RECENT WORK IN AGRICULTURAL SCIENCE. 



AGIlICTJLTiniAL CHEMISTEY— AGEOTECHlTy. 



Methods in chemical analysis, F. A. Gooch (Neto York and London, 1912, 

 pp. XII +536, figs. 29). — This is a compilation of methods of chemical analysis, 

 originated or developed in the chemical laboratory of Yale University. Follow- 

 ing a chapter on appliances and general procedures used in analysis, the 

 various elements are considered in turn. 



Determination of potassium with the perchloric acid and sodium cobalti- 

 nitrite method, A. Vityn (Zhur. Opytn. Agron. (Russ. Jour. Expt. Landw.), 

 IS (1912), No. 2, pp. 192-199). — Potassium was determined in a mixture of 

 potassium and sodium chlorids 7 : 3, soils, and red clover seeds. Each sample 

 contained 0.07 gm. of potassium chlorid, except the seeds, the ash of which con- 

 tained only 0.04 gm. In soils the potash determinations were made in 10 per 

 cent hydrochloric acid extracts. The organic matter was removed previously 

 by ignition and SO3, P-Ob, AUOs, FesOs, CaO, and MgO were separated by the 

 methods used at the Agricultural Chemical Laboratory at St. I'etersburg. For 

 the determination of potash in the clover seeds the organic matter was removed 

 by heating with a mixture of nitric and sulphuric acids. 



In determining potassium with perchloric acid the aqueous solution of the 

 sample was evaporated to a bulk of from 15 to 20 cc. and 5 cc. of perchloric 

 acid of specific gravity 1.125 was added dropwise. Heating on the water bath 

 was continued until the white fumes of perchloric acid disappeared. On cooling 

 15 cc. of 95 per cent alcohol was added and the solid contents were carefully 

 triturated with a glass rod. The alcohol was then poured off through a Gooch 

 crucible, the precipitate was washed 2 or 3 times by decantation with 95 per 

 cent alcohol, containing 0.2 per cent of perchloric acid, and transferred to a 

 Gooch crucible in which it was washed 3 or 4 times more with the same alco- 

 holic solution. Finally the precipitate KClOi was treated with a little pure 

 alcohol, dried for an hour at from 120 to 130° C, and weighed. The results 

 agreed very satisfactorily with those obtained with platinic chlorid. It is 

 deemed important that all free perchloric acid be completely expelled. 



The determination of potash by the sodium cobalti-nitrate method was made 

 according to Drushel's method with some modifications, i. e., decinormal solu- 

 tions of potassium permanganate and oxalic acid were used. The latter con- 

 tained 50 cc. of strong sulphuric acid as indicated by Drushel, but in place of 

 ammonium oxalate pure crystalline oxalic acid was used. The precipitated 

 KNa2Co(N02)« was frequently stirred during evaporation and 2 cc. of 15 per 

 cent acetic acid was added, 1 cc. at a time. The washing was done with a 

 semi-saturated solution of sodium chlorid which was then removed by washing 

 3 times with water. For filtering, hardened filter paper held in a glass funnel 

 (S+S, 9 cm. No. 575) is preferred to a Gooch crucible. The operation is some- 

 what slower, but the results are somewhat nearer to those obtained by precipi- 

 tating with platinic chlorid. 



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