Scientific American Supplement, No. 455, September 20, 1884
Author: Various
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Scientific American Supplement. Vol. XVIII, No. 455.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.

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I. CHEMISTRY AND METALLURGY.—Gallisin, an Unfermentable Substance in Starch Sugar.

The Combining Weights, Volumes, and Specific Gravities of Elements and Compounds.

Analysis of Zinc Ash and Calcined Pyrites by Means of Ammonium Carbonate.

II. ENGINEERING AND MECHANICS.—Petroleum as a Fuel in Locomotive Engines.—By THOMAS URQUHART.—Spray injector.—Driving locomotives.—Storage of petroleum.

Improved Gas Light Buoy.—2 figures.

Project for a Roadstead at Havre.—With map and views of different breakwaters.

Improved Catch Basin.—2 figures.

Water Power with High Pressures and Wrought Iron Water Pipe.—By HAMILTON SMITH, JR.—Methods of conducting water and transmitting power.—Texas Creek pipe and aqueduct.—4 figures.

Parachute Hydraulic Motor.

Improved Shafting Lathe.—1 figure.

Power Straightening Machine.—1 figure.

Hydraulic Mining in California.—By GEO. O'BRIEN.

III. TECHNOLOGY.—Emerald Green: Its Properties and Manufacture.—Use in wall paper.—ROBERT GALLOWAY.

Charcoal Kilns.—Extra yield.—2 figures.

IV. ARCHITECTURE—Entrance, Tiddington House, Oxon.—An engraving.

V. ELECTRICITY, LIGHT, HEAT. ETC.—The Temperature of the Earth as shown by Deep Mines.

New Arrangement of the Bichromate of Potash Pile.—3 figures.

The Distribution of Electricity by Induction.—1 figure.

Electricity Applied to the study of Seismic Movements.—Apparatus for the study of horizontal and vertical seismic movements, etc.—8 figures.

New Accumulators.—3 figures.

Industrial Model of the Reynier Zinc Accumulator.

The History of a Lightning Flash.—By W. SLINGO.

Researches on Magnetism.

VI. NATURAL HISTORY.—The Giraffe.—With engraving.

VII. MEDICINE, AND HYGIENE.—The Treatment of Cholera—By Dr. H.A. RAWLINS.

Temperature. Moisture, and Pressure, in their Relations to Health.—London deaths under 1 year in July, August, and part of September.

Consumption Spread by Chickens.

New Method of Reducing Fever.

VIII. MISCELLANEOUS.—The Crown Diamonds of France at the Exhibition of Industrial Arts.

A New Mode of Testing the Economy of the Expenses of Management in Life Insurance.—By WALTER C. WRIGHT.

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The spirited view herewith presented, representing the "Fall of the Giraffe" before the rifle of a sportsman, we take from the Illustrated London News. Hunting the giraffe has long been a favorite sport among the more adventurous of British sportsmen, its natural range being all the wooded parts of eastern, central, and southern Africa, though of late years it has been greatly thinned out before the settlements advancing from the Cape of Good Hope.

The characteristics of this singular animal are in some particulars those of the camel, the ox, and the antelope. Its eyes are beautiful, extremely large, and so placed that the animal can see much of what is passing on all sides, and even behind it, so that it is approached with the greatest difficulty. The animal when full grown attains sometimes a height of fifteen to seventeen feet. It feeds on the leaves and twigs of trees principally, its immense length of legs and height at the withers rendering it difficult for the animal to graze on an even surface. It is not easily overtaken except by a swift horse, but when surprised or run down it can defend itself with considerable vigor by kicking, thus, it is said, often tiring out and beating off the lion. It was formerly almost universally believed that the fore legs were longer than the hinder ones, but in fact the hind legs are the longer by about one inch, the error having been caused by the great development and height of the withers, to give a proper base to the long neck and towering head. The color varies a good deal, the head being generally a reddish brown, and the neck, back, and sides marked with tessellated, rust colored spots with narrow white divisions. Many specimens have been brought to this country, the animal being extremely docile in confinement, feeding from the hand, and being very friendly to those who are kind to it.

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An experiment has been made in Vienna which proves that even with incandescent lights special precautions must be taken to avoid any risk of fire. A lamp having been enveloped with paper and lighted by a current, the heat generated was sufficient to set fire to the paper, which burnt out and caused the lamp to explode.

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At a recent meeting of the American Society of Civil Engineers, observations on the temperature of the earth, as shown by deep mines, were presented by Messrs. Hamilton Smith, Jr., and Edward B Dorsey. Mr. Smith said that the temperature of the earth varies very greatly at different localities and in different geological formations. There are decided exceptions to the general law that the temperature increased with the depth. At the New Almaden quicksilver mine, in California, at a depth of about 600 feet the temperature was very high—some 115 degrees; but in the deepest part of the same mine, 1,800 feet below the surface and 500 feet below sea level, the temperature is very pleasant, probably less than 80 degrees. At the Eureka mines, in California, the air 1,200 feet below the surface appears nearly as cool as 100 feet below the surface. The normal temperature of the earth at a depth of 50 or 60 feet is probably near the mean annual temperature of the air at the particular place. At the Comstock mines, some years since, the miners could remain but a few moments at a time, on account of the heat. Ice water was given them as an experiment; it produced no ill effects, but the men worked to much better advantage; and since that time, ice water is furnished in all these mines, and drunk with apparently no bad results.

Mr. E.B. Dorsey said that the mines on the Comstock vein, Nevada, were exceptionally hot. At depths of from 1,500 to 2,000 feet, the thermometer placed in a freshly drilled hole will show 130 degrees. Very large bodies of water have run for years at 155 degrees, and smaller bodies at 170 degrees. The temperature of the air is kept down to 110 degrees by forcing in fresh air cooled over ice.

Captain Wheeler, U.S. Engineers, estimated the heat extracted annually from the Comstock by means of the water pumped out and cold air forced in, as equal to that generated by the combustion of 55,560 tons of anthracite coal or 97,700 cords of wood. Observations were then given upon temperature at every 100 feet in the Forman shaft of the Overman mine, running from 53 degrees at a depth of 100 feet to 121.2 degrees at a depth of 2,300 feet. The temperature increased:

100 to 1,000 feet deep, increase 1 degree in 29 feet. 100 to 1,800 feet deep, increase 1 degree in 30.5 feet. 100 to 2,300 feet deep, increase 1 degree in 32.3 feet.

A table was presented giving the temperatures of a large number of deep mines, tunnels, and artesian wells. The two coolest mines or tunnels are in limestone, namely, Chanarcillo mines and Mont Cenis tunnel; and the two hottest are in trachyte and the "coal measures," namely, the Comstock mines in trachyte and the South Balgray in the "coal measures." Mr. Dorsey considered that experience showed that limestone was the coolest formation.

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C. Schmitt and A. Coblenzl have made a careful investigation of the unfermentable substances found in commercial starch sugars, and have succeeded in isolating a definite compound, to which they give the name gallisin. The method of separation and purification which they made use of is as follows: 5 kilogrammes of commercial starch sugar were allowed to ferment. At a temperature of 18-20 deg. C. and with a solution containing 20 per cent. the fermentation was complete in five to six days. It was filtered; the perfectly clear, almost colorless, liquid evaporated as far as possible on the water-bath, and the sirup while still warm brought into a good-sized flask. The sirup was then well shaken with a large excess of absolute alcohol, when it became viscous, but did not mix with the alcohol. The latter was poured off, replaced by fresh alcohol, and again shaken. When this shaking with alcohol has been repeated several times, the sirup is finally changed to a yellowish-gray mass. This is now brought into a large mortar, and rubbed up under a mixture of alcohol and ether. After some time the whole mass is transformed into a gray powder. It is quickly filtered off with the aid of an aspirator, washed with alcohol and then with ether, and brought under a desiccator with concentrated sulphuric acid. In order to purify the substance, it is dissolved in water and treated with bone-black. The solution is then evaporated to a sirup, and this poured into a mixture of equal parts of anhydrous alcohol and ether. In this way the new compound is obtained as a very fine, pure white powder which rapidly settles. It has much the appearance of starch. Under the microscope it is perfectly amorphous. In the air it deliquesces much more rapidly than ignited calcium chloride.

Treated with dilute mineral acids or oxalic acid on the water-bath gallisin is transformed into dextrose. It does not ferment when treated in water solution with fresh yeast. The analyses led to the formula C_{12}H_{24}O_{10}. When treated under pressure with three times its weight of acetic anhydride at 130-140 deg. it dissolves perfectly. From the solution a product was separated which on analysis gave results agreeing with the formula C_{12}H_{18}O_{10}(C_{2}H_{3}O)_{6}. The substance appears therefore to be hexacetylgallisin.

