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| author | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:42:36 -0700 |
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| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:42:36 -0700 |
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diff --git a/13640-h/13640-h.htm b/13640-h/13640-h.htm new file mode 100644 index 0000000..3644602 --- /dev/null +++ b/13640-h/13640-h.htm @@ -0,0 +1,5875 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> +<meta http-equiv="Content-Type" content= +"text/html; charset=UTF-8"> +<title>The Project Gutenberg eBook of Scientific American +Supplement, 821</title> +<style type="text/css"> +<!-- +body {margin-left: 15%; margin-right: 15%; background-color: white} +img {border: 0;} +h1,h2,h3 {text-align: center;} +.note {margin-left: 2em; margin-right: 2em; margin-bottom: 1em;} +.ind {margin-left: 10%; margin-right: 10%;} +hr {text-align: center; width: 50%;} +.ctr {text-align: center;} +th {font-weight: normal;} +--> +</style> +</head> +<body> +<div>*** START OF THE PROJECT GUTENBERG EBOOK 13640 ***</div> + +<p class="ctr"><a href="./images/title.png"><img src="./images/title_th.jpg" alt=""></a> +</p> +<h1>SCIENTIFIC AMERICAN SUPPLEMENT NO. 821</h1> +<h2>NEW YORK, September 26, 1891</h2> +<h4>Scientific American Supplement. Vol. XXXII, No. 821.</h4> +<h4>Scientific American established 1845</h4> +<h4>Scientific American Supplement, $5 a year.</h4> +<h4>Scientific American and Supplement, $7 a year.</h4> +<hr /> +<table summary="Contents" border="0" cellspacing="5"> +<tr> +<th colspan="2">TABLE OF CONTENTS.</th> +</tr> +<tr> +<td valign="top">I.</td> +<td><a href="#arch1"> + Architectural.--The New Labor Exchange in Paris.--With + views of the interior and exterior of the building</a></td> +</tr> +<tr> +<td valign="top">II.</td> +<td><a href="#elec1"> + Electrical.--The Construction and Maintenance of Underground + Circuits.--By S.B. FOWLER.--A comprehensive article, + discussing at length the various devices for protecting underground + circuits, methods of inserting the cables, etc.</a></td> +</tr> +<tr> +<td valign="top">III.</td> +<td><a href="#eng1"> +Engineering.--Railroads to the Clouds.--Sketches of a number + of mountain railroads</a></td> +</tr> +<tr> +<td valign="top">IV.</td> +<td><a href="#mar1"> +Marine Engineering.--The French Armored Turret Ship + the Marceau.--1 engraving.--A full description of the vessel, giving + dimensions and cost</a></td> +</tr> +<tr> +<td></td> +<td><a href="#mar2"> + A Review of Marine Engineering during the Past Decade.--A + paper read before the Institution of Mechanical Engineers by Mr. + Alfred Blechynben, of Barrow-in-Furness.--This paper, which + is continued from Supplement No. 820, treats on steam pipes, + feed water heating, twin screws, etc.</a></td> +</tr> +<tr> +<td valign="top">V.</td> +<td><a href="#misc1"> +Miscellaneous.--The Little House.--An article giving various + hints about the arrangement and management of small + dwellings, with special view to the best sanitary arrangements</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc2"> + Stilt Walking.--A sketch, with engraving, of Sylvain Dornon, + the stilt walker of Landes</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc3"> Remains of a Roman Villa in England</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc4">Gum Arabic and its Modern Substitutes.--A continuation of a + paper by Dr. S. Rideal and W.E. Youle.--With 26 tables</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#misc5">A New Method of Extinguishing Fires.--Invented by George +Dickson and David A. Jones, of Toronto, Canada.--Apparatus designed +to utilize a mixture of water and liquefied carbonic acid</a></td> +</tr> + +<tr> +<td valign="top">VI.</td> +<td><a href="#med1"> +Medicine and Hygiene.--The Hygienic Treatment of + Obesity.--By Dr. Paul Chebon.--Methods of eating, drinking, + and exercising for the purpose of reducing fat.--An extended + article, giving valuable information to people troubled with too + much flesh</a></td> +</tr> +<tr> +<td valign="top">VII.</td> +<td><a href="#pho1"> +Photography.--Spectroscopic Determination of the Sensitiveness + of Dry Plates.--A full description of the new plan of + Mr. G.F. WILLIAMS, for determining the sensitiveness of dry + plates by the use of a small direct vision pocket spectroscope</a></td> +</tr> + +<tr> +<td valign="top">VIII.</td> +<td><a href="#phys1">Physics.--A Physical Laboratory Indicator.--By J.W. +MOORE, of Lafayette College.--1 engraving.--This is a modification +of the old peg board adapted to use in the laboratory.--It indicates +the names of the members of the class, contains a full +list of the experiments to be performed, refers the student +to the book and page where information in reference to experiments +or apparatus may be found, it shows what experiments +are to be performed by each student at a given time, etc.</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#phys2"> Cailletet's Cryogen.--A description, with one engraving, of Mr. +Cailletet's new apparatus for producing temperatures from 70 +degrees to 80 degrees C., below zero, through the expansion of +liquid carbonic acid</a></td> +</tr> + +<tr> +<td valign="top">IX.</td> +<td><a href="#tech1"> +Technology.--The Manufacture of Roll Tar Paper.--An extended + article containing a historical sketch and full information + as to the materials used and the methods of manufacture</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#tech2"> Smokeless Gunpowder.--By Hudson Maxim.--A comprehensive +article on the manufacture and use of smokeless gunpowder, +giving a sketch of its history, and describing the methods of +manufacture and its characteristics</a></td> +</tr> +<tr> +<td> </td> +<td><a href="#tech3">Method of Producing Alcohol.--A description of an improved +process for making alcohol.--Invented by Mr. Alfred Springer, +of Cincinnati, Ohio</a></td> +</tr> +</table> +<hr /> + +<p class="ctr"><a href="./images/1-hall.png"><img src="images/1-hall_th.jpg" width="600" height="364" alt="INTERIOR OF THE NEW LABOR EXCHANGE, PARIS." title=""></a><br clear="all" /> +INTERIOR OF THE NEW LABOR EXCHANGE, PARIS.</p> + +<p class="ctr"><a href="./images/1-bldg.png"><img src="images/1-bldg_th.jpg" width="564" height="400" alt="THE NEW LABOR EXCHANGE, PARIS." title=""></a><br clear="all" /> +THE NEW LABOR EXCHANGE, PARIS.</p> + +<a name="arch1"></a><h2>THE NEW LABOR EXCHANGE, PARIS.</h2> + +<p>The new Labor Exchange is soon to be inaugurated. +We give herewith a view of the entrance facade of the +meeting hall. The buildings, which are the work of +Mr Bouvard, architect, of the city of Paris, are comprised +within the block of houses whose sharp angle +forms upon Place de la Republique, the intersection of +Boulevard Magenta and Bondy street. One of the entrances +of the Exchange is on a level with this street. +The three others are on Chateau d'Eau street, where +the facade of the edifice extends for a length of one +hundred feet. From the facade and above the balcony +that projects from the first story, stand out in bold +relief three heads surrounded by foliage and fruit +that dominate the three entrance doors. These sculptures +represent the Republic between Labor and Peace. +The windows of the upper stories are set within nine +rows of columns, from between the capitals of which +stand out the names of the manufacturers, inventors, +and statesmen that have sprung from the laboring +classes. Upon the same line, at the two extremities of +the facade, two modillions, traversed through their +center by palms, bear the devices "Labor" and +"Peace." Above, there is a dial surmounted by a +shield bearing the device of the city of Paris.</p> + +<p>The central door of the ground floor opens upon a +large vestibule, around which are arranged symmetrically +the post, telegraph, telephone, and intelligence +offices, etc. Beyond the vestibule there is a gallery +that leads to the central court, upon the site of which +has been erected the grand assembly hall. This latter, +which measures 20 meters in length, 22 in width, and +6 in height, is lighted by a glazed ceiling, and contains +ten rows of benches. These latter contain 900 seats, +arranged in the form of circular steps, radiating +around the president's platform, which is one meter +in height. A special combination will permit of increasing +the number of seats reserved for the labor associations +on occasions of grand reunions to 1,200. The +oak doors forming the lateral bays of the hall will +open upon the two large assembly rooms and the three +waiting rooms constructed around the faces of the +large hall. In the assembly rooms forming one with +the central hall will take place the deliberations of the +syndic chambers. The walls of the hall will, ere long, +receive decorative paintings.--<i>L'Illustration.</i></p> + +<hr /> + +<a name="tech1"></a><h2>MANUFACTURE OF ROLL TAR PAPER.</h2> + +<p>Roofing paper was first used in Scandinavia early as +the last century, the invention being accredited to Faxa, +an official of the Swedish Admiralty. The first tar and +gravel roofs in Sweden were very defective. The impregnation +of the paper with a water-proofing liquid had not +been thought of, and the roofs were constructed by +laying over the rafters a boarding, upon which the unsaturated +paper, the sides of which lapped over the +other, was fastened with short tacks. The surface of +the paper was next coated with heated pine tar to make +it waterproof. The thin layer of tar was soon destroyed +by the weather, so that the paper, swelled by the absorption +of rain water, lost its cohesiveness and was +soon destroyed by the elements. This imperfect method +of roof covering found no great favor and was but +seldom employed.</p> + +<p>In Germany the architect Gilly was first to become +interested in tar paper roofing, and recommended it in +his architecture for the country. Nevertheless the new +style of roof covering was but little employed, and was +finally abandoned during the first year of the 19th century. +It was revived again in 1840, when people began +to take a renewed interest in tar paper roofs, the method +of manufacturing an impermeable paper being already +so far perfected that the squares of paper were dipped +in tar until thoroughly saturated. The roof constructed +of these waterproof paper sheets proved itself +to be a durable covering, being unimpenetrable to atmospheric +precipitations, and soon several factories +commenced manufacturing the paper. The product +was improved continually and its method of manufacture +perfected. The good qualities of tar paper roofs +being recognized by the public, they were gradually +adopted. The costly pine tar was soon replaced by the +cheaper coal tar. Square sheets of paper were made +at first; they were dipped sufficiently long in ordinary +heated coal tar, until perfectly saturated. The excess +of tar was then permitted to drip off, and the sheets +were dried in the air. The improvement of passing +them through rollers to get rid of the surplus tar was +reserved for a future time, when an enterprising manufacturer +commenced to make endless tar paper in +place of sheets. Special apparatus were constructed +to impregnate these rolls with tar; they were imperfect +at first, but gradually improved to a high degree. +Much progress was also made in the construction of +the roofs, and several methods of covering were devised. +The defects caused by the old method of nailing +the tar paper direct upon the roof boarding were +corrected; the consequence of this method was that +the paper was apt to tear, caused by the unequal expansion +of the roofing boards and paper, and this soon +led to the idea of making the latter independent of the +former by nailing the sides of the paper upon strips +running parallel with the gable. The use of endless +tar paper proved to be an essential advantage, because +the number of seams as well as places where it had to +be nailed to the roof boarding was largely decreased. +The manufacture of tar paper has remained at about +the same stage and no essential improvements have +been made up to the present. As partial improvement +may be mentioned the preparation of tar, especially +since the introduction of the tar distillery, and the +manufacture of special roof lacquers, which have been +used for coating in place of the coal tar. As an essential +progress in the tar paper roofing may be mentioned +the invention of the double tar paper roof, and the +wood cement roof, which is regarded as an offshoot.</p> + +<p>The tar paper industry has, within the last forty +years, assumed great dimensions, and the preferences +for this roofing are gaining ground daily. In view of +the small weight of the covering material, the wood +construction of the roof can be much lighter, and the +building is therefore less strained by the weight of the +roof than one with the other kind, so that the outer +walls need not be as heavy. Considering the price, the +paper roof is not only cheaper than other fireproof +roofs, but its light weight makes it possible for the +whole building to be constructed lighter and cheaper. +The durability of the tar paper roof is satisfactory, if + +carefully made of good material; the double tar paper +roof, the gravel double roof, and the wood cement +roof are distinguished by their great durability.</p> + +<p>These roofs may be used for all kinds of buildings, +and not only are factories, storehouses, and country +buildings covered with it, but also many dwellings. +The most stylish residences and villas are at present +being inclosed with the more durable kinds; the double +roof, the gravel double roof, and the wood cement +roof. For factory buildings, which are constantly +shaken by the vibrations of the machinery, the tar paper +roof is preferable to any other.</p> + +<p>In order to ascertain to what degree tar paper roofs +would resist fire, experiments were instituted at the +instigation of some of the larger manufacturers of roofing +paper, in the presence of experts, architects, and +others, embracing the most severe tests, and it was +fully proved that the tar paper roof is as fireproof as +any other. These experiments were made in two different +ways; first, the readiness of ignition of the tar +paper roof by a spark or flame from the outside was +considered, and, second, it was tested in how far it +would resist a fire in the interior of the building. In +the former case, it was ascertained that a bright, intense +fire could be kept burning upon the roof for some +time, without igniting the woodwork of the roof, but +heat from above caused some of the more volatile constituents +of the tar to be expelled, whereby small +flames appeared upon the surface within the limits of +the fire; the roofing paper was not completely destroyed. +There always remained a cohesive substance, +although it was charred and friable, which by reason +of its bad conductivity of heat protected the roof +boarding to such an extent that it was "browned" +only by the developed tar vapors. A fire was next +started within a building covered with a tar paper +roof; the flame touched the roof boarding, which partly +commenced to char and smoulder, but the bright burning +of the wood was prevented by the air-tight condition +of the roof; the fire gases could not escape from +the building. The smoke collecting under the roof +prevented the entrance of fresh air, in consequence of +which the want of oxygen smothered the fire. The +roofing paper remained unchanged. By making openings +in the sides of the building so that the fire gases +could escape, the wood part of the roof was consumed, +but the roofing paper itself was only charred and did +not burn. After removing the fire in contact with the +paper, this ceased burning at once and evinced no disposition +whatever to spread. In large conflagrations, +also, the tar paper roofs behaved in identically a similar +manner. Many instances have occurred where the +tar paper roof prevented the fire from spreading inside +the building, and developing with sufficient intensity +to work injury.</p> + +<p>As it is of interest to the roofer to know the manner +of making the material he uses, we give in the following +a short description of the manufacture of roofing +paper. At first, when square sheets were used exclusively, +the raw paper consisted of ordinary dipped or +formed sheets. The materials used in its manufacture +were common woolen rags and other material. In order +to prepare the pulp from the rags it is necessary to +cut them so small that the fabric is entirely dissolved +and converted into short fibers. The rags are for this +purpose first cut into pieces, which are again reduced by +special machines. The rags are cut in a rag cutting +machine, which was formerly constructed similar to a +feed cutter; later on, more complicated machines of +various constructions were employed. It is not our +task to describe the various kinds, but we remain content +with the general remark that they are all based +on the principles of causing revolving knives to operate +upon the rags. The careful cleansing of the cut rags, +necessary for the manufacture of paper, is not required +for roofing paper. It is sufficient to rinse away +the sand and other solid extraneous matter. The further +reduction of the cut rags was formerly performed +in a stamp mill, which is no longer employed, the pulp +mill or rag engine being universally used.</p> + +<p>The construction of this engine may be described as +follows: A box or trough of wood, iron, or stone is by +a partition divided into two parts which are connected +at their ends. At one side upon the bottom of the +box lies an oakwood block, called the back fall. In a +hollow of this back fall is sunk the so-called plate, +furnished with a number of sharp steel cutters or +knives, lying alongside of each other. A roller of solid +oakwood, the circumference of which is also furnished +with sharp steel cutters or knives, is fastened upon a +shaft and revolves within the hollow. The journal +bearings of the shaft are let into and fastened in movable +wooden carriers. The carriers of the bearings +may be raised and lowered by turning suitable thumbscrews, +whereby the distance between the roller and +the back fall is increased or decreased. The whole is +above covered with a dome, the so-called case, to prevent +the throwing out of the mass under the operation +of grinding. The roller is revolved with a velocity +of from 100 to 150 revolutions per minute, whereby +the rags are sucked in between the roller and the back +fall and cut and torn between the knives. At the beginning +of the operation, the distance between the +roller and the back fall is made as great as possible, +the intention being less to cut the rags than to wash +them thoroughly. The dirty water is then drawn off +and replaced by clean, and the space of the grinding +apparatus is lessened gradually, so as to cut the rags +between the knives. The mass is constantly kept in +motion and each piece of rag passes repeatedly between +the knives. The case protects the mass from +being thrown out by the centrifugal force. The work +of beating the rags is ended in a few hours, and the +ensuing thin paste is drawn off into the pulp chest, +this being a square box lined with lead.</p> + +<p>From the pulp chest it passes to the form of the +paper machine. This form consists of an endless fine +web of brass wire, which revolves around rollers. The +upper part of this form rests upon a number of hollow +copper rollers, whereby a level place is formed. The +form revolves uniformly around the two end rollers, +and has at the same time a vibratory motion, by which +the pulp running upon the form is spread out uniformly +and conducted along, more flowing on as the +latter progresses. The water escapes rapidly through +the close wire web. In order to limit the form on the +sides two endless leather straps revolve around the +rollers on each side, which touch with their lower +parts the form on both sides and confine the fluid within +a proper breadth. The thickness of the pulp is regulated + +at the head of the form by a brass rule standing +at a certain height; its function is to level the +pulp and distribute it at a certain thickness. The +continually moving pulp layer assumes greater consistency +the nearer it approaches to the dandy roll. +This is a cylinder covered with brass wire, and is for +the purpose of compressing the paper, after it has left +the form, and free it from a great part of the water, +which escapes into a box. The paper is now freed of a +good deal of the fluid, and assumes a consistency with +which it is enabled to leave the form, which now commences +to return underneath the paper, passing on to +an endless felt, which revolves around rollers and delivers +it to two iron rolls. The paper passes through a +second pair of iron rollers, the interiors of which are +heated by steam. These rollers cause the last of the +water to be evaporated, so that it can then be rolled +upon reels. A special arrangement shaves the edges +to the exact size required.</p> + +<p>The paper is made in different thicknesses and designated +by numbers to the size and weight.</p> + +<p>Waste paper, bookbinders' shavings, etc., can be +used for making the paper. As much wool as possible +should be employed, because the wool fiber has a +greater resistance than vegetable fiber to the effects of +the temperature. By wool fiber is understood the +horny substance resembling hair, with the difference +that the former has no marrowy tissue. The covering +pellicle of the wool fiber consists of flat, mostly elongated +leaves, with more or less corners, lying over +each other like scales, which makes the surface of the +fiber rough; this condition, together with the inclination +of curling, renders it capable of felting readily. +Pure wool consists of a horny substance, containing +both nitrogen and sulphur, and dissolves in a potash +solution. In a clean condition, the wool contains +from 0.3 to 0.5 per cent. of ash. It is very hygroscopical, +and under ordinary circumstances it contains +from 13 to 16 per cent. humidity, in dry air from 7 to +11 per cent., which can be entirely expelled at a temperature +of from 226 to 230 degrees Fahrenheit. Wool +when ignited does not burn with a bright flame, as +vegetable fiber does, but consumes with a feeble +smouldering glow, soon extinguishes, spreading a disagreeable +pungent vapor, as of burning horn. By +placing a test tube with a solution of five parts caustic +potash in 100 parts water, a mixture of vegetable fibers +and wool fibers, the latter dissolve if the fluid is +brought to boiling above an alcohol flame, while the +cotton and linen fibers remain intact.</p> + +<p>The solubility of the woolen fibers in potash lye is a +ready means of ascertaining the percentage of wool +fiber in the paper. An exhaustive analysis of the latter +can be performed in the following manner: A +known quantity of the paper is slowly dried in a drying +apparatus at temperature of 230° Fahrenheit, until +a sample weighed on a scale remains constant. The +loss of weight indicates the degree of humidity. To +determine the ash percentage, the sample is placed in a +platinum crucible, and held over a lamp until all the +organic matter is burned out and the ash has assumed +a light color. The cold ash is then moistened with a +carbonate of ammonia solution, and the crucible +again exposed until it is dark red; the weight of the +ash is then taken. To determine the percentage of +wool, a sample of the paper is dried at 230° Fahrenheit +and weighed, boiled in a porcelain dish in potash +lye 12° B. strong, and frequently stirred with a glass +rod. The wool fiber soon dissolves in the potash lye, +while the vegetable fiber remains unaltered. The +pulpy mass resulting is placed upon a filter, dried at +212° Fahrenheit, and after the potash lye has dripped +off, the residue, consisting of vegetable fiber and earthy +ash ingredients, is washed until the water ceases to +dissolve anything. The residue dried at 212° Fahrenheit +is weighed with a filter, after which that of the +latter is deducted. The loss of weight experienced is +essentially equal to the loss of the wool fiber. If the +filtrate is saturated with hydrochloric acid, the dissolved +wool fiber separates again, and after having +been collected upon a weighed filter, it may be weighed +and the quantity ascertained.</p> + +<p>The weight of the mineral substances in the raw +paper is ascertained by analyzing the ash in a manner +similar to that above described. The several constituents +of the ash and the mineral added to the raw +paper are ascertained as follows: Sufficient of the +paper is calcined in the manner described; a known +quantity of the ash is weighed and thrown into a +small porcelain dish containing a little distilled water +and an excess of chemically pure hydrochloric acid. In +this solution are dissolved the carbonates, carbonate of +lime, carbonate of magnesia, a little of sulphate of +alumina, as well as metallic oxides, while silicate +of magnesia, silicic acid, sulphate of lime (gypsum) remain +undissolved. The substance is heated until the +water and excess of free hydrochloric acid have been +driven off; it is then moistened with a little hydrochloric +acid, diluted with distilled water and heated. +The undissolved residue is by filtering separated from +the dissolved, the filter washed with distilled water, +and the wash water added to the filtrate. The undissolved +residue is dried, and after the filter has also +been burned in due manner and the ash added, the +weight is ascertained. It consists of clay, sand, silicic +acid and gypsum.</p> + +<p>The filtrate is then poured into a cylinder capable of +holding 100 cubic centimeters, and furnished with a +scale; sufficient distilled water is then added until the +well-shaken fluid measures precisely 100 cubic centimeters. +By means of this measuring instrument, the +filtrate is then divided into two equal portions. One +of these parts is in a beaker glass over-saturated with +chemically pure chloride of ammonia, whereby any +iron of oxide present and a little dissolved alumina fall +down as deposit. The precipitate is separated by filtering, +washed, dried at 212° Fahrenheit and weighed. +To the filtrate is then added a solution of oxalate of +ammonia until a white precipitate of oxalate of lime is +formed. This precipitate is separated by filtering, +washed, dried and when separated from the filter, is +collected upon dark satinized paper; the filter itself is +burned and the ash added to the oxalate of lime. This +oxalate of lime is then heated to a dark red heat in a +platinum crucible with lid until the oxalate of lime is +converted into carbonate of lime. By the addition of +a few drops of carbonate of ammonia solution and another +slight heating of the crucible, also the caustic lime +produced in the filter ash by heating, is reconverted into +carbonate of lime, and after cooling in the exsiccator, + +the whole contents of the crucible is weighed as carbonate +of lime, after deducting the known quantity of filter +ash.</p> + +<p>Any magnesia present in the filtrate of the oxalate of +lime is by the addition of a solution of phosphate of +soda separated as phosphate of ammonia and magnesia, +after having stood twenty-four hours. The precipitate +is filtered off, washed with water to which a +little chloride of ammonia is added, dried, and after +calcining the fiber and adding the filter ash, glow +heated in the crucible. The glowed substance is +weighed after cooling, and is pyrophosphate of magnesia, +from which the magnesia or carbonate of magnesia +is calculated stoichiometrically. All the ascertained +sums must be multiplied by 2, if they are to correspond +to the analyzed and weighed quantity of +ash.</p> + +<p>The second half of the filtrate is used for determining +the small quantity of sulphate of lime still contained +in the hydrochlorate solution. By adding +chloride of barium solution the sulphuric acid is bound +to the barytes and sulphate of baryta separates as +white precipitate. This is separated by filtering, +washed, dried and weighed in the customary manner. +From the weight of the sulphate of baryta is then +computed the weight of sulphate of lime, which has +passed over into solution. The ascertained sum is also +to be multiplied with 2.</p> + +<p>The manufacture of roll tar paper from the roll paper +was at first found to be difficult, as it was impossible +to submerge a surface larger than from ten to fifteen +square yards, rolled up, in the tar, because more would +have required too large a pan. Besides this, the +paper tears easily, when it is in the hot tar. All kinds +of experiments were tried, in order to impregnate the +surface of the paper without employing too large a +pan.</p> + +<p>The following method was tried at first: The roll +paper was cut into lengths of ten yards, which were +rolled up loosely, so that a certain space was left between +the different coils. These loose rolls, of course, +occupied much space and could be put into the tar +only in a standing position, because in a horizontal +one the several coils would have pressed together +again. The loose roll was therefore slipped over a vertical +iron rod fastened into a circular perforated +wooden foot. The upper end of this iron rod ended in +a ring, in which the hook of a chain or rope could be +fastened. With the aid of a windlass the roll was +raised or lowered. When placed in the pan with boiling +tar, it was left there until thoroughly saturated. +It was then taken out, placed upon a table, and the +excess of tar allowed to drip off into a vessel underneath. +After partially drying, the roll was spread out +in open air, occasionally turned, until sufficiently dried, +when it was rolled up again.</p> + +<p>In order to neutralize the smeary, sticky condition +of the surface and avoid the disagreeable drying in +open air, the experiment of strewing sand on the sticky +places was tried next. The weight of the paper was +largely increased by the sand, and appeared considerably +thicker. For this reason the method of sanding +the paper was at once universally adopted. To dispense +with the process of permitting the surplus tar to +drip off, means were devised by which it was taken off +by scrapers, or by pressing through rollers. The +scrapers, two sharp edged rods fastened across the pan, +were then so placed that the paper was drawn through +them. The excess of tar adhering to its surface was +thereby scraped off and ran back into the pan.</p> + +<p>This work, however, was performed better and to +more satisfaction by a pair of rollers fastened to the pan. +These performed a double duty; thoroughly removed +the tar from the surface and by reason of their pressure +they caused a more perfect incorporation of the +tar with the fibers of the paper. Finally, different +factories employed different methods of manufacture, +one of which was to cut the rolls into definite lengths +of about ten yards; these were then rerolled very +loosely and immersed in the hot tar until sufficiently +saturated. The paper was then passed through the +roller, much pressure exerted, and then loosely rolled +up again. Being tarred once, it was then laid into a +second pan with hot tar, reeled out after a time, strewn +with sand, and rolled up again. Another method was +to cut clothes lines into lengths of about fifteen yards, +and at a distance of two inches have knots tied in +them. The paper was cut in lengths of ten or fifteen +yards, three pieces of the knotted clothes line were +then rolled between the loose coils of paper, which was +then submerged in the tar, which on account of the +knots could penetrate the paper. The paper was next +sanded by permitting its lower surface to pass over dry +sand in a box standing on the floor. A workman rolled +off the paper, and with his hand he strews sand on the +upper surface. The rolling taking place on the edge +of a table, by means of a crank, the excess of sand +dropped off.</p> + +<p>It is said by this method two workmen, one of which +tends to the rolling and sanding, the other turning +the crank, could turn out eighty rolls per day. This +method is still in use. It is useless to describe the +many antiquated methods in vogue in smaller factories, +and it can truthfully be said that nearly all of them +are out of date. It appears to be the fact of almost +all inventions that when reduced to practical use, +the arrangements, apparatus, and working methods +employed are generally of the most complicated nature, +and time and experience only will simplify them. +This has been also the case with the methods in the +roofing paper industry, which are at present gradually +being reduced to a practical basis. The method gradually +adopted has been described in the preceding. The +pan is of a certain length, whereby it becomes possible +to saturate the paper by slowly drawing it through +the heated tar. This is the chief feature. The work +is much simplified thereby and the workmen need not +dip their hands into the tar or soil them with it. The +work of impregnating has become much cleaner and +easier, while at the same time the tar can be heated to +a much higher temperature. The pan is generally +filled with distilled coal tar, and the heating is regulated +in such a manner that the temperature of the +impregnating mass is raised far beyond 212° Fahrenheit. +This accelerates the penetration, which takes +place more quickly as the degree of heat is raised, +which may be almost up to the boiling point of the tar, +as at this degree the paper is not destroyed by the +heat. In order to prevent the evaporation of the volatile +ingredients of the tar, the pan is covered with a + +sheet iron cover, with a slot at the place where the +paper enters into the impregnating mass and another +at the place where it issues. The tar is always kept +at the same level, by occasional additions.