AGRICULTURAL CHEMISTRY. 9 



Xo. 7, lip. 321-323). — The ■•iiitliors, likt» Perrier and Farcy (see above), found 

 (hat the presence of chlorin caused low results. This is attributed to the 

 formation of aqua reiria and tlie volatilization of some of the nitrogen of the 

 nitrate. 



[Water-soluble material in soils], A. E. Vinson and W. II. Koss (Arizoiid 

 St(i. Ri>t- J!>OS. pp. 3(>'), 3(i(>). — Comparisons of various methods of extracting 

 water-soluble matter from soils are I'eported, with results of analyses of the 

 solubh> constituents of 5 samples of soil. Digesting the soil for 10 hours on a 

 water bath with shaking was found to be the quickest method of extraction. 



Critical studies on humus acids: An improved metliod of determining the 

 acid content of soils, H. Suchting (Landtv. Vers. Stat., 10 (IDOD), No. 1-2, 

 pp. J3-52; uhs. in Chan. Ztg., 33 (1909), No. 2Ji, Rcpcrt., pp. 11',, 115).— A 

 critical study of the original Tacke method and the author's modification of 

 it (E. S. R.. 9, p. 32; 19, p. 1009) is reported. The author shows that there is 

 an inhei-ent error in the Tacke method due to the continued evolution of carbon 

 dioxid (even after 3 hours) resulting from the decomposition of the organic 

 niatter of the soil in the presence of calcium carbonate. Bacteria and other 

 living organisms are not apparently concerned in this decomposition, and cool- 

 ing to 0° C. did not lessen it. 



Various methods based upon other principles are discussed and condemned. 

 The author's new method, involving the determination of total acids, has been 

 found satisfactory. 



Should the determination of magnesia be omitted in the analysis of soils? 

 O. LoEW [CJiciu. Ztg., 33 (l'.)O!)), No. 1',, pp. IIS, 119; fiJ)s. in Ztsclir. Angcw. 

 Vhem., 22 {1909), No. 15, p. 6'cS7; Jour. Chem. Soc. [London], 96 {1909), No. 

 557, II, pp. 258, 259; Chan. ZcnthJ., 1909, I, No. 9, p. 7SS).— The literature bear- 

 ing upon the importance of magnesia as a constituent of soils, particularly in 

 relation to lime, is briefly reviewed in this article, and the conclusion is drawn 

 that it is highly important to know the relative proportions of lime and 

 magnesia in soils. 



Separation of iron and detection of the rare earths in cultivated soil, M. E. 

 Pozzi-EscoT {Bui. Assoc. Chim. Sua: ct Distill., 26 {1909), No. 8, p. 60,J).— The 

 method proposed is based upon precipitation in hydrochloric acid solution by 

 means of caustic soda or ammonia, adding an excess of sodium or ammonium 

 sulphid, acidifying strongly with acetic acid, and stirring and collecting the lare- 

 cipitate of iron and zinc, if the latter is present, on the filter. The iron may 

 be separated from the zinc by dissolving in hydrochloric acid and precipitating 

 with ammonia. 



On plastein, D. D. Van Slyke and P. A. Levene {I'roc. Soc. Expt. Biol, and 

 Med., 6 (1908), No. 1, pp. 11-13). — Studies ai-e reported of the cleavage prod- 

 ucts of plastein, the "protein-like substance or substances precipitated from 

 concentrated albumose solutions by the action of enzyms. , . . 



" Of the 13 amino-acids tested for in plastein the presence was proveil of all 

 except alanin, which was not isolated in pure condition. The proportions other- 

 wise were not greatly different from those found in fibrin. It is evident that 

 the plastein ranks with either the complex native proteins or their higher 

 dec()mp<)sitiou product s. 



" In order to obtain evidence indicating with which of the above classes the 

 plastein is^to be raidvcd. viscosity measurements were employed. . . . 



"These results indicate that the plastein is related to the higher albunidses. 

 and ai)parently. from its resistance to alkali, to the antialbumoses rather than 

 to the native proteins." 



