EXPERIMENT STATION RECORD. 



Vol. 35. Abstract Number. No. 6. 



RECENT WORK IN AGRICULTURAL SCIENCE. 



AGmCITLTUKAL CHEMISTRY— AQKOTECHNY. 



Organic agricultural chemistry, J. S. Chamberlain {New York: The Mac- 

 millan Co., 1916, pp. XVII+SW). — This volume is divided into three sections: 

 (1) Systematic, which includes the study of the composition, constitution, 

 character, and relationship of the more important organic compounds occur- 

 ring in plants and animals; (2) physiological, which embraces a study of the 

 chemical reactions involved in the fundamental processes of living organisms, 

 in the utilization of food by animals, and in photosynthesis in plants ; and 

 (3) crops, foods, and feeding, which includes tho study of the distribution of 

 food constituents in agricultural crops and the principles of animal foods and 

 feeding. The presentation of the subject matter is general and of such a 

 nature as to follow a course in general chemistry. 



An introduction to the physics and chemistry of colloids, E. Hatschek 

 (Philadelphia: P. Blakiston's Son d Co., 1916, 2. ed., pp. IX+Wt, figs. 17).— 

 This is the second edition of a volume, the subject matter of which has been 

 essentially noted (E. S. R., 29, p. 608). The only substantial addition to the 

 text of the first edition is an appendix on experimental technique. 



Studies on plant colloids, II-VI, M. Samec et ax. (KoUoidchem. Beihefte, 

 4 (1912), No. 3-5, pp. 132-174, figs. 13; 5 (1913), No. 5, pp. 141-210, figs. SI; 

 6 (1914), No. 1, pp. 23-54, figs. 12; 7 (1915), No. 6-12, pp. 137-171, figs. 9; 8 

 (1916), No. 1-2, pp. 33-62, figs. 7). — Five papers are presented. 



II. The stability of starch solutions, M. Samec. — Continuing the study pre- 

 viously noted (E. S. R., 30, p. Ill) it is shown that the viscosity of a starch 

 solution decreases appreciably with time. The final viscosity of a 1 per cent 

 starch solution lies within the limits of the viscosity of molecular disperse 

 systems. This decrease in viscosity is greater in dilute than in concentrated 

 solutions. Hydrochloric acid retards the initial viscosity of starch solutions, 

 but later prevents a decrease (stabilizer). Alkalis in the lowest concentration 

 increase the viscosity of starch solutions and in higher concentrations coagu- 

 late them. Of the neutral salts ammonium sulphate and ammonium thiocy- 

 anate also decrease the internal molecular friction of the starch particles. The 

 sensitiveness to the action of electrolytes decreases with increasing age of the 

 starch solution. With a decrease of internal friction the electrical conductivity 

 increases. 



The removal of the ash, the action of electrolytes, and also the change in 

 the behavior of starch in the electrical field can be explained as due to the 

 presence of an ionized starch-phosphoric-acid complex. 



501 



