RECENT WORK IN AGRICULTURAL SCIENCE 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



The chemical constitution of starch. — A review, A. W. Thomas {Biochem. 

 Bui., Jf (1915), No. 14-15, pp. 379-397, figs. 4).— This is a general review ami 

 discussion of the work on the constitution of starch. A list of 29 references to 

 the literature cited is included. 



Further notes on the essential oils of Australian Myrtaceae (Proc. Roy. 

 Soc. Victoria, n. ser., 28 (1915), No. 1, pp. U9-156, fig. i).— Three papers are 

 included. 



I. The essential oil of Eugenia smithii, A. E. Dawkins (pp. 149-152). — The 

 oil distilled from the leaves was of a pale yellow color and possessed a sweet, 

 penetrating odor. The physical constants were determined in May, 1914, with 

 the following results: Percentage yield, 0.44; specific gravity at 15° C, 0.866; 

 optical rotation at 15°, +35°; refractive index at 20°, 1.4701. In July of the 

 same year the following constants were obtained: Percentage yield, 0.28; spe- 

 cific gravity, 0.863 ; optical rotation, +34.6° ; refractive index, 1.4675. The 

 results indicate a slight seasonal variation. Chemical examination showed the 

 oil to have the following percentage composition: d-a-pinene, from 80 to 90; 

 esters, 4 ; and alcohols, 3.7. 



II. The calculation of the oil content of foliage from measurements of the 

 number and size of the oil glands, A. E. Dawkins (pp. 153, 154). — A formula 

 for calculating the approximate yield of oil from oil-producing plants is sub- 

 mitted and its use described in detail. 



III. The essential oil of Eucalyptus platypus, J. C. Earl (pp. 154-156). — A 

 yield of about 1 per cent of oil was obtained by distillation of the fi-esh leaves. 

 It yielded the following constants: Specific gravity at 15°, 0.9045; optical rota- 

 tion at 12°, +9.1°; refractive index at 20°, 1.4675; saponification number, 6; 

 saponification number after acetylation, 24 ; cineol determined by direct absorp- 

 tion with resorcin, 59 per cent by weight. No aldehydes or ketones were 

 present. 



Further examination revealed the following percentage composition of the oil : 

 Pinene, from 20 to 25; phellandrene, from 10 to 15; cineol. from 55 to 60; 

 aromadendrene, from 10 to 15; and alcohols, free and combined as esters, 5. 



The distribution of nitrogen in coagulum and serum of Hevea latex on 

 coagulation with acetic acid, B. J. Eaton and F. W. F. Day (Agr. Bui. Fed. 

 Malay States, 4 (1916), No. 11, pp. 350-353) .—As the rate of vulcanization of 

 Hevea rubber depends on the amount of some substance formed by the decom- 

 position of the nitrogenous constituents of the latex after coagulation of the 

 rubber, the authors determined the nitrogen contents of the' various portions 

 after coagulation, finding in the latex 0.11, the wet coagulum 0.15, and the 

 serum 0.06 per cent by weight. The significance of the results is discussed in 

 some detail. 



Silage and silage fermentation, A. R. Lamb (loica Sta. Bui. 168 (1916), pp. 

 S-11). — This is a general discussion of the subject under the following tt^ics : 

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