</p> + +<p>The roll of paper is mounted upon a shaft at the +back end of the pan, and by suitable arrangement of +guide rollers it unwinds slowly, passes into the tar in +which it is kept submerged. The guide rollers can be +raised so that when a new roller is set up they can be +raised out of the tar. The end of the paper is then +slipped underneath them above the surface of the tar, +when having passed through the squeezing rollers, it +is fastened to the beaming roller, and the guide rollers +are submerged again. A workman slowly turns the +crank of the beaming roller.</p> + +<p>This motion draws the paper slowly through the +fluid, the roll at the back end unwinding. The speed +with which the squeezing rollers are turned is regulated +in such a manner that the paper remains sufficiently +long underneath the fluid to be thoroughly +impregnated with it. The workmen quickly learn by +experience how fast to turn the crank. The hotter the +tar, the more rapid the saturation; the high degree of +heat expels the air and evaporates the hygroscopic +fluid in the pores of the paper. The strong heating of +the tar causes another advantage connected with this +method. The surface of the paper as it issues from the +squeezing rollers is still very hot, and a part of the +volatile oils evaporate very quickly at this high temperature. +The surface is thereby at once dried to a +certain degree and at the same time receives a handsome +luster, as if it had been coated with a black lacquer. +The paper is sanded in a very simple manner +without the use of mechanical apparatus; as it is being +wrapped into a coil, it passes with its lower surface +over a layer of sand, while the workman who tends to +rolling up strews the inside with sand. The lower +surface is coated very equally. Care only being necessary +that the sand lies smooth and even at all times. +When the workman has rolled up ten or fifteen yards, +he cuts it across with a knife and straightedge, so that +the paper is cut at right angles with its sides.</p> + +<p>There are three different sorts of roofing paper, +according to the impregnating fluid used in its manufacture. +The ordinary tar paper is that saturated with +clear cold tar. This contains the greatest amount of +fluid ingredients and is very raggy in a fresh condition. +It is easy to see that the volatile hydrocarbons evaporate +in a short time, and when expelled, the paper +becomes stiffer and apparently drier. This drying, +or the volatilization of the hydrocarbons, causes pores +between the fibers of the paper. These pores are +highly injurious to it, as they facilitate a process of +decomposition which will ruin it in a short time.</p> + +<p>Roofing paper can be called good only when it is +essentially made from woolen rags, and contains either +very few or no earthy additions. It is beyond doubt +that the durability of a roofing paper increases with +the quality of wool fiber it contains--vegetable fibers +and earthy additions cause a direct injury. Reprehensible +altogether is any combination with lime, +either in form of a carbonate or sulphate, because the +lime enters into chemical combination with the decomposition +products of the tar.</p> + +<p>The general nature of gravel is too well known to +require description. The grains of quartz sand are +either sharp cornered or else rounded pieces of stone of +quartz, occasionally mixed with grains of other amorphous +pieces of silica--such as horn stone, silicious +slate, carnelian, etc.; again, with lustrous pieces of +mica, or red and white pieces of feldspar. The gravel +used for a tar paper roof must be of a special nature +and be prepared for the purpose. The size of its grains +must not exceed a certain standard--say, the size of a +pea. When found in the gravel bank, it is frequently +mixed with clay, etc., and it cannot be used in this +condition for a roof, but must be washed. The utensils +necessary for this purpose are of so simple and suggestive +a nature that they need not be described. Slag +is being successfully used in place of the gravel. It is +easily reduced to suitable size, by letting the red hot +mass, as it runs from the furnace, run into a vessel +with water. The sudden chilling of the slag causes it +to burst into fragments of a sharp cornered structure. +It is next passed through a sieve, and the suitably +sized gravel makes an excellent material, as it gives a +clean appearance to the roof.</p> + +<p>The thinking mind can easily go one step further +and imagine that, since the tar contains a number of +volatile hydrocarbons, it might be made more adaptable +for impregnation by paper by distilling it, as by +this process the fluid would lose its tendency to evaporate +and the percentage of resinous substances increase. +Singular to say, there was a prejudice against +the employment of distilled tar, entertained by builders +and people who had no knowledge of chemistry. +Increasing intelligence and altered business circumstances, +however, brought about the almost universal +employment of distilled tar, and every large factory +uses it at present. The roofing paper prepared with +distilled tar is perhaps most suitably called asphaltum +paper, as this has been used in its manufacture. It +possesses properties superior to the ordinary tar paper, +one of which is that immediately after its manufacture, +as soon as cold, it is dry and ready for shipment; +nor does it require to be kept in store for a length of +time, and it has also a good, firm body, being as flexible +and tough as leather. It is very durable upon the roof, +and remains flexible for a long time. It is true that +asphaltum papers will always in a fresh state contain +a small percentage of volatile ingredients, which after +a while make it hard and friable upon the roof; but, +by reason of its greater percentage of resinous components, +it will always preserve a superior degree of +durability and become far less porous. One hundred +parts by weight absorb 140 or 150 parts by weight of coal +tar. A factory which distilled a good standard tar for +roofing paper recovered, besides benzole and naphtha, +also about ten per cent. of creosote oil, used for one +hundred parts raw paper, 176.4 partially distilled tar. +Experiments on a larger as well as a smaller scale +reduced this quantity to an average of 141.5 parts for +one hundred parts raw paper. The weight of sanded +paper is very variable, as it depends altogether upon +the size of the sand grains. It may be stated generally +that the weight of the sand is as large as that of the +tarred paper.</p> + +<p>The kinds of roofing paper saturated with other additions +besides coal tar form a separate class, in order +to neutralize the defects inherent in coal tar. These + +additions were originally for the purpose of thickening +the paper and making it stiffer and drier. The most +ordinary and cheapest thickener was the coal pitch. +Although the resinous substances are increased thereby, +still the light tar oils remain to evaporate, and the +paper prepared with such a substance readily becomes +hard and brittle. A better addition is the natural asphaltum, +because it resists better the destroying influence +of the decomposition process, and also, to a +certain degree, protects the coal tar in which it is dissolved. +The addition of natural asphaltum doubtless +caused the name of "asphaltum roofing paper." +Resin, sulphur, wood tar and other substances were +also used as additions; each manufacturer kept his +method secret, however, and simply pointed out by +high sounding title in what manner his paper was +composed. In most cases, however, this appellation +was applied to the ordinary tar paper; the impregnating +substance was mixed only with coal pitch, or +else a roofing paper saturated with distilled tar. The +costly additions, by the use of which a high grade of +roofing paper can doubtless be produced, largely +increased its price, and on account of the constant fall +of prices of the article, its use became rather one of +those things "more honored in the breach than in the +observance," and was dispensed with whenever practicable. +The crude paper is the foundation of the +roofing paper. The qualities of a good, unadulterated +paper have already been stated. At times, the crude +paper contains too many earthy ingredients which +impair the cohesion of the felted fibrous substance, +and which especially the carbonate of lime is very +injurious, as it readily effects the decomposition of the +coal tar. The percentage of wool, upon which the +durability of the paper depends very largely, is very +small in some of the paper found in the market. In +place of woolen rags, cheap substitutes have been +used, such as waste, which contains vegetable fibers. +Since this cannot resist the decomposition process for +any length of time, it is evident that the roofing paper +which contains a noticeable quantity of vegetable +fibers cannot be very durable. To judge from the endeavors +made to improve the coal tar, it may be concluded +that this material does not fully comply with +its function of making the roofing paper perfectly and +durably waterproof. The coal tar, be it either crude +or distilled, is not a perfect impregnating material, +and the roofing paper, saturated with it, possesses +several defects. Let us in the following try to ascertain +their shortcomings, and then express our idea in +what manner the roofing paper may be improved. It +was previously mentioned that every tar roofing paper +will, after a greater or smaller lapse of time, assume a +dry, porous, friable condition, caused by the volatilization +of a part of the constituents of the tar. This +alteration is materially assisted by the oxygen of the +air, which causes the latter to become resinous and +exerts a chemical influence upon them. By the volatilization +of the lighter tar oils, pores are generated between +the fibers of the roofing paper, into which the +air and humidity penetrate. In consequence of the +greatly enlarged surface, not only the solid ingredients +of the tar, which still remain unaltered, are exposed +to the action of the oxygen, but also the fibers of the +roofing paper are exposed to decomposition. How destructive +the alternating influence of the oxygen and +the atmospheric precipitations are for the roofing +paper will be shown by the following results of tests. +It will have been observed that the rain water running +from an old paper roof, especially after dry weather, +has a yellowish, sometimes a brown yellow color. The +supposition that this colored rain water might contain +decomposition products of the roofing paper readily +prompted itself, and it has been collected and analyzed +at different seasons of the year. After a period of +several weeks of fair weather during the summer, rain +fell, and the sample of water running from a roof was +caught and evaporated; the residue when dried +weighed 1.68 grammes. It was of a brownish black color, +fusible in heat and readily soluble, with a yellow brown +color in water. The dark brown substance readily +dissolved in ammonia, alcohol, dilute acid, hydrochloric +acid, sulphuric acid, and decomposed in nitric +acid, but did not dissolve in benzine or fat oil. After +several days' rain during the summer, a quantity of +the water was caught, evaporated, and the residue +dried. Its characteristics were similar to those above +mentioned. By an experiment instituted in water +under conditions similar to the first mentioned, the +dry brown substance weighed 71 grammes. It possessed +the same characteristics. In the solution effected with +water containing some aqua ammonia of the brown +substance, a white precipitate of oxalate of lime occurred +when an oxalate of ammonia solution was +added, but the brown substance remained in solution. +A further precipitation of oxalate of lime was produced +by a solution of oxalic acid, but the brown organic +substance remained in solution. This organic +substance being liberated from the lime was evaporated, +and left a dry, resinous, fusible brownish black +substance, which also dissolved readily in water. It +will be seen from these trials that the substance obtained +from the rain water running from a paper roof +is a combination of an organic acid with lime, which +readily dissolves in water, and that also the free organic +acid combined with the lime dissolves easily in +water.</p> + +<p>The question concerning the origin of this organic +substance or its combination with lime can only be +answered in one way, viz., that it must have been +washed by the rain water out of the paper. But since +such a solid substance, easily soluble in water, is contained +neither in the fresh roofing paper nor in the +coal tar, the only deduction is that it must have +arisen by the decomposition of the tar, in consequence +of the operation of the oxygen. The lime comes from +the coating substance of the roof, for which tar mixed +with coal pitch was used. The latter was fused with +carbonate of lime. These analyses furthermore show +that the formation of the organic acid easily soluble in +water depends upon the season; and that a larger +quantity of it is generated in warm, sunny weather +than in cold, without sunshine. This peculiarity of +the solid, resinous constituents of the coal tar, to be by +the operation of the atmospheric oxygen altered into +such products that are readily soluble in water, makes +the tar very unsuitable as a saturative substance for a +roofing paper. How rapidly a paper roof can be +ruined by the generation of this injurious organic acid +will be seen from the following calculation: Let us + +suppose that an average of 132 gallons of rain water +falls upon ten square feet roof surface per year, and +that the arithmetical mean 0.932 of the largest (1.680) +and smallest number (0.184) be the quantity of the +soluble brown substance which on an average is dissolved +in one quart of rain water; hence from ten +square feet of roof surface are rinsed away with the +rain water per year 466 grammes of the soluble decomposition +products of the tar. The oxidation process +will not always occur as intensely as by a paper roof, +ten years old and painted two years ago, which instigated +above described experiment. As long as the +roofing paper is fresh and less porous, especially if the +occurring pores are filled and closed again by repeated +coatings, oxidation will take place far less rapidly. +Besides this, the protective coating applied to the roof +surface is exposed most to this oxidation process. +Even by assuming this constantly progressive destructive +action of the oxygen on the roofing paper to be +much less than above stated, we can readily imagine +that it must be quite large. If it is desired to produce +a material free of faults, it is first of all indispensable +that unobjectionable raw material be procured. Coal +tar was formerly used almost exclusively for the coating +of a roof. It was heated and applied hot upon the +surface. In order to avoid the running off of the thinly +fluid mass, the freshly coated surface was strewn with +sand. The most volatile portion of the tar evaporated +soon, whereby the coating became thicker and finally +dried. The bad properties of the coal tar, pointed out +elsewhere, made it very unsuitable even for this purpose, +and experiments were instituted to compound +mixtures, by adding other ingredients to the tar, that +should more fully comply with its function. It may +be said in general that the coating masses for roofs can +be divided into two classes: either as lacquers or as +cements. To the former may be classed those of a +fairly thinly fluid consistency, and which contain +volatile oils in such quantities that they will dry +quickly. Cements are those of a thickly fluid consistency, +and are rendered thus fluid by heating. It is +not necessary that the coating applied should harden +quickly, as it assumes soon after its application a firmness +sufficient to prevent it from running off the roof. +Coal tar is to be classed among lacquers. If it has been +liberated by distillation from the volatile oils, it is +made better suited for the purpose than the ordinary +kind. The mass contains much more asphaltum, and +after drying, which takes place soon, it leaves a far +thicker layer upon the roof surface, while the pores, +which had formed in the roofing paper consequent on +drying, are better filled up. Nevertheless, the distilled +tar also has retained the property of drying with time +into a hard, vitreous mass, and ultimately to be destroyed +by decomposition.--<i>The Roofer</i>.</p> + +<hr /> + +<a name="phys1"></a><h2>A PHYSICAL LABORATORY INDICATOR.</h2> + +<p>The difficulties attending the management of a +physical laboratory are much greater than those of a +chemical one. The cause of this lies in the fact that +in the latter the apparatus is less complicated and the +pieces less varied. Any contrivance that will reduce +the labor and worry connected with the running of a +laboratory is valuable.</p> + +<p>A physical laboratory may be arranged in several +ways. The apparatus may be kept in a store room +and such as is needed may be given to the student each +day and removed after the experiments are performed; +or the apparatus for each experiment or system of experiments +may be kept in a fixed place in the laboratory +ready for assembling; for certain experiments +the apparatus may be kept in a fixed place in the laboratory +and permanently arranged for service.</p> + +<p>Each student may have his own desk and apparatus +or he may be required to pass from desk to desk. The +latter method is preferable.</p> + +<p>When a store room is used the services of a man are +required to distribute and afterward to collect. If the +apparatus is permanently distributed, a large room is +necessary, but the labor of collecting and distributing +is done away with.</p> + +<p>There are certain general experiments intended to +show the use of measuring instruments which all students +must perform. To illustrate the use of the indicator +I have selected an elementary class, although +the instrument is equally applicable to all classes of +experiments.</p> + +<p>Having selected a suitable room, tables may be +placed against the walls between the windows and at +other convenient places. Shallow closets are built +upon these tables against the wall; they have glass +doors and are fitted with shelves properly spaced. A +large number of light wooden boxes are prepared, +numbered from one up to the limit of the storage +capacity of the closets. A number corresponding to +that upon the box is placed upon the shelf, so that +each one after removal may be returned to its proper +place without difficulty. On the front of the box is a +label upon which is written the experiment to be +performed or the name of the apparatus whose use +is to be learned, references to various books, which may +be found in the laboratory library, and the apparatus +necessary for the experiment, which ought to be +found in the box. If any parts of the apparatus are +too large to be placed in the box, the label indicates +by a number where it may be found in the storage +case.</p> + +<p>It is evident that, instead of the above arrangement, +all the boxes can be stacked in piles in a general +store room. The described arrangement is preferable, +as it prevents confusion in collecting and distributing +apparatus when the class is large.</p> + +<p><i>The Indicator</i> (see figure).--Some device is evidently +desirable to direct the work of a laboratory with the +least trouble and friction possible. I have found that +the old fashioned "peg board," formerly used in schools +to record the demerits of scholars, modified as in the +following description, leaves nothing to be desired.</p> + +<p>The requirements of such an instrument are these: +It must show the names of the members of the class; +it must contain a full list of the experiments to be performed; +it must refer the student to the book and +page where information in reference to the experiments +or apparatus may be found; it must show what +experiments are to be performed by each student at a +given time; it must give information as to the place +in the laboratory where the apparatus is deposited; it +must show to the instructor what experiments have +been performed by each student; it must prevent the + +assignment of the same experiment to two students; +it must enable the instructor to assign the same experiment +to two or more students; it must form a complete +record of what has been done, what work is incomplete, +and what experiments have not yet been assigned; +it must also be so arranged that new experiments +or sets of experiments may be exhibited.</p> + +<p class="ctr"><img src="images/4-chart.png" width="264" height="397" alt="" title=""> +<br clear="all" />A, B, C, etc., are cards upon which are the names of +students. 1, 2, 3, etc., are cards like the one +described in the article. The small circles represent +unassigned experiments. The black circles (slate +nails) represent work done. The caudate circles +(brass nail) represent work assigned.</p> + +<p>The indicator consists of a plank of any convenient +length and breadth. The front surface is divided into +squares of such size that the pegs may be introduced +and withdrawn with ease. At each corner of the +squares holes are bored into which nails may be +placed. There is a blank border at the top and another +on the left side. At the top of each vertical +column of holes is placed a card holder. This is made +of light tin turned up on the long edges--which are +vertical--and tacked to the board. Opposite each +horizontal row of holes is a similar tin card holder, +but of greater length, and having its length horizontal. +The holders at the top of the board contain +cards upon which the names of the class are written.</p> + +<p>Cards, like the following, are prepared for the horizontal +holders.</p> + +<pre> +-------------------------------------------------------------- +Stewart & Gee 229 +Physical Manip. 85 Intensity of Gravity--Borda's Method 39 +Glazebrook & Shaw 132 +-------------------------------------------------------------- +</pre> + +<p>These cards are numbered from one to any desired +number and are arranged in the holders consecutively.</p> + +<p>Two kinds of nails are provided to fit the holes in +the board: An ordinary slate nail and a common picture +frame nail with a brass head. The latter indicates +work to be done, the former work done.</p> + +<p>To prepare the board for service, brass headed nails +are placed opposite each experiment, and below the +names, care being taken not to have more than one +nail in the same horizontal row, unless it is intended +that two persons or more are to work upon the same +experiment.</p> + +<p>There will be no conflict when the brass nails occupy +diagonal lines. If they do not, a glance will show the +fact.</p> + +<p>After an experiment has been performed and a report +made upon the usual blank, the brass nail is removed +and a slate nail put in its place.</p> + +<p>The board will show by the slate nails what work +has been done by each student, by the brass nails what +is yet to be done, and by the empty holes, experiments +which have been omitted or are yet to be assigned. A +slate nail opposite an experiment card indicates that +that experiment may now be assigned to another person.</p> + +<p>It is evident that the schedule for a whole term may +be arranged in a few minutes and that the daily +changes require very little time.</p> + +<p>The board is hung in a convenient place. The student +as he enters the laboratory looks for his name on +the upper cards and under it for the first brass nail in +the vertical column: to the left he finds the experiment +card. On the left hand end of the slip he sees the book +references, on the right hand end a number--39 in the +sample card given above. Knowing the number, he +proceeds to a desk and finds a box numbered in the +same manner. He removes the box from the closet. +On the label of the box is a list of all the apparatus +necessary, which he will find in the box; the label also +contains the book references. He performs the experiment, +fills up a blank which he gives to the instructor, +puts all the materials back in the box, replaces the +box in its proper place in the closet and proceeds with +the next experiment. With this indicator there is no +difficulty in managing fifty students or more.</p> + +<p>Comparatively little apparatus need be duplicated. +Where apparatus is fixed against a wall a number may +be tacked upon the wall and a card containing the +information desired. The procedure is then the same as +with the boxes. The cards on the board being removable, +other ones may be inserted containing information +in reference to other boxes having the same number +but containing different materials. + +There can be no successful tampering with the board, +for the record of experiments performed is upon the +blanks which the students turn in and also in the individual +note books which are written up and given +to the instructor for daily examination.</p> + +<p class="ctr"><b>Lafayette College.<br /> J.W. MOORE.</b></p> + +<hr /> + +<a name="misc5"></a><h2>NEW METHOD OF EXTINGUISHING FIRES</h2> + +<p>This is by George Dickson, of Toronto, Canada, and +David Alanson Jones.</p> + +<p>A mixture of water and liquefied carbon dioxide upon +being discharged through pipes at high pressure +causes the rapid expansion of the gas and converts the +mixture into spray more or less frozen, and portions of +the liquid carbon dioxide are frozen, owing to its +rapid expansion, and are thus thrown upon the fire +in a solid state, where said frozen carbon dioxide in its +further expansion not only acts to put out the fire, +but cools the surface upon which it falls, and thus +tends to prevent reignition.</p> + +<p>A represents a receptacle sufficiently strong to stand +a pressure of not less than a thousand pounds to the +square inch.</p> + +<p>B B water receptacles.</p> + +<p class="ctr"><img src="images/4-fig1.png" width="356" height="154" alt="Fig. 1" title=""> +<br clear="all" />FIG. 1</p> + +<p>In the drawings we have shown two receptacles B +and only one receptacle A; but we do not wish to confine +ourselves to any particular number, nor do we +wish to confine ourselves to the horizontal position in +which the receptacles are shown.</p> + +<p>C is a pipe leading from the receptacle A to a point +at or near the bottom of the receptacle B.</p> + +<p>F is a pipe through which the mixture of water and +liquefied gas from the receptacle B is forced by the +expansion of said liquefied gas, the said pipe taking +the mixture of water and liquefied gas from the bottom +of the receptacle.</p> + +<p class="ctr"><img src="images/4-fig2.png" width="310" height="161" alt="Fig. 2" title=""> +<br clear="all" />FIG. 2</p> + +<p>To use the apparatus, open the stop cock D in the +pipe C, leading to one of the receptacles B, whereupon, +owing to the lower pressure in the cylinder B, the +liquid carbon dioxide expands and rises to the top of +the cylinder A and forces the liquid carbon dioxide into +the cylinder B, the same as the superior steam of a +boiler forces the water of the boiler out when the same +is tapped below the surface of the liquid. Now upon +opening the tap H, this superior gas forces out the +mixture of water and liquid carbon dioxide, which +suddenly expanding causes portions of the globules of +liquefied gas to be frozen, and these, being protected +by a rapidly evaporating portion of the liquefied gas, +are thrown on the fire in solid particles. At the same +time the water is blown into a spray, which is more +or less frozen. The fire is thus rapidly extinguished by +the vaporization of the carbon dioxide and water spray.</p> + +<hr /> + +<a name="tech2"></a><h2>SMOKELESS GUNPOWDER.</h2> + +<h3>By HUDSON MAXIM.</h3> + +<p>During the last forty years leading chemists have +continued to experiment with a view to the production +of a gunpowder which should be smokeless. But not +until the last few years has any considerable degree of +success been attained.</p> + +<p>To be smokeless, a gunpowder must yield only gaseous +products of combustion. None of the so-called +smokeless powders are entirely smokeless, although +some of them are very nearly so.</p> + +<p>The smoke of common black gunpowder is largely +due to minute particles of solid matter which float in +the air. About one-half of the total products of combustion +of black gunpowder of ordinary composition +consists of potassium carbonate in a finely divided condition +and of potassium sulphate, which is produced +chiefly by the burning in the air of potassium sulphide, +another production of combustion, as on the outrushing +gases it is borne into the air in a fine state of +division.</p> + +<p>Another cause for the smoke of gunpowder is the +formation of small liquid vesicles which condense from +some of the products of combustion thrown into the +air in a state of vapor, in the same manner as vesicles +of aqueous vapor form in the air on the escape of highly +heated steam from the whistle of a locomotive.</p> + +<p>Broadly speaking, an explosive compound is one +which contains, within itself, all the elements necessary +for its complete combustion, and whose +heated gaseous products occupy vastly more space +than the original compound. Such compound usually +consists of oxygen, associated with other elements, for +which it has great affinity, and from which it is held +from more intimate union, or direct chemical combination, +under normal conditions, by being in combination +as well with other elements for which it has less +affinity, but which it readily gives up for the stronger +affinities when explosion takes place, the other elements +either combining with one another to form new +compounds or being set free in an uncombined state.</p> + +<p>An explosive is said to detonate when the above +changes take place instantaneously, the action being +transmitted with the speed of electricity by a sort of +molecular rhythm from molecule to molecule throughout +the entire substance of the compound.</p> + +<p>An explosive is said to explode when the above + +changes do not occur instantaneously throughout the +whole substance, but whose combustion takes place +from the surface inward of the particles or grains of +which it is composed, thus requiring some definite +lapse of time.</p> + +<p>The elements of an explosive compound may be associated +chemically as in nitro-glycerine and gun-cotton, +which are chemical compounds, being the results of definite +reactions. Or, an explosive may be a mere mechanical +mixture of different substances comprising the +necessary elements, as is ordinary black gunpowder, +which is a compound of charcoal, sulphur and saltpeter, +the saltpeter supplying the necessary oxygen.</p> + +<p>No gunpowder can be smokeless in which saltpeter +or any oxygen-bearing salt having a metallic base is +employed, for when the salt gives up its oxygen, the +base combines with other elements to produce a sulphate, +a carbonate, or other salt, which, being solid, +produces smoke. Therefore, to be smokeless, a gunpowder +must contain no other elements than oxygen, +hydrogen, nitrogen, and carbon, and in such proportions +that the products of combustion shall be +wholly gaseous. The nitric ethers--gun-cotton and +nitro-glycerine--constitute such explosive compounds. +These substances were formerly thought to be nitro-substitution +compounds, but are now known to belong +to the compound ethers of nitric acid.</p> + +<p>Gun-cotton, discovered by Schonbein, in 1845, has +since been looked upon as the most promising material +for a smokeless gunpowder, it being a very powerful +explosive and burning with practically no smoke. To-day, +gun-cotton, in some form or other, constitutes the +base of substantially all of the smokeless powders with +which have been attained any considerable degree of +success.</p> + +<p>Gun-cotton alone and in its fibrous state has been +found to be too quick, or violent, for propulsive purposes, +such as use in firearms; as under such conditions +of confinement it is very likely to detonate and +burst the gun. However, if gun-cotton be dissolved in +a suitable solvent, which is capable of being evaporated +out, such as acetone, or acetate of ethyl, which +are very volatile, it becomes, when thus dissolved and +dried, a very hard, horn-like, amorphous substance, +which may be used for a smokeless gunpowder. But +this substance taken alone is very difficult to mould or +granulate, and the loss of expensive solvents must +necessarily be quite considerable.</p> + +<p>When gun-cotton is reduced to a collodial solid, as +above, and used as a smokeless gunpowder, the grains +must be made comparatively small to insure prompt +and certain ignition, and consequently the pressures +developed in the gun are apt to be too great when +charges sufficiently large are used to give desired velocities.</p> + +<p>If, however, a compound be made of gun-cotton and +nitro-glycerine, in about equal parts, by means of +a volatile solvent or combining agent, such as one of +the before mentioned, and the solvent evaporated out, +we obtain practically a new substance and one which, +as regards its explosive nature, is quite unlike either of +its two constituents taken alone. The nitro-glycerine, +furthermore, being itself a solvent of gun-cotton, much +less of the volatile ether is necessary to render the compound +of an amorphous character. Being quite plastic +this substance may be wrought or moulded into any +desired size or form of grain.</p> + +<p>This simple compound of nitro-glycerine and gun-cotton, +or with some slight modifications, has been +found, when properly granulated, to be the most +smokeless powder that has yet been discovered or invented. +If pure chemicals are employed in the manufacture, +and the gun-cotton and nitro-glycerine be +made of the highest nitration and best quality, we +have a smokeless powder which will possess the following +desirable qualities:</p> + +<p>1st. It is absolutely smokeless, that is, its products +of combustion are entirely gaseous.</p> + +<p>2d. Its products of combustion are in no way deleterious +or unpleasant.