RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



Colloid chemistry, J. Alesandeb {New York: D. Van Nostrand Co., 1919, pp. 

 V-\-90, pis. 3, fig. 1). — Brief chapters on the most important general properties 

 of colloids are followed by a discussion of the practical applications of colloid 

 chemical principles in many different fields. Among the topics included are 

 agriculture, soap, milk, ice cream, confectionery, brewing, tanning, rubber, 

 chemical analysis, pharmacy, foods and their preparation, and physiology and 

 pathology. 



Catalytic hydrog'enation and reduction, E. B. Maxted (London: J. d A, 

 Churchill. 1019, pp. YIII+IOJ,, figs. 12}.— The subject matter in this volume is 

 presented xmder the following heads: Introductory, the pi-oparation of catalysts, 

 the methods of catalytic hydrogenation, the hydrogenation of unsaturated 

 chains, the hydrogenation of unsaturated rings, miscellaneous reductions, de- 

 hydrogenation, and the technical hydrogenation of unsaturated oils. 



Changes in oils upon storage, H. A. Gardner (Jour. Indus, and Engin. Chem., 

 11 {1919), No. 8, pp. 759-761). — Tables are given showing the analytical con- 

 stants of commercial samples of vegetable and fish oils after different periods 

 of storage of from two to eight years in indirect light and at ordinary room 

 temperature. 



The aging of nearly every oil caused a drop in the iodin number and a rise 

 in the specific gravity, saponification number, and acid number. Changes in 

 acid number were particularly marked in fish oils. Samples of American tung 

 oil showed only moderate changes in the acid number but decided changes in 

 the saponification number. Only slight changes took place in samples of corn, 

 cottonseed, lumbang, sunflower, and hempseed oils which were perfectly clear 

 and free from moisture at the time of storage. Sterilized oils were found to 

 undergo less change than unsterilized samples. Oil stored in tin was found to 

 undergo more change in storage than corresponding oil stored in glass. 



The author concludes that " the changes that take place in oil upon standing 

 are due very largely to autohydrolysis caused by the presence of either moisture 

 or, in some instances, fat-splitting enzyms. Whenever oil is heated to a tem- 

 perature of 105° C. for a sufficient period of time to remove the moisture, and 

 then filtered, a moisture-free, clear, and sterile oil will i-esult. Such oil will 

 apparently keep for a long period of time without showing any marked 

 changes." 



The rotatory powers of the amids of active a-hydroxy acids, C. S. Hudson 

 {Jour. Amer. Chem. Soc, 40 {1918), No. 5, pp. 813-^17). 



The rotatory powers of the amids of several a-hydroxy acids of the sugar 

 group, C. S. Hudson and S. Komatsu {Jour. Amer. Chem. Soc, 41 {1919), No. 



7, pp. ll.',l-lim- 



The amid of a-5-mannoheptonic acid, C S. Hudson and K. P. INIonroe {Jour. 

 Amer. Chem. Soc., 4I {1919). No. 7, pp. II40, 1141). 



The constitution of capsaicin, the pungent principle of Capsicum, E. K. 

 Nelson {Jour. Amer. Chem. Soc, 41 {1919), No. 7, pp. 1115-1121). 



[Urease], M. Jacoby {Biochem. Ztsehr., 7^ {1916), No. 1-2. pp. 93-122; ahs. in 

 Chem. Ahs., 10 {1916), No. 13, pp. 1754, 1755). — This is a series of articles deal- 

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