144 



CHEMISTRY. 



containing chlorides a white precipitate of sil- 

 ver chloride. 



The detection of adulterations in oils is often 

 a difficult and trying task ; and the percentage 

 of the oil used to adulterate can seldom be 

 determined. We must often be satisfied by 

 proving that there has been a mixture, without 

 knowing the nature of it. Prof. Bechi, of 

 Florence, recommends for detecting cotton- 

 seed oil in olive-oil, a 1-per-cent. solution of 

 nitrate of silver in absolute alcohol. When 

 heated with the oil in a water-bath at 84 C., 

 the mixture will begin to darken if there be any 

 cotton-seed oil present. 



Mr. Oscar S. Carter recommends the elaidin 

 test in detecting a mixture of a drying and non- 

 drying oil, and in detecting adulterations of 

 olive-oil. It depends upon the fact that olein 

 and oleic acid, in contact with peroxide of ni- 

 trogen, yield a crystalline, solid, fatty body, 

 at 32 C., to which the name elaidin has been 

 given. Non-drying oils, and most animal fats, 

 contain oleic acid. Olive, almond, rape, ara- 

 chis, and castor oils, and the oils made from 

 lard and tallow, contain a high percentage of 

 olein. These oils form, with nitrogen peroxide, 

 solid elaidin of a white or yellow color. The 

 drying oils such as linseed, hemp-seed, and 

 poppy-seed oils do not form elaidin, but re- 

 main liquid for some time, and become slightly 

 colored. A test for lard-oil is its complete sa- 

 ponifi cation with caustic soda. Shark-liver oil 

 and African fish-oil resist saponification. Pure 

 lard-oil gives, with nitric acid, a yellow color, 

 approaching orange. Adulterated oils, with 

 nitric acid of the same strength, gave a dis- 

 tinct brown color on standing ; and the part 

 that resisted saponificatioii gave a much dark- 

 er, a deep-brown, color. The determination of 

 the specific gravity is the most important of 

 the physical tests of oils. Viscosity is an im- 

 portant feature, but the testing by it requires 

 much care. While we can not depend on any 

 single test, the evidence afforded by several 

 tests is often conclusive and satisfactory. 



Mr. Thomas W. Drown, while employing a 

 process for the determination of metallic sul- 

 phides, with especial reference to the estimation 

 of pyrites in coal, by treatment with sodium- 

 hydrate solution saturated with bromine, found 

 that the results secured, though agreeing well 

 together, fell far short of accounting for all 

 the sulphur in the coal. He thence inferred 

 that the sulphur not oxidized by the treatment 

 with the bromine solution was an organic con- 

 stituent of the coal, and could only be deter- 

 mined by a process which would oxidize the 

 coal completely. In the investigation of the 

 question that arose, he performed analyses to 

 determine the effect of coking on the amount 

 and condition of sulphur in coal, using coke 

 prepared in the laboratory and coke baked in 

 ordinary ovens in two distinct series of expert 

 ments. The results of the analyses, while they 

 were- not regarded as complete, indicated the 

 presence of sulphur both as pyrites and as an 



organic constituent of the coal, and also of 

 iron in the two conditions of combination with 

 the sulphur and with silica or other inorganic 

 constituents of the ash. 



Mr. Thomas M. Morgan, in several attempts 

 to determine the nitrogen in organic nitro- 

 derivatives by heating the substance in sealed 

 tubes of hard glass containing oxygen, in the 

 presence of a little mercury, found that in all 

 cases the nitrogen obtained was considerably 

 less than the quantity theoretically present in 

 the substance analyzed. The source of this 

 deficiency was eventually traced to the action 

 which the oxides of nitrogen exerted on the 

 alkali of the glass and on the mercury ; and 

 the reality and extent of this action were con- 

 firmed by a number of significant experiments. 

 The action is much more energetic at a high 

 than at a low temperature, and appears to be 

 very slight till the heat approaches redness. 



Brtigelmann has described a number of ex- 

 periments in crystallization which support the 

 law of Berthollet, that when two salts are 

 dissolved, the solution contains four salts pro- 

 duced by their mutual reaction. Equal vol- 

 umes of cold saturated solutions of cobalt 

 chloride and nickel sulphate gave crystals con- 

 taining both metals, but combined with sul- 

 phuric acid only. Solutions of copper sulphate 

 and cobalt chloride, mixed together, deposit 

 wine-red crystals, consisting principally of sul- 

 phates of both metals, but containing admixed 

 chlorides. A copper sulphate solution and one 

 of potassium dichromate, when mixed, deposit, 

 first, bright-green crystals containing both met- 

 als, principally as sulphates these crystals, 

 in various intermediate stages, yellow-green, 

 green, and blue -green, and finally a dark- 

 brown deliquescent mass, becoming crystalline 

 over sulphuric acid, consisting essentially of 

 both metals combined with chromic acid. 



By a recent modification of Dumas's process 

 for the estimation of nitrogen in coal and in 

 nitrogenous compounds that yield tarry matter 

 on destructive distillation, the gas evolved is 

 collected in two portions : that which escapes 

 during the distillation in CO 2 ; and that which 

 is collected while the residual nitrogenous car- 

 bon is undergoing combustion in oxygen. By 

 this method some insight is given as to the 

 condition of the nitrogen in the compound. 

 The authors have found that different nitro- 

 genous compounds vary greatly as to the pro- 

 portion of their nitrogen which escapes during 

 destructive distillation, and also that the ratio 

 between the two portions of nitrogen is sim- 

 ple and constant in each compound. 



Chemical Synthesis. P. W. Latham reports a 

 successful synthesis of uric acid in the manner 

 indicated by Horbaczewski. He exposes gly- 

 cocine and urea in the proportion of one to ten 

 to a temperature of from 210 to 212; dis- 

 solves the resultant mixture in warm water as- 

 sisted by solution of potash ; and treats with 

 ammonium chloride and ammonia, ammonio- 

 nitrate of silver, ammonio-sulphate of magnesia, 



