AGRICULTURAL CHEMISTRY AGROTECHNY. 311 



of a new method for estimating undigested nucleic acids, which consists in 

 adding a proclpitnut to a dilute solution of the nucleic acids and estimating 

 the resulting suspensoids nephelonietrically (E. S. R., 30, p. 410). 



The results show that " the nephelometer can be used for the study of di- 

 gestion of yeast nucleic acid when a 0.2 per cent solution acid egg albumin is 

 used as a precipitant. This reagent is not appreciably affected in dilute solu- 

 tions by most substances met with in physiological work, and will easily detect 

 one part yeast nucleic acid in 1.000.000 jjarts of water." 



New methods of soil analysis and the estimation of colloids in soils, II. 

 VAN DEE Leeden and F. Schneider {Intertmt. Mitt. Bodenlc, 2 {1912), No. 1, 

 pp. 81-109; ahs. in Zenthl. Agr. Chcm., J,2 {1918), No. 3, pp. US-liT; Jour. 

 Chem. Soc. [London'i, lOJf {WIS), No. 607, II, pp. 433, 4-3^).— Some experiments 

 with soils resulting from the weathering of gneiss showed " that for the com- 

 parison of the hygroscopicity of a soil with that of the silicates dissolved 

 by hydrochloric acid, extraction with aqueous hydrochloric acid is tmsuitable, 

 since the solution of colloidal silica, its precipitation with adhering oxids of 

 iron and aluminum and other dissolved substances, introduce errors. The acid 

 may also dissolve colloids which possess only slight hygroscopicity; this could 

 be avoided by employing gaseous hydrogen chlorid. 



" The assumption that the absorption of dyes rises and falls with the amount 

 of colloids is not accepted. Exact experiments on the absorption of dyes and 

 hygroscopicity can only be made when the surfaces of the soils are estimated on 

 the one hand by the employment of a dye solution and on the other by using 

 the vai>ors of organic substances of high molecular weight. 



" The results of analyses as well as estimations of hygroscopicity indicated 

 that unweathered minerals are dissolved by hot hydrochloric acid." 



The estimation of the lime requirement of soils by means of the hydroxid 

 of the alkaline earths, C. R. Moulton and P. F. Trowbridge {Jour. Indus, and 

 Engin. Chcm., 6 {191J,), No. 10, pp. S35-837).—''X brief survey of the data pre- 

 sented seems to establish the fact that the lime requirement found by the 

 metliod of Bizzell and Lyon [E. S. R., 30, p. 422] is proiwrtionate to the barium 

 hydroxid used and not to the acidity of the soil. The lime requirement is con- 

 siderably lower than when the Yeiteh method is used. The lime requirement 

 varies with the length of time of the distillation and volume of distillate until 

 a zero lime requirement is obtained. 



" No consideration of the speed of a method is worth while when its per-* 

 formance is such as is indicated by this studj'. However, the experience in 

 this laboratory shows that at least as much attention on the part of the oper- 

 ator is needed for the method of Bizzell and Lyon as for the Veitch method. 

 The time consumed in evaporating, and so forth, does not enter into considera- 

 tion when a chemist has other work in progress." 



A comparative compilation of reactions for detecting nitrites in drinking 

 water, M. Bornand (.1////. Lchcufon. Vntcrsuch. u. Hyg., Sehweiz. Gsmlhtsamt., 

 It {1913), No. 5, pp. 2S5-28D; abs. in Chcm. Ztg., 38 {1914), No. 32, Repert.. 

 p. 146). — Neutral red (Rochaix's reagent) is deemed unsatisfactory for detect- 

 ing nitrites in drinking water, and Deniges' strychnin sulphate reagent is con- 

 sidered impracticable for use under the usual laboratory conditions because it 

 decomposes very easily. The resorciu-sulphuric acid test of Barbet and Jan- 

 drier, the indol test of Mnoucha Chwilewizky, and the Van Ilosva-Lunge sul- 

 phanilic acid method are deemed the most reliable. 



The bacteriological examination of food and water, W. G. Savage {Cam- 

 Iridgc, England, IDV,. pp. Vlll + nS, figs. 76).— Books on pathological bacteri- 

 ology as a rule do not adequately supply methods for the examination of water, 

 air, foods, and the like. This book, which is one of the Cambridge Public 