</p> + +<p>3d. It is perfectly safe to manufacture, handle and +transport. There is no more danger of its exploding +accidentally than there would be of an explosion of +shavings or sawdust; for, unless well confined and set +off with a strong primer, it will not explode at all. In +the open its combustion is so slow as to in no way resemble +or partake of the nature of an explosion.</p> + +<p>4th. It is perfectly stable, and will keep any length +of time absolutely without undergoing any change +whatever, under all conditions of temperature or exposure +to which gunpowder would ever be subjected.</p> + +<p>5th. It is not hygroscopic, and may be soaked in water +without being at all affected by it.</p> + +<p>6th. It will not corrode the cartridge case.</p> + +<p>7th. It will not foul the gun.</p> + +<p>8th. It is sure of ignition with a good primer, and +may be made to burn as slowly as desired by varying +the character and size of the grains. Indeed, it may +be made to burn so slowly as to fail of complete combustion +before the bullet leaves the gun, and after firing +several rounds, partly burned pieces of the powder +may be picked up in front of the gun.</p> + +<p>9th. In a shoulder arm, a velocity of 2,000 feet per +second may be imparted to the bullet with this powder, +and with a pressure in the chamber of the gun of +not more than fifteen English tons. This is, of course, +when the gun, cartridge case, primer, and projectile +are adapted to the use of smokeless powder, and the +granulation of the powder is adapted to them.</p> + +<p>If what I have here claimed for the above smokeless +powder be true, it would appear that it may be taken +as really an ideal smokeless powder. Why, then, has +it not already been universally adopted? Surely such +a powder is just what every government is seeking. In +reply to this, let me say that, in order for the above +compound to be an effective and successful smokeless +powder, with the manifestation of the many desirable +qualities which I have recited, a great many other conditions +are necessary, some of which I will mention. +To arrive at the knowledge that this compound would +constitute the best smokeless powder has required a +great deal of experimenting. It was first thought that +gun-cotton colloid, without any nitro-glycerine, that is, +gun-cotton dissolved and dried, would burn more slowly, +keep better, and give better ballistics than it would +if combined with nitro-glycerine. It was also thought +that gun-cotton of a high degree of nitration when +made into colloidal form would even then burn too +quickly to be suitable for use in firearms. Consequently, +the first experiments were with low grade + +gun-cotton, what is called collodion cotton, such as is +employed in the manufacture of celluloid. But, as +this would not explode without the addition of some +oxygen-bearing element, various oxygen-bearing salts +were combined with it, such as nitrate of potassium, +nitrate of ammonia, nitrate of baryta, etc. Also a +great many of the first smokeless powders were made +of low grade gun-cotton combined with nitro-glycerine +in varying proportions. These powders would often +give very good results when first made; but low grade +gun-cotton or di-nitro-cellulose, as it is called, is a very +unstable compound, and these powders, after giving +very promising results, were found to be constantly +undergoing change, sooner or later resulting in complete +decomposition.</p> + +<p>When nitro-glycerine was first combined with gun-cotton +in small quantities, camphor was often added, +to lessen the rapidity of combustion which the nitro-glycerine +was supposed to impart and also to render +the compound more plastic, and to tend to prevent the +decomposition of the low grade gun-cotton. But +camphor being volatile, would, by its evaporation, +cause the powder to constantly change in character. +Castor oil has been found to be a better diluent, as +this will not evaporate.</p> + +<p>As all of the smokeless powders made of a low grade +gun-cotton were found to deteriorate and spoil, experiments +were made with gun-cotton of the highest degree +of nitration, both alone and in combination with +nitro-glycerine. These experiments were first conducted +in England by private parties and by the British government, +when it was found that high grade gun-cotton +would give excellent results if made into a colloidal +solid and used alone, or in combination with certain +other constituents. With a view to saving the large +quantity of solvents necessary to reduce the gun-cotton, +and to get a more prompt and certain ignition +with a larger grain, experiments were cautiously made +by the admixture of varying proportions of nitro-glycerine +to the gun-cotton when dissolved, or rather +along with other solvents in the process of dissolving +it.</p> + +<p>It was soon found that nitro-glycerine added in quantities, +even equal in weight to the gun-cotton itself, did +not materially increase the rapidity of the explosion +of the compound. And it was also found that high +grade gun-cotton, when combined with nitro-glycerine, +gave very much better results than low grade gun-cotton.</p> + +<p>I have spoken here of high and low grade gun-cotton, +when in fact the word gun-cotton should be applied +only to the highest nitro-compound of cellulose. +The word gun cotton has always been rather loosely +used. Pyroxyline would be a better word, as this applies +to all grades. When cotton fiber is soaked in a +large excess of a mixture of the strongest nitric and +sulphuric acids, gun-cotton proper, or that of the +highest grade, is produced. When weaker acids are +used, lower grades of nitro-cellulose are formed.</p> + +<p>The first mentioned or highest grade gun-cotton, +when thoroughly freed from its acids, has always +proved to be a perfectly stable compound. The lower +grades have always been found to be unstable and subject +to spontaneous decomposition. Nitro-glycerine +has also been erroneously thought to be a very unstable +compound. But experiments have proved that, +when made pure, it is perfectly stable.</p> + +<p>Having now explained how the knowledge came to +be arrived at that the aforementioned compound of +highest grade nitro-glycerine and highest grade gun-cotton +would constitute the best basis for a smokeless +powder, I will now mention a few of the other conditions +necessary to success with its use, without assuming +that smokeless powder has yet passed its experimental +stage, and is beyond further improvement. +Nevertheless, such is the compound which has come to +stay as the basis of all smokeless powders; and any +smokeless powder, if a successful one, may be counted +upon as being made of this compound of gun-cotton +and nitro-glycerine, or of a colloid of gun-cotton, either +alone or combined with diluents, oxygen-bearing +salts, or inert matter. The fact that smokeless powder +may still be said to be in somewhat of an experimental +stage is not to admit that it is not a success. Firearms, +cartridge cases, and projectiles are also still in an experimental +stage, for they are constantly being improved; +yet their use has been a great success for a good +many years.</p> + +<p>The question of success of a smokeless powder does +not rest alone with the powder itself. The gun, the +cartridge case, primer, and bullet have been as much +the subjects of experiments in adapting them to the +use of smokeless powder as has the smokeless powder +in being adapted to them. To impart a velocity of +2,000 feet per second to a rifle ball, with corresponding +long range and accuracy of flight, has been a question +as much of improvement in rifles and projectiles as +in the powder. To give a velocity of 2,000 feet per +second to a bullet, requires a pressure of at least 15 +English tons in the chamber of a gun. This would be +a dangerous pressure in an old-fashioned shoulder +arm; while a bullet made only of lead would strip on +striking the rifling and pass right through the barrel +of the gun without taking any rotary motion whatever. +It might at first seem that the powder is the only +thing to be considered; but high ballistics can only be +obtained when everything else is adapted to its use.</p> + +<p>The projectile, the cartridge case, the fulminating +cap, and the gun have had to be all built up together, +and a very large amount of experimenting has been +necessary to determine what would constitute the +best projectile, best cartridge case, best fulminating +cap, and what should be the character of the rifling +and the quality and temper of the steel of the gun +barrel.</p> + +<p>It has been necessary first to conduct experiments to +test the smokeless powders for velocities and pressures, +and then with the powders test various kinds of +projectiles and guns. In order to obtain the high ballistics +which have been secured, it has been found +necessary to cover the bullet with something harder +than lead and to rifle the gun in a special manner.</p> + +<p>The French, who were the first to definitely adopt +smokeless powder, were the first also to make a rifle, +projectile, cartridge case and primer suited to its use.</p> + +<p>To obtain long range with a small long bullet such +as is now used, it should rotate at a very high speed. +It is well known to artillerists that a projectile of four +or more calibers in length has to be rotated at a much +higher speed than one of half that length, in order to + +keep the projectile stiff in the air, and to prevent it +from ending over in its flight. To communicate this +very high rotary movement to the bullet in the instant +of time during which it is passing through the barrel, +the rifling of the gun has to exert an enormous torsion +on the bullet. Lead, no matter how hardened, is not +sufficiently strong, as it will not only strip and pass +straight through the gun without taking any rotary +movement whatever, but under such very high pressures +it behaves like wax, and is thrown from the gun +in a distorted mass.</p> + +<p>The French cover their bullets with German silver, +a substance made of nickel, zinc and copper; and in +order to put as little strain upon the rifling and projectile +as possible, the rifling of the gun is made with an +increasing twist, and has no sharp edges. The French +rifle is made very strong at the breech and is of tempered +steel throughout. In this way the French have +made smokeless powder a success--a smokeless powder +made substantially of a character such as I have +herein described. With smokeless powder, the French +rifle imparts a muzzle velocity of 2,000 feet per second +to the bullet, with a range of about 2,400 meters.</p> + +<p>If smokeless powder be divided into sufficiently +small grains to be ignited by an ordinary fulminating +cap, it would burn too quickly, thereby causing the +pressure to mount too high, and without giving the +desired velocity. Consequently very large and strong +fulminating caps have to be employed. Smokeless +powder is not ignited in the same manner as black +powder. Something besides ignition is necessary. +Black powder simply requires to be set on fire; while +a smokeless powder, on the contrary, not only requires +that it be set on fire, but that a certain degree +of pressure be set up inside of the cartridge case. For +instance, if a primer of a certain size should be found +to operate perfectly well, giving prompt ignition in the +cartridge case of a rifle of small caliber, it would be +found that the same primer would not ignite a charge +of the same powder if loaded into a gun of one inch +caliber. In the latter case a few grains only lying near +the primer would be ignited, and these would soon +become extinguished by sudden release of pressure +bringing about a cooling effect due to expansion of +the gases. In small cartridges a large fulminating cap +is all that is required, but in large cartridges it is +necessary to resort to additional means of ignition.</p> + +<p>In France, where experiments were conducted with +a 37 millimeter Maxim gun, it was found to be impracticable +to use a fulminating cap sufficiently large to +ignite the powder and cause it to burn. Therefore, a +small ignition charge of black powder was employed, +it being put in a capsule or bag and placed next the +primer. On firing at the rate of 300 rounds per minute, +the black powder, though small in quantity, produced +a cloud of smoke through which it was quite +impossible to see. The inventor of the gun then prepared +for the French some wafers of pyroxyline canvas, +which were placed next to the primer, securing +thereby prompt ignition without the production of +any smoke.</p> + +<p>Smokeless powder, made as I have described, cannot +be detonated by a fulminating cap of any size or by +any means whatever. A large charge of fulminate of +mercury placed inside the cartridge case next the +primer will not detonate the powder, it serving only +to ignite it and cause it to explode. But even this +would not cause the powder to explode except it be +confined behind a projectile, that sufficient pressure +may be run up to make it burn in its own gases.</p> + +<p>Some curious experiments with smokeless powder +may be tried with a shot gun. If the fulminating cap +be large, the powder fine, the wads numerous and +hard and the charge of shot heavy, all being well +rammed down, and the paper case well spun over the +last pasteboard wad, a charge of smokeless powder +about equal in weight to one-half of what would be +employed of black powder would give about the same +results as black powder. But if the charge of shot be +omitted, the primer will only ignite the powder, and +there will be set up sufficient pressure merely to throw +the wads about half way up the barrel of the gun, when +the powder will go out. Now if this same charge of +powder be collected and reloaded into a new cartridge +case and well confined behind wads and a charge of +shot, as above explained, it will all burn, giving the +same results as black powder.</p> + +<p>Attempts have been made to use this powder in pistols +and revolvers, but here it has proved a failure, as +the pressure is not great enough to cause the powder +to be consumed, unless it be in the form of very fine +grains or dust, in which case the pressure mounts too +high. However, this might be overcome to a degree +by making the powder porous. The chemical conditions +of the powder might be the same, but the physical +conditions must be different. A powder suitable +for shot guns and pistols would not be suitable for +rifles.</p> + +<p>One not familiar with the characteristics of smokeless +powder would be almost certain to fail in his first +attempt to fire it. Many persons have been convinced +by their first experiments that this powder would not +burn at all in a gun, any more than so much sand.</p> + +<p>Smokeless powder is consumed with a rapidity +which accords with the conditions of its confinement. +Therefore, the bullets which have been experimented +with by different governments have been the cause of +much of the varying pressures attributed to the smokeless +powders.</p> + +<p>The Austrians use the Mannlicher steel jacketed bullet. +The steel casing or jacket is first tinned on the inside +and then the lead is cast in, thus melting the tin and +adhering firmly to the jacket. This projectile sets up +enormous friction in the barrel of the gun when used +with smokeless powder; as the smokeless powder +leaves the gun barrel perfectly clean and the two steel +surfaces being in absolute contact cause tremendous +friction; and as the coefficient of friction varies with +every shot, the pressure in the gun constantly varies +greatly.</p> + +<p>The German silver covered bullet used by the French +has the disadvantage that when firing rapidly the +chamber of the barrel becomes nickel plated and great +friction is caused, mounting up the pressures and causing +the muzzle velocities to fall off.</p> + +<p>The Austrians, in order to prevent their steel cased +bullets from rusting and to lessen the friction in the +barrel of the gun, cover them with a heavy lubricant, +which gives the cartridges an unsightly appearance +and causes them to gather dust and sand. + +The French employ a lubricant at the base of the +projectile, with a small copper disk between the same +and the powder.</p> + +<p>Col. A.R. Buffington, commander of the National +Armory at Springfield, Mass., has made a steel covered +projectile which he prevents from rusting by blackening +by a niter process. Several grooves are pressed +in the base of the bullet which carry a lubricant, and +when the bullet is inserted in the cartridge case the +grooves are covered by it. Furthermore, these grooves +prevent the lead filling from bursting through the steel +casing, leaving the latter in the barrel, as often occurs +with the Austrian and French projectiles when using +smokeless powder.</p> + +<p>A new projectile has lately come out, the invention +of Captain Edward Palliser, of the British army. This +bullet consists of a jacket made of very soft Swedish +wrought iron, coated with zinc and filled with lead, the +lead being pressed into this jacket. The bullet is corrugated +at its base, after the manner of the one made +by Colonel Buffington. This projectile has been experimented +with very extensively by the British government, +and at the works of the Maxim-Nordenfelt +Guns and Ammunition Company, in England. The +zinc coating of the bullet is too soft to stick to the barrel +of the gun, and also in a measure acts as a lubricant. +This projectile has given better results than any other +that has been experimented with. The great velocities +and the most uniform pressures by the use of smokeless +powder have been attained with this Palliser bullet.</p> + + +<h3>NOISELESSNESS.</h3> + +<p>A great many stories have been told about the noiselessness +of smokeless powder. But there is no such +thing as a noiseless gunpowder. The report of a gun +charged with smokeless powder is very sharp, and is +as loud as when black powder is used, yet the volume +of sound is much less, so that the report cannot be +heard at so great a distance.</p> + +<p>The report of a gun using smokeless powder is a +sound of much higher pitch than when black powder +is used, and consequently cannot be heard at so great +a distance as the lower notes given by black powder.</p> + +<p>As smokeless powder exerts a much greater pressure +than common black powder when burned in a gun, +one would naturally think that the recoil of the barrel +would be greater, owing to the greater pressure exerted +by the smokeless powder on the base of the cartridge +case and the breech mechanism. However, such +is not the fact; for the barrel actually recoils very much +less when smokeless powder is used. This is due to +the suddenness with which the pressure is exerted by +smokeless powder, it acting more like a very sharp +blow on the metal, whereby more of the energy is converted +into heat instead of being spent in overcoming +the inertia of the barrel to give recoil. Similarly when +smokeless powder is fired in a gun, the displacement +of the air is so sudden that the sound waves do not +possess the same amplitude of recoil or vibration as is +given by black powder.</p> + +<hr /> + +<a name="elec1"></a><h2>THE CONSTRUCTION AND MAINTENANCE OF +UNDERGROUND CIRCUITS.</h2> + +<h3>By S.B. FOWLER.</h3> + +<p>The numerous disastrous storms of the last winter +have brought out very vividly the advantages of having +all wires placed underground, and many inquiries +have been addressed to the companies operating underground +circuits as to their success. It is not probable +that all of the answers to these inquiries have +been of the most favorable character. To many central +station managers an underground system means +frequent break-downs and interruptions of service, +with, perhaps, slow and expensive repairs, which bring +in their turn numerous complaints, loss of customers, +and reduced profits. In many installations burn-outs +both underground and in the station are frequent, +with the natural result that the operating of circuits +underground is not there considered an unqualified +success. The writer has in mind two very different +experiences with underground cables. Several +miles of cable were bought by a certain company, +carefully laid, and up to to-day not a single burn-out +or interruption of service can be attributed to failure +of cables; at about the same time another company +bought about an equal amount of the same kind of cable, +and in a comparatively short time the current had +to be shut off the lines and the whole installation repaired +and parts of it replaced. Both of these experiences +have been repeated many times and will be +again, although it is simply a distinction between a +good cable properly laid and a good cable ruined by +careless and incompetent workmanship.</p> + +<p>Every failure can be traced to poor work in the original +installation or to the use of a cheap cable, both +causes being due, generally, to that false economy +which looks for too quick returns. A poorly insulated +line wire and a poorly insulated cable are two very +different things. However, it is a fact that by the use +of a good cable it is not difficult to construct an underground +system for light, power, telegraph or telephone +uses that will be superior to overhead lines in +its service and in cost of maintenance. The ideal underground +system must have as a starting point a system +of subways admitting of the easy drawing in and +out of cables and affording means of making subsidiary +connections readily and with the minimum of expense +and interruption of service. This is practically +accomplished by a subway consisting of lines of pipe +terminating at convenient intervals, say at street intersections, +in manholes, for convenience in jointing +and in running out house connections. These pipes, +or ducts, as they are called, should be for two kinds of +service; the lower or deeper laid lines for the main or +trunk circuits, and a second series of ducts laid nearer +the surface, running into service boxes placed near +together for lines to "house to house" connections. +In some cities where it is allowed to run overhead lines, +the plan of running but one service connection in a +block is followed, all customers in the block being supplied +from a line run over the housetops or strung on +the rear walls.</p> + +<p>This makes unnecessary all subsidiary ducts except a +short one from the manhole to the nearest building in +the block, and effects a considerable saving in pipe, +service boxes, cables and labor. The manholes should +have their walls built up of brick, the floors should be + +of concrete, and there should be an inside lid which +can be fastened down and the manhole thus made +water-tight.</p> + +<p>For ducts wood, iron or cement lined pipe may be +used. To preserve the wood it is generally treated +with creosote, which, in contact with the lead cover of +the cable, sets up a chemical action, resulting in the +destruction of the lead. Wood offers but little protection +for the cable, as it is too easily damaged and broken +through in the frequent street openings made by +companies operating lines of pipe in the streets, and +as one of the main purposes of a subway is that of a +protection to cables, wooden ducts have little to recommend +them except their cheapness.</p> + +<p>Iron pipes are either laid in trenches filled in with +earth or are laid in cement. Iron pipe will of course +rust out in time, and if absolute permanence in construction +is desired, should be laid in cement, for after +the pipe rusts out, the duct of cement is still left. +However, if we are going to the expense of laying in +cement, it would be much preferable to use cement +lined pipe, which is not only cheaper than iron pipe, +but makes the most perfect cable conduit, as it affords +a perfectly smooth surface to draw the cable over and +give a good duct edge.</p> + +<p>It is not necessary, however, in small installations +of cable, especially where additional connections will +not be of frequent occurrence, to go to the expense +of subways, for cable may be safely laid in the ground +in trenches filled in with earth, or can be inclosed in a +plain wooden box or a wooden box filled with pitch.</p> + +<p>There are, of course, many localities where, if the +cable is laid in contact with the earth, a chemical +action would take place which might result in the destruction +of the cable.</p> + +<p>Underground cables are of the following classes: 1. +Rubber insulated cables, insulated with rubber or +other homogeneous material. 2. Fibrous cables, so +called from the conductors being covered with some +fibrous material, as cotton or paper, which is saturated +with the insulating material, paraffine, resin oil, or +some special compound. Under this latter head is +also included the dry core paper cables.</p> + +<p>The first thing to do is to get the cable drawn into the +ducts, and on the proper accomplishment of this depends +to a great extent the success or failure of the whole installation. +Probably the ducts have been wired when +the subway was constructed, but if not a wire must be +run through as a means of pulling in the draw rope. +There are several kinds of apparatus for getting a +wire through a duct--rods, flexible tapes, mechanical +"creepers," etc.; but probably the best is the sectional +rod. This simply consists of three or four foot lengths +of hard wood rods, having metal tips that screw into +each other. A rod is placed in a duct at a manhole, +one screwed to that, both are pushed forward, another +one added and pushed forward, and so on until they +extend the entire length of the duct. Then the wire +is attached and the rods are pulled out and detached +one at a time and with the last rod the wire is through. +At least No. 14 galvanized iron or steel wire should be +used, for any smaller size cannot be used a second time, +as a rule. In starting to pull in the draw rope a wire +brush should be attached to the wire and to this again +the rope, and when the brush arrives at the distant +end of the duct it very likely will bring with it a miscellaneous +collection of material which for the good of +the cable had better be in the manhole than in the +duct.</p> + +<p>The reel or drum carrying the cable should be +mounted on wheels or jacks and placed on the same +side of the manhole as the duct into which the cable +is to be drawn, and must always be so placed that the +cable will run off the top of the reel.</p> + +<p>There are several methods of attaching the draw +rope to the cable. As simple and strong a method as +any is to punch two of these holes through the cable, +lead and all, and attach the rope by means of an iron +wire--some of the draw wire will do--run through +these holes. Depending on the length and weight of +cable to be pulled it can be drawn either by hand or +by a multiplying winch. The rope should run through +a block fastened in the manhole in such a position +that the rope shall have a good straightaway lead from +the mouth of the duct.</p> + +<p>The strain on the cable should be perfectly uniform +and steady; if the power is applied by a series of jerks +either the lead covering may be pulled apart or some of +the conductors broken. At the reel there must always +be a large enough number of men to turn it and keep +the cable from rubbing on anything, and in the manhole +one or more men to see that the cable feeds into +the duct straight and to guide it if necessary. If the +ducts are of iron and are not perfectly smooth at the +ends, these should be made so with a file, and in addition +a protector of some sort should be placed in the +mouths of the duct, both above and below the cable. +Six inches of lead pipe, split lengthwise and bent over +at one end to prevent being drawn into the duct with +the cable, makes a very good protector. The cable +should be reeled off the drum just fast enough to prevent +any of the power used in pulling the cable through +the duct being utilized in unreeling it. If this latter +is allowed to occur the cable will be bent too short and +the lead covering buckled or broken, and also the cable +may be jammed against the upper edge of the duct +and perhaps cut through.</p> + +<p>If the reel is allowed to turn faster than the cable is +drawn in, the first three or four turns on the reel will +slacken up, and the lead covering may either be dented +or cut through by scraping on the ground. If the +cable end when pulled through up to the block is not +long enough to bend around the hole more than half +way, the rope should be unfastened from its end, a +length of rope with a well frayed out end should be run +through the block, and by fastening to the cable close +to the duct, with a series of half hitches, as much slack +as necessary can be pulled in. If this is properly +manipulated there need not be a scratch on the cable, +but unless great care is taken the lead may be pressed +up into ridges and the core itself damaged.</p> + +<p>Immediately after the cable is drawn in, if the joint +is not to be at once made, the open end or ends should +be cut off and the cable soldered up, as most cables are +very susceptible to moisture and readily absorb water +even from the atmosphere. Where practicable it is +always a good plan to pull the cable through as many +manholes as possible without cutting the cable; for +the joint is, especially in telephone or telegraph cables, +the weak point. To do this the rope should be pulled + +through the proper duct in the next section without +unfastening it from the cable; the winch should be +moved to the next manhole, and pulling through then +done as before. There should always be a man in +every hole through which the cable is running to see +that it does not bind anywhere and to keep protectors +around the cable.</p> + +<p>It is not advisable to pull more than one cable into a +duct, and never advisable to pull a cable into a duct +containing another cable, but if two or more cables +have to go into the same duct, they should always be +drawn in together. Lead covered cables and those +with no lead on the outside should never be pulled into +the same duct, for if they bind anywhere the soft +cable will suffer where two lead covered cables would +get through all right. Some manufacturers are now +putting on their cables a tape or braid covering, which +saves the lead many bad bruises and cuts, and is a +valuable addition to a cable at very little additional +expense.</p> + +<p>Practically all electric light and power cables are +either single or double conductors, and the jointing of +these is comparatively a simple matter, although requiring +considerable care. The lead is cut back from +each end about four or five inches, and the conductors +bared of insulation for two or three inches. The bare +conductors should be thoroughly tinned by dipping in +the metal pot or pouring the melted solder over them. +A sperm candle is better than resin or acid for any +part of the operations where solder is used. A lead +sleeve is here slipped back over the cable, out of the +way, and the ends of the conductors brought together +in a copper sleeve which is then sweated to a firm joint. +This part must be as good a piece of work mechanically +as electrically. The bare splice is then wrapped +tightly with cotton or silk tape to a thickness slightly +greater than that of the insulation of the cable, and is +thoroughly saturated with the insulating compound +until all moisture previously absorbed by the tape is +driven off.</p> + +<p>The lead sleeve is then brought over the splice and +wiped to the cable. The joint is then filled with the +insulating compound poured through holes in the top +of the sleeve; these holes are then closed and the joint +is complete, and there is no reason why, in light and +power cables, that joint should not be as perfect as +any other part of the cable. When the cable ends are +prepared for jointing they should be hung up in such +a position that they are in the same plane, both horizontal +and vertically, and firmly secured there, so that +when the lead sleeve is wiped on the conductor may +be in its exact center, and great care must be taken +not to move the cables again until the sleeve is filled +and the insulation sufficiently cooled to hold the conductor +in position.</p> + +<p>It is also very important to see that there are no sharp +points on the conductors themselves, on the copper +sleeve, on the edges of the lead covering or on the lead +sleeve. All these should be made perfectly smooth, for +points facilitate disruptive discharges. Branch joints +had better be made as T-joints rather than as Y-joints, +for they are better electrically and mechanically, although +they occupy more room in the manholes. They +are of course made in the same way as straight joints, +a lead T-sleeve being used, however. For multiple +arc circuits copper T-sleeves and for series circuits +copper L-sleeves are used.</p> + +<p>Telephone and telegraph cables are made of any required +gauge of wire and with from 1 to 150 conductors +in a cable. In jointing these the splices are never +soldered, the conductors being joined either with a +twist joint or with the so-called Western Union splice. +Each splice is covered with a cotton or silk sleeve or a +wrapping of tape, the latter being preferable, although +considerably increasing the time necessary for making +the joint. Great care must be taken that no ends of +wire are left sticking up, for they will surely work +their way through the tape and grounds, and crosses +will be the result. The wires should always be joined +layer to layer and each splice very tightly taped in +order to get as much insulating compound around each +splice as possible in the limited space. The splices +should be "broken" as much as possible, so as to avoid +having adjoining splices coming over each other. After +the joint has been saturated with insulating compound +the wires should have an outside wrapping of tape to +keep them in shape, and then the sleeve is wiped on +and filled. If the insulation resistance of the jointed +telegraph or telephone cable is a quarter of what the +cable tested in the factory, it may be considered that +an exceptionally good piece of work has been done. I +have spoken more particularly of fibrous lead covered +cables, as the handling of them includes practically +every step of the work on any other kind of underground +cable. In insulating dry core paper cables a +paper sleeve is slipped over the splice, and in rubber +cables the splice is wrapped with rubber tape; all +other details are the same for these as for the fibrous +cable.