Physiological experiments on lower animals and human beings demonstrated clearly that gallisin has neither directly nor indirectly any injurious effect on the health.—Berichte der Deutschen Chemischen Gesellschaft, 17, 1000; Amer. Chem. Jour.

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Under the title of "Figures Worth Studying," Mr. William Farmer, of New York, read a paper before a recent meeting of the Society of Gas Lighting, from which the American Gas Light Journal gives the following:

I have prepared the following table, which contains some of the elements and compounds, with their combining weights, volumes, and specific gravities. When the combining weight of any of these elements and compounds is taken in pounds, then the gas or vapor therefrom will always occupy about 377.07 cubic feet of space, at 60 deg. Fahr. and 30 inches barometer. If we divide this constant 377.07 by the combining weight of any of the substances, then the quotient will be the number of cubic feet per pound of the same. If we divide the combining weight of any of the substances given in the table by 2, then the quotient will give the density of the same, as compared with hydrogen. If we divide the combining weight of any of the substances by the constant 28.87, then the quotient will be the specific gravity of the gas or vapor therefrom, as compared with air. All the calculations are based on the atomic weights which are now generally adopted by the majority of chemists.

- Cub. Ft. per Combi- Cub. Ft. Combi- Specific ning per ning Gravity Weight. Pound. Weight. Air = 1. Hydrogen (H{2}) 2.00 188.53 377.07 0.0692 Carbon vapour (C{2}) 23.94 15.75 377.07 0.8292 Nitrogen (N{2}) 28.06 13.43 377.07 0.9719 Oxygen (O{2}) 31.92 11.81 377.07 1.1056 Chlorine (Cl{2}) 71.00 5.31 377.07 2.4593 Bromine (Br{2}) 160.00 2.35 377.07 5.5420 Flourine (F{2}) 38.00 9.92 377.07 1.3162 Iodine (I{2}) 253.20 1.48 377.07 8.7703 Sulphur (S{2}) 63.96 5.89 377.07 2.2154 Phosphorus (P{4}) 123.84 3.04 377.07 4.2895 Carbonic oxide (CO) 27.03 13.50 377.07 0.9674 Carbonic acid (CO{2}) 48.89 8.59 377.07 1.5202 Water vapour (H{2}O) 17.06 20.99 377.07 0.6221 Hydrogen sulphide (H{2}S) 33.08 11.09 377.07 1.1770 Ammonia (H{2}N) 17.03 22.14 377.07 0.5898 Sulphurous oxide (SO{2}) 63.90 5.90 377.07 2.2133 Sulphuric oxide (SO{3}) 79.86 4.72 377.07 2.7662 Cyanogen (C{2}N{2}) 52.00 7.25 377.07 1.8011 Bisulphide of carbon (CS{2}) 75.93 4.96 377.07 2.6300 Ethyl alcohol (C{2}H{6}O) 45.90 8.21 377.07 1.5898 Ethyl ether (C{4}H{10}O) 73.84 5.10 377.07 2.5576 Methyl alcohol (CH{4}O) 31.93 11.81 377.07 1.1059 Methyl chloride (CH{3}Cl) 50.47 7.47 377.07 1.7482 Carbonyl chloride (COCl{2}) 98.93 3.81 377.07 3.4267 Phosphine gas (PH{3}) 33.96 11.10 377.07 1.1769 Hydrochloric acid (HCl) 36.50 10.33 377.07 1.2642 Methane (CH{4}) 15.98 26.61 377.07 0.5531 Ethane (C{2}H{6}) 29.94 12.50 377.07 1.0370 Propane (C{3}H{8}) 43.91 8.58 377.07 1.5209 Butane (C{4}H{10}) 57.88 6.51 377.07 2.0048 Ethene (C{2}H{4}) 27.94 13.49 377.07 0.9677 Propene (C{3}H{6}) 41.91 8.99 377.07 1.4516 Butene (C{4}H{8}) 55.88 6.74 377.07 1.9355 Ethine (C{2}H{2}) 25.94 14.53 377.07 0.8985 Propine (C{3}H{4}) 39.91 9.44 377.07 1.3824 Butine (C{4}H{6}) 53.88 6.98 377.07 1.8662 Quintone (C{5}H{6}) 65.85 5.72 377.07 2.2809 Benzene (C{6}H{6}) 77.82 4.84 377.07 2.6955 Styrolene (C{8}H{8}) 103.75 3.63 377.07 3.5936 Naphtalene (C{10}H{8}) 127.70 2.95 377.07 4.4232 Turpentine (C{10}H{16}) 135.70 2.77 377.07 4.7003 Dry air 28.87 13.06 1.0000

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[Footnote 1: This substance is also known by the name Schweinfurt green.]


The poisonous effects of wall-paper stained with emerald-green (aceto-arsenite of copper) appears to be a very favorite topic in many journals; it is continually reappearing in one form or another in different publications, especially medical ones; there has recently appeared a short reference to it under the title, "The Poisonous Effect of Wall-paper." As some years ago I became practically acquainted with its properties and manufacture, a few observations on these subjects may not be without interest.

In the paragraph referred to, it is stated that the poisonous effect of this pigment cannot be _entirely_ due to its mere mechanical detachment from the paper. This writer therefore attributes the poisonous effects to the formation of the hydrogen compound of arsenic, viz., arseniureted hydrogen (AsH_{3}); the hydrogen, for the formation of this compound, being generated, the writer thinks probable, "by the joint action of moisture and organic matters, viz., of substances used in fixing to walls papers impregnated with arsenic." In some of our chemical manuals, Dr. Kolbe's "Inorganic Chemistry," for example, it is also stated that arseniureted hydrogen is formed by the _fermentation_ of the starch-paste employed for fastening the paper to the walls. It is perfectly obvious that the fermentation of the starch-paste must cease after a time, and therefore the poisonous effects of the paper must likewise cease if its injurious effects are caused by the fermentation. I do not think that arseniureted hydrogen could be formed under the _conditions_, for the oxygen compound of arsenic is in a state of combination, and the compound is in a dry solid state and not in solution and the affinities of the two elements—arsenic and hydrogen—for each other are so exceedingly weak that they cannot be made to unite directly except they are both set free at the same moment in presence of each other. Further, for the formation of this hydrogen compound by the fermentation of the starch, or by the growth of minute fungi, the _entire_ compound must be broken up, and therefore the pigment would become discolored; but aceto-arsenite of copper


is a very stable compound, not readily undergoing decomposition, and is consequently a very permanent color. It has also been not unfrequently stated that the injurious effects of this pigment are due to the arsenious oxide volatilizing from the other constituents of the compound. This volatilization would likewise cause a breaking up of the entire compound, and would consequently cause a discoloration of the paper; but the volatilization of this arsenic compound is in every respect most improbable.

The injurious effects, if any, of this pigment must therefore be due to its mechanical detachment from the paper; but has it ever been conclusively proved that persons who inhabit rooms the wall-paper of which is stained with emerald-green suffer from arsenical poisoning? If it does occur, then the effects of what may be termed homoeopathic doses of this substance are totally different from the effects which arise from larger doses. During the packing of this substance in its dry state in the factory, clouds of its dust ascend in the air, and during the time I had to do with its manufacture I never heard that any of the factory hands suffered, nor did I suffer, from arsenical poisoning. If there is any abrasion of the skin the dust produces a sore, and also the delicate lining of the nostrils is apt to be affected. It is in this way it acts in large doses; I am therefore very skeptical as to its supposed poisonous effects when wall-paper is stained with it.

Different methods are given in works on chemistry for the manufacture of this pigment, but as they do not agree in every respect with the method which was followed in English color factories some years ago, it will be as well, for the full elucidation of the manufacture of this substance, to briefly recite some of these methods before describing the one that was, and probably is still, in use; and I will afterward describe a method which I invented, and which is practically superior to any other, both in the rapidity with which the color can be formed, and for producing it at a less cost.

It is stated in Watts' "Dictionary of Chemistry" that it is "prepared on a large scale by mixing arsenious acid with cupric acetate and water. Five parts of verdigris are made up to a thin paste, and added to a boiling solution of 4 parts or rather more of arsenious acid in 50 parts of water. The boiling must be well kept up, otherwise the precipitate assumes a yellow-green color, from the formation of copper arsenite; in that case acetic acid must be added, and the boiling continued a few minutes longer. The precipitate then becomes crystalline, and acquires the fine green color peculiar to the aceto-arsenite." I do not know from personal knowledge, but I have always understood that the copper salt employed in its manufacture in France is the acetate. This would account, in my opinion, for the larger crystalline flakes in which it is obtained in France than can be produced by the English method of manufacturing it. Cupric acetate is never employed, I believe, in England—the much cheaper copper salt, the sulphate, being always employed.

