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ever, increases with the moisture content and with the amount of dissolved electrolyte, an electric measure of moisture is possible. But since the amount of dissolved electrolyte in the factory water supply, and hence the moisture in the paper, varies within wide limits, a compensating device must be introduced. I n this apparatus it is based on the principle of the Wheatstone bridge. A stream of water from the paper machine flows through a glass tube containing a fixed grounded contact a t one end and a movable contact passing through the other, so that the column of water through which the current passes may be varied. By dividing and balancing the current, the instrument may be standardized so that no current passes when the paper has a given desired moisture content. Full details are given in the article.
HYDROGEN FOR BALLOONS Balloons are generally inflated with hydrogen from scrap iron and hot acid, unless there is some other source of the gas close a t hand. The French army is also making use of some novel processes which would be far too expensive for most commercial purposes, but which have the advantage of requiring none but readily portable materials and apparatus [Engineering, 99 ( I g I j ) , 4151. b‘hen the metals of the alkalies and alkaline earths are heated in hydrogen, so-called hydrides are formed. They are not metallic in appearance a t all-liquid hydrogen itself, it will be remembered, disappointed chemists by turning out to be a snowy paste-but form whitish crystals or crystalline powders, which have to be kept hermetically sealed. In the case of calcium hydride the powder is decomposed, with liberation of hydrogen; when heated up to 600“ C in a vacuum, or when treated with water. The simple apparatus designed by G. F. Jaubert for the decomposition of his calcium hydride, or “hydrolith,” which is essentially CaH2 with some calcium oxide and nitride, yields I cubic meter of hydrogen per kg. of hydrolith. Jaubert has also worked out two other processes which make use of ferro-silicon. In the “silicol” process this material, or mangano silicon, is directly decomposed by means of water and caustic soda; the gas evolution proceeds on the ordinary lines, as in the case of the generation of acetylene from calcium carbide, for instance, but it appears to be difficult to control the reaction. Jaubert therefore introduced another “hydrogenite” process. Ferro-silicon is intimately mixed with dry caustic soda and quicklime, and the bricks obtained are sealed into tin cases t o keep out mokture. Vl’hen wanted, the brick is placed within a water-jacketed apparatus, and a hot wire is forced into the opened brick. The mass burns without giving any flame, some steam is generated in the jacket, and this steam enters the brick and hastens the liberation of hydrogen. The ferro-silicon used is of verJt high grade, containing more than go per cent of silicon. The reactions give, hydrogen, lime, and sodium silicate; the iron is unessential, and is used only because i t is cheaper to manufacture rich ferro-silicon than to isolate silicon itself.
ACCIDENTS IN GERMANY FROM BENZINE The following list of accidents from benzine during 1 9 1 4 is published in the 2.angew. Chem.. 28 ( I ~ I S ) ,111, 73 PERSONS HURT Scene or character of accidents Total N o . Slightly Seriously Deaths Chemical cleaners and dvers. . . . . . . . . 6 .. 4 Druggists, e t c . . . . . . . . . . . . . . . . . . . . . . 21 1 .. 3 Benzine in technical use and transport 62 27 56 i6 7 Benzine in drains and sewers. . . . . . . . 3 Benzine in automobile t r a 5 c . . . . . . . . 104 38 5; 17 Benzine for illumination. . . . . . . . . . . . . 10 I 1 Benzine for household u s e s . . . . . . . . 30 42 , Narcosis from benzine vapors. . . 8 3 ~~
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fact that non-inflammable substitutes for benzine exist which are perfectly suited for most uses except power production and illumination.
THE FIRE DANGER FROM SLAKED LIME In the Royal Saxon Mechanical-Technical Experiment Station, experiments have been carried out which prove that it is easily possible for wood to catch fire from slaking even the poorer qualities of lime [ T o n i d - Z t g . ,1914 p. 14231. Eiaturally the temperature reached depends, besides on other factors, on the quality of the lime; even limes poor in calcium oxide may produce a temperature of 270-300’ C., a t which point wood is charred on exposure t o the air. Lime of poor quality then must be considered to a certain extent dangerous, and highgrade lime must be handled with special care, since it can produce temperatures of 4o0° and over; it must never be shipped in contact with wood.