</p> + +<p>In the laying of light and power cables every joint, +as made, should be tested for insulation with a Thomson +galvanometer, as the insulation must necessarily be +very high, and if one joint or section of cable is any +weaker than another it may be very important in the +future to know it. All tests must be made after the +joint has cooled, for while hot its insulation resistance +will be very low.</p> + +<p>Tests for copper resistance should also be made to +determine if the splices are electrically perfect; an imperfect +splice may cause considerable trouble. In telegraph +and telephone cables the conductors should be +of very soft copper, for in stripping the conductor of +insulation it is very easy to nick the wire, and if of +hard drawn copper open wires will be the result.</p> + +<p>All work should be frequently tested for continuity +with telephones, magnetos, or small portable galvanometers. +It is only necessary to ground the conductors +at one end and try each wire at the other end. For +this sort of work a telephone receiver used with one +cell of some dry battery is most convenient, and has +the additional advantage of affording a means of communication +while testing, and is by far the best thing +for identifying and tagging conductors.</p> + +<p>These cables should be frequently tested during the +progress of the work for grounds and crosses with a +Thomson instrument, and when the cable is complete, +a careful series of tests of the capacity, insulation resistance, +and copper resistance of each wire should be +made and the exact condition of the cable determined +before it is put in service, and thereafter an intelligent + +oversight of the condition of the circuits can thus +be more readily maintained.</p> + +<p>Where a company has extensive underground service, +a regular cable gang should be in its employ, for quick +and safe handling of cables demands the employment +of men accustomed to the work. If the cable +has been properly laid and tests show it to be in good +condition before current is turned on, almost the only +trouble to be anticipated will be due to mechanical +injury. Disruptive discharge, puncturing the lead, +may occur; but the small chance of its occurring can +be greatly lessened by the use of some kind of "cable +protector," which will provide for the spark an artificial +path of less resistance than the dielectric of the +condenser, which the cable in fact becomes.</p> + +<p>If a fault suddenly develops on a circuit, the chances +are it will be found in a manhole, and an inspection +of the cable in the manhole will generally reveal the +trouble without resorting to locating with a Wheatstone +bridge. The cable is often cut through at the +edge of the duct, or damaged by something falling on +it, or by some one "walking all over it." To guard +against these, the ducts should always be fitted with +protectors both above and below the cable. The +cables should never be left across the manholes, for +they then answer the purpose of a ladder, but should +be bent, around the walls of the hole and securely +fastened with lead straps, that they may not be moved +and the lead gradually worn through.</p> + +<p>In telegraph cables, when one or two conductors +"go," it will probably be useless to look for trouble +except with instruments; but if several wires are +"lost" at once it will probably be found to be caused +by mechanical injury, which can be located by inspection. +If it is ever necessary to loop out conductors, +a joint can be readily opened and the conductors +wanted picked out and connected into the branch +cable and the joint again closed without disturbing the +working wires. In doing this a split sleeve must be +used, and the only additional precaution to be taken +is in filling the sleeve to have the insulating compound +not hot enough to melt the solder and open up the +split in the sleeve. In cutting in service on light +and power cables it is entirely practicable to do so +without interruption of service on multiple arc circuits, +even those of very high voltage; but they require +great precaution and involve considerable risk +to the jointer, and where possible the circuit to which +the connection is to be made should previously be cut +dead. Where the voltage is not dangerous to human +life, almost any service connection can be made without +interruption of service.</p> + +<p>I have only indicated a very few of the operations +that may be found necessary, and the probable causes +of troubles that may be encountered in the operating +of underground circuits, believing that the different +problems that arise can, with a little experience, be +successfully met by any one who has a fair knowledge +of the original construction of cable lines.--<i>Electrical +World</i>.</p> + +<hr /> + +<a name="eng1"></a><h2>RAILROADS TO THE CLOUDS.</h2> + +<p>If George Stephenson, when he placed the first locomotive +on the track and guaranteed it a speed of six +miles an hour, could have foreseen that in less than +eighty years the successors of his rude machine would +be climbing the sides of mountain ranges, piercing +gorges hitherto deemed inaccessible, crossing ravines +on bridges higher than the dome of St. Paul's, and +traversing the bowels of the earth by means of tunnels, +no doubt his big blue eyes would have stood out +with wonder and amazement. But he foresaw nothing +of the kind; the only problem present in his mind was +how to get goods from the seaports in western England +to London as easily and cheaply as possible, and to do +this he substituted for horses, which had for 150 years +been drawing cars along wooden or iron tracks, the +wonderful machine which has revolutionized the +freight and passenger traffic of the world.</p> + +<p>It was, indeed, impossible for any one to foresee the +triumphs of engineering which have accompanied the +advances in transportation. To the engineer of the +present day there are no impossibilities. The engineer +is a wizard at whose command space and matter +are annihilated. The highest mountain, the deepest +valley, has no terrors for him. He can bridge the +latter and encircle or tunnel the former. The only requisites +which he demands are that something in his +line be needed, and that the money is forthcoming to +defray the expense, and the thing will be done. But +the railroad he is asked to construct must be necessary, +and the necessity must be plainly shown, or no funds +will be advanced; and although the theory does not +invariably hold good, especially when a craze for railroad +building is raging, as a rule no expense for the +construction of a road will be incurred without a prospect +of remuneration.</p> + +<p>Hence the need of railroad communication has caused +lines to be constructed through districts where only a +few years ago the thing would have been deemed impossible. +The Pacific roads of this country were a necessity +long before their construction, and in the face +of difficulties almost insuperable were carried to successful +completion. So, also, of the railroads in the +Andes of South America. The famous road from +Callao through the heart of Peru is one of the highest +mountain roads in the world, as well as of the most +difficult construction. The grades are often of 300 +feet and more to the mile, and when the mountains +were reached so great were the difficulties the engineers +were forced to confront that in some places laborers +were lowered from cliffs by ropes in order that, with +toil and difficulty, they might carve a foothold in order +to begin the cutting for the roadway.</p> + +<p>In some sections tunnels are more numerous than +open cuts, and so far as the road has gone sixty-one +tunnels, great and small, have been constructed, aggregating +over 20,000 feet in length. The road attains +a height of 15,000 feet above the level of the sea, and +at the highest point of the track is about as high as +the topmost peak of Mont Blanc. It pierces the range +above it by a tunnel 3,847 feet long. The stern necessities +of business compelled the construction of this +road, otherwise it never would have been begun.</p> + +<p>The tunnels of the Andes, however, do not bear +comparison with the tunnels, bridges, and snow sheds +of the Union Pacific, nor do even these compare with +the vast undertakings in the Alps--three great tunnels +of nine to eleven miles in length, which have been prepared + +for the transit of travelers and freight. The requirements +of business necessitated the piercing of the +Alps, and as soon as the necessity was shown, funds in +abundance were forthcoming for the enterprise.</p> + +<p>But tunneling a mountain is a different thing from +climbing it. Many years ago the attention of inventors +was directed to the practicability of constructing a +railroad up the side of a mountain on grades which, to +an ordinary engine, were quite impossible. The improvements +in locomotives twenty-five and thirty years +ago rendered them capable of climbing grades which, +in the early days of railroad engineering, were deemed +out of the question. The improvements proved a serious +stumbling block in the way of the inventors, who +found that an ordinary locomotive was able to climb +a much steeper grade than was commonly supposed. +The first railroads were laid almost level, but it was +soon discovered that a grade of a few feet to the mile +was no impediment to progress, and gradually the +grade was steepened.</p> + +<p>The inventors of mountain railroad transportation +might have been discouraged by this discovery, but it +is a characteristic of an inventor that he is not set +back by opposition, which, in fact, only serves to +stimulate his zeal. The projectors of inclined roads +and mountain engines kept steadily on, and in France, +Germany, England, and the United States many experimental +roads were constructed, each of a few hundred +yards in length, and locomotive models were +built and put in motion to the amazement of the general +public, who jeered alike at the contrivances and +the contrivers, deeming the former impracticable and +the latter crazy.</p> + +<p>But the idea of building a road up the side of a hill +was not to be dismissed. There was money in it for +the successful man, so the cranky inventors kept on at +work in spite of the jeers of the rabble and the discouragements +of capitalists loath to invest their money +in an uncertain scheme. To the energy and perseverance +of railroad inventors the success of the mountain +railroad is due, as also is the construction of the various +mountain roads, of which the road up Mt. Washington, +finished in 1868, was the first, and the road +up Pike's Peak, completed the other day, was the +latest.</p> + +<p>Of all the mountain roads which have been constructed +since the one up Mt. Washington was finished, +the best known is that which ascends the world-famous +Rigi. With the exception of Mont Blanc, Rigi is, perhaps, +the best known of any peak in the Alps, though +it is by no means the highest, its summit being but +5,905 feet above the level of the sea. Although scarcely +more than a third of the height of some other mountains +in the Alps, it seems much higher because of its +isolated position. Standing as it does between lakes +Lucerne, Zug, and Lowertz, it commands a series of +fine views in every direction, and he who looks from +the summit of Rigi, if he does no other traveling in +Switzerland, can gain a fair idea of the Swiss mountain +scenery. Many of the most noted peaks are in sight, +and from the Rigi can be seen the three lakes beneath, +the villages which here and there dot the shores, and, +further on, the mighty Alps, with their glaciers and +eternal snows.</p> + +<p>Many years ago a hotel was built on the summit of +the Rigi for the benefit of the tourists who daily +flocked to this remarkable peak to enjoy the benefit of +its wonderful scenery. The mountain is densely +wooded save where the trees have been cut away to +clear the land for pastures. The ease of its ascent by +the six or eight mule paths which had been made, the +gradual and almost regular slope, and the throngs of +travelers who resorted to it, made it a favorable place +for an experiment, and to Rigi went the engineers in +order to ascertain the practicability of such a road. +The credit of the designs is due to a German engineer +named Regenbach, who, about the year 1861, designed +the idea of a mountain road, and drew up plans not +only for the bed but also for the engine and cars. The +scheme dragged. Capitalists were slow to invest their +money in what they deemed a wild and impracticable +undertaking, and even the owners of the land on +the Rigi were reluctant for such an experiment to be +tried. But Regenbach persevered, and toward the close +of the decade the inhabitants of Vitznau, at the base +of the Rigi, were astonished to see gangs of laborers +begin the work of making a clearing through the +forests on the mountain slope. They inquired what it +meant, and were told that a road up the Rigi was to be +made. The Vitznauers were delighted, for they had no +roads, and there was not a wheeled vehicle in the +town, nor a highway by which it could be brought +thither. The idea of a railroad in their desolate +mountain region, and, above all, a railroad up the Rigi, +never entered their heads, and a report which some +time after obtained currency in the town, that the +laborers were beginning the construction of a railroad, +was greeted with a shout of derision.</p> + +<p>Nevertheless, that was the beginning of the Rigi +line, and in May, 1871, the road was opened for traffic. +It begins at Vitznau, on Lake Lucerne, and extends to +the border of the canton and almost to the top of the +mountain. It is 19,000 feet long, and during that distance +rises 4,000 feet at an average grade of 1 foot in 4. +Though steep, it is by no means so much so as the Mt. +Washington road, which rises 5,285 feet above the sea, +at an average of 1 foot in 3. There are, however, +stretches of the Rigi road at which the grade is about +1 foot in 2½, which is believed to be the steepest in the +world.</p> + +<p>The Rigi road has several special features aside +from its terrific slopes which entitle it to be considered +a triumph of the engineer's skill. About midway +up the mountains the builders came to a solid +mass of rock, which presented a barrier that to a surface +road was impassable. They determined to tunnel +it, and, after an enormous expenditure of labor, +finished an inclined tunnel 225 feet in length, of the +same gradient as the road. A gorge in the side of the +mountain where a small stream, the Schnurtobel, had +cut itself a passage also hindered their way, and was +crossed by a bridge of lattice girder work in three +spans, each 85 feet long. The entire roadbed, from beginning +to end, was cut in the solid rock. A channel +was chiseled out to admit the central beam, which +contains the cogs fitting the driving wheel of the locomotive. +The engine is in the rear of the train, and +presents the exceedingly curious feature of a boiler +greatly inclined, in order that at the steeper gradients +it may remain almost perpendicular. The coal and + +water are contained in boxes over the driving wheels, +so that all the weight of the engine is really concentrated +on the cogs--a precaution to prevent their +slipping. The cost of the road, including three of +these strangely constructed locomotives, three passenger +coaches, and three open wagons, was $260,000, and +it is a good paying investment. The fare demanded +for the trip up the mountains is 5 francs, while half +that sum is required for the downward passage, and +the road is annually traversed by from 30,000 to 50,000 +passengers.</p> + +<p>Curious sensations are produced by a ride up this remarkable +line. The seats of the cars are inclined like +the boiler of the locomotive, and so long as the cars +are on a level the seats tilt at an angle which renders +it almost impossible to use them. But when the start +is made the frightful tilt places the body in an upright +position, and, with the engine in the rear, the train +starts up the hill with an easy, gliding motion, passing +up the ascent, somewhat steeper than the roof of a +house, without the slightest apparent effort. But if the +going up excites tremor, much more peculiar are the +feelings aroused on the down grade. The trip begins +with a gentle descent, and all at once the traveler +looking ahead sees the road apparently come an end. +On a nearer approach he is undeceived and observes +before him a long decline which appears too steep +even to walk down. Involuntarily he catches at the +seats, expecting a great acceleration of speed. Very +nervous are his feelings as the train approaches this +terrible slope, but on coming to the incline the engine +dips and goes on not a whit faster than before and not +more rapidly on the down than on the up grade. +Many people are made sick by the sensation of falling +experienced on the down run. Some faint, and a few +years ago one traveler, supposed to be afflicted with +heart disease, died of fright when the train was going +over the Schnurtobel bridge. The danger is really +very slight, there not having been a serious accident +since the road was opened. The attendants are watchful, +the brakes are strong, but even with all these +safeguards, men of the steadiest nerves cannot help +wondering what would become of them in case anything +went wrong.</p> + +<p>Bold as was the project of a railroad on the Rigi, a +still bolder scheme was broached ten years later, when +a daring genius proposed a railroad up Mt. Vesuvius. +A railroad up the side of an ordinary mountain seemed +hazardous enough, but to build a line on the slope of a +volcano, which in its eruption had buried cities, and +every few years was subject to a violent spasm, seemed +as hazardous as to trust the rails of an ordinary line +to the rotten river ice in spring time. The proposal +was not, however, so impracticable as it looked. +While the summit of Vesuvius changes from time to +time from the frequent eruptions, and varies in height +and in the size of the crater, the general slope and contour +of the mountain are about the same to-day as +when Vesuvius, a wooded hill, with a valley and lake +in the center of its quiescent crater, served as the +stronghold of Spartacus and his rebel gladiators. There +have been scores of eruptions since that in which Herculaneum +and Pompeii were overthrown, but the sides +of the mountain have never been seriously disturbed.</p> + +<p>A road on Vesuvius gave promise of being a good +speculation. Naples and the other resorts of the +neighborhood annually attracted many thousands of +visitors, and a considerable number of these every +year ascended the volcano, even when forced to contend +with all the difficulties of the way. Many, however, +desiring to ascend, but being unable or unwilling to +walk up, a chair service was established--a peculiar +chair being slung on poles and borne by porters. In +course of time the chair service proved to be inadequate +for the numbers who desired to make the ascent, +and the time was deemed fit for the establishment +of more speedy communication.</p> + +<p>Notwithstanding the necessity, the proposal to establish +a railroad met with general derision, but the +scheme was soon shown to be perfectly practicable, and +a beginning was made in 1879. The road is what is +known as a cable road, there being a single sleeper +with three rails, one on the top which really bore the +weight, and one on each side near the bottom, which +supported the wheels, which coming out from the axle +at a sharp angle, prevented the vehicle from being +overturned. The road covers the last 4,000 feet of the +ascent, and the power house is at the bottom, a steel +cable running up, passing round a wheel at the top +and returning to the engine in the power house. The +ascent to the lower terminus of the road is made on +mules or donkeys; then, in a comfortable car, the traveler +is carried to a point not far from the crater. The +car is a combined grip and a passenger car, similar in +some points to the grip car of the present day, while +the seats of the passenger portion are inclined as in +the cars on the Rigi road. But the angle of the road +being from thirty-three to forty-five degrees, makes +both ascent and descent seem fearfully perilous. Every +precaution, however, is taken to insure the safety +of passengers; each car is provided with several strong +and independent brakes, and thus far no accident +worth recording has occurred. The road was opened +in June, 1880. Although there have been several considerable +eruptions since that date, none of them did +any damage to the line but what was repaired in a few +hours.</p> + +<p>The fashion thus set will, no doubt, be followed in +many other quarters. Wherever there is sufficient travel +to pay working expenses and a profit on a steep +grade mountain road it will probably be built. Already +there is talk of a road on Mont Blanc, of another up +the Yungfrau, and several have been projected in the +Schwartz and Hartz mountains. A route on Ben Nevis, +in Scotland, is already surveyed, and it is said surveys +have also been made up Snowden, with a view to +the establishment of a road to the summit of the highest +Welsh peak. Sufficient travel is all that is necessary, +and when that is guaranteed, whenever a mountain +possesses sufficient interest to induce people to +make its ascent in considerable numbers, means +of transportation, safe and speedy, will soon be +provided. The modern engineer is able, willing and +ready to build a road to the top of Mt. Everest in the +Himalayas if he is paid for doing so.--<i>St. Louis Globe-Democrat.</i></p> + +<hr /> + +<p>To clean hair brushes, wash with weak solution of +washing soda, rinse out all the soda, and expose to +sun.</p> + +<hr /> + + + +<a name="mar1"></a><h2>THE MARCEAU.</h2> + +<p class="ctr"><a href="./images/8-ship.png"><img src="images/8-ship_th.jpg " width="600" height="402" alt="THE FRENCH ARMORED TURRET SHIP MARCEAU" title=""></a><br clear="all" /> +THE FRENCH ARMORED TURRET SHIP MARCEAU</p> + +<p>The Marceau, the last ironclad completed and added +to the French navy, was put in commission at +Toulon in April last, and has lately left that town to +join the French squadron of the north at Brest. The +original designs of this ship were prepared by M. +Huin, of the French Department of Naval Construction, +but since the laying down of the keel in the +year 1882 they have been very considerably modified, +and many improvements have been introduced.</p> + +<p>Both ship and engines were constructed by the celebrated +French firm, the Société des Forges et Chantiers +de la Mediterranée, the former at their shipyard in +La Seyne and the latter at their engine works in Marseilles. +The ship was five years in construction on the +stocks, was launched in May, 1887, and not having +been put in commission until the present year, was +thus nearly nine years in construction. She is a barbette +belted ship of somewhat similar design to the +French ironclads Magenta, now being completed at +the Toulon arsenal, and the Neptune, in construction +at Brest.</p> + +<p>The hull is constructed partly of steel and partly of +iron, and has the principal dimensions as follows. +Length, 330 ft. at the water line; beam, 66 ft. outside +the armor; draught, 27 ft. 6 in. aft.; displacement, +10,430 English or 10,600 French tons. The engines are +two in number, one driving each propeller; they are +of the vertical compound type, and on the speed trials +developed 11,300 indicated horse power under forced +and 5,500 indicated horse power under natural +draught, the former giving a speed of 16.2 knots per +hour with 90 revolutions per minute. The boilers are +eight in number, of the cylindrical marine type, and +work at a pressure of 85.3 lb. per square inch. During +the trials the steering powers of the ship were +found to be excellent, but the bow wave is said, by one +critic, to have been very great.</p> + +<p>The ship is completely belted with Creusot steel armor, +which varies in thickness from 9 in. forward to +17¾ in. midships. In addition to this belt the ship is +protected by an armored deck of 3½ in., while the barbette +gun towers are protected with 15¾ in. steel armor +with a hood of 2½ in. to protect the men against machine +gun fire. As a further means of insuring the life +of the ship in combat and also against accidents at sea, +the Marceau is divided into 102 water-tight compartments +and is fitted with torpedo defense netting. +There are two masts, each carrying double military +tops; and a conning tower is mounted on each mast, +from either of which the ship may be worked in time +of action, and both of which are in telegraphic communication +with the engine rooms and magazines. +Provision is made for carrying 600 tons of coal, which, +at a speed of 10 knots, should be sufficient to supply +the boilers for a voyage of 4,000 miles.</p> + +<p>The armament of the Marceau is good for the tonnage +of the ship and consists principally of four guns +of 34 centimeters (13.39 in.) of the French 1884 model, +having a weight of 52 tons, a length of 28½ calibers, +and being able to pierce 30 in. of iron armor at the muzzle. +The projectiles weigh 924 lb., and are fired with +a charge of 387 lb. of powder. The muzzle velocity has +been calculated to be 1,968 ft. per second. The guns +are entirely of steel and are mounted on Canet carriages +in four barbette towers, one forward, one aft, +and one on each side amidships. On the firing trials +both the guns and all the Canet machinery, for working + +the guns and hoisting the ammunition, gave very +great satisfaction to all present at the time. In addition +to the above four heavy guns there are, in the +broadside battery, sixteen guns of 14 centimeters +(5.51 in.), eight on each side, and a gun of equal caliber +is mounted right forward on the same deck. The +armament is completed by a large number of Hotchkiss +quick-firing and revolver guns and four torpedo +tubes, one forward, one aft, and one on each side.</p> + +<p>The crew of the Marceau has been fixed at 600 men, +and the cost is stated to have been about $3,750,000.--<i>Engineering</i>.</p> + +<hr /> + +<h3>[Continued from SUPPLEMENT, No. 820, page 13097.]</h3> + +<a name="mar2"></a><h2>A REVIEW OF MARINE ENGINEERING DURING +THE PAST DECADE.<a name="FNanchor_1"></a><a href="#Footnote_1"><sup>1</sup></a></h2> + +<h3>By Mr. ALFRED BLECHYNDEN, of Barrow-in-Furness</h3> + + +<p><i>Steam Pipes</i>.--The failures of copper steam pipes on +board the Elbe, Lahn, and other vessels have drawn +serious attention both to the material and to the modes +of construction of the pipes. The want of elastic +strength in copper is an important element in the +matter; and the three following remedies have been +proposed, while still retaining copper as the material. +First, in view of the fact that in the operation of brazing +the copper may be seriously injured, to use solid +drawn tubes. This appears fairly to meet the main +dangers incidental to brazing; but as solid drawn +pipes of over 7 inches diameter are difficult to procure, +it hardly meets the case sufficiently. Secondly, to use +electrically deposited tubes. At first much was promised +in this direction; but up to the present time it +can hardly be regarded as more than in the experimental +stage. Thirdly, to use the ordinary brazed or +solid drawn tubes, and to re-enforce them by serving +with steel cord or steel or copper wire. This has been +tried, and found to answer perfectly. For economical +reasons, as well as for insuring the minimum of torsion +to the material during manufacture, it is important +to make as few bends as possible; but in practice +much less difficulty has been experienced in serving +bent pipes in a machine than would have been +expected. Discarding copper, it has been proposed to +substitute steel or iron. In the early days of the +higher pressures, Mr. Alexander Taylor adopted +wrought iron for steam pipes. One fitted in the +Claremont in February, 1882, was recently removed +from the vessel for experimental purposes, and was +reported upon by Mr. Magnus Sandison in a paper +read before the Northeast Coast Institution of Engineers +and Shipbuilders.<a name="FNanchor_2"></a><a href="#Footnote_2"><sup>2</sup></a> The following is a summary +of the facts. The pipe was 5 inches external diameter, +and 0.375 inch thick. It was lap welded in the works +of Messrs. A. & J. Stewart. The flanges were screwed +on and brazed externally. The pipe was not lagged +or protected in any manner. After eight and a half +years' service the metal measured where cut 0.32 and +0.375 inch in thickness, showing that the wasting during +that time had been very slight. The interior surface +of the tube exhibited no signs of pitting or corrosion. +It was covered by a thin crust of black oxide, +the maximum thickness of which did not exceed 1/32 +inch. Where the deposit was thickest it was curiously +striated by the action of the steam. On the scale being +removed, the original bloom on the surface of the +metal was exposed. It would thus appear that the +danger from corrosion of iron steam pipes is not borne +out in their actual use; and hence so much of the way +is cleared for a stronger and more reliable material +than copper. So far the source of danger seems to be +in the weld, which would be inadmissible in larger +pipes; but there is no reason why these should not be +lapped and riveted. There seems, however, a more +promising way out of the difficulty in the Mannesmann +steel tubes which are now being "spun" out +of solid bars, so as to form weldless tubes.</p> + +<p class="ctr">TABLE I.--TENSILE STRENGTH OF GUN METAL AT HIGH TEMPERATURES.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gun Metal Strength"> +<colgroup><col align="left"><col span="4" align="right"></colgroup> +<tr><th>Composition of gun metal.</th><th>Temperature of oil bath</th><th>Tensile strength per square inch.</th><th>Elastic limit per square inch.</th><th>Elongation in length of 2 inches</th></tr> +<tr><td align="right">Per cent.</td><td>Fahr.</td><td>Tons</td><td>Tons</td><td>Per cent. </td></tr> +<tr><th rowspan="2" align="justify">Copper 87 <br />Tin 8<br />Zinc 3½<br />Lead 1½</th> +<td>50°</td><td>12.34</td><td>8.38</td><td>14.64</td></tr> +<tr><td>400°</td><td>10.83</td><td>6.30</td><td>11.79</td></tr> +<tr><th rowspan="2">Copper 87<br />Tin 8<br />Zinc 5</th> +<td>50°</td><td>13.86</td><td>8.33</td><td>20.30</td></tr> +<tr><td>458°</td><td>10.70</td><td>7.43</td><td>12.42</td></tr> +</table> + + +<p>Cast steel has been freely used by the writer for +bends, junction pieces, etc., of steam pipes, as well as +for steam valve chests; and except for the fact that +steel makers' promises of delivery are generally better +than their performance, the result has thus far been +satisfactory in all respects. These were adopted because +there existed some doubt as to the strength of +gun metal under a high temperature; and as the data +respecting its strength appeared of a doubtful character, +a series of careful tests were made to determine +the tensile strength of gun metal when at atmospheric +and higher temperatures. The test bars were all 0.75 +in diameter, or 0.4417 square inch sectional area; and +those tested at the higher temperatures were broken +while immersed in a bath of oil at the temperature here +stated, each line being the mean of four experiments. +The result of these experiments was to give somewhat +greater faith in gun metal as a material to be used +under a higher temperature; but as steel is much +stronger, it is probably the most advisable material +to use, when the time necessary to procure it can be +allowed.</p> + +<p><i>Feed Heating</i>.--With the double object of obviating +strain on the boiler through the introduction of the +feed water at a low temperature, and also of securing +a greater economy of fuel, the principle of previously +heating the feed water by auxiliary means has received +considerable attention, and the ingenious method +introduced by Mr. James Weir has been widely +adopted. It is founded on the fact that, if the +feed water as it is drawn from the hot well be raised +in temperature by the heat of a portion of steam introduced +into it from one of the steam receivers, +the decrease of the coal necessary to generate steam +from the water of the higher temperature bears a +greater ratio to the coal required without feed heating +than the power which would be developed in the +cylinder by that portion of steam would bear to the + +whole power developed when passing all the steam +through all the cylinders. The temperature of the +feed is of course limited by the temperature of the +steam in the receiver from which the supply for heating +is drawn. Supposing, for example, a triple expansion +engine were working under the following conditions +without feed heating: Boiler pressure, 150 lb.;--indicated +horse power in high pressure cylinder +398, in intermediate and low pressure cylinders +together 790, total, 1,188; and temperature of hot well +100° Fahr. Then with feed heating the same engine +might work as follows: The feed might be heated to +220° Fahr., and the percentage of steam from the first +receiver required to heat it would be 12.2 per cent.; +the indicated horse power in the high pressure cylinder +would be as before 398, and in the intermediate +and low pressure cylinders it would be 12.2 per cent, +less than before, or 694, and the total would be 1,092, +or 92 per cent. of the power developed without feed +heating. Meanwhile the heat to be added to each +pound of the feed water at 220° Fahr. for converting it +into steam would be 1,005 units against 1,125 units with +feed at 100° Fahr., equivalent to an expenditure of +only 89.4 per cent. of the heat required without feed +heating. Hence the expenditure of heat in relation to +power would be 89.4 + 92.0 = 97.2 per cent., equivalent to +a heat economy of 2.8 per cent. If the steam for heating +can be taken from the low pressure receiver, the +economy is about doubled. Other feed heaters, more +or less upon the same principle, have been introduced. +Also others which heat the feed in a series of pipes +within the boiler, so that it is introduced into the +water in the boiler practically at boiling temperature; +this is economical, however, only in the sense that +wear and tear of the boiler is saved; in principle the +plan does not involve economy of fuel.