In "Miller's Chemistry" it is stated it "may be obtained by boiling solutions of arsenious anhydride and cupric acetate, and adding to the mixture an equal bulk of cold water." Why it should be recommended to add cold water, I am at a loss to understand.

In Drs. Roscoe and Schorlemmer's large work on "Chemistry," and in the English edition of "Wagner's Handbook of Chemical Technology," edited by Mr. Crookes, the process as described by Dr. Ehrmann in the "Ann. Pharm.," xii., 92, is given. It is thus stated in Wagner's work: "This pigment is prepared by first separately dissolving equal parts by weight of arsenious acid and neutral acetate of copper in boiling water, and next mixing these solutions while boiling. There is immediately formed a flocculent olive-green colored precipitate of arsenite of copper, while the supernatant liquid contains free acetic acid. After a while the precipitate becomes gradually crystalline, at the same time forming a beautiful green pigment, which is separated from the liquid by filtration, and after washing and carefully drying is ready for use. The mode of preparing this pigment on a large scale was originally devised by M. Braconnot, as follows: 15 kilos. of sulphate of copper are dissolved in the smallest quantity of boiling water, and mixed with a boiling and concentrated solution of arsenite of soda or potassa, so prepared as to contain 20 kilos. of arsenious acid. There is immediately formed a dirty greenish-colored precipitate which is converted into Schweinfurt green by the addition of some 15 liters of concentrated wood-vinegar. This having been done, the precipitate is immediately filtered off and washed."

As I have already stated, the copper salt used in the manufacture of this pigment in England is the sulphate, and it is carried out pretty much according to Braconnot's method as described by Dr Ehrmann; but any one would infer, from reading his description of the manufacturing process, that the compound, aceto-arsenite of copper, was formed almost immediately after the addition of the acetic acid, a higher or lower atmospheric temperature having no effect in hastening or retarding the formation. Furthermore, it is not stated whether the compound forms more readily in an acid or neutral solution, or whether it can or cannot be formed in a neutral one; now both these points are important to notice in describing its manufacture. As regards the former I shall notice it presently, and, as far as my knowledge extends, the pigment will not form when the solution is neutral.

The operation is conducted in the following manner in the factory: The requisite quantity of sulphate of copper is placed in a large wooden vat, and hot water added to dissolve it; the requisite quantity of arsenic (arsenious anhydride) and carbonate of soda, the latter not in quantity quite sufficient to neutralize the whole of the sulphuric acid set free from the sulphate of copper on the precipitation of the copper as arsenite, are placed in another wooden vessel; water is then added, and the formation of the arsenite of soda and its solution are aided by the introduction of steam into the liquid. When complete solution has been effected the arsenic solution is run off into the vat containing the solution of the sulphate of copper, arsenite of copper being at once precipitated. The necessary quantity of acetic acid is afterward added. In warm weather the formation of the aceto-arsenite soon commences after the addition of the vinegar; but, even in that case, it takes a week or more to have the whole of a big batch of arsenite converted into the aceto-arsenite; and perfect conversion is necessary, as the presence of a very minute quantity of unchanged arsenite lowers very much the price of the emerald pigment, and a by no means large quantity renders the pigment unsalable, owing to its dirty yellowish-green color. In cold weather a much longer time is required for its complete conversion; even at the end of a fortnight or three weeks there frequently remains sufficient unconverted arsenite to affect seriously the selling price of the color; when this occurs the manufacturer generally removes these last traces by a most wasteful method viz, by adding a quantity of free sulphuric acid. The acid of course dissolves the arsenite, but it dissolves in very much larger quantities the aceto-arsenite; and this costly solution is not utilized, but is run into the factory sewer.

By my method of manufacturing it, it can be produced in winter as well as in summer in one or two hours, and the quantity of free acid required for its formation is reduced to the lowest amount. I proceed as follows: After having dissolved in hot water the requisite quantity of cupric sulphate, I decompose one-fourth of this salt by adding just sufficient of a solution of carbonate of soda to precipitate the copper, in that quantity of the sulphate, as carbonate. I then add just sufficient acetic acid to convert the carbonate into acetate. I have now got in solution—

3CuSO_{4} + Cu(C_{2}H_{3}O_{2})_{2},

and I have to transform it into—

3CuAs{2}O{4} + Cu(C{2}H{3}O{2}){2}.

It is at once seen that I have got the requisite quantity of acetate formed. I next dissolve the requisite quantity of arsenious anhydride in an amount of carbonate of soda rather less than is sufficient to neutralize the acid in the remaining cupric sulphate, and I then bring the solution to or near the boiling-point by introducing steam into it; the arsenic is dissolved not in the same vessel as the copper salt, but in a separate one. When the arsenic solution is fully heated, a small current of it is allowed to flow into the vat containing the copper salts, and brisk stirring is kept up in the vat. The emerald green is at once formed; but if there should be the slightest formation of any arsenite, the flow of the arsenic solution is at once stopped until every trace of the arsenite has been converted; the arsenic solution is then allowed to flow in again, with the same precautions as before; in this way a large batch of emerald-green can he formed in one or two hours, without containing the slightest trace of the arsenite. I keep the arsenic solution near the boiling-point during the whole of the time it is flowing into the other vessel. By varying the proportions of water I could either make it coarse or fine, as I wished, which is an important matter to have complete control over in its manufacture.

Two points of interest occurred to me during the time I was occupied with the research, which I had not time to complete; one was whether the aceto-arsenite can be formed, adopting the old method for its formation, if there is more than a certain quantity of water; from some experiments I made in this direction I was inclined to the opinion it could not. I have already stated that emerald-green is soluble to a certain extent in acids, and that it is formed in a more or less acid solution; consequently a varying amount of the pigment is always lost by being dissolved in the supernatant liquid. To prevent to a certain extent this loss I precipitated the copper from it as arsenite; but I was not successful in the few experiments I had time to make on this part of the subject of reconverting the copper arsenite thus obtained into the aceto-arsenite by the addition of acetic acid.—Jour. of Science.

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In a recent issue of the Chemiker Zeitung Dr. Kosmann has reported an analytical method for the examination of zinciferous products; according to this report, the ash and flue dust produced by the extraction of zinc from its ore comprise:

1. Zinc dust, from the distillation of zinc,

2. Flue dust, condensed in chambers of zinc furnaces with Kleemann's receivers,

3. Zinc ash, of various assortments, from iron blast furnaces.

Of these, zinc dust is the only ready product which is, as color or reducing agent, employed in analytical and technical processes. Its value, when serving the latter purpose, is determined by the percentage of finely divided metallic zinc and cadmium contained therein; of equal reducing power is cadmium, generally associating zinc; injurious, and therefore uneffective, are zinc oxide and oxides of other metals, also metallic lead.

Flue dust, condensed in chambers of zinc furnaces with Kleemann's receivers, is employed with zinc ores in the extraction of zinc, and in small quantities as substitute for zinc white; its commercial value is similarly estimated as that of zinc ores.

The various modifications of zinciferous flue ashes from blast furnaces are an object for continual demand, being both a valuable material for the production of zinc and, in its superior qualities, a desirable pigment. In the regeneration of zinc the presence of foreign substances is of some concern; detrimental are lead, sulphur, and sulphuric acid in form of lead, zinc, and lime sulphate.

The chemico-technical analysis of these products has until recently been confined to the volumetric determination of zinc by means of sodium sulphide (Schaffner's method). But as a remnant of sulphur, as sulphuric acid, in roasted blende causes a material loss during distillation, and otherwise being induced to produce a zinc free of lead, the estimation of sulphur, sulphuric acid, and lead became necessary. These impurities are determined by well-known methods; sulphur is oxidized and precipitated with barium chloride, lead by sulphuric acid and alcohol. The examination of zinc dust, when used for the regeneration of metal, determines the quantity of zinc resident therein, and employed as reducing agent, the quantity of metal which causes the generation of hydrogen. Cadmium, showing the same deportment, must also be considered as well as lead and arsenic.

A most complete and rapidly working method for the examination of zinciferous products has originated with the application of neutral ammonium carbonate as solvent. A solution of this preparation is made, according to H. Rose, by dissolving 230 grm. commercial ammon carbonate in 180 c.c. ammoniacal liquor of 0.92 s.g., and, by addition of water, augmenting it to one liter.

