat, _in lieu_ of oil, afforded like results. + +Hoffman also deprived dogs of fat for a month, causing them to lose as +high as twenty-two pounds weight, then began nourishing with bacon fat +with but little lean; the quantity of fat formed in five days, in the +dog that lost twenty-two pounds, was more than three pounds, which could +have been derived only from the bacon fat. + +It has been stated, however, that alimentary fat seems to preserve from +destruction the fat of the organism which arises from other sources. Be +this as it may, it is a fact that the pre-existence of fat furthers the +accumulation of more adipose; or in other words, fat induces fattening! + +That adipose may be formed through the transformation of albuminous +matters (meat) is an extremely important corollary, one established +beyond cavil by Pettinkofer and Voit, in an indirect way, by first +estimating the nitrogen and carbon ingested, and second the amount +eliminated. Giving a dog meat that was wholly deprived of fat, they +found it impossible to recover more than a portion of the contained +carbon; hence some must necessarily have been utilized in the organism, +and this would be possible only by the transformation of the carbon into +fat! It goes without saying, however, that the amount of adipose thus +deposited is meager. + +Other facts also plead in favor of the transformation of a portion of +albumen into fat within the economy, notably the changing of a portion +of dead organism into what is known as "cadaveric fat," and the very +rapid fatty degeneration of organs that supervenes upon certain forms of +poisoning, as by phosphorus. + +The carbohydrates, or more properly speaking hydrocarbons, are regarded +by all physiologists as specially capable of producing fat, and numerous +alimentary experiments have been undertaken to prove this point. +Chaniewski, Meissl, and Munk obtained results that evidenced, +apparently, sugar and starch provide more fat than do the albuminoids. +Voit, however, disapproves this, maintaining the greater part of the +hydrocarbons is burned (furnishes fuel for the immediate evolution of +force), and that fat cannot be stored up unless a due proportion of +albuminoids is also administered. He believes the hydrocarbons exert a +direct influence only; being more oxidizable than fats, they guard the +latter from oxidation. This protective role of the hydrocarbons applies +also to the albuminoids. + +We may believe, then, that the three great classes of aliment yield fat, +in some degree; that alimentary fat may be fixed in the tissues; and +that hydrocarbons favor the deposition of adipose either directly or +indirectly. + +It is well understood that fat may disappear with great rapidity under +certain conditions; many maladies are accompanied by speedy emaciation; +therefore, as fat never passes into the secretions, at least not in +appreciable quantities, it probably undergoes transformation, perhaps by +oxidation or a form of fermentation, the final results of which are, +directly or indirectly, water and cadaveric acid. It is certain the +process of oxidation favors the destruction of adipose, and that +everything which inhibits such destruction tends to fat accumulation. + +Since the earliest period of history, there seems to have been an +anxiety to secure some regimen of general application that would reduce +or combat obesity. Thus Hippocrates says: + +Fat people, and all those who would become lean, should perform +laborious tasks while fasting, and eat while still breathless from +fatigue, without rest, and after having drunk diluted wine not very +cold. Their meats should be prepared with sesamum, with sweets, and +other similar substances, and these dishes should be free from fat. + +In this manner one will be satiated through eating less. + +But, besides, one should take only one meal; take no bath; sleep on a +hard bed; and walk as much as may be. + +How much has medical science gained in this direction during the +interval of more than two thousand years? Let us see: + +First among moderns to seek to establish on a scientific basis a regimen +for the obese, was Dancel, who forbade fats, starchy foods, etc., +prescribed soups and aqueous aliment, and reduced the quantity of +beverage to the lowest possible limit; at the same time he employed +frequent and profuse purgation. + +This regimen, which permits, at most, but seven to twelve ounces of +fluid at each repast, is somewhat difficult to follow, though it may be +obtained, gradually, with ease. Dr. Constantine Paul records a case in +which this regimen, gradually induced, and followed for ten years, +rewarded the patient with "moderate flesh and most excellent health." + +In Great Britain, a mode of treatment instituted in one Banting, by Dr. +Harvey, whereby the former was decreased in weight forty pounds, has +obtained somewhat wide celebrity; and what is more remarkable, it is +known as "Bantingism," taking its name from the patient instead of the +physician who originated it. The dietary is as follows: + +_Breakfast_.--Five to six ounces of lean meat, broiled fish, or smoked +bacon--veal and pork interdicted; a cup of tea or coffee without milk or +sugar; one ounce of toast or dry biscuit (crackers). + +_Dinner_.--Five or six ounces of lean meat or fish--excluding eel, +salmon, and herring; a small quantity of vegetables, but no potatoes, +parsnips, carrots, beets, peas, or beans; one ounce of toast, fruit, or +fowl; two glasses of red wine--beer, champagne, and port forbidden. + +_Tea_.--Two or three ounces of fruit; one kind of pastry; one cup of +tea. + +_Supper_.--Three or four ounces of lean beef or fish; one or two glasses +of red wine. + +_At bed-time._--Grog without sugar (whisky and water, or rum and water), +and one or two glasses of sherry or Bordeaux. + +"Bantingism," to be effective, must be most closely followed, when, +unfortunately also, it proves extremely debilitating; it is suitable +only for sturdy, hard riding gluttons of the Squire Western type. The +patient rapidly loses strength as well as flesh, and speedily acquires +an unconquerable repugnance to the dietary. Further, from a strictly +physiological point of view, the quantity of meat is greatly in excess, +while with the cessation of the regimen, the fat quickly reappears. + +Next Ebstein formulated a dietary that is certainly much better +tolerated than that of Harvey and Banting, and yields as good, or even +better, results. He allows patients to take a definite quantity--two to +two and a half ounces-of fat daily, in the form of bacon or butter +which, theoretically at least, offers several advantages: It diminishes +the sensations of hunger and thirst, and plays a special role with +respect to the albuminoids; the latter may thus be assimilated by the +economy without being resolved into fat, and thus the adipose of the +organism at this period is drawn upon without subsequent renewal. The +following is the outline: + +_Breakfast_.--At 6 a.m. in summer; 7:30 in winter:--Eight ounces of +black tea without either milk or sugar; two ounces of white bread or +toast, with a copious layer of butter. + +_Dinner_.--2 p.m.:--A modicum of beef marrow soup; four ounces of meat, +preferably of fatty character; moderate quantity of vegetable, +especially the legumines, but no potatoes or anything containing starch; +raw fruits in season, and cooked fruits (stewed, without sugar); two or +three glasses of light wine as a beverage, and after eating, a cup of +black tea without sugar. + +_Supper_.--7:30 p m.:--An egg, bit of fat roast, ham, or bacon; a slice +of white bread well buttered; a large cup of black tea without milk or +sugar; from time to time, cheese and fresh fruits. + +Germain See suggests as a modification of this regimen, the abundant use +of beverage, the addition of gelatins, and at times small doses of +potassium iodide in twenty cases he claims constant and relatively +prompt results. + +Whatever may be urged for Ebstein's system--and it has afforded most +excellent results to Unna and to Lube, as well as its author--it +certainly exposes the patient to the terrors of dyspepsia, when the +routine must needs be interrupted or modified; hence it is not always to +be depended upon. As between dyspepsia and obesity, there are few, I +fancy, who would not prefer the latter. + +Another "system" that has acquired no little celebrity, and which has +for its aim the reduction as far as possible of alimentary hydrocarbons +while permitting a certain proportion of fat, is that, of Denneth, which +necessarily follows somewhat closely the lines laid down by Ebstein. + +Oertels' treatment, somewhat widely known, and not without due measure +of fame, is based upon a series of measures having as object the +withdrawal from both circulation and the economy at large, as much of +the fluids as possible. It is especially adapted for the relief of those +obese who are suffering fatty degeneration of the heart. The _menu_ is +as follows: + +_Breakfast_.--Pour to five ounces of tea or coffee with a little milk; +two to two and a half ounces bread. + +_Dinner_.--Three or four ounces of roast or boiled meat, or moderately +fat food; fish, slightly fat; salad and vegetables at pleasure; one and +a half ounces of bread (in certain cases as much as three ounces of +farinaceous food may be permitted); three to six ounces of fruit; at +times a little pastry for dessert.--In summer, if fruit is not +obtainable, six to eight ounces of light wine may be allowed. + +_Tea_,--A cupful (four to five ounces) of tea or coffee, with a trifle +of milk, as at breakfast; one and three-fourths ounces of bread; and +exceptionally (and at most) six ounces of water. + +_Supper_.--One to two soft boiled eggs; four or five ounces of meat; one +and three fourths ounces of bread; a trifle of cheese, salad, or fruit; +six to eight ounces of light wine diluted with an eighth volume of +water. The quantity of beverage may be slightly augmented at each meal +if necessary, especially if there is no morbid heart trouble. + +Schwenninger (Bismarck's physician), who opened a large sanitarium near +Berlin a few years since for the treatment of the obese, employs +Oertel's treatment, modified in that an abundance of beverage is +permitted, provided it is not indulged in at meals; it is forbidden +until two hours after eating. + +Both Oertel's and Schwenninger's methods have procured grave dyspepsias, +and fatal albuminurias as well, according to Meyer and Rosenfield. It +has been charged the allowance of beverage upon which Schwenninger lays +so much stress in the treatment at his sanitarium has a pecuniary basis, +in other words a commission upon the sale of wines.[2] + +[Footnote 2: The sanitarium is owned by a stock company, Schwenninger +being merely Medical Director.