AGRICULTURAL CHEMISTRY AGROTECHNY. 703 



correct results when Ibo tin-lead composition contains much iron. The autlior 

 proposes a method whicli j^ives better results. 



A new micro-cliemical reaction for arsenic and phosphorus, Deniges 

 ((htcn: Chcm. Ztg., J 2 (1909), No. 16, p. 208).— With this test the author was 

 able to detect quickly and in the cold 1/lOCiO mg. of arsenic and phosi)horus. 

 The reaj^ents employed were either ammoniacal or acetated silver nitrate solu- 

 tion or mercuric nitrate and nia.irnesiuni mixture. The arscuic is obtained in 

 the form of rods or plates. The phosphorus is transformed into phos[)h()ric acid 

 and collected with the condensed water in a Blondlot and Dusart apparatus. 



Quj.litative test and quantitative approximation of small amounts of 

 arsenic, R. Bensemann (Zt.sclir. Angcw. Chcm., 22 {1909), No. 37, pp. ISOJ/- 

 ISOG). — ^A Julius and Robert Otto hydrogen generation apparatus has been 

 modified by the author for arsenic work. For the quantitative approximation 

 analysis he proposes a series of mirrors prepared from known amounts of 

 arsenic. 



The estimation of the citrate soluble phosphoric acid in Thomas slag 

 powder, Soxhlet (Laiidw. Vers. Stat., 11 (1909). No. 1-3, pp. 220-22.'i). — The 

 Association of Agricultural Experiment Stations of Germany has adopted the 

 following methods for the estimation of citrate soluble phosphoric acid in 

 Thomas slag powder: (1) The hydrochloric method with the elimination of 

 silicic acid; (2) the direct precipitation according to Bottcher- Wagner in con- 

 junction with the Kellner preliminary test; (3) the method of Naumann ; (4) 

 the Darmstadt method; and (5) the Lorenz method. The permissible limit 

 established for error is 0.3 per cent. 



The deternaination of potash in potassium fertilizers, Soxhlet (Landw. 

 Vers. Stat., 11 (1909), No. 1-3, pp. 181-205).— This is a criticism of the various 

 methods employed in the determination of potash in- potassium salts for fer- 

 tilizers by the Association of Agricultural Experiment Stations of the German 

 Empire. 



A reaction of acid soils, O. Loew (Ztschr. Landw. Versuchsw. Ostcn:, 12 

 (1009), No. 5, pp. J/6 1-^/63; ahs. in Chem. Abs., 3 (1909), No. 19, p. 2331).— The 

 following method for detecting acidity is given : Boil 10 gm. of the soil with 

 10 cc. of 1 per cent potassium iodid 5 to 10 minutes in a water bath, add a few 

 drops of potassium nitrate and starch paste, and cool quickly. 



The detection of free CO- in water, L. Bitter (Hyg. Rundscliau, 19 (1909), 

 No. 11, pp. 633, 63.'f; ahs. in Chcm. Zcnthh, 1909, II, No. 1, p. 63 ) .—Attention is 

 called to the fact that too much reliance must not be placed in the rosolic acid 

 reaction. It is better to take 50 cc. of water and 10 drops of an alcoholic solu- 

 tion of phenolphthalein in a 200 cc. Erlenmeyer flask and if a red coloration 

 does not ensue to shake the water strongly for 10 minutes or boil it for a time. 

 If a pink color manifests itself, free CO2 is present. For its quantitative de- 

 termination Trillich's titration method is recommended. 



The leg'al coloring matters for foods and the difficulties of their prepa- 

 ration, G. KOHNSTAMM (Ostcrv. Chem. Ztg., 12 (1909), No. 15, p. 19.'t).— Of 189 

 colors examined, it was found that the poorest grade of colors was that gen- 

 erally employed to color foodstuffs. 



All of the <;o samples of Naphthol yellow S examined contained martins yel- 

 low, many had from 2 to .33 per cent of the original synthetizing bodies and de- 

 composition i)roducts present, and 41 contained arsenic, 2!) in large quantities. 

 With Orange I, out of 2S sami)les investigated all contained procbicts of decora- 

 jiosition, most contained free najihthol and lead, and 'some containcMl iron. 

 .\mong .3S Amaranth samples, all contained arsenic and other coloring matters; 

 iron was alsQ found. lu 10 of the 12 Erythrosiu samples examined thery was^ 