This solution dissolves the metallic components, their oxides, and basic zinc sulphate, and transfers cadmium and lead oxide, also lead, magnesium, and lime sulphate, into insoluble carbonates. Iron and manganese, when present as protoxide, are dissolved; of iron sesquioxide but traces, and of cadmium oxide in statu nascendi a small portion enter into solution. The solution of ammonium carbonate contains in each 10 c.c. 1 grm. ammonia, which dissolves 1.5 grm. zinc.

The sample for examination is moistened with water and mixed with an adequate volume of the solvent, is digested at 50-60 deg. C. until complete decomposition is effected. The heating of the liquid prevents the solution of iron, manganese, and cadmium. The content, sediment and liquid, is thrown on a filter and washed with hot water to which a small quantity of the solvent has been added. When the solution contains iron and manganese, it is separated by decantation from the sediment and oxidized with bromine (according to the method of Nic-Wolff) until a flocculent precipitate of iron sesquioxide and manganese dioxide becomes visible; it is united with the original residue and filtered.

The filtrate is diluted till it appears cloudy, boiled to expel ammonia, tested with sodium sulphide upon the presence of zinc, and, when freed of all zinc, decanted. The precipitate of zinc carbonate is filtered, exhausted with water, transferred into zinc oxide by ignition, and weighed. The gravimetric method can be substituted by the volumetric by introducing a solution of sodium sulphide of known strength into the ammoniacal filtrate. On dividing the filtered liquid into various equal portions other substances, arsenic and sulphuric acid, can be determined from the same sample. For this purpose the filtrate is concentrated; divided into two equal portions, one of which is acidified and treated with hydrogen sulphide for the determination of arsenic, the other is acidified and used for the estimation of sulphuric acid by means of barium chloride. The original residue is dissolved in muriatic or acetic acid and filtered. The lead of the filtered liquid is thrown down by sulphuric acid, and alcohol, and cadmium, after dissipation of alcohol into gas, precipitated by hydrogen sulphide. Iron, manganese, alumina, and other substances present in the solution are determined by known methods.

It is manifest that the determination of substances—zinc, lead, and sulphuric acid—which are of importance in technical analysis of zinc ash, can be executed by this method within a comparatively short time. The application of ammonium carbonate as solvent has the advantage, over the application of ammonia, that it is a far better solvent, that it decomposes insoluble basic sulphates, and that the remaining carbonates are readily dissolved by acids.

The decomposition of zinc dust is accompanied by a lively evolution of gas; it is therefore necessary to continue the digestion of the sample till no more hydrogen is given off. Zinc dust contains both metals and their oxides, and methods which, from the volume of hydrogen generated, determine indirectly the percentage of metallic zinc do not give the real composition of the zinc dust. For the determination of the metallic components the material is digested with a solution of copper sulphate, which dissolves zinc and cadmium; the liquid is filtered, acidified, and decomposed with hydrogen sulphide, or treated with a solution of ammonium carbonate. The use of cupric chloride is not advisable, as it corrodes lead, and gives rise to the formation of soluble chloride of lead, which complicates the separation of zinc from cadmium. The best mode of operation is the following: Both copper sulphate and zinc dust are weighed separately, the former is dissolved in water and the latter introduced into the solution of copper sulphate in small portions until it appears colorless. During the operation the vessel is freely shaken, lumps are comminuted with a glass rod, and a few drops of the liquid are ultimately tested with hydrogen sulphide or ammonia. The remainder of zinc dust is then weighed, and its value deducted from the original weight. Zinc and cadmium of the filtrate are determined as above. On repeating this method several times most satisfactory results are obtained.

Another mode of operating is to employ an excess of copper sulphate and to determine the copper dissolved in the filtrate. The separation of copper from cadmium being difficult and laborious, and the volumetric estimation with potassium cyanide not practicable, it is not prudent to apply this method.

When calcined zinciferous pyrites have to be examined, the estimation of zinc is similar to that employed in the analysis of zinc ore. The sample is exhausted with water, filtered, and, to eliminate calcium sulphate and basic iron sulphate, evaporated to dryness. It is then dissolved in a small quantity of alcohol and water, refiltered, and the filtrate decomposed with ammonium carbonate. The original residue is treated with a solution of ammonium carbonate, which dissolves arsenious acid and basic zinc sulphate, filtered, and united with the first filtrate. When iron and manganese are present, the filtrates are treated with bromine. The united filtrates are boiled or examined volumetrically with sodium sulphide.

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[Footnote 2: Abstract of paper read before the Institution of Mechanical Engineers.]


Comparing naphtha refuse and anthracite, the former has a theoretical evaporative power of 16.2 lb. of water per lb. of fuel, and the latter of 12.2 lb., at a pressure of 8 atm. or 120 lb. per square inch; hence petroleum has, weight for weight, 33 per cent. higher evaporative value than anthracite. Now in locomotive practice a mean evaporation of from 7 lb. to 71/2 lb. of water per lb. of anthracite is about what is generally obtained, thus giving about 60 per cent. efficiency, while 40 per cent. of the heating power is unavoidably lost. But with petroleum an evaporation of 12.25 lb. is practically obtained, giving 12.25/16.2 = 75 per cent. efficiency. Thus in the first place petroleum is theoretically 33 per cent. superior to anthracite in evaporative power; and secondly, its useful effect is 25 per cent. greater, being 75 percent. instead of 60 percent.; while, thirdly, weight for weight, the practical evaporative value of petroleum must be reckoned as at least from (12.25 - 7.50)/7.50 = 63 per cent. to (12.25 - 7.00)/7.00 = 75 per cent. higher than that of anthracite.

Spray injector.—Steam not superheated, being the most convenient for injecting the spray of liquid fuel into the furnace, it remains to be proved how far superheated steam or compressed air is really superior to ordinary saturated steam, taken from the highest point inside the boiler by a special internal pipe. In using several systems of spray injectors for locomotives, the author invariably noticed the impossibility of preventing leakage of tubes, accumulation of soot, and inequality of heating of the fire box. The work of a locomotive boiler is very different from that of a marine or stationary boiler, owing to the frequent changes of gradient on the line, and the frequent stoppages at stations. These conditions render firing with petroleum very difficult; and were it not for the part played by properly arranged brickwork inside the fire box, the spray jet alone would be quite inadequate. Hitherto the efforts of engineers have been mainly directed toward arriving at the best kind of "spray injector," for so minutely subdividing a jet of petroleum into a fine spray, by the aid of steam or compressed air, as to render it inflammable and of easy ignition. For this object nearly all the known spray injectors have very long and narrow orifices for petroleum as well as for steam; the width of the orifices does not exceed from 1/2 mm. to 2 mm. or 0.02 in. to 0.08 in., and in many instances is capable of adjustment. With such narrow orifices it is clear that any small solid particles which may find their way into the spray injector along with the petroleum will foul the nozzle and check the fire. Hence in many of the steamboats on the Caspian Sea, although a single spray injector suffices for one furnace, two are used, in order that when one gets fouled the other may still work; but, of course, the fouled orifices require incessant cleaning out.

Locomotives.—In arranging a locomotive for burning petroleum, several details are required to be added in order to render the application convenient. In the first place, for getting up steam to begin with, a gas pipe of 1 inch internal diameter is fixed along the outside of the boiler, and at about the middle of its length it is fitted with a three-way cock having a screw nipple and cap. The front end of the longitudinal pipe is connected to the blower in the chimney, and the back end is attached to the spray injector. Then by connecting to the nipple a pipe from a shunting locomotive under steam, the spray jet is immediately started by the borrowed steam, by which at the same time a draught is also maintained in the chimney. In a fully equipped engine shed the borrowed steam would be obtained from a fixed boiler conveniently placed and specially arranged for the purpose of raising steam. In practice steam can be raised from cold water to 3 atm. pressure—45 lb. per square inch—in twenty minutes. The use of auxiliary steam is then dispensed with, and the spray jet is worked by steam from its own boiler; a pressure of 8 atm.—120 lb.—is thus obtained in fifty to fifty-five minutes from the time the spray jet was first started. In daily practice, when it is only necessary to raise steam in boilers already full of hot water, the full pressure of 7 to 8 atm. is obtained in from twenty to twenty-five minutes. While experimenting with liquid fuel for locomotives, a separate tank was placed on the tender for carrying the petroleum, having a capacity of about 3 tons. But to have a separate tank on the tender, even though fixed in place, would be a source of danger from the possibility of its moving forward in case of collision. It was therefore decided, as soon as petroleum firing was permanently introduced, to place the tank for fuel in the tender between the two side compartments of the water tank, utilizing the original coal space. For a six-wheeled locomotive the capacity of the tank is 3-1/2 tons of oil—a quantity sufficient for 250 miles, with a train of 480 tons gross exclusive of engine and tender. In charging the tender tank with petroleum, it is of great importance to have strainers of wire cloth in the manhole of two different meshes, the outer one having openings, say, of 1/4 in., the inner, say 1/8 in.; these strainers are occasionally taken out and cleaned. If care be taken to prevent any solid particles from entering with the petroleum, no fouling of the spray injector is likely to occur; and even if an obstruction should arise, the obstacle being of small size can easily be blown through by screwing back the steam cone in the spray injector far enough to let the solid particles pass and be blown out into the fire-box by the steam. This expedient is easily resorted to even when running; and no more inconvenience arises than an extra puff of dense smoke for a moment, in consequence of the sudden admission of too much fuel. Besides the two strainers in the manhole of the petroleum tank on the tender, there should be another strainer at the outlet valve inside the tank, having a mesh of 1/3 in. holes.