--ED.] + +Thus, it will be observed that while some forbid beverage, others rather +insist upon its employment in greater or less quantities. Under such +circumstances, it would seem but rational, before undertaking to relieve +obesity, to establish its exact nature, and also the role taken by +fluids in the phenomena of nutrition. + +Physiologists generally admit water facilitates nutritive exchanges, +which is explained by the elimination of a large quantity of urine; the +experiments of Genth and Robin in this direction appear conclusive. + +Bischoff, Voit, and Hermann have shown that water increases, not alone +the elimination of urine, but also of sodium chloride, phosphoric acid, +etc. Grigoriantz observed augmentation of disintegration when the +quantity of beverage exceeded forty-six to eighty ounces ("1,400 to +2,400 cubic centimeters") per diem. Oppenheim, Fraenkel, and Debove, +while believing water has but little influence upon the exchanges, admit +it certainly need not diminish the latter; and Debove and Flament, after +administering water in quantities varying from two to eight pints per +diem, concluded that urine was diminished below the former figure, while +above the latter it increased somewhat, being dependent upon the amount +ingested. It was on the strength of the foregoing that Lallemand +declared water to have no influence upon the exchanges. + +The results claimed by Oppenheim, Debove, et al. were immediately +challenged--and it is now generally admitted, not without some +justice--by Germain See. It seems certain, to say the least, that water +taken during the repast does tend to augment the quantity and facilitate +the elimination of urine. Abundance of beverage, moreover, presents +other advantages, in that it facilitates digestion by reason of its +diluent action, a fact well worth bearing in mind when treating the +obese who are possessed of gouty diathesis, and whose kidneys are +accordingly encumbered with uric and oxalic acids. The foregoing +presents the ground upon which Germain See permits an abundance of +beverage; but he also expresses strong reservation as regards beer and +alcohol, either of which (more especially the former) tends to the +production of adipose. In his opinion, the only beverage of the +alcoholic class that is at all permissible, and then only for cases +suffering from fatty heart, is a little _liqueur_ or diluted wine. +Coffee and tea he commends highly, and recommends the ingestion of large +quantities at high temperature, both during the repasts and their +intervals. Coffee in large doses is undoubtedly a means of de-nutrition, +and so, too, in no less extent, is tea; both act vigorously owing to the +contained alkaloids, though, to be sure, they sometimes, at first, tend +to insomnia and palpitation, to which no attention need be paid, +however. The treatment outlined by See is: + +1. A physiological regimen comprising four to five ounces of nitrogenous +principles as derived from eight to ten ounces animal muscle and +albuminates; three to six ounces of fat; eight to ten ounces of +hydrocarbons as yielded by ten to twelve ounces of sugar or starch food. + +These proportions to be modified in such manner that the +musculo-albuminates shall not sensibly exceed the normal ratio, for meat +in excess itself furnishes fat during transformation. The fatty +substances of easy digestion may, without inconvenience, be utilized in +doses of two to three ounces. The hydrocarbons should be reduced to a +minimum. As for the herbaceous elements, they contain nothing nutritive. + +2. Beverage, far from being suppressed, should be augmented, in order to +facilitate stomachal digestion and promote general nutrition, though +alcoholic liquids must be inhibited; likewise mineral waters, except, +perhaps, for occasional use. Both should be replaced by infusions of +coffee or tea, taken as hot as can be drank. + +Henrich Kisch insists that any method which promises rapid and marked +decrease of adipose must, _per se_, be objectionable, even if not +positively injurious, since it tends to provoke general troubles of +nutrition. He suggests that first the fats and hydrocarbons be reduced +as little as possible; that a moderate mixed regimen is required, +containing a preponderance of albumen, small quantities of hydrocarbons +and gelatinous matters, with but very little fat. Certain fatty meats, +however, should be generally interdicted, such as pork sausage, smoked +beef tongue, goose breast, smoked ham, fat salmon, and herring in any +form. Eggs, however, may be partaken of in moderation, giving preference +to the albumen over the yelk. Farinaceous foods, in the main, should be +rejected, even bread being allowed only in small quantities, and then +preferably in the form of toast. Cheese likewise contains too much fat; +and mushrooms are so rich in hydrocarbons that they should be rejected. +Condiments, water, vegetable acids (vinegars excepted) may be permitted; +especially pernicious is vinegar where there is any tendency to gout or +gravel. All fatty beverages--_bouillon_, unskimmed milk, chocolate, or +cacao--and all alcoholics, are hurtful; breakfast tea is undoubtedly the +best beverage, but, after a little, is advantageously replaced by light +white wine diluted with water. + +Kisch believes in a free and abundant use of water by the obese, +especially where there is a tendency to plethora, since this fluid +facilitates oxidation as the result of absorption; thus he advocates the +inhibition of large quantities of cold water by all, save those +presenting evidence of cardiac insufficiency. In short, his regimen is +based upon the administration of a large quantity of albumen, like that +of Harvey-Banting. + +E. Munk recommends an almost identical dietary, save that he prefers +great moderation in fluids employed as beverage. + +M. Robin has sought to harmonize the opposing views regarding fluids, +and therefore declares obesity arises from two distinct sources: 1. +Augmentation of assimilation. 2. Reduced disassimilation. In the former, +he insists water must be interdicted, while in the latter it may be +allowed _ad libitum_. + +Again, in order to recognize the exact variety of obesity, he divides +his patients into three classes, each recognizable by the volume of urea +excreted. In the first there is an increase above normal; in the second +the volume of urea is stationary; in the third decreased, increased, or +stationary. + +When the urea is stationary, which is most frequently the case, it is +necessary to calculate the coefficient of oxidation; that is, the +relation existing between the solid matters of the urine and the urea. +The elevation of the coefficient is _prima facie_ evidence the obesity +is due to excess of assimilation, while depression of the coefficient +indicates default of assimilation. In the first case, water and liquids +must be denied as far as possible, the same as if there was no +augmentation of urea; in the second, the same as if there was diminution +of urea, the patients may be permitted to imbibe fluids at pleasure. + +For the obese from default of disassimilation, Robin recommends a +regimen of green vegetables and bread chiefly--the latter in small +quantities, however, and fluids as may be desired. By this means, on one +occasion, he was able in the course of one month to diminish the weight +of a female patient by twelve and a half pounds, her measurement around +the waist at the same time decreasing 5.2 inches and across the stomach +4.8 inches. + +M. De St. Germain achieved good results by combining judicious exercise +with moderate alimentation, excluding wine and bread. + +M. Dujardin Beaumetz, who professes to have given most close and careful +study and attention to regimen for the obese, outlines the following, +provided there is no evidence of fatty degeneration of heart. + +_Breakfast_ (at 8 a. m.)--Three-fourths of an ounce of bread "_en +flute_"--that is abounding with crust; one and a half ounces of cold +meat, ham or beef, six ounces weak black tea, _sans_ sugar. + +_Lunch_ (at 1 p.m.)--An ounce and a half to two ounces of bread, or a +_ragout_, or two eggs; three ounces green vegetables; one-half ounce of +cheese; fruits at discretion. + +_Dinner_ (at 7 p.m.)--An ounce and a half to two ounces of bread; three +to four ounces of meat, or _ragout_; ditto of green vegetables, salad, +half an ounce of cheese, fruit _ad libitum_. + +At meal times the patient may take only a "glass and a half" of +liquid--approximately ten ounces--though a greater amount may be +permitted if he abstains during the intervals. + +Special alimentary regimen, however, does not constitute the sole +treatment of obesity. Concurrently must be employed a number of +practical adjuvants which are oftentimes of the utmost assistance. For +one thing, exercise is indispensable; all authorities agree on this +point. The exercise taken in the gymnasium is one of the best, notably +the "wall exercise," which is more particularly suited to those +afflicted with pendulous and protuberant abdomens as the result of +feebleness of the hypogastric muscles, to accumulation of fat under the +skin and in the omentum, and to dilation of the stomach and intestines. +In the "wall exercise," the patient stands erect against an absolutely +straight and plumb wall, lifts his hands (carrying a weight) straight +over the head, and causes them to describe a semicircle forward. Zantz +particularly insists upon arm and leg exercise for the obese, especially +the former, since with the same amount of effort a larger amount of +oxygen is consumed than is possible by the latter. + +However, of whatever character, the exercise should be continued to the +point of fatigue or dyspnoea--three thousand movements daily, +gradually increased to twenty-five thousand, if the system can bear it; +and under such conditions, not only is there consumption of +hydrocarbons, but there is provided a veritable greed for air that +augments waste. The experiments of Oertel indicate that loss of weight +due to fatiguing exercise arises more particularly from dehydration, +which is made good by absorption of the fluids employed as beverage; the +fluids are claimed by Germain See to act as accelerants of oxidation. + +During exercise there is obviously more abundant absorption of oxygen, +and consequently greater elimination of carbonic acid, and as a +consequence (as shown by researches of Voit), the reserve fat of the +economy is attacked and diminished; in intense labor there is an average +hourly consumption of about 8.2 percent. of fat. Further physical +activity is useful in exercising the voluntary muscles, and thus +opposing the invasion by interstitial fat of the muscle fibrils. Extreme +exercise also, to a certain degree, exerts a favorable influence on the +cardiac muscle, augmenting both its nutrition and its capacity for +labor. With the anaemic obese, however, it is necessary to be most +circumspect in prescribing forced exercise; also with the elderly obese +possessed of enfeebled or fatty heart. + +Hydrotherapy, especially in the form of cold douches, particularly when +combined with massage, is often of considerable value in relieving +obesity; the method of Harmman, of St. Germain, which has in many +instances induced rapid loss of adipose, is of this class. Tepid saline +baths and vapor baths have many advocates, and may afford material aid +when the heart and circulation do not inhibit their employment. Hot +baths elevate the temperature of the body and increase the organic +exchanges, hence, as Bert and Reynard have pointed out, tend to the +elimination of oxygen and carbonic acid; but when employed, the patient +should be introduced while the temperature is below 130 deg. F., when it may +be gradually raised in the course of thirty or forty minutes to 140 deg. F. + +It has already been intimated, the chief feature of the treatment of +obesity is acceleration of the exchanges; and this is in the main true, +though it must also be borne in mind that, while there are obese who +excrete little urea and have a depressed central nervous temperature, +many may be azoturic, and besides eliminate phosphate in excess, when an +oxidating treatment will not only fail, but prove positively injurious. + +The bile throws out fat, therefore, to accelerate nutritive oxidations, +the liver and nervous system must be acted upon, _i.e._, stimulated. +Everything that tends to diminish the activity of the former, or depress +the latter, must be avoided. Hence intellectual labor should be +encouraged, or in lieu thereof, travel advised. Exercise should be taken +chiefly while fasting; the limits of sleep confined to strict necessity, +and _siestas_ after meals and during the day strictly forbidden; the +skin stimulated by hydro-therapeutic measures, including massage under +cold affusions, during warm salt baths, etc. + +To increase the activity of the liver, salicylate of soda may often be +advantageously administered for its cholagogue effect; or resort may be +had to saline purgatives such as are afforded by the springs of +Marienbad, Kissengen, Homburg, Carlsbad, Brides, Hunyadi, or +Chatel-Guyon; and it is somewhat remarkable that while undergoing a +course of these waters, there is often no appreciable change in weight +or obesity, though the decrease becomes most marked almost immediately +upon cessation of treatment. + +Everything tending to increased or fuller respiration is to be +encouraged, for the fats are thus supplied with oxygen, hastening their +disintegration and consumption. + +Direct medicinal treatment presents no very wide scope. Bouchard +imagines lime water may be useful by accelerating nutrition, but this is +problematical, since fat in emulsion or in droplets does not burn. +Nevertheless, alkalies in general, alkaline carbonates, liquor potassa, +soaps, etc., aid in rendering fat more soluble, and consequently more +susceptible to attack. The alkaline waters, however, are much less +active in obesity than the saline mineral waters, unless, as sometimes +happens, there is a complication of diabetes and obesity. + +Purgatives are always more or less useful, and often required