</p> + +<p><i>Auxiliary Supply of Fresh Water</i>.--Intimately associated +with the feed is the means adopted for making +up the losses of fresh water due to leakage of steam +from safety valves, glands, joints, etc., and of water +discharged from the air pumps. A few years ago this +loss was regularly made up from the sea, with the result +that the water in the boilers was gradually increased +in density; whence followed deposit on the +internal surfaces, and consequent loss of efficiency, and +danger of accident through overheating the plates. +With the higher pressures now adopted, the danger +arising from overheating is much more serious, and the +necessity is absolute of maintaining the heating surfaces +free from deposit. This can be done only by +filling the boiler with fresh water in the first instance, +and maintaining it in that condition. To do this two +methods are adopted, either separately or in conjunction. +Either a reserve supply of fresh water is carried +in tanks or the supplementary feed is distilled from +sea water by special apparatus provided for the purpose. +In the construction of the distilling or evaporating +apparatus advantage has been taken of two +important physical facts, namely, that, if water be +heated to a temperature higher than that corresponding +with the pressure on its surface, evaporation will +take place; and that the passage of heat from steam +at one side of a plate to water at the other is very +rapid. In practice the distillation is effected by passing +steam, say from the first receiver, through a nest +of tubes inside a still or evaporator, of which the steam +space is connected either with the second receiver or +with the condenser. The temperature of the steam +inside the tubes being higher than that of the steam +either in the second receiver or in the condenser, the +result is that the water inside the still is evaporated, +and passes with the rest of the steam into the condenser, +where it is condensed, and serves to make up +the loss. This plan localizes the trouble of deposit, +and frees it from its dangerous character, because an +evaporator cannot become overheated like a boiler, +even though it be neglected until it salts up solid; and +if the same precautions are taken in working the +evaporator which used to be adopted with low +pressure boilers when they were fed with salt water, +no serious trouble should result. When the tubes +do become incrusted with deposit, they can be +either withdrawn or exposed, as the apparatus is +generally so arranged; and they can then be cleaned.</p> + +<p><i>Screw Propeller</i>.--In Mr. Marshall's paper of 1881 it +was said that "the screw propeller is still to a great extent +an unsolved problem." This was at the time a +fairly true remark. It was true the problem had been +made the subject of general theoretical investigation +by various eminent mathematicians, notably by Professor +Rankine and Mr. William Froude, and of special +experimental investigation by various engineers. As +examples of the latter may be mentioned the +extended series of investigations in the French +vessel Pelican, and the series made by Mr. +Isherwood on a steam launch about 1874. These +experiments, however, such as they were, did little to +bring out general facts and to reduce the subject to a +practical analysis. Since the date of Mr. Marshall's paper, +the literature on this subject has grown rapidly, +and, has been almost entirely of a practical character. +The screw has been made the subject of most +careful experiments. One of the earliest extensive +series of experiments was made under the writer's +direction in 1881, with a large number of models, +the primary object being to determine what value there +was in a few of the various twists which inventive ingenuity +can give to a screw blade. The results led the +experimenters to the conclusion that in free water such +twists and curves are valueless as serving to augment +efficiency. The experiments were then carried further +with a view to determine quantitative moduli for the +resistance of screws with different ratios of pitch to +diameter, or "pitch ratios," and afterward with different +ratios of surface to the area of the circle described +by the tips of the blades, or "surface ratios." As these +results have to some extent been analyzed and published, +no further reference need be made to them now.</p> + +<p>In 1886, Mr. R.E. Froude published in the Transactions +of the Institution of Naval Architects the deductions +drawn from an extensive series of trials made +with four models of similar form and equal diameter, +but having different pitch ratios. Mr. S.W. Barnaby +has published some of the results of experiments made +under the direction of Mr. J.I. Thornycroft; and in +his paper read before the Institution of Civil Engineers +in 1890 he has also put Mr. R.E. Froude's results into +a shape more suitable for comparison with practice. +Nor ought Mr. G.A. Calvert's carefully planned experiments +to pass unnoticed, of which an account was + +given in the Transactions of the Institution of Naval +Architects in 1887. These experiments were made on +rectangular bodies with sections of propeller blade +form, moved through the water at various velocities in +straight lines, in directions oblique to their plane +faces; and from their results an estimate was formed +of the resistance of a screw.</p> + +<p>One of the most important results deduced from experiments +on model screws is that they appear to have +practically equal efficiencies throughout a wide range +both in pitch ratio and in surface ratio; so that great +latitude is left to the designer in regard to the form of +the propeller. Another important feature is that, although +these experiments are not a direct guide to the +selection of the most efficient propeller for a particular +ship, they supply the means of analyzing the performances +of screws fitted to vessels, and of thus indirectly +determining what are likely to be the best dimensions +of screw for a vessel of a class whose results are known. +Thus a great advance has been made on the old method +of trial upon the ship itself, which was the origin of +almost every conceivable erroneous view respecting +the screw propeller. The fact was lost sight of that +any modification in form, dimensions, or proportions +referred only to that particular combination of ship +and propeller, or to one similar thereto; so something +like chaos was the result. This, however, need not be +the case much longer.</p> + +<p>In regard to the materials used for propellers, steel +has been largely adopted for both solid and loose-bladed +screws; but unless protected in some way, the +tips of the blades are apt to corrode rapidly and become +unserviceable. One of the stronger kinds of +bronze is often judiciously employed for the blades, in +conjunction with a steel boss. Where the first extra +expense can be afforded, bronze seems the preferable +material; the castings are of a reliable character, and +the metal does not rapidly corrode; the bronze blades +can therefore with safety be made lighter than steel +blades, which favors their springing and accommodating +themselves more readily to the various speeds of +the different parts of the wake. This might be expected +to result in some slight increase of efficiency; +of which, however, the writer has never had the opportunity +of satisfactorily determining the exact extent. +Instances can be brought forward where bronze blades +have been substituted for steel or iron with markedly +improved results; but in cases of this kind which the +writer has had the opportunity of analyzing, the whole +improvement might be accounted for by the modified +proportions of the screw when in working condition. +In other words, both experiment and practical working +alike go to show that, although cast iron and steel +blades as usually proportioned are sufficiently stiff to +retain their form while at work, bronze blades, being +made much lighter, are not; and the result is that the +measured or set pitch is less than that which the +blades assume while at work. Some facts relative to +this subject have already been given in a recent paper +by the author.</p> + +<p><i>Twin Screws</i>.--The great question of twin screw propulsion +has been put to the test upon a large scale in +the mercantile marine, or rather in what would usually +be termed the passenger service. While engineers, +however, are prepared to admit its advantages so far +as greater security from total breakdown is concerned, +there is by no means thorough agreement as to +whether single or twin screws have the greater propulsive +efficiency. What is required to form a sound +judgment upon the whole question is a series of examples +of twin and single screw vessels, each of which is +known to be fitted with the most suitable propeller for +the type of vessel and speed; and until this information +is available, little can be said upon the subject with +any certainty. So far the following large passenger +steamers, particulars of which are given in table II., +have been fitted with twin screws. It appears t be a +current opinion that the twin screw arrangement necessitates +a greater weight of machinery. This is not +necessarily so, however; on the contrary, the opportunity +is offered for reducing the weight of all that part +of the machinery of which the weight relatively to +power is inversely proportional to the revolutions for a +given power. This can be reduced in the proportion of +1 to the square root of 2, that is 71 per cent. of its weight in the single +screw engine; for since approximately the same total +disk area is required in both cases with similar proportioned +propellers, the twins will work at a greater +speed of revolution than the single screw. From a commercial +point of view there ought to be little disagreement +as to the advantage of twin screws, so long as the +loss of space incurred by the necessity for double tunnels +is not important; and for the larger passenger +vessels now built for ocean service the disadvantage +should not be great. Besides their superiority in the +matter of immunity from total breakdown, and in +greatly diminished weight of machinery, they also offer +the opportunity of reducing to some extent the cost of +machinery. A slightly greater engine room staff is +necessary; but this seems of little importance compared +with the foregoing advantages.</p> + +<p class="ctr">TABLE II.--PASSENGER STEAMERS FITTED WITH +TWIN SCREWS.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Twin screw passenger stemeaers"> +<colgroup><col align="left" width="25%"><col span="2" align="center" width="10%"><col align="center" width="15%"><col span="2" align="right" width="10%"><col align="right" width="15%"></colgroup> +<tr><td>Vessels.</td><td>Length between perpen- diculars.</td><td>Beam.</td><td colspan="2">Cylinders two sets in all cases.</td><td>Boiler pressure per square inch.</td><td>Indicated horsepower.</td></tr> +<tr><td> </td><td>Feet.</td><td>Feet.</td><td>Diameters.<br />Inches.</td><td>Stroke.<br />Inches.</td><td>Lb.</td><td> </td></tr> +<tr><td>City of Paris.<br />City of New York.</td><td>525</td><td>63¼</td><td> 45, 71, 113</td><td>60</td><td>150</td><td>20,000 </td></tr> +<tr><td>Teutonic.<br /> Majestic.</td><td>565</td><td>58</td><td>43, 68, 110</td><td>60</td><td>180</td><td>18,000 </td></tr> +<tr><td>Normannia.</td><td>500</td><td>57½</td><td> 40, 67, 106</td><td>66</td><td>160</td><td>11,500 </td></tr> +<tr><td>Columbia.</td><td>463½</td><td>55½</td><td> 41, 66, 101</td><td>66</td><td>160</td><td>12,500 </td></tr> +<tr><td>Empress of India.<br />Empress of Japan.<br />Empress of China.</td><td>440</td><td>51</td><td>32, 51, 82</td><td>54</td><td>160</td><td>10,125</td></tr> +<tr><td>Orel.</td><td>415</td><td>48</td><td>34, 54, 85</td><td>51</td><td>160</td><td>10,000 </td></tr> +</table> + +<p><i>Weight of Machinery Relatively to Power</i>.--It is interesting +to compare the weight of machinery relatively + +to the power developed; for this comparison has +sometimes been adopted as the standard of excellence +in design, in respect of economy in the use of material. +The principle, however, on which this has generally +been done is open to some objections. It has been usual +to compare the weight directly with the indicated +horse-power, and to express the comparison in pounds +per horse-power. So long as the machinery thus compared +is for vessels of the same class and working at +about the same speed of revolution, no great fault can +be found; but as speed of revolution is a great factor +in the development of power, and as it is often dependent +on circumstances altogether external to the engine +and concerning rather the speed of the ship, the engines +fitted to high speed ships will thus generally +appear to greater advantage than is their due. Leaving +the condenser out of the question, the weight of an +engine would be much better referred to cylinder +capacity and working pressures, where these are materially +different, than directly to the indicated power. +The advantages of saving weight of machinery, so long +as it can be done with efficiency, are well known and +acknowledged. If weight is to be reduced, it must be +done by care in design, not by reduction of strength, +because safety and saving of repairs are much more +important than the mere capability of carrying a +few tons more of paying load. It must also be +done with economy; but this is a matter which generally +settles itself aright, as no shipowner will pay more +for a saving in weight than will bring in a remunerative +interest on his outlay. In his paper on the weight +of machinery in the mercantile marine,<a name="FNanchor_3"></a><a href="#Footnote_3"><sup>3</sup></a> Mr. William +Boyd discussed this question at some length, and proposed +to attain the end of reducing the weight of machinery +by the legitimate method of augmenting the +speed of revolution and so developing the required +power with smaller engines. This method, while promising, +is limited by the efficiency of the screw, but may +be adopted with advantage so long as the increase in +speed of revolution involves no such change in the +screw as to reduce its efficiency as a propeller. But +when the point is reached beyond which a further +change involves loss of propelling efficiency, it is time +to stop; and the writer ventures to say that in many +cargo vessels now at work the limit has been reached, +while in many others it has certainly been passed.</p> + +<p><i>Economy of Fuel</i>.--Coming to the highly important +question of economy of fuel, the average consumption +of coal per indicated horse-power is 1.522 lb. per hour. +The average working pressure is 158.5 lb. per square +inch. Comparing this working pressure with 77.4 lb. in +1881, a superior economy of 19 per cent. might be expected +now, on account of the higher pressure, or +taking the 1.828 lb. of coal per hour per indicated +horse-power in 1881, the present performance under +similar conditions should be 1.48 lb. per hour per indicated +horse-power. It appears that the working +pressures have been increased twice in the last ten +years, and nearly three times in the last nineteen. The +coal consumptions have been reduced 16.7 per cent. in +the last ten years and 27.9 per cent. in the last nineteen. +The revolutions per minute have increased in the +ratios of 100, 105, 114; and the piston speeds as 100, 124, +140. Although it is quite possible that the further investigations +of the Research Committee on Marine +Engine Trials may show that the present actual consumption +of coal per indicated horse-power is understated, +yet it is hardly probable that the relative +results will be affected thereby.</p> + +<p><i>Dimensions</i>.--In the matter of the power put into +individual vessels, considerable strides have been +made. In 1881, probably the greatest power which has +been put into one vessel was in the case of the Arizona, +whose machinery indicated about 6,360 horse-power. +The following table gives an idea of the dimensions +and power of the larger machinery in the later +passenger vessels:</p> + +<p class="ctr">TABLE III.--DIMENSIONS AND POWER OF MACHINERY +IN LATER PASSENGER VESSELS.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Later Passenger Vessels"> +<colgroup><col align="left"><col align="left" width="25%"><col align="center"><col span="2" align="right"></colgroup> +<tr><td>Year.</td><td>Name of vessel. </td><td>Diameters of cylinders<br />Inches.</td><td>Length of Stroke.<br />Inches.</td><td>Indicated horsepower</td></tr> +<tr><td>1881</td><td>Alaska</td><td>68, 100, 100</td><td>72</td><td>10,686</td></tr> +<tr><td>1881</td><td>City of Rome</td><td>46, 86; 46, 86; 46, 86</td><td>72</td><td>11,800</td></tr> +<tr><td>1881</td><td>Servia</td><td>72, 100, 100</td><td>78</td><td>10,300</td></tr> +<tr><td>1881</td><td>Livadia yacht</td><td>60, 78, 78; 60, 78,78; 60, 78, 78</td><td>39</td><td>12,500</td></tr> +<tr><td>1883</td><td>Oregon</td><td>70, 104, 104</td><td>72</td><td>13,300</td></tr> +<tr><td>1884<br />1884</td><td>Umbria<br />Etruria</td><td>71, 105, 105</td><td>72</td><td>14,320</td></tr> +<tr><td>1888<br />1889</td><td>City of New York<br /> City of Paris</td><td>45, 71, 113; 45, 71, 113</td><td>60</td><td>20,000 about</td></tr> +<tr><td>1889<br />1889</td><td>Majestic<br />Teutonic</td><td>43, 68, 110; 43, 68, 110</td><td>60</td><td>18,000</td></tr> +</table> + + +<p>In war vessels the increase has been equally marked. +In 1881 the maximum power seems to have been in the +Inflexible, namely, 8,485 indicated horse-power. The +following will give an idea of the recent advance made: +Howe (Admiral class), 11,600 indicated horse-power; +Italia and Lepanto, 19,000 indicated horse-power; Re +Umberto, 19,000 indicated horse-power; Blake and +Blenheim (building), 18,000 indicated horse-power; Sardegna +(building), 22,800 indicated horse-power. It is +thus evident that there are vessels at work to-day +having about three times the maximum power of any +before 1881.</p> + +<p><i>General Conclusions</i>.--The progress made during the +last ten years having been sketched out, however +roughly, the general conclusions may be stated briefly +as follows: First, the working pressure has been about +doubled. Second, the increase of working pressure and +other improvements have brought with them their +equivalent in economy of coal, which is about 20 per +cent. Third, marked progress has been made in the +direction of dimension, more than twice the power +having been put into individual vessels. Fourth, substantial +advance has been made in the scientific principles +of engineering. It only remains for the writer to +thank the various friends who have so kindly furnished +him with data for some of the tables which have been +given; and to express the hope that the next ten years +may be marked by such progress as has been witnessed +in the past. But it must be remembered that, if +future progress be equal in merit or ratio, it may well +be less in quantity, because advance becomes more difficult +of achievement as perfection is more nearly approached.</p> + +<a name="Footnote_1"></a><a href="#FNanchor_1">[1]</a><div class="note">Paper read before the Institution of Mechanical Engineers, July 28, +1891.</div> + +<a name="Footnote_2"></a><a href="#FNanchor_2">[2]</a><div class="note">Transactions Northeast Coast Institution of Engineers and Shipbuilders, +vol. 7, 1890-91, p. 179.</div> + +<a name="Footnote_3"></a><a href="#FNanchor_3">[3]</a><div class="note">Transactions Northeast Coast Institution of Engineers and Shipbuilders, +vol. 6, 1889-90, p. 253.</div> + +<hr /> + +<a name="misc1"></a><h2>THE LITTLE HOUSE</h2> + +<h3>By M.M.</h3> + + +<p>One of the highest medical authorities is credited +with the statement that "nine-tenths of the diseases +that afflict humanity are caused by neglect to answer +the calls of Nature."</p> + +<p>This state of affairs is generally admitted, but is +usually attributed to individual indolence. That, +doubtless, has a great deal to do with it, but should +not part of the blame be laid upon the often unpleasant +environments, which make us shrink as from the +performance of a painful duty?</p> + +<p>In social life, unless from absolute necessity or charity, +people of refined habits do not call on those whose +surroundings shock their sense of decency; but when +they go to pay the calls of Nature, they are often compelled +to visit her in the meanest and most offensive +of abodes; built for her by men's hands; for Nature +herself makes no such mistakes in conducting her +operations. She does not always surround herself +with the pomp and pride of life, but she invariably +hedges herself in with the thousand decencies and the +pomp of privacy.</p> + +<p>But what do we often do? We build what is sometimes +aptly termed "an out-house," because it is placed +so that the delicate minded among its frequenters may +be made keenly alive to the fact that they can be +plainly seen by every passer-by and by every idle +neighbor on the lookout. This tiny building is seldom +weatherproof; In consequence, keen cold winds from +above, below, and all around find ready entrance, chill +the uncovered person, frequently check the motions, +and make the strong as well as the weak, the young as +well as the old, very sorry indeed that they are so often +uselessly obliged to answer the calls of Nature. It is +true, the floor is sometimes carpeted with snow, but +the feet feel that to be but cold comfort, though the +door may enjoy rattling its broken hasp and creaking +its loose hinges.</p> + +<p>How often, too, are the nose and the eye offended by +disregard of the Mosaic injunction, found in the +twelfth, thirteenth, and fourteenth verses of the +twenty-third chapter of Deuteronomy! Of course this +injunction was addressed to a people who had been +debased by slavery, but who were being trained to fit +them for their high calling as the chosen of God; but +is not some such sanitary regulation needed in these +times, when a natural office is often made so offensive +to us by its environments that it is difficult for us to +believe that "God made man a little lower than the +angels," or that the human body is the temple of the +Holy Ghost?</p> + +<p>Dwellers in the aristocratic regions of a well drained +city, whose wealth enables them to surround themselves +with all devices tending to a refined seclusion, +may doubt all this, but sanitary inspectors who have +made a round of domiciliary visits in the suburbs, or +the older, neglected parts of a large city, of to any part +of a country town or village, will readily affirm as to its +general truth.</p> + +<p>This unpardonable neglect of one of the minor decencies +by the mass of the people seems to be caused +partly by a feeling of false shame, and partly by an +idea that it is expensive and troublesome to make any +change that will improve their sanitary condition or +dignify their daily lives.</p> + +<p>The Rev. Henry Moule, of Fordington Vicarage, +Dorsetshire, England, was one of the first to turn his +attention to this matter. With the threefold object of +improving the sanitary condition of his people, refining +their habits, and enriching their gardens, he invented +what he called the "dry earth closet."</p> + +<p>"It is based on the power of clay and the decomposed +organic matter found in the soil to absorb and retain +all offensive odors and all fertilizing matters; and it +consists, essentially, of a mechanical contrivance (attached +to the ordinary seat) for measuring out and +discharging into the vault or pan below a sufficient +quantity of sifted dry earth to entirely cover the solid +ordure and to absorb the urine.</p> + +<p>"The discharge of earth is effected by an ordinary +pull-up, similar to that used in the water closet, or (in +the self-acting apparatus) by the rising of the seat +when the weight of the person is removed.</p> + +<p>"The vault or pan under the seat is so arranged that +the accumulation can be removed at pleasure.</p> + +<p>"From the moment when the earth is discharged +and the evacuation covered, all offensive exhalation +entirely ceases. Under certain circumstances there +may be, at times, a slight odor as of guano mixed with +earth, but this is so trifling and so local that a commode +arranged on this plan may, without the least +annoyance, be kept in use in any room."</p> + +<p>The "dry earth closet" of the philanthropic clergyman +was found to work well, and was acceptable to +his parishioners. One reason why it was so was because +dry earth was ready to hand, or could be easily +procured in a country district where labor was cheap. +But where labor was dear and dry earth scarce, those +who had to pay for the carting of the earth and the +removal of the deodorized increment found it both +expensive and troublesome.</p> + +<p>But a modification of this dry earth closet, the joint +contrivance of an English church clergyman and his +brother, "the doctor," residents of a Canadian country +town, who had heard of Moule's invention, is a +good substitute, and is within the reach of all. This +will be briefly described.</p> + +<p>The vault was dug as for an ordinary closet, about +fifteen feet deep, and a rough wooden shell fitted in. +About four feet below the surface of this wooden shell +a stout wide ledge was firmly fastened all around. +Upon this ledge a substantially made wooden box was +placed, just as we place a well fitting tray into our +trunks. About three feet of the back of the wooden +shell was then taken out, leaving the back of the box +exposed. From the center of the back of the box a +square was cut out and a trap door fitted in and hasped +down.</p> + +<p>The tiny building, on which pains, paint, and inventive +genius had not been spared to make it snug, +comfortable, well lighted and well ventilated, was +placed securely on this vault.</p> + +<p>After stones had been embedded in the earth at the +back of the vault, to keep it from falling upon the trap + +door, two or three heavy planks were laid across the +hollow close to the closet. These were first covered +with a barrowful of earth and then with a heap of +brushwood.</p> + +<p>Within the closet, in the left hand corner, a tall +wooden box was placed, about two-thirds full of dry, +well sifted wood ashes. The box also contained a +small long-handled fire shovel. When about six inches +of the ashes had been strewn into the vault the closet +was ready for use. No; not quite; for squares of suitable +paper had to be cut, looped together with twine, +and hung within convenient reaching distance of the +right hand; also a little to the left of this pad of paper, +and above the range of sight when seated, a ten pound +paper bag of the toughest texture had to be hung by a +loop on a nail driven into the corner.</p> + +<p>At first the rector thought that his guests would be +"quick-witted enough to understand the arrangement," +but when he found that the majority of them +were, as the Scotch say, "dull in the uptak," he had +to think of some plan to enforce his rules and regulations. +As by-word-of-mouth instructions would have +been rather embarrassing to both sides, he tacked up +explicit written orders, which must have provoked +many a smile. Above the bin of sifted ashes he nailed +a card which instructed "Those who use this closet +must strew two shovelfuls of ashes into the vault." +Above the pad of clean paper he tacked the thrifty +proverb: "Waste not, want not;" and above the +paper bag he suspended a card bearing this warning: +"All refuse paper must be put into this bag; not a +scrap of clean or unclean paper must be thrown into +the vault."</p> + +<p>This had the desired effect. Some complacently +united to humor their host's whim, as they called it, +and others, immediately recognizing its utility and +decency, took notes with a view to modifying their +own closet arrangements.</p> + +<p>Sarah, the maid of all work, caused a good deal of +amusement in the family circle by writing her instructions +in blue pencil on the front of the ash bin. These +were: "Strew two shuffefuls of ashes into the volt, but +don't spill two shuffefuls onto the floor. By order of +the Gurl who has to sweap up." This order was emphatically +approved of by those fastidious ones who +didn't have to "sweep up."</p> + +<p>This closet opened off the woodshed, and besides being +snugly weatherproof in itself, was sheltered on one +side by the shed and on another by a high board fence. +The other two sides were screened from observation by +lattice work, outside of which evergreens were planted +to give added seclusion and shade. A ventilator in the +roof and two sunny little windows, screened at will +from within by tiny Venetian shutters, gave ample +light and currents of fresh air. For winter use, the +rector's wife and daughters made "hooked" mats for +floor and for foot support. These were hung up every +night in the shed to air and put back first thing in the +morning. For the greater protection and comfort of +invalids, an old-fashioned foot warmer, with a handle +like a basket, was always at hand ready to be filled +with live coals and carried out.</p> + +<p>The little place was always kept as exquisitely clean +as the dainty, old-fashioned drawing room, and so +vigilant was the overseeing care bestowed on every detail, +that the most delicate and acute sense of smell +could not detect the slightest abiding unpleasant odor. +The paper bag was frequently changed, and every +night the accumulated contents were burned; out of +doors in the summer, and in the kitchen stove--after a +strong draught had been secured--in the winter.</p> + +<p>At stated times the deodorized mass of solid increment--in +which there was not or ought not to have +been any refuse paper to add useless bulk--was spaded, +through the trap door, out of the box in the upper +part of the vault, into a wheelbarrow, thrown upon +the garden soil, and thoroughly incorporated with it. +In this cleansing out process there was little to offend, +so well had the ashes done their concealing deodorizing +work.</p> + +<p>In using this modified form of Moule's invention, it +is not necessary to dig a deep vault. The rector, given +to forecasting, thought that some day his property +might be bought by those who preferred the old style, +but his brother, the doctor, not troubling about what +might be, simply fitted his well made, four feet deep +box, with its trap door, into a smoothly dug hole that +exactly held it, and set the closet over it. In all other +respects it was a model of his brother's.</p> + +<p>This last is within the reach of all, even those who +live in other people's houses; for, when they find +themselves in possession of an unspeakably foul closet, +they can cover up the old vault and set the well +cleaned, repaired, fumigated closet upon a vault +fashioned after the doctor's plan. A stout drygoods +box, which can be bought for a trifle, answers well for +this purpose, after a little "tinkering" to form a trap +door.</p> + +<p>Of course, dry earth is by far the best deodorizer +and absorbent, but when it cannot be easily and +cheaply procured, well sifted wood or coal ashes--wood +preferred--is a good substitute. The ashes must be +kept dry. If they are not, they lose their absorbing, +deodorizing powers. They must also be well sifted. If +they are not, the cinders add a useless and very heavy +bulk to the increment.</p> + +<p>An ash sifter can be made by knocking the bottom +out of a shallow box, studding the edge all round with +tacks, and using them to cross and recross with odd +lengths of stovepipe wire to form a sieve.--<i>The Sanitarian</i>.</p> + +<hr /> +<a name="med1"></a><h2>THE HYGIENIC TREATMENT OF OBESITY.<a name="FNm1_anc_1"></a><a href="#FNm1_1"><sup>1</sup></a></h2> + +<h3>By Dr. Paul Cheron.</h3> + + +<p>In order to properly regulate the regimen of the +obese, it is first necessary to determine the source of +the superfluous adipose of the organism, since either +the albuminoids or the hydrocarbons may furnish fat.</p> + +<p>Alimentary fat becomes fixed in the tissues, as has +been proved by Lebede, who fed dogs, emaciated by +long fast, with meat wholly deprived of fat, and substituted +for the latter linseed oil, when he was able to +recover the oil in each instance from the animal; +parallel experiments with mutton fat, <i>in lieu</i> of oil, +afforded like results.</p> + +<p>Hoffman also deprived dogs of fat for a month, causing +them to lose as high as twenty-two pounds weight, + +then began nourishing with bacon fat with but little +lean; the quantity of fat formed in five days, in the +dog that lost twenty-two pounds, was more than three +pounds, which could have been derived only from the +bacon fat.</p> + +<p>It has been stated, however, that alimentary fat +seems to preserve from destruction the fat of the organism +which arises from other sources. Be this as it may, +it is a fact that the pre-existence of fat furthers the +accumulation of more adipose; or in other words, fat +induces fattening!</p> + +<p>That adipose may be formed through the transformation +of albuminous matters (meat) is an extremely +important corollary, one established beyond cavil by +Pettinkofer and Voit, in an indirect way, by first +estimating the nitrogen and carbon ingested, and +second the amount eliminated. Giving a dog meat +that was wholly deprived of fat, they found it impossible +to recover more than a portion of the contained carbon; +hence some must necessarily have been utilized in the +organism, and this would be possible only by the transformation +of the carbon into fat! It goes without +saying, however, that the amount of adipose thus +deposited is meager.