Driving locomotives.—In lighting up, certain precise rules have to be followed, in order to prevent explosion of any gas that may have accumulated in the fire box. Such explosions do often take place through negligence; but they amount simply to a puff of gas, driving smoke out through the ash-pan dampers, without any disagreeably loud report. This is all prevented by adhering to the following simple rules: First clear the spray nozzle of water by letting a small quantity of steam blow through, with the ash-pan doors open; at the same time start the blower in the chimney for a few seconds, and the gas, if any, will be immediately drawn up the chimney. Next place on the bottom of the combustion chamber a piece of cotton waste, or a handful of shavings saturated with petroleum and burning with a flame. Then by opening first the steam valve of the spray injector, and next the petroleum valve gently, the very first spray of oil coming on the flaming waste immediately ignites without any explosion whatever; after which the quantity of fuel can be increased at pleasure. By looking at the top of the chimney, the supply of petroleum can be regulated by observing the smoke. The general rule is to allow a transparent light smoke to escape, thus showing that neither too much air is being admitted nor too little. The combustion is quite under the control of the driver, and the regulation can be so effected as to prevent smoke altogether. While running, it is indispensable that the driver and fireman should act together, the latter having at his side of the engine the four handles for regulating the fire, namely, the steam wheel and the petroleum wheel for the spray injector, and the two ash-pan door handles in which there are notches for regulating the air admission. Each alteration in the position of the reversing lever or screw, as well as in the degree of opening of the steam regulator or the blast pipe, requires a corresponding alteration of the fire. Generally the driver generally passes the word when he intends shutting off steam, so that the alteration in the firing can be effected before the steam is actually shut off; and in this way the regulation of the fire and that of the steam are virtually done together. All this care is necessary to prevent smoke, which is nothing less than a waste of fuel. When, for instance, the train arrives at the top of a bank, which it has to go down with the brakes on, exactly at the moment of the driver shutting off the steam and shifting the reversing lever into full forward gear, the petroleum and steam are shut off from the spray injector, the ash-pan doors are closed, and if the incline be a long one, the revolving iron damper over the chimney top is moved into position, closing the chimney, though not hermetically. The accumulated heat is thereby retained in the fire-box; and the steam even rises in pressure, from the action of the accumulated heat alone. As soon as the train reaches the bottom of the incline and steam is again required, the first thing done is to uncover the chimney top; then the steam is turned on to the spray injector, and next a small quantity of petroleum is admitted, but without opening the ash-pan doors, a small fire being rendered possible by the entrance of air around the spray injector, as well as by possible leakage past the ash-pan doors. The spray immediately coming in contact with the hot chamber ignites without any audible explosion; and the ash-pan doors are finally opened, when considerable power is required, or when the air otherwise admitted is not sufficient to support complete combustion. By looking at the fire through the sight hole it can always be seen at night whether the fire is white or dusky; in fact, with altogether inexperienced men it was found that after a few trips they could become quite expert in firing with petroleum. The better men contrive to burn less fuel than others, simply by greater care in attending to all the points essential to success. At present seventy-two locomotives are running with petroleum firing; ten of them are passenger engines, seventeen are eight-wheel coupled goods engines, and forty-five are six-wheel coupled. As might be expected, several points have arisen which must be dealt with in order to insure success. For instance, the distance ring between the plates around the firing door is apt to leak, in consequence of the intense heat driven against it, and the absence of water circulation; it is therefore either protected by having the brick arch built up against it, or, better still, it is taken out altogether when the engines are in for repairs, and a flange joint is substituted, similar to what is now used in the engines of the London and Northwestern Railway. This arrangement gives better results, and occasions no trouble whatever.

Storage of petroleum.—The length of line now worked with petroleum is from Tsaritsin to Burnack, 291 miles. There is a main iron reservoir for petroleum at each of the four engine sheds, namely at Tsaritsin, Archeda, Filonoff, and Borisoglebsk. Each reservoir is 66 ft. internal diameter and 24 ft. high, and when full holds about 2,050 tons. The method of charging the reservoir, which stands a good way from the line, and is situated at a convenient distance from all dwelling houses and buildings, is as follows: On a siding specially prepared for the purpose are placed ten cistern cars full of oil, the capacity of each being about ten tons. From each of these cars a connection is made by a flexible India rubber pipe to one of ten stand pipes which project 1 ft. above the ground line. Parallel with the rails is laid a main pipe, with which the ten stand pipes are all connected, thus forming one general suction main. About the middle of the length of the main, which is laid underground and covered with sawdust or other non-conducting material, is fixed a Blake steam pump. As soon as all the ten connections are made with the cistern cars, the pump is set to work, and in about one hour the whole of the cars are discharged into the main reservoir, the time depending of course upon the capacity of the pump. All the pipes used are of malleable iron, lap-welded, and of 5 in. internal diameter, having screwed coupling muffs for making the connections. At each engine shed, in addition to the main storage reservoir, there is a smaller distributing tank, which is erected at a sufficient height to supply the tenders, and very much resembles the ordinary water tanks. These distributing tanks are circular, about 81/2 ft. diameter and 6 ft. high, and of 1/4 in. plates; their inside mean area is calculated exactly, and a scale graduated in inches stands in the middle of the tank; a glass with scale is used outside in summer time. Each inch in height on the scale is converted into cubic feet, and then by means of a table is converted into Russian poods, according to the specific gravity at various temperatures. As it would be superfluous to graduate the table for each separate degree of temperature, the columns in the table show the weights for every 8 degrees Reaumur, which is quite sufficient: namely, from 24 deg. to 17 deg., from 16 deg. to 9 deg., and so on, down to -24 deg.; the equivalent Fahrenheit range being from 86 deg. down to -22 deg. Suppose the filling of a tender tank draws off a height of 27 in. from the distributing tank, at a temperature of say -20 deg. R., these figures are shown by the table to correspond with 200.61 poods = 7,245 lb., or 3.23 tons, of petroleum. This arrangement does very well in practice; both the quantity and the temperature are entered on the driver's fuel bill at the time of his taking in his supply.

Engines.—The engines used in the trials were built by Borsig, of Berlin, Schneider, of Creusot, and the Russian Mechanical and Mining Company, of St. Petersburg. Their main dimensions and weights were about the same, as follows, all of them having six wheels coupled, and 36 tons adhesive weight; as originally constructed they had ordinary fire boxes for burning anthracite or wood; cylinders 18-1/8 in. diameter and 24 in. stroke; slide valves, outside lap 1-1/16 in., inside lap 3/32 in., maximum travel, 4-9/16 in.; Stephenson link motion; boiler pressure, 120 lb. per square inch; six wheels, all coupled, 4 ft. 3 in. in diameter; distance between centers of leading and middle wheels, 6 ft. 2-3/4 in.; between middle and trailing, 4 ft. 9-1/4 in.; total length of wheel base, 11 ft.; weight empty, on leading wheels, 12.041 tons; middle, 10.782 tons; trailing, 10.685 tons; total weight, 33.508 tons empty; weight in running order, on leading wheels, 12.563 tons; middle, 11.885 tons; trailing 12.790 tons; total weight, 37.238 tons in running order. Tubes number 151; outside diameter, 2-1/8 in.; length between tube plates, 13 ft. 10-1/8 in.; outside heating surface, 1,166 square feet; fire box heating surface, 82 square feet; total heating surface, 1,248 square feet; fire grate area, 17 square feet; tractive power = 65 per cent. of boiler pressure x (cyl. diam.) squared x stroke / diameter of wheels = 0.65 x 120 x (18.125) squared x 24 / 51 = 5.383 tons. Ratio of tractive power to adhesion weight = 5.383 / 37.238 = 1 / 6.9.