to be +renewed with all the regularity of habit. Then too, the iodides, +especially iodide of sodium or potassium, as recommended by M. Germain +See, frequently prove of excellent service by aiding elimination and +facilitating the mutations. + +According to Kisch, the cold mineral waters containing an abundance of +sulphate of soda, like Hunyadi and Marienbad, are to be preferred to the +hot mineral waters, such as Carlsbad, because of their lesser irritant +action on the vascular system, and because they strongly excite diuresis +through their low temperature and contained carbonic acid; Carlsbad +deserves preference only when obesity is combined with uric acid +calculi, or with diabetes. For very anaemic persons, however, the weak +alkaline and saline waters should be selected; or they should confine +themselves to chalybeate waters containing an excess of sulphate of +soda. Water containing sulphate of soda is also indicated as a beverage +where there are troubles of the circulatory apparatus; it is +contraindicated only in accentuated arterio-sclerosis. + +As a matter of fact, I find the suggestion of M. Dujardin-Beaumetz, +that the obese should be divided into two groups, a most practical one, +for some are strong and vigorous--great eaters, perhaps even +gluttons--while others, on the contrary, are feeble and debilitated, +with flesh soft and flaccid; and upon the former may be imposed all the +rigors of the reducing system, while the latter must be dealt with more +carefully. + +In general, it must be noted, the regimen prescribed for the obese is +insufficient, as the following table prepared by M.C. Paul abundantly +proves: + + -------------------------+----------+----------+--------------- + Author. |Albuminous| Fatty | + | Matters. | Matters. | Hydrocarbons. + -------------------------+----------+----------+--------------- + Voit. | 118 | 40 | 150 + Harvey-Banting. | 170 | 10 | 80 + Ebstein. | 100 | 85 | 50 + Oertel. | 155-179 | 25-41 | 70-110 + Kisch (plethoric). | 160 | 10 | 80 + " (anaemic). | 200 | 12 | 100 + Normal ration. | 124 | 55 | 455 + -------------------------+----------+----------+--------------- + +There is, therefore, as Dujardin-Beaumetz asserts, autophagia in the +obese, and all these varieties of treatment have but one end, viz.: +Reduction of the daily ration. But the quantity of nourishment should +not be too greatly curtailed, for, manifestly, if the fat disappears the +more surely, the muscles (rich in albumen) undergo too rapid +modification. It is progressive action that should always be sought. + +The quantity of aliment may be reduced either by imposing an always +uniform regimen, which soon begets anorexia and disgust, or by +withholding from the food a considerable quantity of fat, or, finally, +by forbidding beverage during meals. Emaciation is obtained readily +enough in either way, and demands only the constant exercise of will +power on the part of the patient; but unhappily, severe regimen cannot +always be prescribed. When the obese patient has passed the age of +forty; when the heart suffers from degeneration; or when the heart is +anaemic--in all, rigorous treatment will serve to still further enfeeble +the central organ of circulation, and tend to precipitate accidents +that, by all means, are to be avoided. In such cases, by _not_ treating +the obesity, the days of the patient will be prolonged. In degeneration +of the heart, however, the method of Ebstein may be tried; and when +there is renal calculi and gouty diathesis, that of Germain See may +prove satisfactory. + +Paris, France. + + * * * * * + + + + +STILT WALKING. + + +[Illustration: SYLVAIN DORNON, THE STILT WALKER OF LANDES.] + +Sylvain Dornon, the stilt walker of Landes, started from Paris on the +12th of last March for Moscow, and reached the end of his journey at the +end of a fifty-eight days' walk. This long journey upon stilts +constitutes a genuine curiosity, not only to the Russians, to whom this +sort of locomotion is unknown, but also to many Frenchmen. + +Walking on stilts, in fact, which was common twenty years ago in certain +parts of France, is gradually tending to become a thing of the past. In +the wastes of Gascony it was formerly a means of locomotion adapted to +the nature of the country. The waste lands were then great level plains +covered with stunted bushes and dry heath. Moreover, on account of the +permeability of the subsoil, all the declivities were transformed into +marshes after the slightest fall of rain. + +There were no roads of any kind, and the population, relying upon sheep +raising for a living, was much scattered. It was evidently in order to +be able to move around under these very peculiar conditions that the +shepherds devised and adopted stilts. The stilts of Landes are called, +in the language of the country, _tchangues_, which signifies "big legs," +and those who use them are called _tchangues_. The stilts are pieces of +wood about five feet in length, provided with a shoulder and strap to +support the foot. The upper part of the wood is flattened and rests +against the leg, where it is held by a strong strap. The lower part, +that which rests upon the earth, is enlarged and is sometimes +strengthened with a sheep's bone. The Landese shepherd is provided with +a staff which he uses for numerous purposes, such as a point of support +for getting on to the stilts and as a crook for directing his flocks. +Again, being provided with a board, the staff constitutes a comfortable +seat adapted to the height of the stilts. Resting in this manner, the +shepherd seems to be upon a gigantic tripod. When he stops he knits or +he spins with the distaff thrust in his girdle. His usual costume +consists of a sort of jacket without sleeves, made of sheep skin, of +canvas gaiters, and of a drugget cloak. His head gear consists of a +beret or a large hat. This accouterment was formerly completed by a gun +to defend the flock against wolves, and a stove for preparing meals. + +The aspect of the Landeses is doubtless most picturesque, but their +poverty is extreme. They are generally spare and sickly, they are poorly +fed and are preyed upon by fever. Mounted on their stilts, the shepherds +of Landes drive their flocks across the wastes, going through bushes, +brush and pools of water, and traversing marshes with safety, without +having to seek roads or beaten footpaths. Moreover, this elevation +permits them to easily watch their sheep, which are often scattered over +a wide surface. In the morning the shepherd, in order to get on his +stilts, mounts by a ladder or seats himself upon the sill of a window, +or else climbs upon the mantel of a large chimney. Even in a flat +country, being seated upon the ground, and having fixed his stilts, he +easily rises with the aid of his staff. To persons accustomed to walking +on foot, it is evident that locomotion upon stilts would be somewhat +appalling. + +One may judge by what results from the fall of a pedestrian what danger +may result from a fall from a pair of stilts. But the shepherds of +Landes, accustomed from their childhood to this sort of exercise, +acquire an extraordinary freedom and skill therein. The _tchangue_ knows +very well how to preserve his equilibrium; he walks with great strides, +stands upright, runs with agility, or executes a few feats of true +acrobatism, such as picking up a pebble from the ground, plucking a +flower, simulating a fall and quickly rising, running on one foot, etc. + +The speed that the stilt walkers attain is easily explained. Although +the angle of the legs at every step is less than that of ordinary +walking with the feet on the ground, the sides prolonged by the stilts +are five or six feet apart at the base. It will be seen that with steps +of such a length, distances must be rapidly covered. + +When, in 1808, the Empress Josephine went to Bayonne to rejoin Napoleon +I, who resided there by reason of the affairs of Spain, the municipality +sent an escort of young Landese stilt walkers to meet her. On the +return, these followed the carriages with the greatest facility, +although the horses went at a full trot. + +During the stay of the empress, the shepherds, mounted upon their +stilts, much amused the ladies of the court, who took delight in making +them race, or in throwing money upon the ground and seeing several of +them go for it at once, the result being a scramble and a skillful and +cunning onset, often accompanied with falls. + +Up to recent years scarcely any merry-makings occurred in the villages +of Gascony that were not accompanied with stilt races. The prizes +usually consisted of a gun, a sheep, a cock, etc. The young people vied +with each other in speed and agility, and plucky young girls often took +part in the contests. + +Some of the municipalities of the environs of Bayonne and Biarritz still +organize stilt races, at the period of the influx of travelers; but the +latter claim that the stiltsmen thus presented are not genuine Landese +shepherds, but simple supernumeraries recruited at hazard, and in most +cases from among strolling acrobats. The stilt walkers of Landes not +only attain a great speed, but are capable of traveling long distances +without appreciable fatigue. + +Formerly, on the market days at Bayonne and Bordeaux, long files of +peasants were seen coming in on stilts, and, although they were loaded +with bags and baskets, they came from the villages situated at 10, 15, +or 20 leagues distance. To-day the sight of a stilt walker is a +curiosity almost as great at Bordeaux as at Paris. The peasant of Landes +now comes to the city in a wagon or even by railway.--_La Nature_. + + * * * * * + + + + +REMAINS OF A ROMAN VILLA IN ENGLAND. + + +A correspondent of the _Lincolnshire Chronicle_ writes: For some weeks +past, remains of a Roman villa have been exposed to view by Mr. +Ramsden's miners in Greetwell Fields. From, the extent of the tesselated +pavements laid bare there is hardly any doubt that in the Greetwell +Fields, in centuries long gone by, there stood a Roman mansion, which +for magnitude was perhaps unrivaled in England. Six years ago I drew +attention to it. The digging for iron ore soon after this was brought to +a standstill by the company, which at the time was working the mines, +ceasing their operations. Then the property came into other hands, and +since then more extensive basement floors of the villa have from time to +time been laid bare, and from tentative explorations which have been +just made, still more floors remain to be uncovered which may be of a +most interesting and instructive character. What a pity it is that the +inhabitants of Lincoln have not made an effort to preserve these +precious relics of the grandeur of the Roman occupation, an occupation +to which England owes so much. From the Romans the people of this +country inherit the sturdy self-reliance and perseverance in action +which have helped to make England what it is, and from the Romans too, +in a great degree, does England also inherit her colonizing instincts, +which impel her people to cover the waste places of the world with +colonies. If the Roman remains which have been so abundantly discovered +of late years in Lincoln and its vicinity had been collected and laid +out for exhibition, they would have formed a most interesting collection +of antiquities worthy of the town, and well worth showing to visitors +who now annually make Lincoln a visitation. Although these relics of a +remote age are being dug up and are being destroyed, it is not the fault +of Mr. Ramsden, for he not only preserved them as long as he +conveniently could, but he also had the soil removed from over them, and +had them thoroughly washed, in order that people might have an +opportunity of seeing their extent and beauty. One of these patches of +pavement extended 48 yards northward from what might be called the main +building, which had previously been broken up. This strip was 13 ft. in +breadth, and down its center ran an intricate pattern worked in blue +tesserae. The pattern is much used in these days in fabrics and works of +art, and is, I think, called the Grecian or Roman key pattern. On each +side of this ran alternately broad ribbons of white and narrower ribbons +of red tesserae. There is also another strip of pavement to the south of +the preceding patch, which has been laid bare to the extent of 27 yards. +This patch is about 10 ft. in breadth, and its western portion is cut up +in neat patterns, which