88 



CHEMISTKY. 



and prepare the way for it. Other causes 

 which have been suggested, to account partly 

 for the deterioration of bindings, are the in- 

 feriority of the modern quick processes of tan- 

 ning, particularly those in which soda is used; 

 the use of split leathers, and the impurities in 

 the air disseminated by hot-air furnaces. 



Industrial Chemistry. For the following 

 notes on improved appliances and processes in 

 the chemical industries, we are indebted to the 

 interesting summary of Professor J. W. Mallet, 

 published in the "American Chemical Journal " 

 during 1880. 



The improvements in mechanical appliances 

 include the adaptation of grinding-mills to true 

 grinding rather than crushing, the extended 

 use of steam coils and steam jackets for heating 

 purposes, the utilization of the waste heat from 

 vapors under treatment, and the application of 

 heat under pressure greater than that of the 

 atmosphere, which is made practicable by the 

 use of ingenious apparatus, giving special facil- 

 ities for manipulation and for observing the 

 operations going on within. 



Ice-machines for the production of artificial 

 cold have given important aid in a variety of 

 operations; their use has in turn stimulated 

 the demand for a number of chemical produc- 

 tions which are employed in them to induce 

 cold by evaporation, and has thus contributed to 

 the increased manufacture of such substances. 



Under the head of improved mechanical ar- 

 rangements for the agitation or stirring of 

 liquids are included, besides revolving paddle- 

 wheels and similar contrivances, the blowing 

 in of air and steam, by which the work of 

 heating, oxidation, etc., is often performed at 

 the same time with that which is merely me- 

 chanical. The nice fractional separation of liq- 

 uids, differing often but little in their boiling- 

 point, has been facilitated by the introduction 

 of improved apparatus for distillation. 



The operation of distillation by means of su- 

 perheated steam, or along with it, often makes 

 the use of elaborate and tedious chemical pro- 

 cesses unnecessary by effecting a simple physi- 

 cal purification of special materials. 



The operations of washing solid matters and 

 of filtration have been made more efficient by 

 the general application of centrifugal machines 

 or "hydro-extractors," by the use of filters ar- 

 ranged to work with a partial vacuum, and by 

 the use of filter presses to squeeze out mechan- 

 ically the liquid which is tenaciously retained 

 by precipitates, sediments, skimmings, etc. 



One of the cheapest processes for the exten- 

 sive manufacture of oxygen gas is that of Tessie" 

 du Motay, in which sodium manganate is ex- 

 posed at a low red heat to a current of super- 

 heated steam. The manganate may be repro- 

 duced from the residue of manganese sesqui- 

 oxide and sodium hydrate, by passing purified 

 air over it at the same temperature. This gas 

 has become to some extent a commercial prod- 

 uct ; and its application in certain directions 

 has been made more feasible by the system of 



storing it under a pressure of several atmos- 

 pheres in portable iron cylinders. In the med- 

 ical application of oxygen, in diseases affecting 

 the function of respiration, the idea of its 

 having a particular chemical value is no longer 

 held, but it is used with real benefit in those 

 diseases which interfere in a purely mechanical 

 way with the volume of air with which the 

 lungs can be supplied. 



Hydrogen may be made industrially, chiefly 

 to be employed with oxygen in the production 

 of the calcium-light, by the process of Tessie 

 du Motay, in which surplus carbon is heated 

 with slacked lime, and calcium hydrate is re- 

 produced by passing steam over the heated 

 carbonate of lime which is formed. Except 

 for a few special purposes, the place of pure 

 hydrogen in industrial applications can proba- 

 bly be supplied by the mixture known as water- 

 gas, or generated gas, which contains that ele- 

 ment along with carbon monoxide, nitrogen, 

 and other substances. 



Carbon disulphide has acquired greatly in- 

 creased importance on account of its furnish- 

 ing the means of dissolving out fats and oils 

 from various materials which could not be 

 treated with equal advantage in any other 

 way. Large quantities of fat are thus recov- 

 ered from oil-seed cakes, from the marc of olive- 

 oil pressing, from woolen rags and waste, from 

 cotton waste used in wiping machinery and 

 packing stuffing-boxes and axles, and from 

 bones from which gelatine and phosphates are 

 afterward to be made. The same solvent has 

 been used to a limited extent to collect sulphur 

 from poor "sulphur-stone," and to extract 

 delicate perfumes and the aromatic constituents 

 of spices and condiments. The so-called pe- 

 troleum-spirit or petroleum-naphtha is also 

 used for all these purposes, and has the ad- 

 vantage of being much cheaper than the carbon 

 disulphide. The disulphide, the sulpho-carbon- 

 ates, and the ethyl- and amyl-disulpho-carbon- 

 ates have lately been used in European vine- 

 yards with considerable success for checking 

 the ravages of the phylloxera. Potassium amyl- 

 disulpho-carbonate is most easily prepared bj> 

 bringing together, with precautions against a 

 too great rise of temperature, a strong solu- 

 tion of potassium hydrate, amyl alcohol or 

 fusel-oil, and carbon disulphide. 



In the production of phosphorus, mineral 

 phosphates, the so-called coprolites, guano, etc., 

 have largely replaced bone-ash as the crude 

 material used. Instead of a part (two thirds) 

 of the calcium, the whole is now removed as 

 calcium sulphate, and sirupy phosphoric acid, 

 dried up with charcoal-powder, is submitted as 

 the material for distillation. The process once 

 suggested by Woehler for procuring phosphorus 

 by distilling a mixture of calcium phosphate, 

 silica, and carbon, is said to have been adopted 

 on an industrial scale some years ago in France, 

 but the result of the experiment has not been 

 reported. Amorphous phosphorus is used to 

 some extent in making friction-matches, though 