Tender.—Contents: water, 310 cubic feet, or 1,933 gallons, or 81/2 tons; anthracite, 600 poods, or 10 tons; or wood, 11/2 cubic sajene, or 514 cubic feet; weight empty, 13.477 tons; weight in running order, 28.665 tons; six wheels.

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Petroleum Refuse—Comparative Trials with Petroleum, Anthracite, Bituminous Coal, and Wood, between Archeda and Tsaritsin on Grazi and Tsaritsin Railway, in Winter Time.

- - - - - - - L o Train Consumption c alone. Including Date. o Lighting up. 1883. m - Cost o Train Num- Dis- Car of Atmospheric t ber Gross tance miles. Fuel. - - fuel temperature i of load. run. Per per and v Loa- Total train train weather. e ded mile. mile. . cars - - - - - - - - No. Tons Miles Pence. - - - - - - - - 8 32-23 25 400 388 9,700 Anthracite. 31799 81.90 11.957 -17 deg. to -18 deg. 32-23 lb. lb. Reau., Feb. equiv. to 8 24-21 -6 deg. to -81/2 deg. 14 24-21 25 400 388 9,700 Bituminous 37557.5 96.53 14.093 Fah. Coal. lb. lb. 7 26-29 25 400 194 4,830 Petroleum 9462 48.77 5.487 Strong refuse. lb. lb. side wind. - - - - - - - - 24 32-23 25 400 194 4,850 Anthracite. 12639.5 65.15 9.512 -5 deg. to -9 deg. March lb. lb. Reau., 6 21 24-21 25 400 194 4,850 Wood, in 1071.8 5.52 8.5 equiv. to billets. c. ft. c. ft 21 deg. to 12 deg. Fah. 23 26-27 25 400 194 4,850 Petroleum 7228 37.28 4.188 Light refuse. lb. lb. side wind. - - - - - - - -

Prices of fuel: Petroleum refuse, 21s. per ton; Anthracite and bituminous coal, 27s. 3d. per ton; Wood, in billets, 42s. per cubic sajene = 343 cubic feet; equivalent to 1.47d. per cubic foot.

Dimensions of locomotives: Cylinders, 18 1/8 in. diam. and 24 in. stroke; Wheels, 4 feet 3 in. diam.; Total heating surface, 1,248 sq. feet: Total adhesion weight, 36 tons; Boiler pressure, 8 to 9 atm.

The preceding table shows the results of comparative trials made in winter with different sorts of fuel, under exactly similar conditions as to type of engine, profile of line, and load of train. Two sets of comparative trials were made, both of them in winter. The three engines used were some of those built by Schneider. In comparison with anthracite, the economy in favor of petroleum refuse was 41 per cent. in weight, and 55 per cent. in cost. With bituminous coal there was a difference of 49 per cent. in favor of petroleum as to weight and 61 per cent. as to cost. As compared with wood petroleum was 50 per cent. cheaper. At a speed of fourteen miles an hour up an incline of 1 in 125 the steam pressure was easily kept up at 9 to 91/2 atm. with a No. 9 injector feeding the boiler all the time.

Up to the present time the author has altered seventy-two locomotives to burn petroleum; and from his own personal observations made on the foot plate with considerable frost he is satisfied that no other fuel can compare with petroleum either for locomotives or for other purposes. In illustration of its safety in case of accident, a photograph was exhibited of an accident that occurred on the author's line on 30th December, 1883, when a locomotive fired with petroleum ran down the side of an embankment, taking the train after it; no explosion or conflagration of any kind took place under such trying circumstances, thus affording some proof of the safety of the petroleum refuse in this mode of firing. Although it is scarcely possible that petroleum firing will ever be of use for locomotives on the ordinary railways of coal-bearing England, yet the author is convinced chat, even in such a country, its employment would be an enormous boon on underground lines.

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In answer to the inquiry of a correspondent about charcoal making, we offer two illustrations that show a method of manufacture differing from that usually adopted, which is that of burning on the bare ground, and covering with soil or sods to exclude the air. These kilns are made of brick, one course being sufficient, bands of iron or timber framework being added to strengthen the brickwork with greater economy. The usual style is conical, and the size is 24 feet in diameter, with an equal height, holding about 40 cords of wood. The difference in price is 1-1/8 d. per bushel in favor of these kilns as compared with the usual mounds, the burner being furnished with the use of the kilns, and the timber standing, the kiln burning costing 2-1/8 d., and the other 3-1/4 d. The kilns must be lined to about halfway up with fire-brick, the cost of which will vary with the locality, but will be about L200, and as 40 to 50 bushels of coal have been made per cord the extra yield on good charcoal and the lessening of the cost of making soon covers any extra outlay on the cost of the kilns. The wall of the kiln is carried up nearly straight for 6 feet, when it is drawn in, so as to become bluntly conical. Upon the top a plate of iron is fastened in the manner of the keystone of an arch, and bands of iron are passed round the kiln and drawn tight with screw bolts and nuts to strengthen it. Double doors of sheet-iron are made at the bottom and near the tops, by which it is either filled or emptied, and a few air-holes (B), which may be stopped with loose bricks, left in the bottom. The second figure shows a kiln of another shape made to burn 3,000 bushels of charcoal, or about 80 cords of wood. The shape is a parallelogram, having an arched roof, and it is strengthened by a framework of timber 10 inches square. As the pressure of the gas is sometimes very great, the walls must be built a brick and a half thick to prevent their bursting. The usual size is 16 feet wide and high, and 40 feet in length, outside measure. The time occupied in filling, burning, and emptying a small cone is about three weeks, and four weeks is required for the larger ones.—The Gardeners' Chronicle.

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Our illustration is a view of the entrance facade to Tiddington House, Oxfordshire, the residence of the Rev. Joshua Bennett. The house is an old building of the Georgian period, and though originally plain and unpretentious, its bold coved cornices under the eaves, its rubbed and shaped arches, moulded strings, and thick sash bars, made it of considerable interest to the admirers of the "Queen Anne" school of architecture, and led to the adoption of that style in the alterations and additions made last year, of which the work shown in our illustration formed a small part. Between the "entrance facade" and the wall of the house there is a space of some twenty feet in length, which is inclosed by a substantially built conservatory-like erection of Queen Anne design, forming an outer hall.

The works were executed by Messrs. Holly & Butler, of Nettlebed. The brick carving was beautifully done by the late Mr. Finlay; and the architects were Messrs. Morris & Stallwood, of Reading.—The Architect.

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Since Poggendorff in 1842 thought of substituting in the Bunsen battery a solution of bichromate of potash and sulphuric acid for nitric acid, and of thus making a single liquid pile of it, in suppressing the porous vessel, his idea has been taken up a considerable number of times. Some rediscovered it simply, while others, who were better posted in regard to the work of their predecessors, took Poggendorff's pile as he conceived it, and, considering the future that was in store for it, thought only of modifying it in order to render it better. Among these, Mr. Grenet was one of the first to present the bichromate of potash pile under a truly practical form. As long ago as 1856, in fact, he gave it the form that is still in use, and that is known as the bottle pile. Thus constructed, this pile, as is well known, presents a feeble internal resistance, and a greater electro-motive power than the Bunsen element. Unfortunately, its energy rapidly decreases, and the alteration of the liquid, as well as the large deposit of oxide of chromium that occurs on the positive electrode, prevents its being employed in experiments of quite long duration. Mr. Grenet, it is true, obviated these two defects by first renewing the liquid slowly and continuously, and causing a current of air to bubble up in the pile so as to detach the oxide of chromium in measure as the deposit formed. Thus improved, the bichromate pile was employed on a large scale in the lighting of the Comptoir d'Escompte. In an extensive application like this latter, the use of compressed air for renewing the liquid can be easily adapted to the bichromate pile, as the number of elements is great enough to allow of the putting in of all the piping necessary; but when it is only desired to use this pile for laboratory purposes, and when there is need of but a small number of elements, it is impossible to adopt Mr. Grenet's elements in the form required by an electric lighting installation. It becomes absolutely necessary, then, to come back to a simpler form, and attempt at the same time to obviate the defects which are inherent to its very principle. In accordance with this idea, it will be well to point out the arrangement adopted by Mr. Courtot for his bichromate of potash piles—an arrangement that is very simple, but, sufficiently well worked out to render the use of it convenient in a laboratory.