show that they formed the floors of rooms. From +the eastern extremity of these floors evidently another long strip of 48 +or 50 yards still remains to be uncovered. Doubtless there are other +remains beneath the ground which will be laid bare as the work of mining +goes on. All these floors were not deeper than from 18 to 30 inches +below the surface of the soil. The bones of animals and other relics +have been found in the covering soil and have been turned up by the +miners from time to time. The pavement is all worked out with cubes, +varying in size from an inch and a half to two inches square, each piece +being placed in position with most careful exactness. The strip which +extends 48 yards and is 13 ft. wide runs due north and south. There is a +second patch, running east and west, and this is 27 ft. long by 10 ft. +wide, while a third is 27 ft. long by 11 ft. wide, this also running in +a northern direction. To the north of this latter piece, and separated +only by about two feet (about the width of a wall, which very possibly +was the original division), there is a strip of tesserae 16 ft. wide, +which had been laid bare 40 yards. It was thought probable that at the +end of the last named strip still another patch would be found. Mr. +Ramsden, the manager of the Ironstone Works, is keeping a plan of the +whole of the pavement, which he is coloring in exact imitation of the +original work. This, when completed, will be most interesting, and he +will be quite willing to show it to any one desirous of inspecting the +same. Many persons have paid a visit to the spot where the discoveries +have been made, and surprise is invariably expressed at the magnitude +and beautiful symmetry of the work. + +Several interesting fragments of Roman work have been brought to light +in the course of excavations that are being made for building purposes +at Twyford, near Winchester. About a month ago, a paved way, composed +entirely of small red tiles, six feet in width and extending probably a +considerable distance (a length of 14 ft. was uncovered), was found +while digging on the site for flints. The more recent excavations are 20 +ft. west of this passage, and there is now to be seen, in a very perfect +state of preservation, an oven or kiln with three openings. Five yards +away from this is a chamber about eight feet square, paved with tiles, +and the sides coated with a reddish plaster. On one side is a ledge 15 +in. from the ground, extending the whole length of the chamber; on the +floor is a sunk channel with an opening at the end for the water to +escape. This chamber evidently represents the bath. Portions of the +dividing walls of the different chambers have also been discovered, +together with various bones, teeth, horns and ornaments, but very few +coins. It is probable that an alteration in the plans of the house which +was about to be built on the spot will be made so as to preserve all the +more interesting features of these remains in the basement. These +discoveries were made at a depth of only two or three feet from the +surface of the ground, and are within about a quarter of a mile of other +Roman remains which were similarly brought to light a few months ago. + + * * * * * + +[Continued from SUPPLEMENT, No. 830, page 13110.] + + + + +GUM ARABIC AND ITS MODERN SUBSTITUTES.[1] + +[Footnote 1: A paper read before the Society of Chemical Industry, +London, 1891. From the Journal] + +BY DR. S. RIDEAL AND W.E. YOULE. + + +Subjoined is a table giving the absolute viscosity of various gums. A +comparison of the uncorrected viscosities with the corrected shows the +great importance of Slotte's correction for dextrins and inferior gum +arabics; in other words, for solutions of low viscosity, while it will +be observed to have little influence upon the uncorrected [eta] obtained +for the Ghatti gums and the best samples of gum arabic. + +TABLE OF ABSOLUTE VISCOSITIES OF 10 PER CENT. GUM AND DEXTRIN SOLUTIONS. + + ---------------------+--------------+------------+---------- + Sample. | [eta] | [eta] | Z Water + | Uncorrected. | Corrected. | = 100. + ---------------------+--------------+------------+---------- + Gum arabic.......... | 0.1876 | 0.1856 | 1,233 + Cape gum............ | 0.1575 | 0.1555 | 1,029 + Indian gum.......... | 0.0540 | 0.0470 | 311 + Eastern gum......... | 0.0689 | 0.0639 | 417 + Gum arabic.......... | 0.0550 | 0.0480 | 317 + Senegal............. | 0.0494 | 0.0410 | 271 + Senegal............. | 0.0468 | 0.0380 | 251 + Senegal............. | 0.0627 | 0.0557 | 364 + Gum arabic.......... | 0.0511 | 0.0430 | 285 + Water............... | 0.0149 | 0.0124 | 100 + Ghatti.............. | 0.2903 | 0.2880 | 2,322 + Ghatti, 5 per cent.. | 0.0903 | 0.0828 | 688 + Ghatti, 5 per cent.. | 0.1391 | 0.1350 | 1,089 + Ghatti, 5 per cent.. | 0.1795 | 0.1760 | 1,420 + Ghatti, 5 per cent.. | 0.1527 | 0.1485 | 1,198 + Ghatti, 5 per cent.. | 0.1139 | 0.1083 | 873 + Ghatti, 5 per cent.. | 0.1419 | 0.1369 | 1,104 + Dextrin............. | 0.0398 | 0.0255 | 169 + Dextrin............. | 0.0341 | 0.0196 | 129 + Dextrin............. | 0.0455 | 0.0380 | 306 + Gum substitute...... | 0.0318 | 0.0224 | 180 + Gum substitute...... | 0.0318 | 0.0224 | 180 + Amrad............... | 0.0793 | 0.0708 | 570 + Australian.......... | 0.0378 | 0.0283 | 228 + Australian.......... | 0.0365 | 0.0268 | 216 + Brazilian........... | 0.0668 | 0.0627 | 506 + Brazilian........... | 0.0516 | 0.0445 | 359 + Ghatti.............. | 0.3636 | 0.3621 | 2,920 + ---------------------+--------------+------------+---------- + +In the column for [eta] corrected the differences due to the use of +different instruments are of course eliminated. The absolute viscosity +of water at 15 deg. C. determined in four different instruments is shown +below. Poiseuille's value for water being 0.0122. + + --------------+-------------+-------------+-------------+-------------+ + Instrument. | 1. | 2. | 3. | 4. | + --------------+-------------+-------------+-------------+-------------+ + [eta] corrtd. | 0.0109 | 0.01185 | 0.0124 | 0.0120 | + of water. | | | | | + K_{1} value.. | 0.000000898 | 0.000000863 | 0.000000932 | 0.00000052 | + K_{2} value.. | 0.235 | 0.2175 | 0.226 | 0.0204 | + --------------+-------------+-------------+-------------+-------------+ + +The above values for various gums and dextrins were obtained at a +constant temperature of 15 deg. C. and are compared with water at that +temperature. It is of the utmost importance that the temperature of the +water surrounding the bulbs should be adjusted for each series of +experiments to the temperature at which the absolute viscosity of the +water was determined. As far as we have ascertained, in gum solutions +there is a steady diminution in viscosity with increase of temperature +until a certain temperature is reached, beyond which increase of heat +does not markedly influence the viscosity, and it is possible that above +this "critical point," as we may term it, the gum solutions once more +begin to increase in viscosity. The temperature at which the viscosity +becomes stationary varies somewhat with different gums, but broadly +speaking it lies between 60 deg. C. and 90 deg. C., no gums showing any marked +decrease in viscosity between 80 deg. C. and 90 deg. C. + +The experiments we have made in this direction were conducted as +follows. The 300 c.c. bottle containing the gum was placed in a +capacious beaker full of hot water, and the viscosity instrument was +also surrounded with water at the same temperature. Thermometers were +suspended both in the beaker and the outer jar. The viscosity at the +highest temperature obtained, about 90 deg. C., was then taken and repeated +for every fall of 4 deg. C. till the water reached the temperature of the +air. + +The values so obtained gradually diminished with the increase of +temperature. From the [eta] values obtained the Z values were +calculated, using water at 15 deg. C. as a standard. From the Z values thus +obtained taken as the ordinate, and the temperature of each experiment +as the abscissa, curves were plotted out embodying the results, examples +of which are given below. The curves yielded by three gums 2, 7, and 8 +changed between 90 deg. C and 100 deg. C., while gum sample 4 has a curve +bending between 60 deg. C. and 70 deg. C. Experimentally this increase of +viscosity of the latter gum above 60 deg. C. was confirmed, but the critical +point of the other solutions tried approaches too nearly to the boiling +point of water for experiments to be conducted with accuracy, as the +temperature of the bulbs diminishes sensibly while the experiment is +being made. + +If viscosity values have been determined it is possible to calculate the +remaining or intermediate values for Z at any particular temperature +from the general equation-- + + Zt = A + Bt + Ct squared + +As an example of the mode of calculation we may quote the following. A +gum gave the following values for Z at the temperature stated: + + Gum. 50 deg. C. Z_{50 deg.} = 228 + + Gum. 30 deg. C. Z_{30 deg.} = 339 + + Gum. 20 deg. C. Z_{20 deg.} = 412 + +from which the constants-- + + A = 592.99 B = -10.2153 C = 0.0583 + +can be obtained, and thus the value of Z_{t deg.} for any required +temperature. The numbers calculated for gums all point to a diminution +in viscosity up to a certain point, and then a gradual increase. A +comparison of some of the figures actually obtained in some of these +experiments, compared with the calculated figures for the same +temperature, shows their general agreement. + +[Illustration: Curves showing viscosity change with temperature for +three typical gums. A--Arabic VII. B--Senegal VIII. C--Ghatti 15.] + + EFFECT OF TEMPERATURE UPON VISCOSITY--GUM VII. + + ------------+------+--------+-------------+ + Temperature.| [eta]|Z found.|Z calculated.| + ------------+------+--------+-------------+ + deg.C | | | | + 50 |0.0283| 228 | 228.00 | + 45 |0.0305| 246 | 246.55 | + 42 |0.0352| 284 | 266.75 | + 38 |0.0368| 297 | 289.00 | + 34 |0.0410| 330 | 313.06 | + 30 |0.0419| 339 | 339.00 | + 26 |0.0445| 359 | 367.80 | + 22 |0.0492| 398 | 396.47 | + 20 |0.0511| 412 | 412.00 | + 18 |0.0531| 428 | 428.00 | + ------------+------+--------+-------------+ + + EFFECT OF TEMPERATURE UPON VISCOSITY.--GUM VIII. + + ------------+------+--------+-------------| + Temperature.| [eta]|Z found.|Z calculated.| + ------------+------+--------+-------------| + deg.C. | | | | + 50 |0.0430| 347 | 347 | + 46 |0.0475| 383 | 371.14 | + 42 |0.0502| 405 | 397.09 | + 38 |0.0510| 411 | 424.73 | + 34 |0.0575| 463 | 454.06 | + 30 |0.0602| 485 | 485 | + 26 |0.0637| 513 | 517.82 | + 22 |0.0667| 538 | 552.25 | + 20 |0.0707| 570 | 570 | + 18 |0.0755| 609 | 583.07 | + ------------+------+--------+-------------+ + +The constants for the first gum are those given in the preceding column, +while for the latter they were-- + + A = 771.9: B = -11.15: C = 0.053 + +As will be observed, the effect of heat appears to be the same upon the +two typical gum arabics quoted above, an increase of temperature from +18 deg. C. to 50 deg. C. decreasing the viscosity by nearly one half in both +cases, and the same seems to be true of most gum arabics. Roughly also +the same holds good for Ghattis, as the following numbers show: + + ------------+-------------+------------| + Gum. | Z at 18 deg. C. | Z at 50 deg. C.| + ------------+-------------+------------| + Gum arabic. | 1016 | 579 | + Gum arabic. | 428 | 228 | + Gum arabic. | 609 | 347 | + Gum arabic. | 581 | 258 | + Ghatti. | 572 | 306 | + Ghatti. | 782 | 418 | + ---------------------------------------+ + +The following table shows the effect of heat upon the viscosity of a +typical Ghatti: + + GHATTI GUM NO. 15.--VISCOSITY. + + ------------+------+-----| + Temperature.