RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEinSTRY— AGROTECHNY. 



Principles of agricultural chemistry, G. S. Fraps (Easton, Pa., and London, 

 1913, pp. 493, figs. 94). — This book is adapted for the uses of the student and 

 those wishing an introduction to the field of agricultural chemistry, as well as 

 for a reference book. It is plentifully illustrated with reproductions of photo- 

 graphs taken chiefly from experiment station literature and that of the United 

 States Department of Agriculture. Considerable attention is given to the chem- 

 istry relating to problems of both plant and animal physiology. 



The chapter headings are as follows : Essentials of plant life'; the plant and 

 the atmosphere ; origin of soils ; physical composition and classes of soils ; physi- 

 cal properties of soils; the soil and water; chemical constituents of the soil; 

 chemical composition of the soil; active plant food and water-soluble constitu- 

 ents of the soil; chemical changes; soil deficiencies; losses and gains by the 

 soil ; manure ; sources and composition of fertilizers ; purchase and use of ferti- 

 lizers ; constituents of plants ; composition of plants and feeds ; digestion ; utili- 

 zation of food; maintenance ration and fattening; feeding work animals and 

 growing animals; feeding milk cows; and feeding standards and feeding. 



About the pentosans, S. Got (Fiihling's Landw. Ztg., 61 (1912), No. 18, pp. 

 606-612). — A discussion in regard to the chemistry and biology of pentosans 

 and their occurrence in nature. 



The temperature at which starch granules gelatinize, M. Nyman (Ztschr. 

 Untersuch. Nahr. u. Genussmtl,, 24 {1912), No. 11, pp. 673-676, figs. 8).— The 

 temperature at which starch does not affect polarized light is looked upon as 

 the gelatinization point. For rye starch it was found to be 57° C, for barley 

 starch 58°, and for wheat starch 59°. 



The chemistry of wood. — The resins of the Doug-las fir, G. B. Frankfoeteb 

 and H. H. Beown {Orig. Commun. 8. Internat. Cong. Appl. Chem. IWashing- 

 ton and New York], 25 (1912), Sects. I-Ve, p. 359). — ^An acid which the authors 

 chose to call betic acid was isolated from the resin obtained from the wood 

 of the Douglas fir. When it was recrystallized from 62 per cent alcohol, it 

 appeared as well-formed crystals with a melting point of from 143.5 to 144.5° C. 

 The figures obtained on elementary analysis pointed to the formula G17H24O2, 

 which was verified by the analyses of its salts and by its neutral equivalent. 

 " Molecular weight determinations by the freezing point method, however, gave 

 numbers nearly twice too high for the above formula, doubtless a result of 

 polymerization. In addition to the preparation of the metallic salts, bromin 

 and iodin compounds were made and studied." The molecular constitution is 

 regarded as still undecided. 



The investig-ation of the chemical action of bacteria, A. Haeden (Chem. 

 World, 1 (1912), No. 12, pp. 403, 404). — A review of work by various in- 

 vestigators as to the bacteria which are hygienically and industrially important. 

 The changes brought about by bacteria are regarded as principally due to the 

 enzyms which they contain or elaborate. 



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