Fig. 1 gives the most elementary form. It consists of an earthen vessel into which dip four carbon plates connected with each other by a copper ring which carries one of the terminals. In the center there is a cylindrical porous vessel that contains a very dilute and feebly acidulated solution of bichromate of potash into which dips a prism of zinc, which may be lifted by means of a rod when the pile ceases to operate. It is true that the presence of the porous vessel in the bichromate of potash element increases the internal resistance, but, as an offset, although it decreases the discharge, it secures constancy and quite a long duration for it.

The elements thus constituted may be grouped, to the number of six, in a frame analogous to that shown in the engraving, and, sum total, form a small sized battery adapted to the current experiments of the laboratory, and capable of supplying two small four volt lamps for ten or twelve hours. We have had occasion to make use of these elements for the graduation of galvanometers, and, after ascertaining the constancy of the discharge, have found that the internal resistance of each couple is nearly 0.175 ohm, with an electro-motive force of two volts. As may be seen, these elements should, in general, all be mounted for tension, as they are in the figure, inasmuch as the mobility of the zincs permits, according to circumstances, of employing a variable number of them without changing anything. Moreover, with zincs amalgamated in a special manner, the attack is imperceptible, and the work in open circuit need scarcely to be taken into consideration.

Yet, despite the qualities inherent to the arrangement that we have just described, that defect common to all bichromate of potash piles—the deposit of oxide of chromium upon the carbon—is not here avoided. It occurs quite slowly, to be sure, but it does occur, and, from this point of view, the arrangement shown in Fig. 2 is preferable. The elements here are composed of prismatic porcelain vessels containing, as before, the solution and porous vessel.

The whole is covered with a sheet of ebonite connected with the zinc and the two carbon plates in such a way that when the pile is not in operation the whole can be lifted from the liquid. Under such circumstances the deposit of oxide is notably diminished, and the duration of the discharge is consequently greatly increased.

Fig. 3 shows the details of a windlass that permits of lifting, according to circumstances, all the elements of the same trough or only a part of them. To effect this, the drum around which the chain winds that carries the carbons is mounted upon a sleeve fixed upon the axle. This latter is actuated by a winch; and a ratchet wheel, R, joined to a click which is actuated by a spiral spring, prevents the ebonite plates from falling back when it is desired to place the bolt under the button, B, of the spring.

When it is desired to put an element out of the circuit, it is only necessary to act with the finger upon the extremity of the lever, D. Under the action of the latter, the piece, s, which carries a groove for the passage of the screws that fix it to the upper cross-piece, takes on a longitudinal motion and consequently gears with the drum through the toothed sleeve, E. When an experiment is finished the zinc may thus be lifted from the liquid, and the deposit of oxide be prevented from forming upon the carbon. As may be seen, the arrangements which we have just described exhibit nothing that is particularly original. The windlasses used for removing the elements from a pile when the circuit is open have been employed for a long time; the bichromate pile is itself old, and, as we said in the beginning, it has been modified in its details a number of times. In spite of this, we have thought it well to point out the mode of construction adopted by Mr. Courtot, since, owing to the simplicity of the arrangements, it renders convenient and easily manageable a pile of very great constancy that may be utilized for supplying incandescent lamps, as well as for the most varied experiments of the laboratory.—La Lumiere Electrique.

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There has been much said in recent times about the distribution of electricity by means of induction coils, and the use of this process has given rise to several systems that differ but little from one another in principle.

The following are a few details in regard to a system due to a Dutch engineer:

In the month of December, 1881, a patent relating to the distribution of electricity was taken out in Germany and other countries by Mr. B. Haitzema Enuma, whose system is based upon a series of successive inductions. The primary current developed by a dynamo-electric machine gives rise to secondary, tertiary, etc., currents. The principal line runs through the streets parallel with their axes, and, when the arrangement of the places is adapted thereto, it is closed upon the generator itself. In those frequent cases where it is necessary to cause the line to return over a path that it has already traversed, it is more advantageous to effect the return through the earth or to utilize the street water mains or gas pipes as conductors. This return arrangement may likewise be applied to the lines of secondary, tertiary, etc., order, as may easily be seen.

The induction is effected by the aid of bobbins whose interior consists of a bundle of soft iron. The wire of the inducting current is wound directly around this core. The wire of the induced current is superposed upon the first and presents a large number of spirals. It is useless to say that these wires must be perfectly insulated from each other, as well as from the soft iron core. We shall call primary bobbins those which are interposed in the principal line, and secondary bobbins those in which the inducting current is a secondary one, and so on.

It will be at once seen that this arrangement permits of continuing the distribution of electricity to the interior of buildings by the simple adjunction of one or several bobbins. Each electric apparatus, whether it be a lamp or other mechanism, is furnished with a special current. If the number of these apparatus be increased, it is only necessary to increase the number of bobbins in the same ratio, on condition, be it understood, that the intensity of the currents remain sufficient to secure a proper working of the apparatus in question. When such intensity diminishes to too great a degree, the bobbin must be replaced by a stronger one.

It results from what precedes that each apparatus must be put in in such a way as to permit, of the opening and closing of the corresponding circuit. This arrangement, moreover, has no need of being dependent upon the apparatus, and may just as well be transferred to any part of this same circuit. As regards lighting, it is preferable to employ alternating current dynamo machines; yet there is nothing to prevent the use of continuous current ones, provided that there is an arrangement that permits of constantly opening and closing this same circuit. That portion of the line which is placed under ground is insulated in the ordinary way at the places where it is necessary. As for the underground circuit and the induction coils connected therewith, these are protected against all external influence, and are at the same time insulated very economically by covering them with a coat of very fine silicious sand mixed with asphalt.

It is only necessary to inspect the annexed figure to get an accurate idea of this system of distribution. C represents the building in which the generator of electricity, D, is placed; B, the public street, and Q the house of a subscriber. The principal line, E, starts from the terminals, a, b, of the machine, passes through the primary bobbins, G, and is closed through the earth at F. It will be seen that the primary current communicates through d and c with the internal winding of the bobbins, G, while the secondary currents, H, are connected through e and f with the external winding. The same arrangement is repeated for the tertiary currents, M, and the quaternary ones, o, p. In the annexed example all the lines that run parallel with the axis of the streets are closed through the earth, while those that have a direction perpendicular thereto enter the houses of subscribers and form a closed circuit. In the interior of these houses the wires, as well as the induction coils, are insulated and applied to the walls. At Q is represented the arrangement that would have to be adopted in the case of a structure consisting of a vestibule, r, and two rooms, s, lighted by two electric lamps, R. In the portion of the figure situated to the left it is easy to see the process employed for insulating the line. A commencement is made by digging a ditch in the street and paving the bottom of it with bricks. Upon these latter there is laid a mixture of sand and asphalt, and then the wires and bobbins are put in, and the whole is finally covered with a new insulating layer.

It is a simple statement that we make here, and it is therefore not for us to discuss the advantages and disadvantages of the system. If we are to believe Mr. Enuma, the advantages are very numerous, to wit: (1) The cables have no need of being of large size; (2) the intensity is the same through the entire extent of the primary circuit, secondary one, etc.; (3) the resistance is invariable in all portions of the line; (4) the apparatus are independent of each other, and consequently there may be a disturbance in one or several of them without the others suffering therefrom; (5) either a strong or weak luminous intensity may be produced, since, that depends only upon the size of the coil employed; (6) there is no style of lamp that may not be used, since each lamp is mounted upon a special circuit; (7) any number of lamps may be lighted or extinguished without the others being influenced thereby; (8) when a fire or other accident happens in a house, it in no wise interferes with the service in the rest of the line; (9) the system could, were it required, be connected with any other kind of existing line; and (10) the cost of installation is infinitely less than that of a system of gas pipes embracing the same extent of ground.—La Lumiere Electrique.

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Italy, with her volcanic nature, has very naturally made a specialty of movements of the ground, or seismic perturbations. So the larger part of the apparatus designed for such study are due to Italians. Several of these instruments have already been, described in this journal, and on the present occasion we shall make known a few others that will serve to give an idea of the methods employed.

For the observation of the vertical and horizontal motions of the ground, different apparatus are required. The following is a description of those constructed for each of such purposes by the Brassart Brothers.

Apparatus for Studying Horizontal Movements.—A lever, (Fig. 1), movable about a horizontal axis, carries a corrugated funnel, i, at one of its extremities. At the other extremity it is provided with a counterpoise which permits of its being exactly balanced, while not interfering with its sensitiveness.