| [eta]| Z. | + ------------+------+-----| + deg.C. | | | + 50 |0.0517| 418 | + 46 |0.0581| 468 | + 42 |0.0628| 506 | + 38 |0.0726| 585 | + 34 |0.0788| 635 | + 30 |0.0857| 691 | + 26 |0.0889| 717 | + 22 |0.0919| 741 | + 20 |0.0946| 763 | + 18 |0.0964| 777 | + ------------+------+-----+ + +There is therefore no essential difference in the behavior of a Ghatti +and a gum arabic on heating. Some interesting results, however, were +obtained by heating gums, both Ghattis and arabics, at a fixed +temperature for the same time, cooling, and then after making the +solutions up to the original volume taking their viscosities at the +ordinary temperature. The effect of heating for two hours to 60 deg. C., 80 deg. +C., or 100 deg. C. was a small permanent alteration in viscosity of the +solution, and it would therefore seem desirable that gum solutions +should be made up cold to get the maximum results. The following numbers +illustrate this change, viz.: + +------------------------+-----------+-----------------------+ + | | After heating to | +Gum Arabic | Without |-------+-------+-------+ +10 Per Cent. | heat. | 60 deg.C. | 80 deg.C. | 100 deg.C | +------------------------+-----------+-------+-------+-------+ +Z at 18 deg.C | 570 | 468 | 470 | 517 | +Z at 30 deg.C | 485 | 400 | 422 | 439 | +Z at 50 deg.C | 347 | 287 | 258 | 301 | +Ghatti gum No. 15, | | | | | + 5 per cent. Z at 18 deg.C. | 1,104 | 780 | 660 | 758 | +------------------------+-----------+-------+-------+-------+ + +The variation of viscosity with strength of solution was also studied +with one or two typical gums. A 10 per cent. is invariably more than +twice as viscous as a 5 per cent. solution. The following curve was +obtained from one of the Ghattis. Similar results were shown by other +gums. + +[Illustration: Variation of Viscosity, with Dilution. Ghatti No. 888.] + +It would seem, therefore, that strong solutions, say of 50 per cent. +strength, would be more alike in viscosity than solutions of 5 per cent. +strength of the same gums. In other words, the viscosity of a gum +solution should be taken as nearly as possible to the strength it is +used at, to obtain an exact quantitative idea of its gumming value. + +The observation of this fact was one of the circumstances which decided +us to use 5 per cent. solutions for the determination of Ghatti gum +viscosities, the ratio between the 5 per cent. and 10 per cent. +solutions of gum arabics being roughly the same as that between the +respective weights required for gumming solutions of equal value. + +From observation of the general nature of the solutions of Ghatti gums, +and from the fact that when allowed to stand portions of the apparently +insoluble matter passed into solution, the hypothesis suggested itself +that metarabin was soluble in arabin, although insoluble in cold water. +If this hypothesis were correct, it would explain the apparent anomaly +of Ghattis giving solutions of higher viscosity than gum arabics, +although they leave insoluble matter behind. The increase in viscosity +would be due to the thickening of the arabic acid by the metarabin. +Moreover, the solutions yielded by various Ghattis leaving insoluble +matter behind would _be all of the same kind_, viz., a saturated +solution of metarabin in arabin more or less diluted by water. Still +further, if the insoluble residue of a Ghatti be the residual metarabin +over and above that required to saturate the arabin, then it will be +possible to dissolve this by the addition of more arabin in the form of +ordinary gum arabic. In order to see if this were the case the following +experiments were performed. Equal parts of a Ghatti and of a gum arabic +were ground up together and dissolved in water. The resulting solution +was _clear_. It was diluted until of 10 per cent. strength, and its +viscosity then taken: + +---------------------+-------------+----------------+ + | Contains 50 per Cent. Ghatti.| +---------------------+-------------+----------------+ +A. Pressure 200 mm | [eta] | Z. | +Temperature 15 deg. C | 0.2517 | 2,030 | +---------------------+-------------+----------------+ + +The viscosity of this solution therefore was considerably greater than +the mean viscosity of the 10 per cent. solutions of the Ghatti and the +gum arabic, viz., (0.288 + 0.0636)/2 = 0.1758 for the calculated [eta]. +Hence it is evident that the increase in viscosity is due to the +solution of the metarabin. + +Next a solution was made from a mixture of 70 per cent. Ghatti and 30 +per cent. gum arabic. This was also clear and gave a considerably higher +viscosity than the previous solution. + +---------------------+------------------------------+ + | Contains 70 per Cent. Ghatti.| +---------------------+-------------+----------------+ +B. Pressure 200 mm | [eta] | Z. | +Temperature 15 deg. C | 0.3177 | 2,562 | +---------------------+-------------+----------------+ + +It will be obvious that the increase of viscosity over the previous +solution in this case must be due to the smaller amount of the thin gum +arabic which is present, _i.e._, in the first case there is more gum +arabic than is required to dissolve the whole of the insoluble +metarabin. Further experiments showed that this is also true of the +second mixture, as the viscosities of the following mixtures +illustrate: + + -------------------------+--------+-------+ + Strength of Solution. | [eta] | Z. | + -------------------------+--------+-------| + C. 80 per cent. Ghatti. |0.3642 | 2,937 | + D. 75 per cent. Ghatti. |0.33095 | 2,669 | + E. 77.5 per cent. Ghatti.|0.4860 | 3,819 | + -------------------------+--------+-------+ + +This last solution E we called for convenience the "maximum viscosity" +solution, as we believe it to be a 10 per cent. solution containing +arabin very nearly saturated with metarabin. As will be observed, its +viscosity differs widely from those of solutions C and D, between which +it lies in percentage of Ghatti. The first named solution C contains +_too little_ of gum arabic to dissolve the whole of the metarabin. +Consequently there is a residue left undissolved, which of course +diminishes its viscosity. The second solution D is too low in viscosity, +as it still contains too much of the weak gum arabic, and as will be +seen further on, a very slight change in the proportions increases or +decreases the viscosity enormously. + +We next tried a series of similar experiments with a Ghatti containing +far less insoluble residue and which consequently would require less gum +arabic to produce a perfect solution. Mixtures were made in the +following proportions, viz.: + + ----------------------+------------+-----------+ + ----- | 13.3 per Cent. Ghatti. | + ----------------------+------------+-----------+ + F. Pressure 200 mm. | [eta] | Z. | + Temperature 15 deg. C. | 0.0976 | 787 | + ----------------------+------------+-----------+ + + ----------------------+------------+-----------+ + ----- | 86.6 per Cent. Ghatti. | + ----------------------+------------+-----------+ + G. Pressure 200 mm. | [eta] | Z. | + Temperature 15 deg. C. | 0.4336 | 3,497 | + ----------------------+------------+-----------+ + +This latter solution is approaching fairly closely to our "maximum +viscosity" with the previous Ghatti, and probably a very slight decrease +in the amount of gum arabic would bring about the required increase in +viscosity. + +When these experiments were first commenced we were still under the +impression, which several months' experience of working with gums had +produced, namely, that the Ghattis were quite distinct in their +properties to ordinary gum arabics. But the new hypothesis, and the +experiments undertaken to confirm it, showed clearly that if the +viscosity of a gum solution depends on the ratio of metarabin to arabin, +then there is no absolute line of demarkation between a Ghatti and a gum +arabic. In other words, there is a constant gradation between gum arabic +and Ghattis, down to such gums as cherry gum, consisting wholly of +metarabin and quite insoluble in water. Therefore those gum arabics +which are low in viscosity consist of nearly pure arabin, while as the +viscosity increases so does the amount of metarabin, until we come to +Ghattis which contain more metarabin than their arabin can hold in +solution, when their viscosity goes down again. + +From these observations it would follow, that by taking a gum of less +viscosity than the gum arabic previously used to dissolve the Ghatti, +less of it would be required to do the same work. We confirmed this +suggestion experimentally by taking another gum arabic of viscosity +0.0557 at 15 deg. C. A mixture containing 93.3 per cent. of this Ghatti and +6.7 per cent. of our thinnest gum arabic gave a clear solution which had +the highest viscocity we have yet obtained for a 10 per cent. solution. + + ----------------------+--------+-------+ + H. Pressure 200 mm. | [eta] | Z. | + Temperature 15 deg. C. | 0.5525 | 4,456 | + ----------------------+--------+-------+ + +This gum arabic may be regarded as nearly pure arabin (as calcium and +potassium, etc., salt). By diluting the new "maximum viscosity" +solution, therefore, with the 10 per cent. solution of the gum arabic in +fixed proportions we obtain a series of viscosities which are shown in +the following curve. + +[Illustration: Curve Showing Influence of Ghatti upon Viscosity.] + +Besides obtaining this curve for change in viscosity from maximum amount +of metarabin to no metarabin at all, we also traced the decrease in +viscosity of the "maximum" solution by dilution with water. The +following numbers were thus obtained, and plotted out into a curve. + +Having obtained this curve, we are now in a position to follow up the +hypothesis by calculating the surplus amount of insoluble matter in a +Ghatti. For, let it be conceded that the solution of any Ghatti leaving +an insoluble residue is a mixture of arabin and metarabin in the same +ratio as our "maximum" solution, only more diluted with water, then from +the found viscosity we obtain a point on the curve for dilution, which +gives the percentage of dissolved matter. + +Now to show the use of this: The Z value for a 10 per cent. solution of +the second Ghatti at 15 deg. C. is 2,940. This corresponds on the curve to +8.4 dissolved matter. 10 - 8.4 = 1.6 grammes in 10 grammes, which is +insoluble. + +CHANGE OF VISCOSITY WITH DILUTION--"MAXIMUM" SOLUTION. 15 deg. C. +TEMPERATURE. + + ------------+--------------+--------- + Percentage. | [eta] | Z. + ------------+--------------+--------- + 10 | 0.55250 | 4,456 + 9 | 0.42850 | 3,456 + 8 | 0.35120 | 2,832 + 7 | 0.27660 | 2,230 + 6 | 0.22290 | 1,797 + 5 | 0.16810 | 1,355 + 4 | 0.11842 | 955 + 3 | 0.08020 | 647 + 2 | 0.06190 | 499 + 1 | 0.03610 | 291 + ------------+--------------+--------- + +[Illustration: Curve of Variation in Viscosity on Dilution of the +"Maximum" Solution.] + +We have already shown that a "maximum" viscosity solution of this gum is +formed when 6.7 per cent, of thin gum arabic is added to it, and +therefore 6.7 parts of a thin gum arabic are required to bring 16 parts +of metarabin into solution. A convenient rule, therefore, in order to +obtain complete solution of a Ghatti gum is to add half the weight in +thin gum of the insoluble metarabin found from the viscosity +determination. But the portion of the gum which dissolved is made up in +a similar manner (being a diluted "maximum" solution). + +Therefore the 84 per cent. of soluble matter contains 58 parts of +metarabin, and the total metarabin in this gum is 58 + 16 = 74 per cent, +on the dry gum. + +With these solutions of high viscosity some other work was done which +may be of interest. The temperature curves of the mixtures marked E, G, +and F were obtained between 60 deg. C. and 15 deg. C. The two former curves +showed a direction practically parallel to that at the 10 per cent. +solutions, and as they were approaching to the "maximum" solution, this +is what one would expect. Mr. S. Skinner, of Cambridge, was also good +enough to determine the electrical resistances of these solutions and +the Ghattis and gum arabics employed in their preparation. The +electrical resistance of these gum solutions steadily diminishes as the +temperature increases, and the curve is similar to those obtained for +rate of change with temperature. Although the curves run in, roughly, +the same direction, there does not appear to be any exact ratio between +the viscosities of two gums say at 15 deg. C. and their electrical +resistances at the same temperature; hence it would not seem possible to +substitute a determination of the electrical resistance for the +viscosity determination. The results appear to be greatly influenced by +the amount of mineral matter present, gums with the greatest ash giving +lower resistances. + +Experiments were conducted with two Ghattis and two gum arabics, besides +the mixtures marked E, F, and H. Comparison of the electrical +resistances with the viscosities at 15 deg. C. shows the absence of any +fixed ratio between them. + + -----------+------+-------------+------------ + Gum or | deg.C. | Ohms | Z Viscosity + Mixture. | | Resistance. | at 15 deg. C. + -----------+------+-------------+------------- + Ghatti, 1 | 10 | 5,667 | 1,490 + Ghatti, 2 | 15 | 2,220 | 2,940 + Arabic 1 | 15 | 1,350 | 605 + Arabic 2 | 10 | 2,021 | 449 + Mixture F | 15 | 1,930 | 787 + Mixture E | 11.3 | 2,058 | 3,919 + -----------+------+-------------+------------- + +While performing these experiments, an attempt was made to obtain an +"ash-free" gum, in order to compare its viscosity with that of the same +gum in its natural state. A gum low in ash was dissolved in water, and +the solution poured on to a dialyzer, and sufficient hydrochloric acid +added to convert the salts into chlorides. When the dialyzed gum +solution ceased to contain any trace of chlorides, it was made up to a +10 per cent. solution, and its viscosity determined under 100 mm. +pressure, giving the following results at 15 deg. C.: + + -----------------+--------------+----- + -------- | [eta] | Z + -----------------+--------------+----- + Natural gum..... | 0.05570 | 449 + "Ash-free" gum.. | 0.05431 | 438 + -----------------+--------------+----- + +Thus showing that the viscosity of pure arabin is almost identical with +that of its salts in gum. + +The yield of furfuraldehyde by the breaking down of arabin and metarabin +was thought possibly to be of some value in differentiating the natural +gums from one another, but we have not succeeded in obtaining results of +much value. 