RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



Annual reports on the progress of chemistry for 1919, edited by J. C. 

 Cain (Ann. Rpts. Prog. Chcin. [London^, IG {1919), pp. IX+2S^, figs. 10).— 

 This is tlie usual annual report (E. S. R., 41, p. 201) of progress in various 

 brandies of chemistry including, among others, sections on analytical chemistry 

 by C. A. Mitchell, physiological chemistry by G. Barger, and agricultural chem- 

 istry and vegetable physiology by E. T. Russell. 



Work of the chemist in tlie food industries, L. M. Tolman {Chem. Age 

 [Xcw Yurk], 1 (1919), No. 6, pp. 2.'fl-2.'f5, fig. l).—\ brief summary of the 

 development of chendcal control in the manufacture of food. 



Wood and chemistry, L. F. Hawley (Chem. Age [Neiv York], 1 (1919), 

 No. 6, pp. 247, 24s, fig. 1). — This is a general discussion of the relation between 

 wood and chemistry as shown in the manufacture of pulp and paper, wood 

 preservation, wood distillation, the manufacture of methyl alcohol, ethyl alco- 

 hol, oxalic arid, tanning materials, etc. 



Continuation and extension of work on vegetable proteins, T. B. Osborne 

 and L. B. Mendel {Carnegie Inst. Wash. Year Book, 18 {1919), pp. 352-360).— 

 The progress report for 1919 in continuation of work previously noted (E. S. R., 

 43, p. 10) contains brief statements concerning investigations in progress and 

 discu.ssions of the significance of the results obtained in studies which have 

 been previously noted from other sources. 



The proteins of green leaves. — I, Spinach leaves, T. B. Osborne and 

 A. J. Wakeman (Jour. Biol. Cheni., 42 {1920), No. 1, pp. J-26).— The authors, 

 with the cooperation of C. S. Leavenworth and O. L. Nolan, have investigated 

 the proteins of spinuch leaves by the following method: 



The fresh gieon leaves were ground with water to break up the cell walls 

 and set free the contents of the cells. By centrifuging or filtering through soft 

 paper a green turbid extract was obtained in which only minute particles were 

 visible under the microscope. The addition of about one-third volume of alcohol 

 to this extract resulted in the formation of a voluminous green precipitate 

 containing chlorophyll, phosphatids, and fats which were removed by extrac- 

 tion with alcohol and ether, leaving a residue consisting of about 20 per cent 

 of the solids of the leaves and composed almost entirely of protein. This was 

 found to be practically insoluble in aqueous alkaline solutions at room tempera- 

 ture, but soluble in boiling CO per cent alcohol containing 0.3 per cent sodium 

 hydroxid. On neutralizing this solution with acid the protein was precipitated 

 In a form readily sohible in a slight excess of either acid or alkali, and con- 

 taining about 15.25 per cent of nitrogen. This colloidal protein is thought to 

 be a mixture of several individual proteins, possibly combined with carbo- 

 hydrate-containing groups. The presence in it of nucleic acid has not been 

 detected. 



The filtrate from the original alcohol precipitate contained the water-soluble 

 con.stltuents of the cells, constituting about 50 per cent of the solids of the leaf 

 and containing proteoses to the extent of 1.7 per cent, proteins coagulable by 

 heat 1.4 per cent, and nonprotein organic substances 28 per cent of the total 

 solids of the leaf, the balance consisting of mineral matter. The nonprotein 



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