RECENT WORK IN AGRICULTURAL SCIENCE. 



AGEICULTURAL CHEMISTRY. 



On the quantitative determination of nitric acid, A. Gutbier (Chem. Ztg., 

 33 (1909), No. IS, p. 158; abs. in Chem. Zenthl., 1909, I, No. 13, p. 11U).~ 

 Referring to a recent article by Hes (E. S. R., 20, p. 1104), the .Author reiter- 

 ates conchisious expressed in a previous article (E. S. R., 17, p. 112). The use 

 of filter paper dried at 110° C. for collecting the precipitate as proposed by 

 Hes is condemned. 



The determination of nitrates by the Grandval and Lajoux method, L. 

 Farcy (Bui. Soc. Chim. Frame, 4. ser., 5 (1909), No. 10, pp. 562, 563). — 

 Attention is called to the fact that the author is covering in his investigations 

 much the same ground as Lombard and Lafore (E. S. R.. 21, p. 8). 



Influence of bromids and iodids on the determination of nitrates in ■water, 

 L. Farcy (Bui. Soc. Chim. France, 4. scr., 5 (1909), No. 10, pp. 563-566, fig. 

 1). — Investigations are reported from which the author concludes that the 

 halogen salts have a disturbing influence in the application of Grandval and 

 Lajoux's method for the determination of nitrates in waters, the coefficient of 

 decoloration varying with the kind of halogen salt present. lodids stand inter- 

 mediate between chlorids and bromids. The mechanism of the reaction is 

 evidently the same for the three classes of halogen salts. 



On the determination of osmotic pressure, J. Konig and J. Hasenbaumer 

 (Ztschr. Angew. Chem., 22 (1909), Nos. 22, pp. 1009-1018, figs. 2; 23, pp. 1010- 

 1074). — The method proposed as well as a new form of osmometer are de- 

 scribed in detail, with results of numerous tests of the method. See also a 

 previous note (E. S. R., 20, p. 713). 



The use of the histological method for the microscopical determination of 

 colloids, particularly in soil investigation, F. Cornu (Ztschr. Chem,. u. Indus. 

 KoUoide, J, (1909), No. 6, pp. 30.',, 30.5).— The possibility and advantage of using 

 such methods are briefly pointed out. 



Studies on the determination of clay in soils, E. Akntz (Latidw. Vers. 

 Stat., HO (1909), No. 3-.',, pp. 269-306; ahs. in Chem. Abs., 3 (1909), No. 13, pp. 

 1565, 1566). — As a result of an extended series of studies of methods, the au- 

 thor proposes the following procedure : 



" Heat 5 gm. of fine soil with about 50 cc. of water and 2 cc. of 10 per cent 

 hydrochloric acid (with soils containing larger amounts of lime the hydro- 

 chloric acid should be correspondingly increased), remove the solution by filtra- 

 tion, wash the soil, and remove to a 300 cc. beaker. Add 30 cc. of 18 to 20 

 per cent ammonia, boil gently for 4 hour, keeping the beaker covered with a 

 watch glass, cool, add water to a depth of 11 cm. over the soil, and after 24 

 hours' standing, siphon off the supernatant solution to a depth of 1 cm. Re- 

 move the residue to a porcelain dish, stir up repeatedly with a little water, and 

 decant until a clear solution is obtained. Remove the residue and the solutions, 

 to a be&ker and boil gently for \ hour in 20 cc. of ammonia. Cool, cover with 

 water to a depth of 11 cm., and siphon off after 24 hours, repeating this opera- 



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