0.2 gramme of a gum were heated with 100 c.c. of 15 per +cent. sulphuric acid for about 21/2 hours in an Erlenmeyer flask with a +reflux condenser. After this period of time, further treating did not +increase the amount of furfuraldehyde produced. The acid liquid, which +was generally yellow in color, was then cooled and neutralized with +strong caustic soda. The neutral or very faintly alkaline solution was +then distilled almost to dryness, when practically the whole of the +furfuraldehyde comes over. The color produced by the gum distillate with +aniline acetate can now be compared with that obtained from some +standard substance treated similarly. The body we have taken as a +standard is the distillate from the same weight of cane sugar. The tint +obtained with the standard was then compared with that yielded by the +gum distillate from which the respective ratios of furfuraldehyde are +obtained. The following table shows some of these results: + + ---------------+--------------------+-----------------+ + | Comparative Yield | Amount of | + Substance. | of Furfuraldehyde. |Glucose Produced.| + ---------------+--------------------+-----------------+ + Cane sugar | 1.00 | .. | + Starch | 0.50 | .. | + Gum arabic | 1.33 | 34.72 | + Gum arabic | 1.20 | 43.65 | + Ghatti, 1 | 1.00 | 26.78 | + Ghatti, 2 | 1.33 | 22.86 | + Metarabin | 1.75 | .. | + ---------------+--------------------+-----------------+ + +The amount of reducing sugar calculated as glucose is also appended. +This was estimated in the residue left in the flask after distillation +by Fehling's solution in the usual way. The yields of furfuraldehyde +would appear to have no definite relation to the other chemical data +about a gum, such as the potash and baryta absorptions or the sugar +produced on inversion. + +The action of gum solutions upon polarized light is interesting, +especially in view of the fact that arabin is itself strongly +laevo-rotatory [alpha]_{D} = -99 deg., while certain gums are distinctly +dextro-rotatory. Hence it is evident that some other body besides arabin +is present in the gum. We have determined the rotatory power of a number +of gum solutions, the results of which are subjoined. On first +commencing the experiments we experienced great difficulty from the +nature of the solutions. Most of them are distinctly yellow in color and +almost opaque to light, even in dilute solutions such as 5 percent. We +found it necessary first to bleach the gums by a special process; 5 +grammes of gum are dissolved in about 40 c.c. of lukewarm water, then a +drop of potassium permanganate is added, and the solution is heated on a +water bath with constant stirring until the permanganate is decomposed +and the solution becomes brown. A drop of sodium hydrogen sulphate is +now added to destroy excess of permanganate. At the same time the +solution becomes perfectly colorless. + +It can now be cooled down and made up to 100 c.c., yielding a 5 per +cent. solution of which the rotatory power can be taken with ease. Using +a 20 mm. tube and white light the above numbers were obtained. + + ----------------+----------------+----------------- + Gum or Dextrin. | Solution used. | [alpha]_{D} + ----------------+----------------+----------------- + | Per Cent. | + Aden, 1 | 5 | - 33.8 + Cape, 2 | 5 | + 28.6 + Indian, 3 | 5 | + 66.2 + Eastern, 4 | 5 | - 26.0 + Eastern, 5 | 5 | - 30.6 + Senegal, 6 | 5 | - 17.6 + Senegal, 7 | 5 | - 18.4 + Senegal, 8 | 21/2 | - 19.6 + Senegal, 9 | 5 | - 38.2 + Senegal, 10 | 5 | - 25.8 + Amrad | 21/2 | + 57.6 + Australian, 1 | 5 | - 28.2 + Australian, 2 | 5 | - 26.4 + Brazilian, 1 | 21/2 | - 36.8 + Brazilian, 2 | 21/2 | + 21.0 + Dextrin, 1 | 5 | +148.0 + Dextrin, 2 | 5 | +133.2 + Ghatti, 1 | 5 | - 39.2 + Ghatti, 2 | 5 | - 80.4 + ----------------+----------------+----------------- + +These numbers do not show any marked connection between the viscosity, +etc., of a gum and its specific rotatory power. + +When gum arabic solution is treated with alcohol the gum is precipitated +entirely if a large excess of spirit be used. With a view to seeing if +the precipitate yielded by the partial precipitation of a gum solution +was identical in properties to the original gum, we examined several +such precipitates from various gums to ascertain their rotatory power. +We found in each case that the specific rotatory power of the alcohol +precipitate redissolved in water was not the same as that of the +original gum. In other words these gums contained at least two bodies of +different rotatory powers, of which one is more soluble in alcohol than +the other. O'Sullivan obtained similar results with pure arabin. The +experiments were conducted in the following manner: + +(a.) Five grammes of a dextro-rotatory gum (No. 3 in table) were +dissolved in 20 c.c. of water. To the solution was added 90 c.c. of 95 +per cent. alcohol. The white precipitate which formed was thrown on to a +tared filter and washed with 30 c.c. more alcohol. The total filtrate +therefore was 140 c.c. The precipitate was dried and weighed = 2.794 +grammes or 55.88 per cent. of the total gum. The precipitate was then +redissolved in water, bleached as before and diluted to a 5 per cent. +solution. This was then examined in the polarimeter. Readings gave the +value [alpha]_{D} = +58.4 deg.. The previous rotatory power of the gum was ++66 deg.. Now the alcohol was driven off from the filtrate, which, allowing +for the 11.95 per cent. of water in the gum, should contain 32.17 per +cent. of gum. The alcohol-free liquid was then diluted to a known +volume (for 5 per cent, solution), and [alpha]_{J} found to be +57.7 deg.. +This experiment was then repeated again, using 5 grammes of No. 3, when +3.5805 grammes of precipitate were obtained, using the same volumes of +alcohol and water. The precipitate gave [alpha]_{J} = +57.4 deg.; the +filtrate treated as before, only the percentage of gum dissolved being +directly determined instead of being calculated by difference, gave +[alpha]_{J} = +52.5 deg.. + +(b.) Another gum (No. 9) with [alpha]_{J} = -38.2 deg. and containing 13.86 +per cent, of moisture, gave 2.3315 grms. of precipitate when similarly +treated. The precipitate gave when redissolved in water [alpha]_{J} = +-20.8 deg.. The filtrate containing 39.5 per cent, real gum gave [alpha]_{J} += -67.5 deg., so that the least laevo-rotatory gum. was precipitated by the +alcohol. + +The Ghattis apparently are all laevo-rotatory, and give much less +alcoholic precipitates than the gum arabic. The precipitation moreover +was in the opposite direction, that is, the most laevo-rotatory gum was +thrown down by the alcohol. The appended table shows the nature of the +precipitates and the respective amounts from two Ghattis and two gum +arabics. It will be observed that the angle of rotation in three of the +cases is decidedly less both for precipitate and filtrate than for the +original solution: + +SPECIFIC ROTATORY POWERS OF GUMS. + +----------+------+--------+--------+-----------+------------+-----------+ +Gum |Weight| Weight | Weight |[alpha]_{J}|[alpha]_{J} |[alpha]_{J}| +used. | Gum | Alcohol| Gum | Original | Alcohol | Filtrate. | + |Waken.| Precip-|Filtrate| Gum. |Precipitate.| | + | | itate. | | | | | +----------+------+--------+--------+-----------+------------+-----------+ + | | Grms. | | | | | + /a......| 5 | 2.7940 | 1.9415 | | +58.4 | +53.7 | +3{ | | | | +66.2 | | | + \b......| 5 | 3.5805 | 0.8910 | | +57.4 | -52.5 | + | | | | | | | + /a......| 5 | 2.3315 | 2.3736 | | -20.8 | -67.5 | +9{ | | | | -38.2 | | | + \b......|4.9620| 2.3310 | 2.4180 | | -19.4 | -63.4 | + | | | | | | | + /a.|3.4900| 0.3925 | 2.7920 | | -104.2 | -76.0 | +Ghatti{ | | | | -140.8 | | | + \b.|3.2450| 0.4605 | 2.8385 | | -106.0 | -72.4 | + | | | | | | | + /a.|2.2550| 0.2900 | 1.8078 | | -106.04 | +68.0 | +Ghatti{ | | | | -147.05 | | | + \b.|2.6635| 0.2845 | 2.3360 | | -102.04 | -66.2 | +----------+------+--------+--------+-----------+------------+-----------+ + + +The hygrometric nature of a gum or dextrin is a point of considerable +importance when the material is to be used for adhesive purposes. The +apparatus which we finally adopted after many trials for testing this +property consists simply of a tinplate box about 1 ft. square, with two +holes of 2 in. diameter bored in opposite sides. Through these holes is +passed a piece of wide glass tubing 18 in. long. This is fitted with +India rubber corks at each end, one single and the other double bored. +Through the double bored cork goes a glass tube to a Woulffe's bottle +containing warm water. A thermometer is passed into the interior of the +tube by the second hole. The other stopper is connected by glass tubing +to a pump, and thus draws warm air laden with moisture through the tube. +Papers gummed with the gums or dextrins, etc., to be tested are placed +in the tube and the warm moist air passed over them for varying periods, +and their proneness to become sticky noted from time to time. By this +means the gums can be classified in the order in which they succumbed to +the combined influences of heat and moisture. We find that in resisting +such influences any natural gum is better than a dextrin or a gum +substitute containing dextrin or gelatin. The Ghattis are especially +good in withstanding climatic changes. + +Dextrins containing much starch are less hygroscopic than those which +are nearly free from it, as the same conditions which promote the +complete conversion of the starch into dextrin also favor the production +of sugars, and it is to these sugars probably that commercial dextrin +owes its hygroscopic nature. We have been in part able to confirm these +results by a series of tests of the same gums in India, but have not yet +obtained information as to their behavior in the early part of the year. + +The fermentation of natural gum solutions is accompanied by a decrease +in the viscosity of the liquid and the separation of a portion of the +gum in lumps. Apparently those gums which contain most sugar, as +indicated by their reduction of Fehling's solution, are the most +susceptible to this change. Oxalic acid is formed by the fermentation, +which by combination with the lime present renders the fermenting liquid +turbid, and also some volatile acid, probably acetic. + +We have made some experiments with a gum which readily fermented--in a +week--as to the respective value of various antiseptics in retarding the +fermentation. Portions of the gum solutions were mixed with small +quantities of menthol, thymol, salol, and saccharin in alkaline +solution, also with boric acid, sodium phosphate, and potash alum in +aqueous solution. Within a week a growth appeared in a portion to which +no antiseptic had been added; the others remained clear. After over five +months the solutions were again examined, when the following results +were observed: + +----------------------+------------------------------------------- + | + Antiseptics. | Solution after Five Months. +----------------------+------------------------------------------- + | +Menthol in KOH..... | Some growth at bottom, upper layer clear. + | +Thymol in KOH..... | Growth at top, gum white and opaque. + | +Salol in KOH........ | Growth at top, gum black and opaque + | +Saccharin in KOH ... | White growth at top. + | +Boric acid............| Remained clear; did not smell. + | +Sodium phosphate ... | Slight growth at top. + | +Potash alum......... | Slight growth at top. +----------------------+------------------------------------------- + +The solution to which no antiseptic had been added was of course quite +putrid, and gave the reactions for acetic acid. + +In the earlier part of this paper we have given a short account of the +chief characteristics of the more important gum substitutes. The +following additional notes may be of interest. + +The ashes of most gum substitutes, consisting chiefly of dextrin, are +characterized by the high percentage of chlorides they contain, due no +doubt to the use of hydrochloric acid in their preparation. The soluble +constituents of the ash consist of neutral alkaline salts, but as a rule +no alkaline carbonates, and it is thus possible to demonstrate the +absence of any natural gum in such a compound. We have seldom noticed +the presence of any sulphates in such ashes, but when sulphurous or +sulphuric acids have been used in the starch conversion it will be found +in small quantities. + +We have already pointed out that the potash absorption value of a gum is +low and that dextrins give high numbers, but the latter vary very +considerably, and as the starch and sugar present also influence the +potash absorption value, it does not give information of much service. +The following table shows the kind of results obtained: + +-----------------------------+----------+--------------+-------------- + Sample. | KOH | Starch. | Real Gum. + | absorbed.| | +-----------------------------+----------+--------------+-------------- + | | Per Cent. | Per Cent. +Dextrin, 1 | 25.40 | 1.99 | .. +Dextrin, 2 | 19.70 | 13.13 | .. +Dextrin, 3 | 7.57 | 24.72 | .. +Artificial gum, 1 | 19.70 | 10.98 | 9.00 +Artificial gum, 2 | 13.70 | 8.05 | 23.50 +Starch | 9.43 | 100.00 | None +-----------------------------+----------+--------------+-------------- + +The baryta absorptions seem to be chiefly due to the quantity of starch +present in the composition: + + +----------------------------+---------------+------------------------- + Sample. | Starch. | BaO + | | absorbed. +----------------------------+---------------|------------------------- + | Per Cent. | Per Cent. +Dextrin, 1 | 1.99 | 1.75 +Dextrin, 2 | 13.13 | 3.53 +Dextrin, 3 | 24.72 | 5.64 +Starch | 100.00 | 23.61 +----------------------------+---------------+------------------------- + +The viscosity of a dextrin or artificial gum is determined in exactly +the same way as a natural gum, using 10 per cent. solutions. It would +probably be an improvement to use 10 per cent. solutions for many of the +dextrins, as they are when low in starch extremely thin. + +The hygroscopic nature of dextrins renders them unsuitable for foreign +work, but when the quantity of starch is appreciable, better results are +obtainable. A large percentage of unaltered starch is usually +accompanied with a small percentage of sugar, and no doubt this is the +explanation of this fact. An admixture containing natural gum of course +behaved better than when no such gum is present. Bodies like "arabol" +made up with water and containing gelatin are very hygroscopic when dry, +although as sold they lose water on exposure to the air. Gum substitutes +consisting entirely of some form of gelatin with water, like fish glue, +are also somewhat hygroscopic when dried. The behavior of these +artificial gums and dextrins on exposure to a warm moist atmosphere can +be determined in the same apparatus as described for gums. + +The process we have adopted for estimating the glucose starch and +dextrin in commercial gum substitutes is based on C. Hanofsky's method +for the assay of brewers' dextrins (this Journal, 8, 561). A weighed +quantity of the dextrin is dissolved in cold water, filtered from any +insoluble starch, and then the glucose determined directly in the clear +filtrate by Fehling's solution. The real dextrin is determined by +inverting a portion of the filtered liquid with HCl, and then +determining its reducing power. The starch is estimated by inverting a +portion of the solid dextrin, and determining the glucose formed by +Fehling. After deducting the amounts due to the original glucose and the +inverted dextrin present, the residue is calculated as starch. A +determination of the acidity of the solution is also made with decinormal +soda, and results returned in number of c.c. alkali required to +neutralize 100 grammes of the dextrin. Results we have obtained using +this method are embodied in the following table: + + ANALYSIS OF GUM SUBSTITUTES + +----+---------+---------+--------+----------+-------+-------+--------- + No.| Glucose.| Dextrin.| Starch.| Moisture.| Gum, | Ash. |Acidity. + | | | | | &c. | | +----+---------+---------+--------+----------+-------+-------+--------- + | | | | | | | cc. + 1 | 8.92 | 81.57 | 1.99 | 10.12 | None | 0.207 | 57.3 + 2 | 7.19 | 71.46 | 13.13 | 10.40 | None | 0.120 | 44.8 + 3 | 1.29 | 69.42 | 24.72 | 4.17 | 1.12 | 0.280 | 5.22 + 4 | 8.40 | 60.98 | 10.98 | 10.09 | 9.02 | 0.530 | 20.0 + 5 | 10.60 | 44.98 | 8.05 | 12.20 | 23.57 | 0.600 | 52.0 + 6 | 14.80 | 11.57 | 36.46 | 34.87 | 1.89 | 0.580 | 8.0 + 7 | 8.00 | 29.61 | 26.78 | 33.98 | 0.88 | 0.750 | 88.0 + 8 | 2.29 | 52.38 | 37.65 | None | 7.335 | 0.315 | 9.6 +----+---------+---------+--------+----------+-------+-------+--------- + +In those cases in which the substitute is made by admixture with gelatin +or liquid glue the quantity of other organic matter obtained can be +checked by a Kjeldahl determination of the total nitrogen. If a natural +gum is added, it will be partially converted into sugar when the +filtered liquid is inverted, and so make the dextrin determination +slightly too high. + + * * * * * + + + + +MR. CAILLETET'S CRYOGEN. + + +The "cryogen," a new apparatus constructed by Mr. E. Ducretet, from +instructions given by Mr. Cailletet, is designed for effecting a fall of +temperature of from 70 deg. to 80 deg. C. below zero, through the expansion of +liquid carbonic acid. + +The apparatus consists of two concentric vessels having an annular space +between them of a few centimeters. A worm, S, is placed in the internal +vessel R. All this is of nickel plated copper. The worm, S carries, at +Ro', an expansion cock and ends, at O in the annular space, R'. A very +strong tube is fixed to the cock, Ro', and to the ajutage, A'. It +receives the tube, Tu, which, at the time of an experiment, is coupled +with the cylinder of carbonic acid, CO squared. A tubulure, D, usually closed +by a plug, Bo, communicates with the inner receptacle, R. This is +capable of serving in certain experiments in condensation. The table, +Ta, of the tripod receives the various vessels or bottles for the +condensed products. + +The entire apparatus is placed in a box, B, lined with silk waste and +provided with a cover, C, of the same structure. Apertures, Th, Ro, and +T", allow of the passage of a key for acting upon the cock, Ro', as well +as of thermometers and stirrers if they are necessary. + +When it is desired to operate, the internal vessel, R, is filled with +alcohol (3 quarts for the ordinary model). This serves as a refrigerant +bath for the experiments to be made. The worm, S, having been put in +communication with the carbonic acid cylinder, CO squared, the cock, Ro, of the +latter is turned full on. The cock of the worm, which is closed, is +opened slightly. The vaporization and expansion of the liquid carbonic +acid cause it to congeal in the form of snow, which distributes itself +and circulates in the worm, S, and then in R. The flakes thus coming in +contact with the metallic sides of S rapidly return to the gaseous state +and produce an energetic refrigeration. At the lower part of the annular +space, R', are placed fragments of sponge impregnated with alcohol. The +snow that has traversed the worm without vaporizing reaches R'. and +dissolves in this alcohol, and the refrigeration that results therefrom +completes the lowering of the temperature. The gas finally escapes at O, +and then through the bent tube, T". + +[Illustration: CAILLETET'S CRYOGEN.] + +The apparatus may be constructed with an inverse circulation, the +carbonic acid then entering the annular vessel, R, directly, and +afterward the worm, S, whence it escapes to the exterior of the +apparatus. The expansion cock sometimes becomes obstructed by the +solidification of the snow. It will then suffice to wait until the +circulation becomes re-established of itself. It may be brought about by +giving the cock, Ro', a few turns with the wooden handled key that +serves to maneuver the latter. It is not necessary to have a large +discharge of carbonic acid, and consequently the expansion cock needs to +be opened but a little bit. A few minutes suffice to reduce the +temperature of the alcohol bath to 70 deg., with an output of about from 41/2 +to 51/2 lb. of liquid carbonic acid. When the circulation is arrested, the +apparatus thus surrounded by its isolating protective jackets becomes +heated again with extreme slowness. In one experiment, it was observed +that at the end of nine hours the temperature of the alcohol had risen +but from 70 deg. to 22 deg.. On injecting a very small quantity of liquid +carbonic acid from time to time, a sensibly constant and extremely low +temperature may be maintained indefinitely.--_Le Genie Civil_. + + * * * * * + + + + +METHOD OF PRODUCING ALCOHOL. + + +In carrying out my improved process in and with the apparatus employed +in ordinary commercial distilleries, says Mr. Alfred Springer, of +Cincinnati, O., I preferably employ separate vats or tubs for the nitric +acid solution and the material to be treated, and a convenient +arrangement is to locate the nitric acid tub directly under the grain +tub, so that one may discharge into the other. In the upper vat is +placed the farinaceous material, preferably ground, thoroughly steeped +in three times its weight of water, and, where whole grain is used, +preferably "cooked" in the ordinary manner. The vat into which the +dilute acid is placed is an ordinary cooking tub of suitable material to +resist the acid, provided with closed steam coils and also nozzles for +the discharge of steam into the contained mass. Into this vat is placed +for each one hundred parts of the grain to be treated one part of +commercial nitric acid diluted with fifty parts of water and brought to +a state of ebullition and agitation by the steam coils and the discharge +through the nozzles, the latter being regulated so that the gain by +condensation of steam approximately equals the loss by evaporation. The +farinaceous contents of the upper vat are allowed to flow slowly into +the nitric acid solution while the ebullition and agitation of the mass +is continued. This condition is then maintained for six to eight hours, +after which the mass is allowed to stand for one day or until the +saccharification becomes complete. The conversion can be followed by the +"iodine test" for intermediary dextrins and the "alcohol test" for +dextrin. After the saccharification is complete I may partially or +wholly neutralize the nitric acid, preferably with potassium or Ammonium +carbonate, preferably employing only one-half the amount necessary to +neutralize the original quantity of nitric acid used, so that the mass +now ready to undergo fermentation has an acid reaction. The purpose in +view here is to keep the peptones in solution also, because an acid +medium is best adapted to the propagation of the yeast cells. It is not +absolutely necessary to even partially neutralize the nitric acid, but +it is preferable. Yeast is now added, and the remaining processes are +similar to those generally employed in distilleries, excepting that just +prior to distillation potassium carbonate sufficient to neutralize the +remaining nitric acid is added, in order to avoid corrosion of the still +and correct the acid reaction of the slop. + +As a variant of the process I sometimes add to the usual amount of +nitric acid an additional one one-hundredth part of phosphoric acid on +account of its beneficial nutritive powers--that is to say, to one +hundred parts of grain one part of nitric acid and one one-hundredth +part of phosphoric acid. + +While my improved process is based on the well-known converting power of +acids on starch, I am not aware that it has