RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



The Kjeldahl method for nitrogen, W. Van Run (Pharm. Wcckbl., J/S 

 (1911), No. 2, pp. 27, 28; abs. in Jour. Chcm. Soc. [London.], 100 (1911), No. 

 581, II, p. 226). — "If it should be necessary to temporarily stop the heating 

 with sulphuric acid, the Kjeldahl flask may be fitted with a perforated rubber 

 cork, through which passes a tube bent at right angles and furnished near 

 its lower end with a glass bulb. The end of the tube is made to dip into a 

 small quantity of sulphuric acid. As the flask cools, the acid is drawn up 

 into the bulb, and the air which follows has to bubble through the acid, and 

 is thus freed from water vapor and any ammonia." 



Apparatus for determining nitrogen according to Kjeldahl's method, 

 Krieger (Cheni. Ztg., 35 (1911), No. 116, p. 1063, figs. 3).— A description of an 

 apparatus for preventing losses during neutralization of the digested fluid with 

 sodium hydrate and for removing the ammonia present in the bottle. 



In regard to the analysis of calcium nitrate (Norge saltpeter), lime nitro- 

 gen (calcium cyanamid), and nitrogen lime, E. Dinslage (Chem. Ztg., So 

 (1911), No. 114, pp. 1045, 1046).— A comparative study of the methods for 

 determining moisture in calcium nitrate indicated that the highest results 

 were obtained by heating the sample dii'ectly over a micro burner, and the 

 lowest in a vacuum over phosphoric acid or sulphuric acid. The intermediary 

 figures were obtained by heating the sample for 3 days in sand in a drying 

 oven. The higher results obtained with the micro burner were not due to a 

 decomposition of the salt. 



For determining nitrogen in calcium cyanamid and nitrogen lime, the author 

 points out that the usual Kjeldahl method does not furnish good results, but 

 when modified in the following manner is found to be more accurate: One gm. 

 of calcium cyanamid is boiled in an open flask with 30 cc. of a mixture (cooled) 

 consisting of equal volumes of sulphuric acid and water, and a drop of mer- 

 cury. After li to 2 hours the reaction is complete. If necessary, potassium 

 sulphate can be added at the end of the heating period. The remainder of the 

 process is the usual one, and according to the author, presents no difiiculties. 

 Twenty cc. of normal sulphuric acid is necessary for catching the distillate. 



Nitrogen lime difl'ers from lime nitrogen in that the former contains chlorin 

 and yields an unsaponifiable oily substance, which can be extracted with ether. 

 See also previous notes (E. S. R., 25, p. 805; 26, p. 109). 



The valuation of calcium nitrite and nitrate, Stutzer and Gov (Chem. Ztg., 

 35 (1911), No. 91, p. 891). — It was found by determining the nitrite present 

 with potassium permanganate by titration and determining the total nitrate 

 in the oxidized fiuid by Busch's nitron method that this procedure will yield 

 satisfactory results for examining commercial calcium nitrite and nitrate alone 

 or in a mixture with each other. The figures obtained were as follows: Total 

 nitrogen as obtained by Devarda's method 19.10, nitrite nitrogen by titration 

 with potassium permanganate 17.52, and the total nitrogen in the oxidized 

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