</p> + +<p>Other facts also plead in favor of the transformation +of a portion of albumen into fat within the economy, +notably the changing of a portion of dead organism +into what is known as "cadaveric fat," and the very +rapid fatty degeneration of organs that supervenes +upon certain forms of poisoning, as by phosphorus.</p> + +<p>The carbohydrates, or more properly speaking +hydrocarbons, are regarded by all physiologists as +specially capable of producing fat, and numerous alimentary +experiments have been undertaken to prove +this point. Chaniewski, Meissl, and Munk obtained +results that evidenced, apparently, sugar and starch +provide more fat than do the albuminoids. Voit, however, +disapproves this, maintaining the greater part of +the hydrocarbons is burned (furnishes fuel for the +immediate evolution of force), and that fat cannot be +stored up unless a due proportion of albuminoids is +also administered. He believes the hydrocarbons exert +a direct influence only; being more oxidizable than +fats, they guard the latter from oxidation. This protective +role of the hydrocarbons applies also to the +albuminoids.</p> + +<p>We may believe, then, that the three great classes of +aliment yield fat, in some degree; that alimentary fat +may be fixed in the tissues; and that hydrocarbons +favor the deposition of adipose either directly or indirectly.</p> + +<p>It is well understood that fat may disappear with +great rapidity under certain conditions; many maladies +are accompanied by speedy emaciation; therefore, +as fat never passes into the secretions, at least not in +appreciable quantities, it probably undergoes transformation, +perhaps by oxidation or a form of fermentation, +the final results of which are, directly or +indirectly, water and cadaveric acid. It is certain +the process of oxidation favors the destruction of +adipose, and that everything which inhibits such +destruction tends to fat accumulation.</p> + +<p>Since the earliest period of history, there seems to +have been an anxiety to secure some regimen of general +application that would reduce or combat obesity. +Thus Hippocrates says:</p> + +<p>Fat people, and all those who would become lean, +should perform laborious tasks while fasting, and eat +while still breathless from fatigue, without rest, and +after having drunk diluted wine not very cold. Their +meats should be prepared with sesamum, with sweets, +and other similar substances, and these dishes should +be free from fat.</p> + +<p>In this manner one will be satiated through eating +less.</p> + +<p>But, besides, one should take only one meal; take +no bath; sleep on a hard bed; and walk as much as +may be.</p> + +<p>How much has medical science gained in this direction +during the interval of more than two thousand +years? Let us see:</p> + +<p>First among moderns to seek to establish on a scientific +basis a regimen for the obese, was Dancel, who +forbade fats, starchy foods, etc., prescribed soups and +aqueous aliment, and reduced the quantity of beverage +to the lowest possible limit; at the same time he employed +frequent and profuse purgation.</p> + +<p>This regimen, which permits, at most, but seven to +twelve ounces of fluid at each repast, is somewhat +difficult to follow, though it may be obtained, gradually, +with ease. Dr. Constantine Paul records a case +in which this regimen, gradually induced, and followed +for ten years, rewarded the patient with "moderate +flesh and most excellent health."</p> + +<p>In Great Britain, a mode of treatment instituted in +one Banting, by Dr. Harvey, whereby the former was +decreased in weight forty pounds, has obtained somewhat +wide celebrity; and what is more remarkable, it +is known as "Bantingism," taking its name from the +patient instead of the physician who originated it. +The dietary is as follows:</p> + +<p><i>Breakfast</i>.--Five to six ounces of lean meat, broiled +fish, or smoked bacon--veal and pork interdicted; a +cup of tea or coffee without milk or sugar; one ounce +of toast or dry biscuit (crackers).</p> + +<p><i>Dinner</i>.--Five or six ounces of lean meat or fish--excluding +eel, salmon, and herring; a small quantity of +vegetables, but no potatoes, parsnips, carrots, beets, +peas, or beans; one ounce of toast, fruit, or fowl; two +glasses of red wine--beer, champagne, and port forbidden.</p> + +<p><i>Tea</i>.--Two or three ounces of fruit; one kind of +pastry; one cup of tea.</p> + +<p><i>Supper</i>.--Three or four ounces of lean beef or fish; +one or two glasses of red wine.</p> + +<p><i>At bed-time.</i>--Grog without sugar (whisky and water, +or rum and water), and one or two glasses of sherry or +Bordeaux.</p> + +<p>"Bantingism," to be effective, must be most closely +followed, when, unfortunately also, it proves extremely +debilitating; it is suitable only for sturdy, hard +riding gluttons of the Squire Western type. The +patient rapidly loses strength as well as flesh, and +speedily acquires an unconquerable repugnance to the +dietary. Further, from a strictly physiological point +of view, the quantity of meat is greatly in excess, while +with the cessation of the regimen, the fat quickly reappears.</p> + +<p>Next Ebstein formulated a dietary that is certainly +much better tolerated than that of Harvey and Banting, + +and yields as good, or even better, results. He +allows patients to take a definite quantity--two to two +and a half ounces-of fat daily, in the form of bacon +or butter which, theoretically at least, offers several +advantages: It diminishes the sensations of hunger +and thirst, and plays a special role with respect to the +albuminoids; the latter may thus be assimilated by +the economy without being resolved into fat, and thus +the adipose of the organism at this period is drawn +upon without subsequent renewal. The following is +the outline:</p> + +<p><i>Breakfast</i>.--At 6 a.m. in summer; 7:30 in winter:--Eight +ounces of black tea without either milk or sugar; +two ounces of white bread or toast, with a copious layer +of butter.</p> + +<p><i>Dinner</i>.--2 p.m.:--A modicum of beef marrow soup; +four ounces of meat, preferably of fatty character; +moderate quantity of vegetable, especially the legumines, +but no potatoes or anything containing starch; +raw fruits in season, and cooked fruits (stewed, without +sugar); two or three glasses of light wine as a +beverage, and after eating, a cup of black tea without +sugar.</p> + +<p><i>Supper</i>.--7:30 p m.:--An egg, bit of fat roast, ham, +or bacon; a slice of white bread well buttered; a large +cup of black tea without milk or sugar; from time to +time, cheese and fresh fruits.</p> + +<p>Germain See suggests as a modification of this regimen, +the abundant use of beverage, the addition of +gelatins, and at times small doses of potassium iodide +in twenty cases he claims constant and relatively +prompt results.</p> + +<p>Whatever may be urged for Ebstein's system--and it +has afforded most excellent results to Unna and to +Lube, as well as its author--it certainly exposes the +patient to the terrors of dyspepsia, when the routine +must needs be interrupted or modified; hence it is not +always to be depended upon. As between dyspepsia +and obesity, there are few, I fancy, who would not +prefer the latter.</p> + +<p>Another "system" that has acquired no little celebrity, +and which has for its aim the reduction as far +as possible of alimentary hydrocarbons while permitting +a certain proportion of fat, is that, of Denneth, +which necessarily follows somewhat closely the lines +laid down by Ebstein.</p> + +<p>Oertels' treatment, somewhat widely known, and not +without due measure of fame, is based upon a series of +measures having as object the withdrawal from both +circulation and the economy at large, as much of the +fluids as possible. It is especially adapted for the relief +of those obese who are suffering fatty degeneration of +the heart. The <i>menu</i> is as follows:</p> + +<p><i>Breakfast</i>.--Pour to five ounces of tea or coffee with +a little milk; two to two and a half ounces bread.</p> + +<p><i>Dinner</i>.--Three or four ounces of roast or boiled +meat, or moderately fat food; fish, slightly fat; salad +and vegetables at pleasure; one and a half ounces of +bread (in certain cases as much as three ounces of farinaceous +food may be permitted); three to six ounces of +fruit; at times a little pastry for dessert.--In summer, +if fruit is not obtainable, six to eight ounces of light +wine may be allowed.</p> + +<p><i>Tea</i>,--A cupful (four to five ounces) of tea or coffee, +with a trifle of milk, as at breakfast; one and three-fourths +ounces of bread; and exceptionally (and at +most) six ounces of water.</p> + +<p><i>Supper</i>.--One to two soft boiled eggs; four or five +ounces of meat; one and three fourths ounces of bread; +a trifle of cheese, salad, or fruit; six to eight ounces of +light wine diluted with an eighth volume of water. +The quantity of beverage may be slightly augmented +at each meal if necessary, especially if there is no morbid +heart trouble.</p> + +<p>Schwenninger (Bismarck's physician), who opened a +large sanitarium near Berlin a few years since for the +treatment of the obese, employs Oertel's treatment, +modified in that an abundance of beverage is permitted, +provided it is not indulged in at meals; it is forbidden +until two hours after eating.</p> + +<p>Both Oertel's and Schwenninger's methods have procured +grave dyspepsias, and fatal albuminurias as well, +according to Meyer and Rosenfield. It has been +charged the allowance of beverage upon which Schwenninger +lays so much stress in the treatment at his sanitarium +has a pecuniary basis, in other words a commission +upon the sale of wines.<a name="FNm1_anc_2"></a><a href="#FNm1_2"><sup>2</sup></a></p> + + +<p>Thus, it will be observed that while some forbid +beverage, others rather insist upon its employment in +greater or less quantities. Under such circumstances, +it would seem but rational, before undertaking to +relieve obesity, to establish its exact nature, and also +the role taken by fluids in the phenomena of nutrition.</p> + +<p>Physiologists generally admit water facilitates nutritive +exchanges, which is explained by the elimination +of a large quantity of urine; the experiments of Genth +and Robin in this direction appear conclusive.</p> + +<p>Bischoff, Voit, and Hermann have shown that water +increases, not alone the elimination of urine, but also +of sodium chloride, phosphoric acid, etc. Grigoriantz +observed augmentation of disintegration when the +quantity of beverage exceeded forty-six to eighty +ounces ("1,400 to 2,400 cubic centimeters") per diem. +Oppenheim, Fraenkel, and Debove, while believing +water has but little influence upon the exchanges, admit +it certainly need not diminish the latter; and Debove +and Flament, after administering water in quantities +varying from two to eight pints per diem, concluded +that urine was diminished below the former +figure, while above the latter it increased somewhat, +being dependent upon the amount ingested. It was on +the strength of the foregoing that Lallemand declared +water to have no influence upon the exchanges.</p> + +<p>The results claimed by Oppenheim, Debove, <i>et al.</i> +were immediately challenged--and it is now generally +admitted, not without some justice--by Germain See. +It seems certain, to say the least, that water taken during +the repast does tend to augment the quantity and +facilitate the elimination of urine. Abundance of beverage, +moreover, presents other advantages, in that it +facilitates digestion by reason of its diluent action, a +fact well worth bearing in mind when treating the +obese who are possessed of gouty diathesis, and whose +kidneys are accordingly encumbered with uric and +oxalic acids. The foregoing presents the ground upon +which Germain See permits an abundance of beverage; +but he also expresses strong reservation as regards beer + +and alcohol, either of which (more especially the former) +tends to the production of adipose. In his opinion, +the only beverage of the alcoholic class that is at all +permissible, and then only for cases suffering from fatty +heart, is a little <i>liqueur</i> or diluted wine. Coffee and +tea he commends highly, and recommends the ingestion +of large quantities at high temperature, both during +the repasts and their intervals. Coffee in large doses +is undoubtedly a means of de-nutrition, and so, too, in +no less extent, is tea; both act vigorously owing to the +contained alkaloids, though, to be sure, they sometimes, +at first, tend to insomnia and palpitation, to +which no attention need be paid, however. The treatment +outlined by See is:</p> + +<p>1. A physiological regimen comprising four to five +ounces of nitrogenous principles as derived from eight +to ten ounces animal muscle and albuminates; three +to six ounces of fat; eight to ten ounces of hydrocarbons +as yielded by ten to twelve ounces of sugar or +starch food.</p> + +<p>These proportions to be modified in such manner +that the musculo-albuminates shall not sensibly exceed +the normal ratio, for meat in excess itself furnishes +fat during transformation. The fatty substances +of easy digestion may, without inconvenience, be utilized +in doses of two to three ounces. The hydrocarbons +should be reduced to a minimum. As for the herbaceous +elements, they contain nothing nutritive.</p> + +<p>2. Beverage, far from being suppressed, should be +augmented, in order to facilitate stomachal digestion +and promote general nutrition, though alcoholic liquids +must be inhibited; likewise mineral waters, except, +perhaps, for occasional use. Both should be replaced +by infusions of coffee or tea, taken as hot as can be +drank.</p> + +<p>Henrich Kisch insists that any method which promises +rapid and marked decrease of adipose must, <i>per se</i>, +be objectionable, even if not positively injurious, since +it tends to provoke general troubles of nutrition. He +suggests that first the fats and hydrocarbons be reduced +as little as possible; that a moderate mixed +regimen is required, containing a preponderance of +albumen, small quantities of hydrocarbons and gelatinous +matters, with but very little fat. Certain fatty +meats, however, should be generally interdicted, such +as pork sausage, smoked beef tongue, goose breast, +smoked ham, fat salmon, and herring in any form. +Eggs, however, may be partaken of in moderation, +giving preference to the albumen over the yelk. Farinaceous +foods, in the main, should be rejected, even +bread being allowed only in small quantities, and then +preferably in the form of toast. Cheese likewise contains +too much fat; and mushrooms are so rich in hydrocarbons +that they should be rejected. Condiments, +water, vegetable acids (vinegars excepted) may be permitted; +especially pernicious is vinegar where there is +any tendency to gout or gravel. All fatty beverages--<i>bouillon</i>, +unskimmed milk, chocolate, or cacao--and +all alcoholics, are hurtful; breakfast tea is undoubtedly +the best beverage, but, after a little, is advantageously +replaced by light white wine diluted with water.</p> + +<p>Kisch believes in a free and abundant use of water +by the obese, especially where there is a tendency to +plethora, since this fluid facilitates oxidation as the +result of absorption; thus he advocates the inhibition +of large quantities of cold water by all, save those presenting +evidence of cardiac insufficiency. In short, +his regimen is based upon the administration of a +large quantity of albumen, like that of Harvey-Banting.</p> + +<p>E. Munk recommends an almost identical dietary, +save that he prefers great moderation in fluids employed +as beverage.</p> + +<p>M. Robin has sought to harmonize the opposing +views regarding fluids, and therefore declares obesity +arises from two distinct sources: 1. Augmentation of +assimilation. 2. Reduced disassimilation. In the former, +he insists water must be interdicted, while in the +latter it may be allowed <i>ad libitum</i>.</p> + +<p>Again, in order to recognize the exact variety of +obesity, he divides his patients into three classes, each +recognizable by the volume of urea excreted. In the +first there is an increase above normal; in the second +the volume of urea is stationary; in the third decreased, +increased, or stationary.</p> + +<p>When the urea is stationary, which is most frequently +the case, it is necessary to calculate the coefficient of +oxidation; that is, the relation existing between the +solid matters of the urine and the urea. The elevation +of the coefficient is <i>prima facie</i> evidence the obesity +is due to excess of assimilation, while depression of +the coefficient indicates default of assimilation. In the +first case, water and liquids must be denied as far as +possible, the same as if there was no augmentation of +urea; in the second, the same as if there was diminution +of urea, the patients may be permitted to imbibe +fluids at pleasure.</p> + +<p>For the obese from default of disassimilation, Robin +recommends a regimen of green vegetables and bread +chiefly--the latter in small quantities, however, and +fluids as may be desired. By this means, on one occasion, +he was able in the course of one month to diminish +the weight of a female patient by twelve and a half +pounds, her measurement around the waist at the same +time decreasing 5.2 inches and across the stomach 4.8 +inches.</p> + +<p>M. De St. Germain achieved good results by combining +judicious exercise with moderate alimentation, +excluding wine and bread.</p> + +<p>M. Dujardin Beaumetz, who professes to have given +most close and careful study and attention to regimen +for the obese, outlines the following, provided there +is no evidence of fatty degeneration of heart.</p> + +<p><i>Breakfast</i> (at 8 a. m.)--Three-fourths of an ounce of +bread "<i>en flute</i>"--that is abounding with crust; one +and a half ounces of cold meat, ham or beef, six ounces +weak black tea, <i>sans</i> sugar.</p> + +<p><i>Lunch</i> (at 1 p.m.)--An ounce and a half to two ounces +of bread, or a <i>ragout</i>, or two eggs; three ounces green +vegetables; one-half ounce of cheese; fruits at discretion.</p> + +<p><i>Dinner</i> (at 7 p.m.)--An ounce and a half to two +ounces of bread; three to four ounces of meat, or +<i>ragout</i>; ditto of green vegetables, salad, half an ounce +of cheese, fruit <i>ad libitum</i>.</p> + +<p>At meal times the patient may take only a "glass and +a half" of liquid--approximately ten ounces--though +a greater amount may be permitted if he abstains during +the intervals.</p> + +<p>Special alimentary regimen, however, does not constitute + +the sole treatment of obesity. Concurrently +must be employed a number of practical adjuvants +which are oftentimes of the utmost assistance. For +one thing, exercise is indispensable; all authorities +agree on this point. The exercise taken in the gymnasium +is one of the best, notably the "wall exercise," +which is more particularly suited to those afflicted +with pendulous and protuberant abdomens as the result +of feebleness of the hypogastric muscles, to accumulation +of fat under the skin and in the omentum, +and to dilation of the stomach and intestines. In the +"wall exercise," the patient stands erect against an +absolutely straight and plumb wall, lifts his hands +(carrying a weight) straight over the head, and causes +them to describe a semicircle forward. Zantz particularly +insists upon arm and leg exercise for the obese, +especially the former, since with the same amount of +effort a larger amount of oxygen is consumed than is +possible by the latter.</p> + +<p>However, of whatever character, the exercise should +be continued to the point of fatigue or dyspn#oelig;a--three +thousand movements daily, gradually increased to +twenty-five thousand, if the system can bear it; and +under such conditions, not only is there consumption +of hydrocarbons, but there is provided a veritable +greed for air that augments waste. The experiments +of Oertel indicate that loss of weight due to fatiguing +exercise arises more particularly from dehydration, +which is made good by absorption of the fluids employed +as beverage; the fluids are claimed by Germain +See to act as accelerants of oxidation.</p> + +<p>During exercise there is obviously more abundant +absorption of oxygen, and consequently greater elimination +of carbonic acid, and as a consequence (as +shown by researches of Voit), the reserve fat of the +economy is attacked and diminished; in intense labor +there is an average hourly consumption of about 8.2 +percent. of fat. Further physical activity is useful in +exercising the voluntary muscles, and thus opposing +the invasion by interstitial fat of the muscle fibrils. +Extreme exercise also, to a certain degree, exerts a +favorable influence on the cardiac muscle, augmenting +both its nutrition and its capacity for labor. With the +anæmic obese, however, it is necessary to be most circumspect +in prescribing forced exercise; also with the +elderly obese possessed of enfeebled or fatty heart.</p> + +<p>Hydrotherapy, especially in the form of cold douches, +particularly when combined with massage, is often of +considerable value in relieving obesity; the method of +Harmman, of St. Germain, which has in many instances +induced rapid loss of adipose, is of this class. +Tepid saline baths and vapor baths have many advocates, +and may afford material aid when the heart and +circulation do not inhibit their employment. Hot baths +elevate the temperature of the body and increase the +organic exchanges, hence, as Bert and Reynard have +pointed out, tend to the elimination of oxygen and carbonic +acid; but when employed, the patient should be +introduced while the temperature is below 130° F., +when it may be gradually raised in the course of thirty +or forty minutes to 140° F.</p> + +<p>It has already been intimated, the chief feature of +the treatment of obesity is acceleration of the exchanges; +and this is in the main true, though it must +also be borne in mind that, while there are obese who +excrete little urea and have a depressed central nervous +temperature, many may be azoturic, and besides +eliminate phosphate in excess, when an oxidating +treatment will not only fail, but prove positively injurious.</p> + +<p>The bile throws out fat, therefore, to accelerate +nutritive oxidations, the liver and nervous system +must be acted upon, <i>i.e.</i>, stimulated. Everything +that tends to diminish the activity of the former, or +depress the latter, must be avoided. Hence intellectual +labor should be encouraged, or in lieu thereof, travel +advised. Exercise should be taken chiefly while fasting; +the limits of sleep confined to strict necessity, and +<i>siestas</i> after meals and during the day strictly forbidden; +the skin stimulated by hydro-therapeutic +measures, including massage under cold affusions, during +warm salt baths, etc.</p> + +<p>To increase the activity of the liver, salicylate of +soda may often be advantageously administered for its +cholagogue effect; or resort may be had to saline purgatives +such as are afforded by the springs of Marienbad, +Kissengen, Homburg, Carlsbad, Brides, Hunyadi, +or Chatel-Guyon; and it is somewhat remarkable +that while undergoing a course of these waters, there +is often no appreciable change in weight or obesity, +though the decrease becomes most marked almost immediately +upon cessation of treatment.</p> + +<p>Everything tending to increased or fuller respiration +is to be encouraged, for the fats are thus supplied with +oxygen, hastening their disintegration and consumption.</p> + +<p>Direct medicinal treatment presents no very wide +scope. Bouchard imagines lime water may be useful +by accelerating nutrition, but this is problematical, +since fat in emulsion or in droplets does not burn. +Nevertheless, alkalies in general, alkaline carbonates, +liquor potassa, soaps, etc., aid in rendering fat more +soluble, and consequently more susceptible to attack. +The alkaline waters, however, are much less active in +obesity than the saline mineral waters, unless, as sometimes +happens, there is a complication of diabetes and +obesity.</p> + +<p>Purgatives are always more or less useful, and often +required to be renewed with all the regularity of +habit. Then too, the iodides, especially iodide of +sodium or potassium, as recommended by M. Germain +See, frequently prove of excellent service by +aiding elimination and facilitating the mutations.</p> + +<p>According to Kisch, the cold mineral waters containing +an abundance of sulphate of soda, like Hunyadi +and Marienbad, are to be preferred to the hot +mineral waters, such as Carlsbad, because of their lesser +irritant action on the vascular system, and because +they strongly excite diuresis through their low +temperature and contained carbonic acid; Carlsbad +deserves preference only when obesity is combined with +uric acid calculi, or with diabetes. For very anæmic +persons, however, the weak alkaline and saline waters +should be selected; or they should confine themselves +to chalybeate waters containing an excess of sulphate +of soda. Water containing sulphate of soda is also indicated +as a beverage where there are troubles of the +circulatory apparatus; it is contraindicated only in accentuated +arterio-sclerosis.</p> + +<p>As a matter of fact, I find the suggestion of M. + +Dujardin-Beaumetz, that the obese should be divided +into two groups, a most practical one, for some are +strong and vigorous--great eaters, perhaps even gluttons--while +others, on the contrary, are feeble and +debilitated, with flesh soft and flaccid; and upon the +former may be imposed all the rigors of the reducing +system, while the latter must be dealt with more carefully.</p> + +<p>In general, it must be noted, the regimen prescribed +for the obese is insufficient, as the following table prepared +by M.C. Paul abundantly proves:</p> + + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Regimen For Obese"> +<colgroup><col align="left"><col span="3" align="center"></colgroup> +<tr><td align="center">Author.</td><td>Albuminous Matters.</td><td>Fatty Matters.</td><td>Hydrocarbons.</td></tr> +<tr><td>Voit.</td><td>118</td><td>40</td><td>150</td></tr> +<tr><td>Harvey-Banting.</td><td>170</td><td>10</td><td>80</td></tr> +<tr><td>Ebstein.</td><td>100</td><td>85</td><td>50</td></tr> +<tr><td>Oertel.</td><td>155-179</td><td>25-41</td><td>70-110</td></tr> +<tr><td>Kisch (plethoric).</td><td>160</td><td>10</td><td>80</td></tr> +<tr><td>Kisch (anæmic).</td><td>200</td><td>12</td><td>100</td></tr> +<tr><td>Normal ration.</td><td>124</td><td>55</td><td>455</td></tr> +</table> + +<p>There is, therefore, as Dujardin-Beaumetz asserts, +autophagia in the obese, and all these varieties of treatment +have but one end, viz.: Reduction of the daily +ration. But the quantity of nourishment should not +be too greatly curtailed, for, manifestly, if the fat disappears +the more surely, the muscles (rich in albumen) +undergo too rapid modification. It is progressive action +that should always be sought.</p> + +<p>The quantity of aliment may be reduced either by +imposing an always uniform regimen, which soon begets +anorexia and disgust, or by withholding from the +food a considerable quantity of fat, or, finally, by forbidding +beverage during meals. Emaciation is obtained +readily enough in either way, and demands +only the constant exercise of will power on the part of +the patient; but unhappily, severe regimen cannot +always be prescribed. When the obese patient has +passed the age of forty; when the heart suffers from +degeneration; or when the heart is anæmic--in all, +rigorous treatment will serve to still further enfeeble +the central organ of circulation, and tend to precipitate +accidents that, by all means, are to be avoided. +In such cases, by <i>not</i> treating the obesity, the days of +the patient will be prolonged. In degeneration of the +heart, however, the method of Ebstein may be tried; +and when there is renal calculi and gouty diathesis, +that of Germain See may prove satisfactory.</p> + +<h3>Paris, France.</h3> + +<a name="FNm1_1"></a><a href="#FNm1_anc_1">[1]</a><div class="note"> +Translated by Mr. Jos. Helfman, Detroit, Mich.</div> + +<a name="FNm1_2"></a><a href="#FNm1_anc_2">[2]</a><div class="note">The sanitarium is owned by a stock company, Schwenninger being +merely Medical Director.--ED.</div> + +<hr /> + + + +<a name="misc2"></a><h2>STILT WALKING.</h2> + +<p class="ctr"><a href="./images/12-stilt.png"><img src="images/12-stilt_th.jpg " width="256" height="391" alt="THE FRENCH ARMORED TURRET SHIP MARCEAU" title=""></a> +<br clear="all" />SYLVAIN DORNON, THE STILT WALKER OF LANDES.</p> + +<p>Sylvain Dornon, the stilt walker of Landes, started +from Paris on the 12th of last March for Moscow, +and reached the end of his journey at the end of a fifty-eight +days' walk. This long journey upon stilts constitutes +a genuine curiosity, not only to the Russians, +to whom this sort of locomotion is unknown, but also +to many Frenchmen.</p> + +<p>Walking on stilts, in fact, which was common twenty +years ago in certain parts of France, is gradually tending +to become a thing of the past. In the wastes of +Gascony it was formerly a means of locomotion adapted +to the nature of the country. The waste lands +were then great level plains covered with stunted bushes +and dry heath. Moreover, on account of the permeability +of the subsoil, all the declivities were transformed +into marshes after the slightest fall of rain.</p> + +<p>There were no roads of any kind, and the population, +relying upon sheep raising for a living, was much +scattered. It was evidently in order to be able to +move around under these very peculiar conditions +that the shepherds devised and adopted stilts. The +stilts of Landes are called, in the language of the +country, <i>tchangues</i>, which signifies "big legs," and +those who use them are called <i>tchanguès</i>. The stilts +are pieces of wood about five feet in length, provided +with a shoulder and strap to support the foot. The +upper part of the wood is flattened and rests against +the leg, where it is held by a strong strap. The lower +part, that which rests upon the earth, is enlarged and +is sometimes strengthened with a sheep's bone. The +Landese shepherd is provided with a staff which he +uses for numerous purposes, such as a point of support +for getting on to the stilts and as a crook for directing +his flocks. Again, being provided with a board, the +staff constitutes a comfortable seat adapted to the +height of the stilts. Resting in this manner, the shepherd +seems to be upon a gigantic tripod. When he +stops he knits or he spins with the distaff thrust in his +girdle. His usual costume consists of a sort of jacket +without sleeves, made of sheep skin, of canvas gaiters, +and of a drugget cloak. His head gear consists of a +beret or a large hat. This accouterment was formerly +completed by a gun to defend the flock against wolves, +and a stove for preparing meals.</p> + +<p>The aspect of the Landeses is doubtless most picturesque, +but their poverty is extreme. They are generally +spare and sickly, they are poorly fed and are +preyed upon by fever. Mounted on their stilts, the +shepherds of Landes drive their flocks across the wastes, +going through bushes, brush and pools of water, and +traversing marshes with safety, without having to seek +roads or beaten footpaths. Moreover, this elevation +permits them to easily watch their sheep, which are +often scattered over a wide surface. In the morning +the shepherd, in order to get on his stilts, mounts by a +ladder or seats himself upon the sill of a window, or else +climbs upon the mantel of a large chimney. Even in a +flat country, being seated upon the ground, and having +fixed his stilts, he easily rises with the aid of his staff. +To persons accustomed to walking on foot, it is evident +that locomotion upon stilts would be somewhat +appalling.</p> + +<p>One may judge by what results from the fall of a +pedestrian what danger may result from a fall from a +pair of stilts. But the shepherds of Landes, accustomed +from their childhood to this sort of exercise, acquire +an extraordinary freedom and skill therein. The +<i>tchanguè</i> knows very well how to preserve his equilibrium; +he walks with great strides, stands upright, +runs with agility, or executes a few feats of true acrobatism, +such as picking up a pebble from the ground, +plucking a flower, simulating a fall and quickly rising, +running on one foot, etc.</p> + +<p>The speed that the stilt walkers attain is easily explained. +Although the angle of the legs at every step + +is less than that of ordinary walking with the feet on +the ground, the sides prolonged by the stilts are five +or six feet apart at the base. It will be seen that with +steps of such a length, distances must be rapidly +covered.</p> + +<p>When, in 1808, the Empress Josephine went to +Bayonne to rejoin Napoleon I, who resided there by +reason of the affairs of Spain, the municipality sent an +escort of young Landese stilt walkers to meet her. On +the return, these followed the carriages with the greatest +facility, although the horses went at a full trot.</p> + +<p>During the stay of the empress, the shepherds, +mounted upon their stilts, much amused the ladies of +the court, who took delight in making them race, or +in throwing money upon the ground and seeing several +of them go for it at once, the result being a scramble +and a skillful and cunning onset, often accompanied +with falls.</p> + +<p>Up to recent years scarcely any merry-makings occurred +in the villages of Gascony that were not accompanied +with stilt races. The prizes usually consisted +of a gun, a sheep, a cock, etc. The young people vied +with each other in speed and agility, and plucky young +girls often took part in the contests.</p> + +<p>Some of the municipalities of the environs of Bayonne +and Biarritz still organize stilt races, at the period of +the influx of travelers; but the latter claim that the +stiltsmen thus presented are not genuine Landese shepherds, +but simple supernumeraries recruited at hazard, +and in most cases from among strolling acrobats. The +stilt walkers of Landes not only attain a great speed, +but are capable of traveling long distances without appreciable +fatigue.