AGRICULTURAL CHEMISTRY AGROTECHNY. 409 



The behavior of this method with soaps, paint materials, infant foods, leather 

 powders, vanilla beans, lubricating oil, and flour is described in detail. 



The Kjeldahl method, M. Siegfried and O. Weidenhaupt (Hoppe-Scyler's 

 Ztschr. Physiol. Chem., 76 (1912), No. 2-3, pp. 238-240; ahs. in Zcnfbl. Expt. 

 Med., 1 {1912), No. 6, p. 21)2) . — Boiling should not be resorted to after potassium 

 permanganate has been added to the solution. The author takes the flask from 

 the burner or turns the burner out, adds permanganate, heats, and then adds 

 permanganate again for a period of 3 minutes until the pink color remains 

 permanently. 



A practical method for reducing' potassium platinic chlorid when deter- 

 mining' potash as potassium platinic chlorid, A. Fiechteb {Ztschr. Analyt. 

 Chem., 50 {1911), No. 10, pp. 629-632). — The process consists of adding some 

 magnesium filings or chips in dilute hydrochloric acid to the potassium platinic 

 chlorid, which has been previously washed with alcohol and dissolved in a 

 little hot water. The process is completed in a few minutes if the mixture is 

 heated on a wire gauze. Some comparative tests between the method and 

 Neubauer's show a difference of only from 0.1 to 0.2 per cent. 



The determination of potassium as potassium platinic chlorid, B. Trnka 

 {Ztschr. Analyt. Chem., 51 {1912), No. 2, p. 103). — A discussion in regard to 

 priority of the method described by Fiochter above. 



In reg'ard to iron metabolism. — I, Method for the quantitative determi- 

 nation of small amounts of iron, F. Jahn (Hoppe-Seyler's Ztschr. Physiol. 

 Chem., 75 {1911), No. fi, pp. 308-338; ahs. in ZentU. Biochem. u. Biophys., 12 

 {1912), No. 21-22, p. 863). — For determining iron in organic substances, espe- 

 cially in small amounts, the author utilizes the Knecht and Hil)bert method, 

 which rests on the following equation : FeCl3+TiCl3=TiCl44-FeCl2. The method 

 gives results which differentiate amounts of 0.1 mg. of iron very definitely and 

 allows the titration to be done in 15 minutes. 



The substances required in the test are concentrated sulphuric acid and 

 nitric acid of knowm iron content for ashing according to the Neumann method, 

 a solution of potassium sulphocyanate, approximately 40 per cent strength, a 

 1/250-normal to 1/500-normal titanic trichlorid solution, which is preserved by 

 pouring paraffin oil upon it, a ferric sulphate solution containing 1 mg. of iron 

 per liter, and air-free water. 



A modification of Marsh's apparatus for the detection of arsenic, L. Cohen 

 {Dept. Agr. N. S. Wales, Set. Bui. J,, 1911, pp. 5, fig. i).— The following modi- 

 fication of Marsh's apparatus, as used by the author, is described : 



" Impure hydrogen, generated from dilute sulphuric acid and ordinary granu- 

 lated commercial zinc, is purified by passing through a neutral aqueous solu- 

 tion of silver nitrate, which combines with the AsHs with reduction to metallic 

 silver. It then passes through a mixture of the suspected liquid with dilute 

 sulphuric acid, in contact with a small quantity of pure arsenic-free zinc, or a 

 bundle of magnesium wire (in which latter case the solution must contain only 

 very little free acid, so as to avoid much heating), and carries over the small 

 quantity of hydrogen thus produced, with the AsHs resulting from the reduction 

 of any arsenic present in the suspected matter. The combined gases, after 

 drying, are tested in the usual way." 



The chemical composition of the clay obtained in the Schloesing-Grandeau 

 method, E. Blanck {Jour. Landw., 60 {1912), No. 1, pp. 75-81) .—The results of 

 examining the clays elutriated by the Schloesing-Grandeau method from 7 

 Silesian soils, taken chiefiy in the vicinity of Breslau, Germany, are given. 

 The conclusion is reached that the chemical composition of the clay varies 

 markedly, but within certain limits, and furthermore that the chemical compo- 