A WOOD CHARCOAL FILTER FOR THE WASTE GASES FROM A SULFATE PLANT A paper by Keinhard on a charcoal filter used t o deodorize the gases escaping from the sulfate plant of the gas works in Leipsic appeared in the J . Gasbel., February 6, 1915, The gases escaping from sulfate plant consist chiefly of carbonic acid and sulfuretted hydrogen, which on account of their very disagreeable smell, cannot be discharged directly into the atmosphere. The Government Factory Department of Saxony requires in most cases special treatment of these gasessuch treatment generally consisting in their being passed through atmospheric or hydraulic tubular condensers or coolers, thence through iron oxide purifiers, and finally into a flue for combustion. The discharge of the gases without combustion led to some complaints of nuisance, and the management was compelled to take some action. The combustion of the waste gases could not be readily effected, as the boiler and other furnaces were far distant from the sulfate plant. Some preliminary experiments on a small scale showed that the empyreumatic, strongly smelling substances in the waste gases could be gotten rid of by passage through wood charcoal, and as a result of these experiments a plant was erected. To the pipe which conveys the spent gases from the purifiers to a place above the roof, two vertical pipes 13~/’pin. in diameter have been connected. These pipes are each packed with about 165 lbs. of wood charcoal, costing, for the two, about $3.24. After six weeks’ working the wood charcoal has been taken out and regenerated by heating in a gas retort for about three hours. This regeneration causes a loss of about 2 0 per cent of the charge. Data iannot be given as to the quantity of waste gases purified in this way, but the liquor worked up in this period in the plant amounted t o 550,000 gallons. It should be added that a steamjet blower has been introduced into the vertical pipe leading to the roof in order to exhaust the waste gases, which are heavier than air. Hence the whole waste-gas connections are under auction. The process has answered quite satisfactorily, and there have been no further complaints from neighbors. .. .-
GAS FROM SAWDUST In a recent issue of the American Gas Institute A’v*ezls, a paper read by Nessrs. James Lawrence and James C. Lawrence.
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There has been an increase of accidents from the use of pocket lighters, and the number of explosions of benzine used for autompbiles has nearly doubled. Emphasis should be laid on the
before the hTew York Section of the Society of Chemical Industry, and published in 30, 7 2 8 of their Journal is quoted on the subject of the distillation of sawdust, in answer t o an inquiry by a correspondent. I t had previously been supposed that wood less than 4 to 6 inches diameter could not be advantageously distilled, because of its tendency t o burn up rapidly by reasoli of an exothermic reaction which starts when the temperature of the charge reaches about 275’ C., but the authors found that by heating the retort very slowly up t o 100’C., then a
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little more rapidly to 280’ C., and then stopping the external heating until the temperature reached a maximum, when the heat was again applied and the distillation finished by raising the temperature as rapidly as possible t o a little over 400’ C., fine wood and sawdust could be successfully distilled. They give the results of some ten distillations, but do not give any for sawdust. These results show t h a t from IOO lbs. of wood they were able t o get about the following products: Acid liquor, 43.75 Ibs.; tar, 3.45 Ibs.; charcoal residue, 31.12 lbs.; gas, 21.68 lbs. ,4 specimen analysis of gas is given, which shows that IOO cu. f t . had a weight of 8.62 lbs., so that the yield per lb. of wood was about 2 . 5 cu. ft. The calorific value of the gas was given as 11,493 B. t. 11. per lb., and this figures out at 990 B. t . u. per cu. f t . The percentage analysis of the gas is given, however, as being : Heavy hydrocarbons. . . . . . . . . . . . . . . . . . . . . . . . . 8.16 12.32 Marsh g a s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.45 Carbon dioxide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Carbon monoxide . . . . . . . . . . . . . . . . . . . . . . . Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen.,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35.08 10.94 2.05
From this analysis the calorific value is calculated as 436 B. t. u. per cu. f t . If larger wood were being used, more gas could be obtained by carrying on the distillation a t a higher temperature; but from what the authors say, it would be impossible to do this with sawdust, since it would burn up under this treatment and the charcoal remaining after the distillation was completed would be so fine that it would be impossible to keep i t from burning, unless the retorts were discharged into an air-tight chamber. ECONOMY I N REINFORCED CONCRETE I n a paper on “Economy in Reinforced-Concrete Construction” read by Mr. T. A. Watson before the British Concrete Institute on February 18th, and quoted in Engineering, QQ (191j), 246, i t was stated that while great savings can be made on retaining walls, it is generally not economical t o employ reinforced concrete for the external walls of buildings, as brick walls up to a thickness of 14 in. are cheaper, but t h a t when walls have to be thicker than this the use of reinforced concrete is advisable. As under the proposed London County Council regulations nearly all external walls need