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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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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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