</p> + +<p>Formerly, on the market days at Bayonne and Bordeaux, +long files of peasants were seen coming in on +stilts, and, although they were loaded with bags and +baskets, they came from the villages situated at 10, 15, +or 20 leagues distance. To-day the sight of a stilt +walker is a curiosity almost as great at Bordeaux as at +Paris. The peasant of Landes now comes to the city +in a wagon or even by railway.--<i>La Nature</i>.</p> + +<hr /> +<a name="misc3"></a><h2>REMAINS OF A ROMAN VILLA IN +ENGLAND.</h2> + +<p>A correspondent of the <i>Lincolnshire Chronicle</i> +writes: For some weeks past, remains of a Roman villa +have been exposed to view by Mr. Ramsden's miners in +Greetwell Fields. From, the extent of the tesselated +pavements laid bare there is hardly any doubt +that in the Greetwell Fields, in centuries long gone +by, there stood a Roman mansion, which for magnitude +was perhaps unrivaled in England. Six years +ago I drew attention to it. The digging for iron ore +soon after this was brought to a standstill by the company, +which at the time was working the mines, ceasing +their operations. Then the property came into +other hands, and since then more extensive basement +floors of the villa have from time to time been laid +bare, and from tentative explorations which have +been just made, still more floors remain to be uncovered +which may be of a most interesting and instructive +character. What a pity it is that the inhabitants +of Lincoln have not made an effort to preserve these +precious relics of the grandeur of the Roman occupation, +an occupation to which England owes so much. +From the Romans the people of this country inherit +the sturdy self-reliance and perseverance in action +which have helped to make England what it is, and +from the Romans too, in a great degree, does England +also inherit her colonizing instincts, which impel her +people to cover the waste places of the world with colonies. +If the Roman remains which have been so abundantly +discovered of late years in Lincoln and its vicinity + +had been collected and laid out for exhibition, they +would have formed a most interesting collection of antiquities +worthy of the town, and well worth showing to +visitors who now annually make Lincoln a visitation. +Although these relics of a remote age are being dug +up and are being destroyed, it is not the fault of Mr. +Ramsden, for he not only preserved them as long as he +conveniently could, but he also had the soil removed +from over them, and had them thoroughly washed, in +order that people might have an opportunity of seeing +their extent and beauty. One of these patches of pavement +extended 48 yards northward from what might +be called the main building, which had previously +been broken up. This strip was 13 ft. in breadth, and +down its center ran an intricate pattern worked in blue +tesseræ. The pattern is much used in these days in +fabrics and works of art, and is, I think, called the +Grecian or Roman key pattern. On each side of this +ran alternately broad ribbons of white and narrower +ribbons of red tesseræ. There is also another strip of +pavement to the south of the preceding patch, which +has been laid bare to the extent of 27 yards. This +patch is about 10 ft. in breadth, and its western portion +is cut up in neat patterns, which show that they +formed the floors of rooms. From the eastern extremity +of these floors evidently another long strip of 48 or +50 yards still remains to be uncovered. Doubtless +there are other remains beneath the ground which will +be laid bare as the work of mining goes on. All +these floors were not deeper than from 18 to 30 inches +below the surface of the soil. The bones of animals +and other relics have been found in the covering soil +and have been turned up by the miners from +time to time. The pavement is all worked out with +cubes, varying in size from an inch and a half to two +inches square, each piece being placed in position +with most careful exactness. The strip which extends +48 yards and is 13 ft. wide runs due north and south. +There is a second patch, running east and west, and +this is 27 ft. long by 10 ft. wide, while a third is 27 ft. +long by 11 ft. wide, this also running in a northern +direction. To the north of this latter piece, and separated +only by about two feet (about the width of a +wall, which very possibly was the original division), +there is a strip of tesseræ 16 ft. wide, which had been +laid bare 40 yards. It was thought probable that at +the end of the last named strip still another patch +would be found. Mr. Ramsden, the manager of the +Ironstone Works, is keeping a plan of the whole of the +pavement, which he is coloring in exact imitation of +the original work. This, when completed, will be +most interesting, and he will be quite willing to show +it to any one desirous of inspecting the same. Many +persons have paid a visit to the spot where the discoveries +have been made, and surprise is invariably +expressed at the magnitude and beautiful symmetry +of the work.</p> + +<p>Several interesting fragments of Roman work have +been brought to light in the course of excavations that +are being made for building purposes at Twyford, near +Winchester. About a month ago, a paved way, composed +entirely of small red tiles, six feet in width and +extending probably a considerable distance (a length +of 14 ft. was uncovered), was found while digging on +the site for flints. The more recent excavations are +20 ft. west of this passage, and there is now to be seen, +in a very perfect state of preservation, an oven or kiln +with three openings. Five yards away from this is a +chamber about eight feet square, paved with tiles, and +the sides coated with a reddish plaster. On one side is +a ledge 15 in. from the ground, extending the whole +length of the chamber; on the floor is a sunk channel +with an opening at the end for the water to escape. +This chamber evidently represents the bath. Portions +of the dividing walls of the different chambers have + +also been discovered, together with various bones, +teeth, horns and ornaments, but very few coins. It is +probable that an alteration in the plans of the house +which was about to be built on the spot will be made +so as to preserve all the more interesting features of +these remains in the basement. These discoveries +were made at a depth of only two or three feet from +the surface of the ground, and are within about a +quarter of a mile of other Roman remains which were +similarly brought to light a few months ago.</p> + +<hr /> +<h3>[Continued from SUPPLEMENT, No. 830, page 13110.]</h3> + + +<a name="misc4"></a><h2>GUM ARABIC AND ITS MODERN SUBSTITUTES.<a name="FNms4_anc_1"></a><a href="#FNms4_1"><sup>1</sup></a></h2> + +<h3>By Dr. S. RIDEAL and W.E. YOULE.</h3> + +<p>Subjoined is a table giving the absolute viscosity +of various gums. A comparison of the uncorrected +viscosities with the corrected shows the great importance +of Slotte's correction for dextrins and inferior +gum arabics; in other words, for solutions of low viscosity, +while it will be observed to have little influence +upon the uncorrected η obtained for the Ghatti gums +and the best samples of gum arabic.</p> + +<p class="ctr">TABLE OF ABSOLUTE VISCOSITIES OF 10 PER CENT. GUM +AND DEXTRIN SOLUTIONS.</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gum Viscosity"> +<colgroup><col align="left"><col span="3" align="right"></colgroup> +<tr><td align="center">Sample.</td><td>η Uncorrected.</td><td>η Corrected.</td><td>Z Water = 100.</td></tr> +<tr><td>Gum arabic</td><td>0.1876</td><td>0.1856</td><td>1,233</td></tr> +<tr><td>Cape gum</td><td>0.1575</td><td>0.1555</td><td>1,029</td></tr> +<tr><td>Indian gum</td><td>0.0540</td><td>0.0470</td><td>311</td></tr> +<tr><td>Eastern gum</td><td>0.0689</td><td>0.0639</td><td>417</td></tr> +<tr><td>Gum arabic</td><td>0.0550</td><td>0.0480</td><td>317</td></tr> +<tr><td>Senegal</td><td>0.0494</td><td>0.0410</td><td>271</td></tr> +<tr><td>Senegal</td><td>0.0468</td><td>0.0380</td><td>251</td></tr> +<tr><td>Senegal</td><td>0.0627</td><td>0.0557</td><td>364</td></tr> +<tr><td>Gum arabic</td><td>0.0511</td><td>0.0430</td><td>285</td></tr> +<tr><td>Water</td><td>0.0149</td><td>0.0124</td><td>100</td></tr> +<tr><td>Ghatti</td><td>0.2903</td><td>0.2880</td><td>2,322</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.0903</td><td>0.0828</td><td>688</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1391</td><td>0.1350</td><td>1,089</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1795</td><td>0.1760</td><td>1,420</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1527</td><td>0.1485</td><td>1,198</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1139</td><td>0.1083</td><td>873</td></tr> +<tr><td>Ghatti, 5 per cent</td><td>0.1419</td><td>0.1369</td><td>1,104</td></tr> +<tr><td>Dextrin</td><td>0.0398</td><td>0.0255</td><td>169</td></tr> +<tr><td>Dextrin</td><td>0.0341</td><td>0.0196</td><td>129</td></tr> +<tr><td>Dextrin</td><td>0.0455</td><td>0.0380</td><td>306</td></tr> +<tr><td>Gum substitute</td><td>0.0318</td><td>0.0224</td><td>180</td></tr> +<tr><td>Gum substitute</td><td>0.0318</td><td>0.0224</td><td>180</td></tr> +<tr><td>Amrad</td><td>0.0793</td><td>0.0708</td><td>570</td></tr> +<tr><td>Australian</td><td>0.0378</td><td>0.0283</td><td>228</td></tr> +<tr><td>Australian</td><td>0.0365</td><td>0.0268</td><td>216</td></tr> +<tr><td>Brazilian</td><td>0.0668</td><td>0.0627</td><td>506</td></tr> +<tr><td>Brazilian</td><td>0.0516</td><td>0.0445</td><td>359</td></tr> +<tr><td>Ghatti</td><td>0.3636</td><td>0.3621</td><td>2,920</td></tr> +</table> + + +<p>In the column for η corrected the differences due to +the use of different instruments are of course eliminated. +The absolute viscosity of water at 15° C. determined +in four different instruments is shown below. +Poiseuille's value for water being 0.0122.</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Instrument Differences"> +<colgroup><col align="left"><col span="4" align="right"> +<tr><td align="center">Instrument.</td><td>1.</td><td>2.</td><td>3.</td><td>4.</td></tr> +<tr><td>η corrtd. of water.</td><td>0.0109</td><td>0.01185</td><td>0.0124</td><td>0.0120 </td></tr> +<tr><td>K<sub>1</sub> value.</td><td>0.000000898</td><td>0.000000863</td><td>0.000000932</td><td>0.00000052 </td></tr> +<tr><td>K<sub>2</sub> value.</td><td>0.235</td><td>0.2175</td><td>0.226</td><td>0.0204 </td></tr> +</table> + +<p>The above values for various gums and dextrins were +obtained at a constant temperature of 15° C. and are +compared with water at that temperature. It is of the +utmost importance that the temperature of the water +surrounding the bulbs should be adjusted for each series +of experiments to the temperature at which the absolute +viscosity of the water was determined. As far as +we have ascertained, in gum solutions there is a steady +diminution in viscosity with increase of temperature +until a certain temperature is reached, beyond which +increase of heat does not markedly influence the viscosity, +and it is possible that above this "critical +point," as we may term it, the gum solutions once more +begin to increase in viscosity. The temperature at +which the viscosity becomes stationary varies somewhat +with different gums, but broadly speaking it lies +between 60° C. and 90° C., no gums showing any marked +decrease in viscosity between 80° C. and 90° C.</p> + +<p>The experiments we have made in this direction were +conducted as follows. The 300 c.c. bottle containing +the gum was placed in a capacious beaker full of hot +water, and the viscosity instrument was also surrounded +with water at the same temperature. Thermometers +were suspended both in the beaker and the outer +jar. The viscosity at the highest temperature obtained, +about 90° C., was then taken and repeated for +every fall of 4° C. till the water reached the temperature +of the air.</p> + +<p>The values so obtained gradually diminished with +the increase of temperature. From the η values obtained +the Z values were calculated, using water at 15° C. +as a standard. From the Z values thus obtained +taken as the ordinate, and the temperature of each +experiment as the abscissa, curves were plotted out +embodying the results, examples of which are given +below. The curves yielded by three gums 2, 7, and 8 +changed between 90° C and 100° C., while gum sample +4 has a curve bending between 60° C. and 70° C. Experimentally + +this increase of viscosity of the latter gum +above 60° C. was confirmed, but the critical point of the +other solutions tried approaches too nearly to the boiling +point of water for experiments to be conducted +with accuracy, as the temperature of the bulbs diminishes +sensibly while the experiment is being made.</p> + +<p>If viscosity values have been determined it is possible +to calculate the remaining or intermediate values +for Z at any particular temperature from the general +equation--Zt = A + Bt + Ct²</p> + +<p>As an example of the mode of calculation we may +quote the following. A gum gave the following values +for Z at the temperature stated:</p> + +<blockquote><p>Gum. 50° C. Z<sub>50°</sub> = 228</p> + +<p>Gum. 30° C. Z<sub>30°</sub> = 339</p> + +<p>Gum. 20° C. Z<sub>20°</sub> = 412</p> +</blockquote> + +<p>from which the constants--</p> + +<blockquote><p>A = 592.99 B = -10.2153 C = 0.0583</p></blockquote> + +<p>can be obtained, and thus the value of Z<sub>t°</sub> for any required +temperature. The numbers calculated for gums +all point to a diminution in viscosity up to a certain +point, and then a gradual increase. A comparison of +some of the figures actually obtained in some of these +experiments, compared with the calculated figures for +the same temperature, shows their general agreement.</p> + +<p class="ctr"> <img src="./images/13-gr1.png" height="320" width="306" alt=""> +<br clear="all" /> Curves showing viscosity change with temperature +for three typical gums. A--Arabic VII. B--Senegal +VIII. C--Ghatti 15.</p> + +<p class="ctr">EFFECT OF TEMPERATURE UPON VISCOSITY--GUM VII.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gum VII"> +<colgroup><col align="center"><col span="3" align="right"></colgroup> +<tr><td>Temperature. ºC.</td><td align="center"> η</td><td>Z found.</td><td>Z calculated.</td></tr> +<tr><td>50</td><td>0.0283</td><td>228</td><td>228.00</td></tr> +<tr><td>45</td><td>0.0305</td><td>246</td><td>246.55</td></tr> +<tr><td>42</td><td>0.0352</td><td>284</td><td>266.75</td></tr> +<tr><td>38</td><td>0.0368</td><td>297</td><td>289.00</td></tr> +<tr><td>34</td><td>0.0410</td><td>330</td><td>313.06</td></tr> +<tr><td>30</td><td>0.0419</td><td>339</td><td>339.00</td></tr> +<tr><td>26</td><td>0.0445</td><td>359</td><td>367.80</td></tr> +<tr><td>22</td><td>0.0492</td><td>398</td><td>396.47</td></tr> +<tr><td>20</td><td>0.0511</td><td>412</td><td>412.00</td></tr> +<tr><td>18</td><td>0.0531</td><td>428</td><td>428.00</td></tr> +</table> + + +<p class="ctr">EFFECT OF TEMPERATURE UPON VISCOSITY.--GUM VIII.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Gum VIII"> +<colgroup><col align="center"><col span="3" align="right"></colgroup> +<tr><td>Temperature. ºC.</td><td align="center"> η</td><td>Z found.</td><td>Z calculated.</td></tr> +<tr><td>50</td><td>0.0430</td><td>347</td><td>347</td></tr> +<tr><td>46</td><td>0.0475</td><td>383</td><td>371.14</td></tr> +<tr><td>42</td><td>0.0502</td><td>405</td><td>397.09</td></tr> +<tr><td>38</td><td>0.0510</td><td>411</td><td>424.73</td></tr> +<tr><td>34</td><td>0.0575</td><td>463</td><td>454.06</td></tr> +<tr><td>30</td><td>0.0602</td><td>485</td><td>485</td></tr> +<tr><td>26</td><td>0.0637</td><td>513</td><td>517.82</td></tr> +<tr><td>22</td><td>0.0667</td><td>538</td><td>552.25</td></tr> +<tr><td>20</td><td>0.0707</td><td>570</td><td>570</td></tr> +<tr><td>18</td><td>0.0755</td><td>609</td><td>583.07</td></tr> +</table> + +<p>The constants for the first gum are those given in +the preceding column, while for the latter they were--</p> + +<blockquote><p>A = 771.9: B = -11.15: C = 0.053</p></blockquote> + +<p>As will be observed, the effect of heat appears to be +the same upon the two typical gum arabics quoted +above, an increase of temperature from 18° C. to 50° C. +decreasing the viscosity by nearly one half in both +cases, and the same seems to be true of most gum arabics. +Roughly also the same holds good for Ghattis, +as the following numbers show:</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Heat Effect on Gums"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">Gum.</td><td>Z at 18° C.</td><td>Z at 50° C.</td></tr> +<tr><td>Gum arabic.</td><td>1016</td><td>579</td></tr> +<tr><td>Gum arabic.</td><td>428</td><td>228</td></tr> +<tr><td>Gum arabic.</td><td>609</td><td>347</td></tr> +<tr><td>Gum arabic.</td><td>581</td><td>258</td></tr> +<tr><td>Ghatti.</td><td>572</td><td>306</td></tr> +<tr><td>Ghatti.</td><td>782</td><td>418</td></tr> +</table> + + +<p>The following table shows the effect of heat upon +the viscosity of a typical Ghatti:</p> + +<p class="ctr">GHATTI GUM NO. 15.--VISCOSITY.</p> +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Ghatti 15 Viscosity"> +<colgroup><col align="center"><col span="2" align="right"></colgroup> +<tr><td>Temperature. <br/>°C.</td><td>η</td><td>Z.</td></tr> +<tr><td>50</td><td>0.0517</td><td>418 </td></tr> +<tr><td>46</td><td>0.0581</td><td>468 </td></tr> +<tr><td>42</td><td>0.0628</td><td>506 </td></tr> +<tr><td>38</td><td>0.0726</td><td>585 </td></tr> +<tr><td>34</td><td>0.0788</td><td>635 </td></tr> +<tr><td>30</td><td>0.0857</td><td>691 </td></tr> +<tr><td>26</td><td>0.0889</td><td>717 </td></tr> +<tr><td>22</td><td>0.0919</td><td>741 </td></tr> +<tr><td>20</td><td>0.0946</td><td>763 </td></tr> +<tr><td>18</td><td>0.0964</td><td>777 </td></tr> +</table> + + +<p>There is therefore no essential difference in the behavior +of a Ghatti and a gum arabic on heating. Some +interesting results, however, were obtained by heating +gums, both Ghattis and arabics, at a fixed temperature +for the same time, cooling, and then after making the +solutions up to the original volume taking their viscosities +at the ordinary temperature. The effect of heating +for two hours to 60° C., 80° C., or 100° C. was a small +permanent alteration in viscosity of the solution, and +it would therefore seem desirable that gum solutions +should be made up cold to get the maximum results. +The following numbers illustrate this change, viz.:</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Effect of Heating"> +<colgroup><col align="left"><col span="4" align="right"></colgroup> +<tr><td> </td><td> </td><td colspan="3" align="center">After heating to</td></tr> +<tr><td>Gum Arabic<br /> 10 Per Cent.</td><td>Without heat.</td><td>60°C.</td><td>80°C.</td><td>100°C. </td></tr> +<tr><td>Z at 18°C</td><td>570</td><td>468</td><td>470</td><td>517</td></tr> +<tr><td>Z at 30°C</td><td>485</td><td>400</td><td>422</td><td>439</td></tr> +<tr><td>Z at 50°C</td><td>347</td><td>287</td><td>258</td><td>301</td></tr> +<tr><td>Ghatti gum No. 15,<br /> 5 per cent.<br /> Z at 18°C.</td><td>1,104</td><td>780</td><td>660</td><td>758</td></tr> +</table> + +<p>The variation of viscosity with strength of solution +was also studied with one or two typical gums. A 10 +per cent. is invariably more than twice as viscous as a +5 per cent. solution. The following curve was obtained +from one of the Ghattis. Similar results were +shown by other gums.</p> + +<p class="ctr"><img src="./images/13-gr2.png" height="396" width="399" alt="Variation of Viscosity With Dilution"> +<br clear="all" />Variation of Viscosity, with Dilution. +Ghatti No. 888.</p> + +<p>It would seem, therefore, that strong solutions, say of +50 per cent. strength, would be more alike in viscosity +than solutions of 5 per cent. strength of the same +gums. In other words, the viscosity of a gum solution +should be taken as nearly as possible to the strength +it is used at, to obtain an exact quantitative idea of its +gumming value.</p> + +<p>The observation of this fact was one of the circumstances +which decided us to use 5 per cent. solutions +for the determination of Ghatti gum viscosities, the +ratio between the 5 per cent. and 10 per cent. solutions +of gum arabics being roughly the same as that between +the respective weights required for gumming solutions +of equal value.</p> + +<p>From observation of the general nature of the solutions +of Ghatti gums, and from the fact that when +allowed to stand portions of the apparently insoluble +matter passed into solution, the hypothesis suggested +itself that metarabin was soluble in arabin, +although insoluble in cold water. If this hypothesis +were correct, it would explain the apparent anomaly +of Ghattis giving solutions of higher viscosity than +gum arabics, although they leave insoluble matter +behind. The increase in viscosity would be due to +the thickening of the arabic acid by the metarabin. +Moreover, the solutions yielded by various Ghattis +leaving insoluble matter behind would <i>be all of the +same kind</i>, viz., a saturated solution of metarabin in +arabin more or less diluted by water. Still further, if +the insoluble residue of a Ghatti be the residual metarabin +over and above that required to saturate the +arabin, then it will be possible to dissolve this by the +addition of more arabin in the form of ordinary gum +arabic. In order to see if this were the case the following +experiments were performed. Equal parts of a +Ghatti and of a gum arabic were ground up together +and dissolved in water. The resulting solution was +<i>clear</i>. It was diluted until of 10 per cent. strength, +and its viscosity then taken:</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="50-50 Ghatti-Gum"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td> </td><td colspan="2" align="center">Contains 50 per Cent. Ghatti.</td></tr> +<tr><td>A. Pressure 200 mm</td><td>η</td><td>Z</td></tr> +<tr><td>Temperature 15° C</td><td>0.2517</td><td>2,030</td></tr> +</table> + +<p>The viscosity of this solution therefore was considerably +greater than the mean viscosity of the 10 per cent. +solutions of the Ghatti and the gum arabic, viz., +(0.288 + 0.0636)/2 = 0.1758 for the calculated η. Hence it is +evident that the increase in viscosity is due to the +solution of the metarabin.</p> + +<p>Next a solution was made from a mixture of 70 per +cent. Ghatti and 30 per cent. gum arabic. This was +also clear and gave a considerably higher viscosity than +the previous solution.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="70-30 Ghatti-Gum"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td> </td><td colspan="2" align="center">Contains 70 per Cent. Ghatti.</td></tr> +<tr><td>B. Pressure 200 mm</td><td>η</td><td>Z.</td></tr> +<tr><td>Temperature 15° C</td><td>0.3177</td><td>2,562</td></tr> +</table> + + +<p>It will be obvious that the increase of viscosity over +the previous solution in this case must be due to the +smaller amount of the thin gum arabic which is present, +<i>i.e.</i>, in the first case there is more gum arabic than +is required to dissolve the whole of the insoluble metarabin. +Further experiments showed that this is also +true of the second mixture, as the viscosities of the +following mixtures illustrate:</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="High Concentrations of Ghatti"> +<colgroup><col align="left"><col span="2" align="right"> +<tr><td align="center">Strength of Solution.</td><td align="center">η</td><td>Z.</td></tr> +<tr><td>C. 80 per cent. Ghatti.</td><td>0.3642</td><td>2,937 </td></tr> +<tr><td>D. 75 per cent. Ghatti.</td><td>0.33095</td><td>2,669 </td></tr> +<tr><td>E. 77.5 per cent. Ghatti.</td><td>0.4860</td><td>3,819 </td></tr> +</table> + + +<p>This last solution E we called for convenience the +"maximum viscosity" solution, as we believe it to be a +10 per cent. solution containing arabin very nearly +saturated with metarabin. As will be observed, its +viscosity differs widely from those of solutions C and +D, between which it lies in percentage of Ghatti. The +first named solution C contains <i>too little</i> of gum arabic +to dissolve the whole of the metarabin. Consequently +there is a residue left undissolved, which of course diminishes +its viscosity. The second solution D is too +low in viscosity, as it still contains too much of the +weak gum arabic, and as will be seen further on, a +very slight change in the proportions increases or decreases +the viscosity enormously.</p> + +<p>We next tried a series of similar experiments with a +Ghatti containing far less insoluble residue and which +consequently would require less gum arabic to produce +a perfect solution. Mixtures were made in the following +proportions, viz.:</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="13.3% Ghatti"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">----</td><td colspan="2" align="center">13.3 per Cent. Ghatti.</td></tr> +<tr><td>F. Pressure 200 mm</td><td>η</td><td>Z.</td></tr> +<tr><td>Temperature 15° C</td><td> 0.0976</td><td>787</td></tr> +</table> +<br /><br /> +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="86.6% Ghatti"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">----</td><td colspan="2" align="center">86.6 per Cent. Ghatti.</td></tr> +<tr><td>G. Pressure 200 mm</td><td>η</td><td>Z.</td></tr> +<tr><td>Temperature 15° C</td><td> 0.4336</td><td> 3,497</td></tr> +</table> + + +<p>This latter solution is approaching fairly closely to +our "maximum viscosity" with the previous Ghatti, +and probably a very slight decrease in the amount of +gum arabic would bring about the required increase in +viscosity.</p> + +<p>When these experiments were first commenced we +were still under the impression, which several months' +experience of working with gums had produced, namely, +that the Ghattis were quite distinct in their properties +to ordinary gum arabics. But the new hypothesis, +and the experiments undertaken to confirm it, +showed clearly that if the viscosity of a gum solution +depends on the ratio of metarabin to arabin, then +there is no absolute line of demarkation between a +Ghatti and a gum arabic. In other words, there is a +constant gradation between gum arabic and Ghattis, +down to such gums as cherry gum, consisting wholly +of metarabin and quite insoluble in water. Therefore +those gum arabics which are low in viscosity consist +of nearly pure arabin, while as the viscosity increases +so does the amount of metarabin, until we come to +Ghattis which contain more metarabin than their arabin +can hold in solution, when their viscosity goes +down again.</p> + +<p>From these observations it would follow, that by +taking a gum of less viscosity than the gum arabic previously +used to dissolve the Ghatti, less of it would be +required to do the same work. We confirmed this suggestion +experimentally by taking another gum arabic +of viscosity 0.0557 at 15° C. A mixture containing +93.3 per cent. of this Ghatti and 6.7 per cent. of our +thinnest gum arabic gave a clear solution which had +the highest viscocity we have yet obtained for a 10 per +cent. solution.</p> + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Highest Viscosity"> +<colgroup><col align="left"><col span="2" align="center"></colgroup> +<tr><td>H. Pressure 200 mm.<br />Temperature 15° C.</td><td>η<br /> 0.5525</td><td> Z.<br />4,456 </td></tr> +</table> + + +<p>This gum arabic may be regarded as nearly pure arabin +(as calcium and potassium, etc., salt). By diluting +the new "maximum viscosity" solution, therefore, with +the 10 per cent. solution of the gum arabic in fixed proportions +we obtain a series of viscosities which are +shown in the following curve.</p> + +<p class="ctr"><img src="./images/14-gr1.png" height="397" width="353" alt="Ghatti Viscosity Curve"> +<br clear="all" />Curve Showing Influence of Ghatti +upon Viscosity.</p> + +<p>Besides obtaining this curve for change in viscosity +from maximum amount of metarabin to no metarabin +at all, we also traced the decrease in viscosity of the +"maximum" solution by dilution with water. The +following numbers were thus obtained, and plotted +out into a curve.</p> + +<p>Having obtained this curve, we are now in a position +to follow up the hypothesis by calculating the surplus +amount of insoluble matter in a Ghatti. For, let it be +conceded that the solution of any Ghatti leaving an insoluble +residue is a mixture of arabin and metarabin in +the same ratio as our "maximum" solution, only more +diluted with water, then from the found viscosity we +obtain a point on the curve for dilution, which gives +the percentage of dissolved matter.</p> + +<p>Now to show the use of this: The Z value for a 10 per +cent. solution of the second Ghatti at 15° C. is 2,940. +This corresponds on the curve to 8.4 dissolved matter. +10-8.4 = 1.6 grammes in 10 grammes, which is insoluble.</p> + + +<p class="ctr">CHANGE OF VISCOSITY WITH DILUTION--"MAXIMUM" +SOLUTION. 15° C. TEMPERATURE.</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Viscosity Changes With Dilution"> +<colgroup><col span="3" align="right"></colgroup> +<tr><td align="center">Percentage.</td><td align="center">η</td><td align="center">Z.</td></tr> +<tr><td>10</td><td>0.55250</td><td>4,456</td></tr> +<tr><td>9</td><td>0.42850</td><td>3,456</td></tr> +<tr><td>8</td><td>0.35120</td><td>2,832</td></tr> +<tr><td>7</td><td>0.27660</td><td>2,230</td></tr> +<tr><td>6</td><td>0.22290</td><td>1,797</td></tr> +<tr><td>5</td><td>0.16810</td><td>1,355</td></tr> +<tr><td>4</td><td>0.11842</td><td>955</td></tr> +<tr><td>3</td><td>0.08020</td><td>647</td></tr> +<tr><td>2</td><td>0.06190</td><td>499</td></tr> +<tr><td>1</td><td>0.03610</td><td>291</td></tr> +</table> + + +<p class="ctr"><img src="./images/14-gr2.png" height="402" width="396" alt="Variation in Viscosity on Dilution(Maximum)"> +<br clear="all" /> Curve of Variation in Viscosity on Dilution +of the "Maximum" Solution.</p> + +<p>We have already shown that a "maximum" viscosity +solution of this gum is formed when 6.7 per cent, of thin +gum arabic is added to it, and therefore 6.7 parts of a +thin gum arabic are required to bring 16 parts of metarabin +into solution. A convenient rule, therefore, in +order to obtain complete solution of a Ghatti gum is +to add half the weight in thin gum of the insoluble +metarabin found from the viscosity determination. +But the portion of the gum which dissolved is made +up in a similar manner (being a diluted "maximum" +solution).</p> + +<p>Therefore the 84 per cent. of soluble matter contains +58 parts of metarabin, and the total metarabin in this +gum is 58 + 16 = 74 per cent, on the dry gum.</p> + +<p>With these solutions of high viscosity some other +work was done which may be of interest. The temperature +curves of the mixtures marked E, G, and F +were obtained between 60° C. and 15° C. The two former +curves showed a direction practically parallel to +that at the 10 per cent. solutions, and as they were approaching +to the "maximum" solution, this is what +one would expect. Mr. S. Skinner, of Cambridge, was +also good enough to determine the electrical resistances +of these solutions and the Ghattis and gum arabics employed +in their preparation. The electrical resistance +of these gum solutions steadily diminishes as the temperature +increases, and the curve is similar to those +obtained for rate of change with temperature. Although +the curves run in, roughly, the same direction, +there does not appear to be any exact ratio between +the viscosities of two gums say at 15° C. and their electrical +resistances at the same temperature; hence it +would not seem possible to substitute a determination +of the electrical resistance for the viscosity determination. +The results appear to be greatly influenced by the +amount of mineral matter present, gums with the +greatest ash giving lower resistances.</p> + +<p>Experiments were conducted with two Ghattis and +two gum arabics, besides the mixtures marked E, F, +and H. Comparison of the electrical resistances with +the viscosities at 15° C. shows the absence of any fixed +ratio between them.</p> + + +<table align='center' border='1' cellpadding='2' cellspacing='0' summary=''> +<colgroup><col align="left"><col span="3" align="right"></colgroup> +<tr><td>Gum or Mixture.</td><td>°C.</td><td>Ohms Resistance.</td><td>Z Viscosity at 15° C.</td></tr> +<tr><td>Ghatti, 1</td><td>10</td><td>5,667</td><td>1,490</td></tr> +<tr><td>Ghatti, 2</td><td>15</td><td>2,220</td><td>2,940</td></tr> +<tr><td>Arabic 1</td><td>15</td><td>1,350</td><td>605</td></tr> +<tr><td>Arabic 2</td><td>10</td><td>2,021</td><td>449</td></tr> +<tr><td>Mixture F</td><td>15</td><td>1,930</td><td>787</td></tr> +<tr><td>Mixture E</td><td>11.3</td><td>2,058</td><td>3,919</td></tr> +</table> + +<p>While performing these experiments, an attempt +was made to obtain an "ash-free" gum, in order to +compare its viscosity with that of the same gum in +its natural state. A gum low in ash was dissolved in +water, and the solution poured on to a dialyzer, and +sufficient hydrochloric acid added to convert the salts +into chlorides. When the dialyzed gum solution ceased +to contain any trace of chlorides, it was made up to +a 10 per cent. solution, and its viscosity determined +under 100 mm. pressure, giving the following results +at 15° C.:</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Ash-free Gum"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td align="center">--------</td><td align="center">η</td><td align="center">Z</td></tr> +<tr><td>Natural gum</td><td>0.05570</td><td>449</td></tr> +<tr><td>"Ash-free" gum</td><td>0.05431</td><td>438</td></tr> +</table> + +<p>Thus showing that the viscosity of pure arabin is almost +identical with that of its salts in gum.</p> + +<p>The yield of furfuraldehyde by the breaking down +of arabin and metarabin was thought possibly to be +of some value in differentiating the natural gums from +one another, but we have not succeeded in obtaining +results of much value. 