ever been applied in the +manner and for the purposes I have described. For example, sulphuric and +hydrochloric, also sulphuric and nitric, acids have been employed in the +manufacture of glucose; but in every such case the resulting products +were not capable of superseding those obtained by the existing methods +of saccharification used in distilleries. In my process, on the other +hand, the product is so capable. Not only may malted grain be entirely +omitted, but more fermentable products are formed and the products of +fermentation are purer. The saccharification being more complete, there +are less intermediary and nonfermentable dextrins, and the yield of +spirits is therefore increased. Malted grain being omitted or used in +reduced quantity, there is less lactic acid and few or foreign ferments +to contaminate the fermenting mass; also, the formation of higher +alcohols than the ethyl alcohol is almost totally suppressed. +Consequently the final yield of spirits is purer in quality and requires +little or no further purification. Also, further, the nitrates +themselves acting as nutrients to the yeast cells, these become more +active and require less nutrition to be taken from the grain. + + * * * * * + + + + +SPECTROSCOPIC DETERMINATION OF THE SENSITIVENESS OF DRY PLATES. + + +After describing other methods of determining the sensitiveness of +plates, Mr. G.F. Williams, in the _Br. Jour. of Photo_., thus explains +his plan. I will now explain the method I adopt to ascertain the +relative sensitiveness of plates to daylight. Procure a small direct +vision pocket spectroscope, having adjustable slit and sliding focus. To +the front of any ordinary camera that will extend to sixteen or eighteen +inches, fit a temporary front of soft pine half an inch thick, and in +the center of this bore neatly with a center bit a hole of such diameter +as will take the eye end of the spectroscope; unscrew the eyehole, and +push the tube into the hole in wood, bushing the hole, if necessary, +with a strip of black velvet glued in to make a tight fit. By fixing the +smaller tube in the front of camera we can focus by sliding the outer +tube thereon; if we fix the larger tube in the front, we should have to +focus inside the camera, obviously most inconvenient in practice. Place +the front carrying the spectroscope _in situ_ in the camera, and rack +the latter out to its full extent; point the camera toward a bright sky, +or the sun itself, if you can, while you endeavor to get a good focus. +The spectrum will be seen on the ground glass, probably equal in +dimensions to that of a quarter plate. Proceed to focus by sliding the +outer tube to and fro until the colors are quite clear and distinct, and +at same time screw down the slit until the Fraunhofer lines appear. By +using the direct rays of the sun, and focusing carefully, and adjusting +the slit to the correct width, the lines can be got fairly sharply. +Slide your front so that the spectrum falls on the ground glass in just +such a position as a quarter plate glass would occupy when in the dark +slide, and arrange matters so that the red comes to your left, and the +violet to the right, and invariably adopt that plan. It is advisable to +include the double H lines in the violet on the right hand edge of your +plate. They afford an unerring point from which you can calculate +backward, finding G, F, E, etc., by their relative positions to the +violet lines. Otherwise you may be mistaken as to what portion of the +spectrum you are really photographing. The red should just be seen along +the left edge of the quarter plate. When all is arranged thus, you +utilize three-fourths of your plate with the spectrum, with just a +little clear glass at each end. Before disturbing the arrangement of +the apparatus, it is desirable to scratch a mark on the sliding tube, +and make a memorandum of the position of all the parts, so that they may +be taken away and replaced exactly and thus save time in future. + +To take a photograph of the spectrum, put a quarter plate in the dark +slide and place in camera; point the camera toward a bright sky, or +white cloud, near the sun--not at the sun, as there is considerable +difficulty in keeping the direct rays exactly in the axis of the +spectroscope--draw the shutter, and give, say, sixty seconds. On +development, you will probably obtain a good spectrum at the first +trial. The duration of exposure must, of course, depend upon the +brightness of the day; but if the experiments are to have relative +values, the period of exposure must be distinctly noted, and comparisons +made for a normal exposure of sixty seconds, ninety seconds, two minutes +or more, just according to whatever object one has in view in making the +experiments. With a given exposure the results will vary with the light +and the width of the slit, as well as being influenced by the character +of the instrument itself. Further, all such experiments should be made +with a normal developer, and development continued for a definite time. +The only exception to this rule would be in the event of wishing to +ascertain the utmost that could be got out of a plate, but, under +ordinary circumstances, the developer ought never to vary, nor yet the +duration of development. To try the effect of various developers, or +varying time in development, a departure must be made of such a nature +as would operate to bring out upon each plate, or piece of a plate, the +utmost it would develop short of fog, against which caution must be +adopted in all spectrum experiments. + +On development, say for one, two, or three minutes, wash off and fix. +You will recognize the H violet lines and the others to the left, and +this experiment shows what is the sensitiveness of this particular plate +to the various regions of the spectrum with this particular apparatus, +and with a normal exposure and development. So far, this teaches very +little; it merely indicates that this particular plate is sensitive or +insensitive to certain rays of colored light. To make this teaching of +any value, we must institute comparisons. Accordingly, instead of simply +exposing one plate, suppose we cut a strip from two, three, four, or +even half a dozen different plates, and arrange them side by side, +horizontally, in the dark slide, so that the spectrum falls upon the +whole when they are placed in the camera and exposed. There is really no +difficulty in cutting strips a quarter of an inch wide, the lengthway of +a quarter plate. Lay the gelatine plate film up, and hold a straight +edge on it firmly, so that when we use a suitable diamond we can plow +through the film and cut a strip which will break off easily between the +thumb and finger. A quarter plate can thus be cut up into strips to +yield about a dozen comparative experiments. When cut and snapped off, +mark each with pencil with such a distinguishing mark as shall be +clearly seen after fixing. The cut up strips can be kept in the maker's +plate box. + + * * * * * + + +The deep down underground electric railway in London has so far proved +an unprofitable concern for its stockholders. It is 31/2 miles long, +touches some of the greatest points of traffic, but somehow or other +people won't patronize it. The total receipts for the last six months +were a little under $100,000, and they only carried seventeen persons +per train mile. On this road the passengers are carried on elevators up +and down from the street level to the cars. The poor results so far make +the stockholders sick of the project of extending the road. + + * * * * * + + +A NEW CATALOGUE OF VALUE + + +Contained in Scientific American Supplement during the past ten years, +sent _free of charge_ to any address. Munn & Co., 361 Broadway, New +York. + + * * * * * + + +THE SCIENTIFIC AMERICAN + +ARCHITECTS AND BUILDERS EDITION + + +$2.50 a Year. Single Copies, 25 cts. + +This is a Special Edition of the Scientific American, issued monthly--on +the first day of the month. Each number contains about forty large +quarto pages, equal to about two hundred ordinary book pages, forming, +practically, a large and splendid Magazine of Architecture, richly +adorned with _elegant plates in colors_ and with fine engravings, +illustrating the most interesting examples of modern Architectural +Construction and allied subjects. + +A special feature is the presentation in each number of a variety of the +latest and best plans for private residences, city and country, +including those of very moderate cost as well as the more expensive. +Drawings in perspective and in color are given, together with full +Plans, Specifications, Costs, Bills of Estimate, and Sheets of Details. + +No other building paper contains so many plans, details, and +specifications regularly presented as the Scientific American. Hundreds +of dwellings have already been erected on the various plans we have +issued during the past year, and many others are in process of +construction. + +Architects, Builders, and Owners will find this work valuable in +furnishing fresh and useful suggestions. All who contemplate building or +improving homes, or erecting structures of any kind, have before them in +this work an almost _endless series of the latest and best examples_ +from which to make selections, thus saving time and money. + +Many other subjects, including Sewerage, Piping, Lighting, Warming, +Ventilating, Decorating, Laying out of Grounds, etc., are illustrated. +An extensive Compendium of Manufacturers' Announcements is also given, +in which the most reliable and approved Building Materials, Goods, +Machines, Tools, and Appliances are described and illustrated, with +addresses of the makers, etc. + +The fullness, richness, cheapness, and convenience of this work have won +for it the Largest Circulation of any Architectural publication in the +world. + +A Catalogue of valuable books on Architecture, Building, Carpentry, +Masonry, Heating, Warming, Lighting, Ventilation, and all branches of +industry pertaining to the art of Building, is supplied free of charge, +sent to any address. + +MUNN & CO., PUBLISHERS, 361 BROADWAY, NEW YORK. + + * * * * * + + +BUILDING PLANS AND SPECIFICATIONS. + + +In connection with the publication of the Building; EDITION of the +Scientific American, Messrs, Munn; & Co. furnish plans and +specifications for buildings' of every kind, including Churches, +Schools, Stores, Dwellings, Carriage Houses, Barns, etc. + +In this work they are assisted by able and experienced architects. Full +plans, details, and specifications for the various buildings illustrated +in this paper can be supplied. + +Those who contemplate building, or who wish to alter, improve, extend, +or add to existing buildings, I whether wings, porches, bay windows, or +attic rooms, fare invited to communicate with the undersigned. Our work +extends to all parts of the country. Estimates, plans, and drawings +promptly prepared. Terms moderate. Address + +MUNN & CO., 361 BROADWAY, NEW YORK. + + * * * * * + + +THE SCIENTIFIC AMERICAN SUPPLEMENT. + + +Published Weekly. Terms of Subscription, $5 a year. + +Sent by mail, postage prepaid, to subscribers in any part of the United +States or Canada. Six dollars a year, sent, prepaid, to any foreign +country. + +All the back numbers of The Supplement, from the commencement. January +I, 1876, can be had. Price, 10 cents each. + +All the back volumes of The Supplement can likewise be supplied. Two +volumes are issued yearly. Price of each volume, $2.50 stitched in +paper, or $3.50 bound in stiff covers. + +Combined Rates.--One copy of Scientific American and one copy of +Scientific American Supplement, one year, postpaid, $7.00. + +A liberal discount to booksellers, news agents, and canvassers. + +MUNN & CO., PUBLISHERS, + +361 BROADWAY, NEW YORK, N.Y. + + * * * * * + + +USEFUL ENGINEERING BOOKS + + +Manufacturers, Agriculturists, Chemists, Engineers, Mechanics, Builders, +men of leisure, and professional men, of all classes, need good books in +the line of their respective callings. Our post office department +permits the transmission of books through the mails at very small cost. +A comprehensive catalogue of useful books by different authors, on more +than fifty different subjects, has recently been published, for free +circulation, at the office of this paper. Subjects classified with names +of author. Persons desiring a copy have only to ask for it, and it will +be mailed to them. 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