RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY. 



The determination of nitrogen in nitrate of soda, U. Van Dam (Rec. Trav. 

 Chim. Paijs-Bas et Belg., 25 (1906), pi). 291-296; abs. in Chem. Abs., 1 (1907), 

 No. 2, p. 152; Jour. Chcm. Sac. [London], 90 (1906), No. 530, II, p. 898). ~ 

 A method based upon the oxidation of oxalic acid by the nitrate in presence of 

 niansanese sulphate AA'ith subsequent determination of the excess of oxalic 

 by titration Avith potassium permanganate, is described, and comparisons of it 

 with the Schloesing method are reported. The oxidation is effected by heating 

 the mixture at 100° C. for 3^ hours in a flask provided with a reflux condenser 

 and charged with carbon dioxid. 



Detection of nitric acid, P. Soltsein (Pliann. Zfg., 51 (1906), No. 69, pp. 

 765, 766; abs. in Cliem. Centbl., 1906, II, No. 12, pp. 1020, 1021; Jour. Chem. 

 Soc. [London], 90 (1906), No. 530, II, p. 898).— The interference of nitrous 

 acid with the diphenylamin and brucin reactions is noted and attention is 

 called to the fact that in testing for nitric acid by reduction to nitrous acid 

 with zinc the reduction may be carried so far that the formation of starch 

 iodid will be prevented. It is recommended that in presence of such substances 

 as ferric or manganic oxids metadiamido benzol be used. Attention is called 

 to the occurrence of traces of nitrate in filter paper. 



Phosphomolybdic acid as a reagent for potassium, A. Schlicht (Chem. Ztg., 

 30 (1906), No. 104, PP- 1299, 1300; abs. in Analyst, 32 (1907), No. 371, p. 64)-— 

 Attention is called to the fact- that phosphomolybdic acid forms with potash 

 insoluble compounds of constant composition, and studies by the author of the 

 reaction uuder various conditions indicate that it may be employed with 

 advantage as a moans of quantitative determination of potash. The reagent 

 used consists of a nitric-acid solution of phosphomolybdic acid prepared by 

 fusing ammonium phosphomolybdate with sodium carbonate and nitrate and 

 dissolving the fusion in water acidified with nitric acid. The reagent is added 

 to the nitric-acid solution of the potash salt and the yellow potassium phos- 

 phomolybdate is precipitated by heating the soluti)n. Calcium, magnesium, and 

 sodium compounds do not interfere, but ammonium salt, of course, gives the 

 same reaction. 



Causticizing of alkali carbonates by lime, M. Le Blanc and K. Novotny 

 (Ztschr. Anorgan. Chem., 51 (1906). pp. 181-201; abs. in Jour. Soe. Chem. 

 Indus., 25 (1906), No. 23, p. 1145; abs. in Jour. Chem. Soc. [London], 92 

 (1907), No. 531. II, p. 22). — The authors report determinations by direct and 

 by conductivity methods of the solubility of calcium carbonate in water at 

 18 and 100° C. The amounts dissolved at these temperatures were 13 and 21 

 rag. per liter respectively, of which 65 and 72 per cent, respectively, were hydro- 

 lized, leaving the amounts actually in solution as carbonate 4 mg. per liter at 

 18° and nearly G mg. per liter at 100° C. 



From these data and from others for the solubility of calcium hydroxid the 

 authors calculated the equilibrium constants for the I'eaction of calcium hy- 

 droxid on potassium or sodium carbonate and also carried out experiments, 

 starting both with alkali carbonate and lime and with alkali hydroxid and 

 calcium carbonate. The results showed in general that the temperature and 

 also the pressure were practically without iuHuence on the final result. The 

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