0.2 gramme of a gum were +heated with 100 c.c. of 15 per cent. sulphuric acid for +about 2½ hours in an Erlenmeyer flask with a reflux +condenser. After this period of time, further treating +did not increase the amount of furfuraldehyde produced. +The acid liquid, which was generally yellow in +color, was then cooled and neutralized with strong +caustic soda. The neutral or very faintly alkaline solution +was then distilled almost to dryness, when practically +the whole of the furfuraldehyde comes over. +The color produced by the gum distillate with +aniline acetate can now be compared with that +obtained from some standard substance treated +similarly. The body we have taken as a standard +is the distillate from the same weight of cane sugar. +The tint obtained with the standard was then compared +with that yielded by the gum distillate from which +the respective ratios of furfuraldehyde are obtained. +The following table shows some of these results:</p> + + +<table align="center" border="1" cellpadding="2" cellspacing="0" summary="Yield of Furfuraldehyde"> +<colgroup><col align="left"><col span="2" align="center"></colgroup> +<tr><td>Substance.</td><td>Comparative<br /> Yield of <br />Furfuraldehyde.</td><td>Amount of<br /> Glucose Produced.</td></tr> +<tr><td>Cane sugar</td><td>1.00</td><td>..</td></tr> +<tr><td>Starch</td><td>0.50</td><td>..</td></tr> +<tr><td>Gum arabic</td><td>1.33</td><td>34.72</td></tr> +<tr><td>Gum arabic</td><td>1.20</td><td>43.65</td></tr> +<tr><td>Ghatti, 1</td><td>1.00</td><td>26.78</td></tr> +<tr><td>Ghatti, 2</td><td>1.33</td><td>22.86</td></tr> +<tr><td>Metarabin</td><td>1.75</td><td>..</td></tr> +</table> + + +<p>The amount of reducing sugar calculated as glucose is +also appended. This was estimated in the residue left +in the flask after distillation by Fehling's solution in +the usual way. The yields of furfuraldehyde would +appear to have no definite relation to the other chemical +data about a gum, such as the potash and baryta +absorptions or the sugar produced on inversion.</p> + +<p>The action of gum solutions upon polarized light is +interesting, especially in view of the fact that arabin is +itself strongly lævo-rotatory α<sub>D</sub> = -99°, while certain +gums are distinctly dextro-rotatory. Hence it is evident +that some other body besides arabin is present in +the gum. We have determined the rotatory power of +a number of gum solutions, the results of which are +subjoined. On first commencing the experiments we +experienced great difficulty from the nature of the +solutions. Most of them are distinctly yellow in color +and almost opaque to light, even in dilute solutions +such as 5 percent. We found it necessary first to bleach +the gums by a special process; 5 grammes of gum are +dissolved in about 40 c.c. of lukewarm water, then a +drop of potassium permanganate is added, and the +solution is heated on a water bath with constant stirring +until the permanganate is decomposed and the +solution becomes brown. A drop of sodium hydrogen +sulphate is now added to destroy excess of permanganate. +At the same time the solution becomes perfectly +colorless.</p> + +<p>It can now be cooled down and made up to 100 c.c., +yielding a 5 per cent. solution of which the rotatory +power can be taken with ease. Using a 20 mm. tube +and white light the above numbers were obtained.</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Rotatory values of Gums"> +<colgroup><col align="left"><col align="center"><col align="right"></colgroup> +<tr><td>Gum or Dextrin.</td><td>Solution used.<br /> Per Cent.</td><td align="center">α<sub>D</sub></td></tr> +<tr><td>Aden, 1</td><td>5</td><td>- 33.8</td></tr> +<tr><td>Cape, 2</td><td>5</td><td>+ 28.6</td></tr> +<tr><td>Indian, 3</td><td>5</td><td>+ 66.2</td></tr> +<tr><td>Eastern, 4</td><td>5</td><td>- 26.0</td></tr> +<tr><td>Eastern, 5</td><td>5</td><td>- 30.6</td></tr> +<tr><td>Senegal, 6</td><td>5</td><td>- 17.6</td></tr> +<tr><td>Senegal, 7</td><td>5</td><td>- 18.4</td></tr> +<tr><td>Senegal, 8</td><td>2½</td><td>- 19.6</td></tr> +<tr><td>Senegal, 9</td><td>5</td><td>- 38.2</td></tr> +<tr><td>Senegal, 10</td><td>5</td><td>- 25.8</td></tr> +<tr><td>Amrad</td><td>2½</td><td>+ 57.6</td></tr> +<tr><td>Australian, 1</td><td>5</td><td>- 28.2</td></tr> +<tr><td>Australian, 2</td><td>5</td><td>- 26.4</td></tr> +<tr><td>Brazilian, 1</td><td>2½</td><td>- 36.8</td></tr> +<tr><td>Brazilian, 2</td><td>2½</td><td>+ 21.0</td></tr> +<tr><td>Dextrin, 1</td><td>5</td><td>+148.0</td></tr> +<tr><td>Dextrin, 2</td><td>5</td><td>+133.2</td></tr> +<tr><td>Ghatti, 1</td><td>5</td><td>- 39.2</td></tr> +<tr><td>Ghatti, 2</td><td>5</td><td>- 80.4</td></tr> +</table> + + +<p>These numbers do not show any marked connection +between the viscosity, etc., of a gum and its specific +rotatory power.</p> + +<p>When gum arabic solution is treated with alcohol +the gum is precipitated entirely if a large excess of +spirit be used. With a view to seeing if the precipitate +yielded by the partial precipitation of a gum solution +was identical in properties to the original gum, we examined +several such precipitates from various gums to +ascertain their rotatory power. We found in each case +that the specific rotatory power of the alcohol precipitate +redissolved in water was not the same as that of +the original gum. In other words these gums contained +at least two bodies of different rotatory powers, of which +one is more soluble in alcohol than the other. O'Sullivan +obtained similar results with pure arabin. +The experiments were conducted in the following +manner:</p> + +<p>(a.) Five grammes of a dextro-rotatory gum (No. 3 in +table) were dissolved in 20 c.c. of water. To the solution +was added 90 c.c. of 95 per cent. alcohol. The +white precipitate which formed was thrown on to +a tared filter and washed with 30 c.c. more alcohol. +The total filtrate therefore was 140 c.c. The precipitate +was dried and weighed = 2.794 grammes or 55.88 +per cent. of the total gum. The precipitate was then +redissolved in water, bleached as before and diluted +to a 5 per cent. solution. This was then examined +in the polarimeter. Readings gave the value α<sub>D</sub> = ++58.4°. The previous rotatory power of the gum was ++66°. Now the alcohol was driven off from the filtrate, +which, allowing for the 11.95 per cent. of water in the +gum, should contain 32.17 per cent. of gum. The alcohol-free +liquid was then diluted to a known volume + +(for 5 per cent, solution), and α<sub>J</sub> found to be + 57.7°. +This experiment was then repeated again, using 5 +grammes of No. 3, when 3.5805 grammes of precipitate +were obtained, using the same volumes of alcohol and +water. The precipitate gave α<sub>J</sub> = +57.4°; the filtrate +treated as before, only the percentage of gum dissolved +being directly determined instead of being calculated +by difference, gave α<sub>J</sub> = + 52.5°.</p> + +<p>(b.) Another gum (No. 9) with α<sub>J</sub> = -38.2° and containing +13.86 per cent, of moisture, gave 2.3315 grms. of +precipitate when similarly treated. The precipitate +gave when redissolved in water α<sub>J</sub> = -20.8°. The +filtrate containing 39.5 per cent, real gum gave α<sub>J</sub> = +-67.5°, so that the least lævo-rotatory gum. was precipitated +by the alcohol.</p> + +<p>The Ghattis apparently are all lævo-rotatory, and +give much less alcoholic precipitates than the gum +arabic. The precipitation moreover was in the opposite +direction, that is, the most lævo-rotatory gum was +thrown down by the alcohol. The appended table +shows the nature of the precipitates and the respective +amounts from two Ghattis and two gum arabics. It +will be observed that the angle of rotation in three of +the cases is decidedly less both for precipitate and filtrate +than for the original solution:</p> + +<p class="ctr">SPECIFIC ROTATORY POWERS OF GUMS.</p> + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Specific Rotatory values of Gums"> +<colgroup><col span="2" align="left"><col align="left"><col span="5" align="right"></colgroup> +<tr><td colspan="2" align="center">Gum used.</td><td align="center">Weight Gum Waken. <br />Grms.</td><td align="center">Weight Alcohol Precipitate.</td><td align="center">Weight Gum Filtrate.</td><td align="center">α<sub>J</sub> Original Gum.</td><td align="center">α<sub>J</sub> Alcohol Precipitate.</td><td align="center">α<sub>J</sub> Filtrate.</td></tr> +<tr><td>3</td><td><i>a</i><br /><i>b</i></td><td>5<br />5</td><td>2.7940<br/>3.5805</td><td>1.9415<br /> 0.8910</td><td>+ 66.2</td><td> + 58.4<br /> + 57.4</td><td> + 53.7<br /> - 52.5</td></tr> +<tr><td>9</td><td><i>a</i><br /><i>b</i></td><td>5<br />4.9620</td><td>2.3315<br/>2.3310</td><td>2.3736<br />2.4180</td><td> - 38.2 </td><td>- 20.8 <br />- 19.4</td><td> - 67.5<br /> - 63.4 </td></tr> +<tr><td>Ghatti:</td><td><i>a</i><br /><i>b</i></td><td>3.4900<br />3.2450</td><td>0.3925<br />0.4605</td><td>2.7920<br />2.8385</td><td>-140.8</td><td> -104.2 <br /> -106.0</td><td>- 76.0<br /> - 72.4</td></tr> +<tr><td>Ghatti</td><td><i>a</i><br /><i>b</i></td><td>2.2550<br />2.6635 </td><td>0.2900<br />0.2845 </td><td>1.8078<br />2.3360 </td><td>-147.05</td><td> -106.04<br /> -102.04</td><td>+ 68.0<br />- 66.2 </td></tr> +</table> + +<p>The hygrometric nature of a gum or dextrin is a +point of considerable importance when the material is +to be used for adhesive purposes. The apparatus +which we finally adopted after many trials for testing +this property consists simply of a tinplate box about 1 +ft. square, with two holes of 2 in. diameter bored in +opposite sides. Through these holes is passed a piece +of wide glass tubing 18 in. long. This is fitted with +India rubber corks at each end, one single and the other +double bored. Through the double bored cork goes a +glass tube to a Woulffe's bottle containing warm water. +A thermometer is passed into the interior of the tube +by the second hole. The other stopper is connected +by glass tubing to a pump, and thus draws warm air +laden with moisture through the tube. Papers gummed +with the gums or dextrins, etc., to be tested are placed +in the tube and the warm moist air passed over them +for varying periods, and their proneness to become +sticky noted from time to time. By this means the +gums can be classified in the order in which they succumbed +to the combined influences of heat and moisture. +We find that in resisting such influences any +natural gum is better than a dextrin or a gum substitute +containing dextrin or gelatin. The Ghattis are +especially good in withstanding climatic changes.</p> + +<p>Dextrins containing much starch are less hygroscopic +than those which are nearly free from it, as the same +conditions which promote the complete conversion of +the starch into dextrin also favor the production of +sugars, and it is to these sugars probably that commercial +dextrin owes its hygroscopic nature. We have +been in part able to confirm these results by a series of +tests of the same gums in India, but have not yet obtained +information as to their behavior in the early +part of the year.</p> + +<p>The fermentation of natural gum solutions is accompanied +by a decrease in the viscosity of the liquid and +the separation of a portion of the gum in lumps. Apparently +those gums which contain most sugar, as +indicated by their reduction of Fehling's solution, are +the most susceptible to this change. Oxalic acid is +formed by the fermentation, which by combination +with the lime present renders the fermenting liquid +turbid, and also some volatile acid, probably acetic.</p> + +<p>We have made some experiments with a gum which +readily fermented--in a week--as to the respective +value of various antiseptics in retarding the fermentation. +Portions of the gum solutions were mixed with +small quantities of menthol, thymol, salol, and saccharin +in alkaline solution, also with boric acid, sodium +phosphate, and potash alum in aqueous solution. +Within a week a growth appeared in a portion to +which no antiseptic had been added; the others remained +clear. After over five months the solutions +were again examined, when the following results were +observed:</p> + + +<table align='center' border="1" cellpadding="4" cellspacing="0" summary="Gum Fermentation"> +<colgroup><col span="2" align="left"></colgroup> +<tr><td align="center">Antiseptics.</td><td align="center"> Solution after Five Months.</td> +<tr><td> Menthol in KOH</td><td> Some growth at bottom, upper layer clear.</td></tr> +<tr><td> Thymol in KOH</td><td> Growth at top, gum white and opaque.</td></tr> +<tr><td> Salol in KOH</td><td> Growth at top, gum black and opaque</td></tr> +<tr><td> Saccharin in KOH</td><td> White growth at top.</td></tr> +<tr><td> Boric acid</td><td> Remained clear; did not smell.</td></tr> +<tr><td> Sodium phosphate</td><td> Slight growth at top.</td></tr> +<tr><td> Potash alum</td><td> Slight growth at top.</td></tr> +</table> + + + +<p>The solution to which no antiseptic had been added +was of course quite putrid, and gave the reactions for +acetic acid.</p> + +<p>In the earlier part of this paper we have given a +short account of the chief characteristics of the more +important gum substitutes. The following additional +notes may be of interest.</p> + +<p>The ashes of most gum substitutes, consisting chiefly +of dextrin, are characterized by the high percentage of +chlorides they contain, due no doubt to the use of + +hydrochloric acid in their preparation. The soluble +constituents of the ash consist of neutral alkaline salts, +but as a rule no alkaline carbonates, and it is thus +possible to demonstrate the absence of any natural +gum in such a compound. We have seldom noticed +the presence of any sulphates in such ashes, but when +sulphurous or sulphuric acids have been used in the +starch conversion it will be found in small quantities.</p> + +<p>We have already pointed out that the potash absorption +value of a gum is low and that dextrins give high +numbers, but the latter vary very considerably, and as +the starch and sugar present also influence the potash +absorption value, it does not give information of much +service. The following table shows the kind of results +obtained:</p> + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Starch Absorbed"> +<colgroup><col align="left"><col span="3" align="right"></colgroup> +<tr><td>Sample.</td><td>KOH absorbed.</td><td>Starch.<br />Per Cent.</td><td>Real Gum.<br />Per Cent.</td></tr> +<tr><td>Dextrin, 1</td><td>25.40</td><td>1.99</td><td>..</td></tr> +<tr><td>Dextrin, 2</td><td>19.70</td><td>13.13</td><td>..</td></tr> +<tr><td>Dextrin, 3</td><td>7.57</td><td>24.72</td><td>..</td></tr> +<tr><td>Artificial gum, 1</td><td>19.70</td><td>10.98</td><td>9.00</td></tr> +<tr><td>Artificial gum, 2</td><td>13.70</td><td>8.05</td><td>23.50</td></tr> +<tr><td>Starch</td><td>9.43</td><td>100.00</td><td>None</td></tr> +</table> + + +<p>The baryta absorptions seem to be chiefly due to the +quantity of starch present in the composition:</p> + + +<table align="center" border="1" cellpadding="4" cellspacing="0" summary="Starch Present"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td>Sample.</td><td>Starch.<br />Per Cent.</td><td>BaO absorbed.<br />Per Cent.</td></tr> +<tr><td>Dextrin, 1</td><td>1.99</td><td>1.75</td></tr> +<tr><td>Dextrin, 2</td><td>13.13</td><td>3.53</td></tr> +<tr><td>Dextrin, 3</td><td>24.72</td><td>5.64</td></tr> +<tr><td>Starch</td><td>100.00</td><td>23.61</td></tr> +</table> + +<p>The viscosity of a dextrin or artificial gum is determined +in exactly the same way as a natural gum, using +10 per cent. solutions. It would probably be an improvement +to use 10 per cent. solutions for many of the +dextrins, as they are when low in starch extremely +thin.</p> + +<p>The hygroscopic nature of dextrins renders them +unsuitable for foreign work, but when the quantity of +starch is appreciable, better results are obtainable. A +large percentage of unaltered starch is usually accompanied +with a small percentage of sugar, and no doubt +this is the explanation of this fact. An admixture +containing natural gum of course behaved better than +when no such gum is present. Bodies like "arabol" +made up with water and containing gelatin are very +hygroscopic when dry, although as sold they lose water +on exposure to the air. Gum substitutes consisting +entirely of some form of gelatin with water, like fish +glue, are also somewhat hygroscopic when dried. The +behavior of these artificial gums and dextrins on +exposure to a warm moist atmosphere can be determined +in the same apparatus as described for gums.</p> + +<p>The process we have adopted for estimating the glucose +starch and dextrin in commercial gum substitutes +is based on C. Hanofsky's method for the assay of +brewers' dextrins (this Journal, 8, 561). A weighed +quantity of the dextrin is dissolved in cold water, +filtered from any insoluble starch, and then the glucose +determined directly in the clear filtrate by Fehling's +solution. The real dextrin is determined by inverting +a portion of the filtered liquid with HCl, and then +determining its reducing power. The starch is estimated +by inverting a portion of the solid dextrin, and +determining the glucose formed by Fehling. After +deducting the amounts due to the original glucose and +the inverted dextrin present, the residue is calculated +as starch. A determination of the acidity of the solution +is also made with decinormal soda, and results +returned in number of c. c. alkali required to neutralize +100 grammes of the dextrin. Results we have obtained +using this method are embodied in the following table:</p> + +<p class="ctr">ANALYSIS OF GUM SUBSTITUTES</p> + + +<table align='center' border='1' cellpadding='2' cellspacing='0' summary=''> +<colgroup><col span="8" align="right"></colgroup> +<tr><td> No.</td><td> Glucose.</td><td> Dextrin.</td><td> Starch.</td><td> Moisture.</td><td> Gum, &c.</td><td> Ash.</td><td> Acidity.<br />c.c. </td></tr> +<tr><td> 1</td><td> 8.92</td><td> 81.57</td><td> 1.99</td><td> 10.12</td><td> None</td><td> 0.207</td><td>57.3</td></tr> +<tr><td> 2</td><td> 7.19</td><td> 71.46</td><td> 13.13</td><td> 10.40</td><td> None</td><td> 0.120</td><td> 44.8</td></tr> +<tr><td> 3</td><td> 1.29</td><td> 69.42</td><td> 24.72</td><td> 4.17</td><td> 1.12</td><td> 0.280</td><td> 5.22</td></tr> +<tr><td> 4</td><td> 8.40</td><td> 60.98</td><td> 10.98</td><td> 10.09</td><td> 9.02</td><td> 0.530</td><td> 20.0</td></tr> +<tr><td> 5</td><td> 10.60</td><td> 44.98</td><td> 8.05</td><td> 12.20</td><td> 23.57</td><td> 0.600</td><td> 52.0</td></tr> +<tr><td> 6</td><td> 14.80</td><td> 11.57</td><td> 36.46</td><td> 34.87</td><td> 1.89</td><td> 0.580</td><td> 8.0</td></tr> +<tr><td> 7</td><td> 8.00</td><td> 29.61</td><td> 26.78</td><td> 33.98</td><td> 0.88</td><td> 0.750</td><td> 88.0</td></tr> +<tr><td> 8</td><td> 2.29</td><td> 52.38</td><td> 37.65</td><td> None</td><td> 7.335</td><td> 0.315</td><td> 9.6</td></tr> +</table> + +<p>In those cases in which the substitute is made by +admixture with gelatin or liquid glue the quantity of +other organic matter obtained can be checked by a +Kjeldahl determination of the total nitrogen. If a +natural gum is added, it will be partially converted +into sugar when the filtered liquid is inverted, and so +make the dextrin determination slightly too high.</p> + +<a name="FNms4_1"></a><a href="#FNms4_anc_1">[1]</a><div class="note">A paper read before the Society of Chemical Industry, London, 1891. +From the Journal</div> + +<hr /> + + +<a name="phys2"></a><h2>MR. CAILLETET'S CRYOGEN.</h2> + + +<p>The "cryogen," a new apparatus constructed by +Mr. E. Ducretet, from instructions given by Mr. Cailletet, +is designed for effecting a fall of temperature of +from 70° to 80° C. below zero, through the expansion of +liquid carbonic acid.</p> + +<p>The apparatus consists of two concentric vessels having +an annular space between them of a few centimeters. +A worm, S, is placed in the internal vessel R. +All this is of nickel plated copper. The worm, S carries, +at Ro', an expansion cock and ends, at O in the +annular space, R'. A very strong tube is fixed to the + +cock, Ro', and to the ajutage, A'. It receives the tube, +Tu, which, at the time of an experiment, is coupled +with the cylinder of carbonic acid, CO². A tubulure, +D, usually closed by a plug, Bo, communicates with +the inner receptacle, R. This is capable of serving in +certain experiments in condensation. The table, Ta, +of the tripod receives the various vessels or bottles for +the condensed products.</p> + +<p>The entire apparatus is placed in a box, B, lined +with silk waste and provided with a cover, C, of the +same structure. Apertures, Th, Ro, and T", allow of +the passage of a key for acting upon the cock, Ro', as +well as of thermometers and stirrers if they are necessary.</p> + +<p>When it is desired to operate, the internal vessel, R, +is filled with alcohol (3 quarts for the ordinary model). +This serves as a refrigerant bath for the experiments to +be made. The worm, S, having been put in communication +with the carbonic acid cylinder, CO², the cock, +Ro, of the latter is turned full on. The cock of the +worm, which is closed, is opened slightly. The vaporization +and expansion of the liquid carbonic acid cause +it to congeal in the form of snow, which distributes itself +and circulates in the worm, S, and then in R. The +flakes thus coming in contact with the metallic sides +of S rapidly return to the gaseous state and produce +an energetic refrigeration. At the lower part of the +annular space, R', are placed fragments of sponge impregnated +with alcohol. The snow that has traversed +the worm without vaporizing reaches R'. and dissolves +in this alcohol, and the refrigeration that results therefrom +completes the lowering of the temperature. The +gas finally escapes at O, and then through the bent +tube, T'. </p> + +<p class="ctr"><a href="./images/15-cry.png"><img src="./images/15-cry_th.jpg" alt="" height="360" width="389"></a> +<br clear="all" />CAILLETET'S CRYOGEN.</p> + +<p>The apparatus may be constructed with an inverse +circulation, the carbonic acid then entering the annular +vessel, R, directly, and afterward the worm, S, +whence it escapes to the exterior of the apparatus. +The expansion cock sometimes becomes obstructed by +the solidification of the snow. It will then suffice to +wait until the circulation becomes re-established of itself. +It may be brought about by giving the cock, Ro', +a few turns with the wooden handled key that serves +to maneuver the latter. It is not necessary to have +a large discharge of carbonic acid, and consequently +the expansion cock needs to be opened but a little +bit. A few minutes suffice to reduce the temperature + of the alcohol bath to 70°, with an output of +about from 4½ to 5½ lb. of liquid carbonic acid. +When the circulation is arrested, the apparatus thus +surrounded by its isolating protective jackets becomes +heated again with extreme slowness. In one experiment, +it was observed that at the end of nine hours the +temperature of the alcohol had risen but from 70° to +22°. On injecting a very small quantity of liquid carbonic +acid from time to time, a sensibly constant and +extremely low temperature may be maintained indefinitely.--<i>Le +Genie Civil</i>.</p> + +<hr /> + + + + +<a name="tech3"></a><h2>METHOD OF PRODUCING ALCOHOL.</h2> + + +<p>In carrying out my improved process in and with +the apparatus employed in ordinary commercial distilleries, +says Mr. Alfred Springer, of Cincinnati, O.. I preferably +employ separate vats or tubs for the nitric acid +solution and the material to be treated, and a convenient +arrangement is to locate the nitric acid tub directly +under the grain tub, so that one may discharge into +the other. In the upper vat is placed the farinaceous +material, preferably ground, thoroughly steeped in +three times its weight of water, and, where whole +grain is used, preferably "cooked" in the ordinary +manner. The vat into which the dilute acid is placed +is an ordinary cooking tub of suitable material to resist +the acid, provided with closed steam coils and also +nozzles for the discharge of steam into the contained +mass. Into this vat is placed for each one hundred +parts of the grain to be treated one part of commercial +nitric acid diluted with fifty parts of water and +brought to a state of ebullition and agitation by the +steam coils and the discharge through the nozzles, the +latter being regulated so that the gain by condensation +of steam approximately equals the loss by evaporation. +The farinaceous contents of the upper vat are allowed +to flow slowly into the nitric acid solution while +the ebullition and agitation of the mass is continued. +This condition is then maintained for six to eight +hours, after which the mass is allowed to stand for one +day or until the saccharification becomes complete. +The conversion can be followed by the "iodine test" +for intermediary dextrins and the "alcohol test" for +dextrin. After the saccharification is complete I may +partially or wholly neutralize the nitric acid, preferably +with potassium or Ammonium carbonate, preferably +employing only one-half the amount necessary + +to neutralize the original quantity of nitric acid used, +so that the mass now ready to undergo fermentation +has an acid reaction. The purpose in view here is to +keep the peptones in solution also, because an acid +medium is best adapted to the propagation of the +yeast cells. It is not absolutely necessary to even partially +neutralize the nitric acid, but it is preferable. +Yeast is now added, and the remaining processes are +similar to those generally employed in distilleries, excepting +that just prior to distillation potassium carbonate +sufficient to neutralize the remaining nitric +acid is added, in order to avoid corrosion of the still +and correct the acid reaction of the slop.</p> + +<p>As a variant of the process I sometimes add to the +usual amount of nitric acid an additional one one-hundredth +part of phosphoric acid on account of its beneficial +nutritive powers--that is to say, to one hundred +parts of grain one part of nitric acid and one one-hundredth +part of phosphoric acid.</p> + +<p>While my improved process is based on the well-known +converting power of acids on starch, I am not +aware that it has ever been applied in the manner and +for the purposes I have described. For example, sulphuric +and hydrochloric, also sulphuric and nitric, +acids have been employed in the manufacture of +glucose; but in every such case the resulting products +were not capable of superseding those obtained by the +existing methods of saccharification used in distilleries. +In my process, on the other hand, the product is +so capable. Not only may malted grain be entirely +omitted, but more fermentable products are formed and +the products of fermentation are purer. The saccharification +being more complete, there are less intermediary +and nonfermentable dextrins, and the yield +of spirits is therefore increased. Malted grain being +omitted or used in reduced quantity, there is less lactic +acid and few or foreign ferments to contaminate the +fermenting mass; also, the formation of higher alcohols +than the ethyl alcohol is almost totally suppressed. +Consequently the final yield of spirits is purer in quality +and requires little or no further purification. Also, +further, the nitrates themselves acting as nutrients to +the yeast cells, these become more active and require +less nutrition to be taken from the grain.</p> + +<hr /> + + + + +<a name="pho1"></a><h2>SPECTROSCOPIC DETERMINATION OF THE +SENSITIVENESS OF DRY PLATES.</h2> + + +<p>After describing other methods of determining the +sensitiveness of plates, Mr. Gf. F. Williams, in the <i>Br. +Jour, of Photo</i>., thus explains his plan. I will now explain +the method I adopt to ascertain the relative +sensitiveness of plates to daylight. Procure a small +direct vision pocket spectroscope, having adjustable +slit and sliding focus. To the front of any ordinary +camera that will extend to sixteen or eighteen inches, +fit a temporary front of soft pine half an inch thick, +and in the center of this bore neatly with a center bit +a hole of such diameter as will take the eye end of the +spectroscope; unscrew the eyehole, and push the tube +into the hole in wood, bushing the hole, if necessary, +with a strip of black velvet glued in to make a tight +fit. By fixing the smaller tube in the front of camera +we can focus by sliding the outer tube thereon; if we +fix the larger tube in the front, we should have to focus +inside the camera, obviously most inconvenient in +practice. Place the front carrying the spectroscope +<i>in situ</i> in the camera, and rack the latter out to its +full extent; point the camera toward a bright sky, or +the sun itself, if you can, while you endeavor to get a +good focus. The spectrum will be seen on the ground +glass, probably equal in dimensions to that of a quarter +plate. Proceed to focus by sliding the outer tube +to and fro until the colors are quite clear and distinct, +and at same time screw down the slit until the Fraunhofer +lines appear. By using the direct rays of the +sun, and focusing carefully, and adjusting the slit to +the correct width, the lines can be got fairly sharply. +Slide your front so that the spectrum falls on the +ground glass in just such a position as a quarter plate +glass would occupy when in the dark slide, and arrange +matters so that the red comes to your left, and +the violet to the right, and invariably adopt that plan. +It is advisable to include the double H lines in the violet +on the right hand edge of your plate. They afford +an unerring point from which you can calculate backward, +finding Gr, F, E, etc., by their relative positions +to the violet lines. Otherwise you may be mistaken as +to what portion of the spectrum you are really photographing. +The red should just be seen along the left +edge of the quarter plate. When all is arranged thus, +you utilize three-fourths of your plate with the spectrum, +with just a little clear glass at each end. Before +disturbing the arrangement of, the apparatus, it is desirable +to scratch a mark on the sliding tube, and +make a memorandum of the position of all the parts, so +that they may be taken away and replaced exactly +and thus save time in future.</p> + +<p>To take a photograph of the spectrum, put a quarter +plate in the dark slide and place in camera; point the +camera toward a bright sky, or white cloud, near the +sun--not at the sun, as there is considerable difficulty +in keeping the direct rays exactly in the axis of the +spectroscope--draw the shutter, and give, say, sixty +seconds. On development, you will probably obtain +a good spectrum at the first trial. The duration of +exposure must, of course, depend upon the brightness +of the day; but if the experiments are to have relative +values, the period of exposure must be distinctly noted, +and comparisons made for a normal exposure of sixty +seconds, ninety seconds, two minutes or more, just according +to whatever object one has in view in making +the experiments. With a given exposure the results will +vary with the light and the width of the slit, as well as +being influenced by the character of the instrument +itself. Further, all such experiments should be made +with a normal developer, and development continued +for a definite time. The only exception to this rule +would be in the event of wishing to ascertain the utmost +that could be got out of a plate, but, under ordinary +circumstances, the developer ought never to vary, +nor yet the duration of development. To try the effect +of various developers, or varying time in development, +a departure must be made of such a nature as would +operate to bring out upon each plate, or piece of a +plate, the utmost it would develop short of fog, against +which caution must be adopted in all spectrum experiments.</p> + +<p>On development, say for one, two, or three minutes, +wash off and fix. You will recognize the H violet lines +and the others to the left, and this experiment shows +what is the sensitiveness of this particular plate to the +various regions of the spectrum with this particular +apparatus, and with a normal exposure and development. +So far, this teaches very little; it merely indicates +that this particular plate is sensitive or insensitive +to certain rays of colored light. To make this +teaching of any value, we must institute comparisons. +Accordingly, instead of simply exposing one plate, +suppose we cut a strip from two, three, four, or even +half a dozen different plates, and arrange them side +by side, horizontally, in the dark slide, so that the +spectrum falls upon the whole when they are placed +in the camera and exposed. There is really no difficulty +in cutting strips a quarter of an inch wide, the +lengthway of a quarter plate. Lay the gelatine plate +film up, and hold a straight edge on it firmly, so that +when we use a suitable diamond we can plow through +the film and cut a strip which will break off easily between +the thumb and finger. A quarter plate can +thus be cut up into strips to yield about a dozen comparative +experiments. When cut and snapped off, +mark each with pencil with such a distinguishing mark +as shall be clearly seen after fixing. The cut up strips +can be kept in the maker's plate box.</p> + +<hr /> + +<p>The deep down underground electric railway in +London has so far proved an unprofitable concern for +its stockholders. It is 3½ miles long, touches some of +the greatest points of traffic, but somehow or other +people won't patronize it. The total receipts for the +last six months were a little under $100,000, and they +only carried seventeen persons per train mile. On this +road the passengers are carried on elevators up and +down from the street level to the cars. The poor +results so far make the stockholders sick of the project +of extending the road.</p> + +<hr /> + + +<h3>A New Catalogue of Value</h3> + +<p>Contained in Scientific American Supplement +during the past ten years, sent <i>free of charge</i> to any +address. MUNN & CO., 361 Broadway, New York.</p> + +<hr /> + +<h3>THE SCIENTIFIC AMERICAN</h3> + +<h2>Architects and Builders Edition</h2> + +<p class="ctr"><b>$2.50 a Year. 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