not exceed 14 in. in a framed building, it is probable that reinforced concrete walls for this purpose will soon cease to be used from the point of view of economy. With regard t o the economy of reinforced-concrete framed buildings outside the London area the economy is very considerable; inside the London area the London County Council, by their regulations, propose t o reduce it as much as possible. There are, however, opportunities to effect savings over a steel-framed building even in London. I n the construction of bridges, say up to 300 f t . span a t least, reinforced concrete is nearly always the most suitable material. There are, of course, exceptions, but the mere question of the cost of maintenance of a steel bridge seems enough t o condemn it. The question of maintenanceis also enough t o decide a n architect or engineer to choose reinforced concrete for the construction of, say, small water towers, coalbunkers, gasometer tanks, or any similar structure heretofore built in steel, and exposed to atmospheric conditions, even if reinforced concrete is not cheaper in the first instance. T H E RUSSIAN PEAT INDUSTRY The remunerative exploitation of the vast peat deposits which many countries possess has for years been the subject of many experiments and much labor, although the results, perhaps, in most cases have been somewhat disappointing. In no country, according to Engineering, 99 (I~IS),4 7 7 , is there a greater wealth of raw material of this kind than in Russia, with her ho,ooo,oooacres of bogs, about 6.7 per cent of the country’s entire European area. Efforts are now being made to encourage
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the peat industry, which in some districts has attained t o a fair importance, although the bulk of the deposits are still left unexploited. A special section for peat exploitation has been formed under the Department for Agriculture, with a staff of experts, who in the first place are to examine and report upon the peat deposits near the railway stations and the large industrial centers The State owns a very material portion of the country’s peat deposits, which, where this is found practicable, are let to private contractors for a fee of from 4 to 6 cents per cubic meter of peat. Only a small portion of the production is retailed out, the bulk being worked by large industrial concerns for their own requirements of fuel. Some few years ago seventy large manufacturing concerns in Central Russia produced 1,230,000 tons of air-dried peat. The output averages 2000 to 2 j 0 0 tons per season per machine, and the cost of production, as a rule, lies between Sz.00 and 8 2 . 2 5 per ton. In Russia, as elsewhere, the use of peat fuel for locomotives is a t present much to the fore, and extensive experiments. are being carried on with a view to arriying a t a satisfactory practical solution. Pulverized peat seems to have attracted most attention, and the Russians are being guided, t o some extent a t least, by the results obtained in Sweden in this direction. .~~~~
IRON, COBALT AND CARBON ’
In a paper on cobalt steels, by Prof. J. 0. Arnold and Prof.
A . Read of Sheffield University, read a t a recent meeting of the (British) Institute of Mechanical Engineers, a comparison of the effects of cobalt and nickel in steel will be of interest, because nickel and cobalt have been commonly considered to be identical in their properties [Engineering, QQ (191j ) , 3631. Cobalt is not nearly such a great graphite precipitator as nickel. Cobaltsteel ingots can be hammered down to I-in. bars with only a very small separation of graphite, 0 . 0 7 per cent in the highest member of the series, containing 20.85 per cent of cobalt. In the case of nickel-steel ingots treated in exactly the same way as the cobalt-steel ingots, a small separation of graphite began with only 3 per cent of nickel, and when 7 per cent of nickel was present the precipitation of graphite amounted t o about 1 2 per cent of the total carbon. Cobalt carbide appears, then, to be much more stable than nickel carbide, a conclusion which is also borne out by the analysis of the carbide residues obtained by electrolysis from cobalt and nickel steels. Cobalt does not form a definite solid solution or cobaltide of iron like that formed by nickel, having a composition corresponding to the formula FejNi, which, with only 0 . 1 per cent of carbon present, registers a maximum stress of about 90 tons per sq. in., associated with a reduction of area of 4 j per cent. An alloy containing about 13 per cent of nickel, and, sap, 0.6 per cent carbon, is so hard that i t is impossible to machine i t , whereas in the present series of cobalt steels, in which the carbon ranged from 0.62 to 0.93 per cent, and the cobalt from about 2 . 7 to 20.9 per cent, all the alloys, without any annealing, machined with the gr.eatest ease. The hardness, as measured by maximum stress, seems, with equal carbon, to rise with the cobalt. A%.
MANUFACTURE OF LABORATORY GLASSWARE IN GREAT BRITAIN A very important stage has now been reached in the investigations made by British scientists into the question of the manufacture of glassware to replace the supplies which were formerly obtained from Germany and Austria. Early in the war the Council of the Institute of Chemists appointed a Glass Research Committee to conduct experiments with a view to establishing suitable formulas which should be available to British manufacturers willing to assist in making laboratory glassware. The chief aims of the research work, which has been going on continuously, were to produce working formulas for glass used in