The opening of the funnel passes freely around a column, v (Fig. 2), upon which is placed in equilibrium a rod that terminates in a weight, P. The corrugations of the funnel carry letters indicating the four cardinal points, and the funnel itself is capable of revolving in such a way that the marked indications shall always correspond to the real position of the cardinal points. When a horizontal shock occurs, the weight, P, falls in a direction opposite thereto, and into one of the corrugations, where it rests, so that the direction of the shock is indicated. But, in falling, it causes the lever, F, to tilt, and this brings about an electric contact between the screw, h, and the column, n, which sends a current into the electro, E, so that the armature of the latter is attracted. In its position of rest this armature holds a series of parts, S, A, L, which have the effect of stopping the pendulum of a clock placed upon the same apparatus. At the moment, then, that the armature is attracted the pendulum is set free and the clockwork is started. As the current, at the same time, sets a bell ringing, the observer comes and arranges the apparatus again to await a new shock. Knowing the hour at which the hand of the clock was stopped, he sees how long it has been in motion again and deduces therefrom the precise moment of the shock.

The small rod, f, which is seen at the extremity of F, is for the purpose of allowing electricity to be dispensed with, if need be. In this case the screw, h, is so regulated that F descends farther, and that f may depress the armature of the magnet just as the current would have done.

Apparatus for the Study of Vertical Movements.—In this apparatus (Fig. 4), the contact is formed between a mercury cup, T, and a weight, D. The cup is capable of being raised and lowered by means of a screw, so that the two parts approach each other very closely without touching. At the moment of a vertical shock a contact occurs between the mercury and weight, and there results a current which, acting upon the electro, E, frees the pendulum of the clock as in the preceding apparatus. In this case, in order that the contact may be continuous and that the bell may be rung, the piece, A, upon falling, sets up a permanent contact with the part, a (Fig. 3).

Brassart's Seismic Clock.—This apparatus is designed for being put in connection at a distance with an indicator like the ones just described. It is a simple clock to which a few special devices have been added. Seismic clocks may be classed in two categories, according as they are stopped by the effect of a shock or are set running at the very instant one occurs. The Messrs. Brassart have always given preference to those of the second category, because there is no need of watching them during a seismic calm, and because they are much more easily constructed. It is to this class, then, that their seismic clock belongs. It is capable of being used for domestic purposes in place of any other clock, and of becoming a seismoscopic clock as soon as it is put in electric communication with the seismic telltales.

To the cross-piece that holds the axle of the drums the inventors have added (Fig. 5) a support formed of a strip of brass, S, with whose extremity is jointed (at the lower part) a double lever, A. This latter is held in a horizontal position by a small counterpoise, i, so that the finger at the opposite extremity shall prevent the pendulum, P, from swinging. To keep the latter in a position of rest a bent lever, n n', is jointed to the upper part of the support, S. The longer arm, n', of this lever is bent forward at right angles, so that it may come into contact with and repel the small rod of the pendulum as soon as the lever has been lifted by means of a small cord which is connected with the larger arm, n, and runs up to a small hook, from whence it descends and makes its exit under the clock-case.

In order to stop the clock, then, it is only necessary to pull on this cord slightly, when, by moving the pendulum to the left, it will thrust it against the inclined plane of the finger of the lever arm, A. It is clear that the extremity of the pendulum, upon striking against the finger, will depress it slightly and go beyond the projection against which it remains fixed owing to the counterpoise, i. The fever, n n', is brought back to its position of rest by means of a small counterpoise at the extremity of the arm, n. When the lever, A, is depressed, the pendulum escapes and sets the clock running. This depression is effected by means of an electro-magnet, E, whose armature, which is connected with the rod, t, t, lifts the arm, i, of the lever, and depresses A. The wires of the two bobbins of the electro-magnet end in two clamps, 1 and 2. The second of these latter is insulated from the clock-case. Both communicate with the extremities of the circuit in which is interposed the seismic telltale that brings about a closing of the current. Having noted the position of the hands on the dial when the clock was running, one can deduce therefrom the moment at which the shock occurred that set the clock in motion.

In addition to the parts that we have described, there are other accessory ones, R Rr, and a third clamp, 3, which constitute a sort of rheotome that is designed to keep the circuit closed after the momentary closing that is produced by the telltale has occurred. This little mechanism is indispensable when the disturbed telltale has also to act upon an electric bell. This rheotome, which is very simple, is constructed as follows: A small brass rod, R, which is screwed to the support, S, carries at its left extremity a brass axis, X, which is insulated from the rod, R, by means of an ivory piece. Toward the center of this small rod, the bent lever, r, carries a small arm that is bent forward, and against which abuts the axis of the pendulum, thus causing it to be thrust toward the left when the pendulum is arrested by the projection of the finger, A. As soon as the pendulum is set free, the lever, r, redescends and places itself against the axis, X. This latter communicates with clamp 3, which is insulated, while the rod, R, communicates with clamp 1. The external communications are so arranged that the circuit in which the bell is interposed remains definitely closed when the lever, r, is in contact with the rod, X.

Rossi's Tremitoscope.—This instrument (Fig. 6) unites, upon the same stone base, three different arrangements for showing evidences of trepidations of the earth. On one side we find (protected by a glass tube) a weight suspended over a mercury cup by a spring, and designed to show vertical motions. The two other parts of the apparatus are designed for registering horizontal motions. The first is a pendulum which causes a contact with four distinct springs, and whose movements are watched with a spy-glass. The second is a steel spring which carries at its upper part a heavy ball that vibrates at the least shock. This ball is provided with a point which is movable within a second ball, so that its motion produces a contact. All these different contacts are signaled or registered electrically.

Scateni's Registering Seismograph.—This apparatus, which is shown in Figs. 7 and 8, consists of two parts—of a transmitter and of a registering device.

The transmitter consists of a glass vessel supported upon a steel point and provided beneath with a platinum circle connected with a pile. All around this circle are four strips of platinum, against one of which abuts the circle at every movement of the glass. Each strip of platinum communicates, through a special wire, with one of the electro-magnets of the registering device (Fig. 8). This latter consists of an ordinary clock that carries three concentric dials—one for minutes, one for hours, and one for seconds. In a direction with the radii of these dials there are four superposed levers, each of which is actuated by one of the electros. On another hand, each dial is divided into four zones that correspond to the four cardinal points. When a shock coming from the north, for example, produces a contact, the corresponding electro is affected, and its lever falls and marks upon each of the dials a point in its north zone. We thus obtain the exact hour of the shock, as well as its direction. As may be seen, the apparatus, as regards principle, is one of the simplest of its kind.—La Lumiere Electrique.

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In Messrs. Arnould and Tamine's accumulators, shown in Fig. 1, the formation is effected directly by the current, as in the Plante pile, but the plates are formed of wires connected horizontally at their extremities by soldering. These plates are held apart either by setting them into paraffined wooden grooves at the ends of the trough or by interposing between them pieces of paraffined wood.

In Messrs. Barrier and Tourville's Electrodock (Fig. 2) the plates are formed of concentric leaden tubes fixed into a wooden cover. These tubes are threaded internally and externally, and the grooves thus produced are filled with a peculiar cement composed of litharge, powdered charcoal, and permanganate of potash, triturated together, sifted, and then mixed with glucose or sugar sirup so as to make a paste of them. This mixture forms a cement that is very adhesive after, as well as before, the electrolytic action.

In Kornbluh's accumulators the plates consist of ribbed leaden gratings between which is compressed red lead prepared in a peculiar manner, and constituting, 48 hours after formation, a compact mass with the lead. The tangs of the plates are widened so as to touch one another while leaving a proper distance between the plates themselves, and are hollowed out for the reception of a rod provided at its extremities with a winged nut and jam nut for passing them up close to one another. The plates, properly so called, are held apart by rubber bauds. The glass vessels are placed in osier baskets.—La Lumiere Electrique.

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The three models of a secondary battery that I recently made known to the readers of this journal have been the object of continuous experiment. Conformably to the provisions of theory, the zinc accumulator has shown itself practically superior to the two others, and I have therefore chosen this type for getting up an industrial model, which is shown in the annexed cut. The accumulator contains four Plante positives, having a wide surface, and three negatives constructed of smooth sheets of lead covered with zinc by the electrolysis of the acidulated solution of zinc sulphate in which the couple is immersed. Accidental contact with the interior of the pile is prevented by glass tubes fixed to the negatives by means of leaden bands. The seven electrodes are carried by as many distinct crosspieces of paraffined wood, which rest upon the edges of the trough and hold the plates at a certain distance from the bottom. These various crosspieces, which touch one another, take the place of a cover. Each plate is provided with a terminal. The four positive terminals are all on the same side, and the three negatives are on the opposite side. Two brass rods ending in a wire-clamp connect the respective terminals of the same name. The trough consists of two oblong wooden receptacles, one within the other, and having a play of several millimeters. This space is lined with a tight, elastic, insulating cement having tar for a base.

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