RPXHNT WORK IN AGRICULTURAI. SCIENCE. 



CHEMISTRY. 



Determination of nitrogen in nitrates {Kentiicl}/ 8ta. Rpt. 1891, 

 pp.l7-l!i). — 111 the deteriiiiiiatioii of nitrogen in nitiatesby tlie Kjeldabl 

 method the effect was tried of using potassium iodid, liydrogen sul- 

 l)hid,and mercuric hyposulphite in place of the reducing agents com- 

 monly used. The sami)le tested, a mixture of sodium and potassium 

 nitrates, contained theoretically 14.7L' per cent of nitrogen. The results 

 with hydrogen sulphid "approach nearest of all to the theoretical and 

 are a trifle higher than was obtained by the use either of zinc sulphid 

 or hyposulphite of mercury." The hydrogen sulphid was conducted 

 into the digestion Hask after the addition of salicylic acid for about 10 

 minutes, until a copious deposit of sulphur had been formed. 



The determination of nitric acid in alkaline nitrates, M Breutel 

 {Ber. Ot-sferr. Gcs., isQi^ p, :Jis; nh.s. in ZtscJn: angtir. Chcin., 1894, Xo. 

 I'^^jp. 568). — One gram of the nitrate dried at li'O to 130^ C.is weighed 

 out into a crucible, mixed with 3 to 4 times its weight of fresh ignited 

 tungstic acid, and covered with the same substance to adej)thof a few 

 millimeters. The whole is weighed again and heated, gently at first, 

 but at a gradually increasing temperature as the decomposition pro- 

 ceeds, maintaining the temperature below red heat until no further 

 fumes of nitric acid pass off, Avhich usually requires from 15 to 20 

 minutes. The loss of weight gives the amount of nitric acid. Chlorid 

 of sodium and sulphate of sodium are not decomposed iu this process. 



The determination of phosphoric acid by the citrate method, 

 F. GLASEii [Ztschr. (ou/eiu. Chem., 1894, Xo. 18, pp. 54o-54'j). — Dtiterini- 

 nations of phosphoric acid in sodium and potassium phosphate solutions 

 by the citrate method, using amounts of magnesia mixture varying 

 from 25 to 100 cc. are iei)orted, together with the results of check analy- 

 ses by the molybdate method. 



With 25 cc. of magnesia mixture the results were nuich too low, the 

 full percentage of phosphoric acid not being obtained until 60 cc. of 

 the solution was added. It appeared that the greater portion of this 

 error was due to the volatilization of phosphoric acid in igniting the 

 precipitates, as pointed out by Neubauer,' but a part was undoubtedly 



Ztsclir. uiioro-aii. Clicin., 2 (1892), p. 4.") (E. S. R., 4, p. 584 i. 



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