RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



Practical physiological chemistry, P. B. Hawk (PMladelphia: P. Blakiston's 

 Son & Co., 1916, 5. ed., rev. and enl., pp. XIV+638, pis. 6, figs. i72).— This is the 

 fifth edition of the volume previously noted (E. S. R., 21, p. 63). The chapters 

 on nucleic acids and nucleoproteins, gastric analysis, intestinal digestion, blood 

 analysis, and metabolism are new and have been inserted to increase the use- 

 fulness of the volume and to keep thoroughly abreast with recent developments 

 in physiological chemistry. The latest methods of quantitative analysis have 

 also been introduced throughout the volume. Thirty-five new illustrations 

 have been incorporated. 



Yearly report in reg'ard to the prog'ress made in agricultural chemistry, 

 edited by T. Dietbich and F. Mach (Jahresber. Agr. Chem., 3. ser., 17 (1014), 

 pp. XXIX+563). — A report of the work of 1914 in continuation of that pre- 

 viously noted (E. S. R., 34, p. 311). 



Report of the committee on editing methods of analysis {Jour. Assoc. Off. 

 Agr. Chem., 1 (1916), No. 4, pt. 2, pp. 57, figs. 4). — This report contains the 

 recommendations of the committee on editing methods for official and tentative 

 methods of analysis of fertilizers, soils, inorganic plant constituents, waters, 

 and tanning materials, presented at the annual meeting of the Association of 

 Official Agricultural Chemists, November 16-17, 1915. 



On the origin of the humin formed by the acid hydrolysis of proteins, 

 R. A. GoRTNER and M. J. Blish (Jour. Amer. Chem. Soc, 37 (1915), No. 6, pp. 

 1630-1636; abs. in Internat. Inst. Agr. [jBome], Mo. Bui. Agr. Intel, and Plant 

 Diseases, 6 (1915), No. 8, p. 1026). — It has been demonstrated that "in all 

 probability the humin nitrogen of protein hydrolysis has its origin in the 

 tryptophan nucleus." When tryptophan is boiled alone with mineral acids no 

 humin is formed ; when protein or carbohydrate is present, however, an 

 abundance is formed. With large amounts of carbohydrate present nearly 

 90 per cent of the tryptophan nitrogen remains in the humin fraction. Histidin 

 causes no increase of nitrogen in the humin fraction and can be quantita- 

 tively recovered in the bases. The humin is probably formed by condensation 

 of an aldehyde (formed by the action of the acid on carbohydrate) with the 

 NH group of the tryptophan nucleus. It is indicated that a distinct value 

 can thus be assigned to the humin nitrogen determinations. 



Fractionation of the phosphotungstic-acid precipitate with acetone as a 

 useful method for the preparation of the vitamin fraction from yeast, C. 

 Funk (Biochem. Bui., 5 (1916), No. 17, pp. 1-16).— The author has demon- 

 strated that "the phosphotungstate precipitate from alcohol extract of yeast 

 can be divided, by means of acetone, into two fractions: A small insoluble 

 fraction which contains the bulk of vitamin, and a large soluble one which is 

 totally inactive." Lead acetate was used to decompose the phosphotungstates 

 instead of baryta, as this procedure offered the advantage of yielding clear 

 solutions which facilitated further purification and avoided the use of alkali. 

 From autolyzed yeast an insoluble fraction could be obtained by the acetone 

 method which represented 84 per cent of the total phosphotungstate precipitate. 



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