EXPERIMENT STATION RECORD. 



Vol. XXXIII. Abstract Number. No. 9. 



RECENT WORK IN AGRICULTURAL SCIENCE. 



AGKICULTTJRAL CHEMISTRY— AGROTECHNY." 



Progress made in the field of agricultural chemistry in the years 1912 

 and 1913, P. Ehrenberg {Chein. Ztg., 3S (1914), Xos. 99, pp. 1022, 1023; 

 102-103, pp. 1038, 1039).— A retrospect. 



Francis Humphreys Storer, L, W. Fetzeb (Biochem. Bui., 4 {1915), No. 13, 

 pp. 1-9, pi. 1). — A tribute to the services of Francis Humphreys Storer in the 

 advancement of agricultural chemistrj-. 



Publications of Prancis Humphreys Storer, L. W. Fetzeb {Biochem. Bui., 

 4 {1914), No. 13, pp. 9-11). — A comparatively complete bibliography of the 

 contributions of Francis Humphreys Storer to the literature on general, tech- 

 nical, and agricultural chemistry. 



The chemistry of colloids and some technical applications, W. W. Taylor 

 (London: Edward Arnold, 1915, pp. VIII-{-328, figs. 22). — After a general con- 

 sideration of the topic, the methods of preparation, absorption, and tlie applica- 

 tions of colloid chemistry to dyeing, tanning, the soil, purification of sewage, 

 and biologj' are gone into. 



The arsenates of lead, R. H. Robinson and H. V. Tartar {Oregon Sta. Bui. 

 128 {1915), pp. 3-32, figs. 3). — After considerable worlv was done, the Holland 

 and Reed method (E, S. R., 28, p. 308) was not regarded as a safe one to use 

 for the preparation of pure lead hydrogen arsenates, but it was found that 

 fairly pure hydrogen arsenates can be prepared by the use of the reaction be- 

 tween lead nitrate and di-sodium hydrogen arsenate. 



All attempts to prepare pure lead ortho-arsenate were unsuccessful. " Lead 

 ortho-arsenate is not formed under the ordinary aqueous conditions employed in 

 the manufacture of commercial lead arsenate, and it is not a component of the 

 commercial material as has been formerly supposed." 



Lead pyro-arsenate was prepared by heating lead hydrogen arsenate to a 

 temperature slightly higher than 200° C. As the lead hydrogen arsenate has to 

 be heated to a comparatively high temperature before loss of water occurs, it 

 seemed evident that lead pyro-arsenate is not a constituent of commercial lead 

 arsenate. 



Basic lead arsenate is much less bulky than lead hydrogen arsenate. The 

 latter has a very fluffy appearance, similar to that of wheat flour. The basic 

 compound, owing to a tendency of its particles to collect together and settle out 

 more rapidly from suspension, "perhaps prevents its being spread so evenly 

 over the foliage of fruit trees by the usual methods of spraying as can be accom- 

 plished with the lead hydrogen arsenate." The specific gi-avity of lead hydro- 

 gen arsenate at from 4 to 20° C. is 5.7S6 and of basic arsenate is 7.105. Both 

 of the compounds were found to be very insoluble. 



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