520 EXPEKIMENT STATION RECORD. 



the total amounts of plant food elements are to be determined" are reported. 

 From the results of a chemical examination of soils prepared by passing samples 

 thronjjh 0.5 and 2 mm. sieves the author concludes that "if we assume that the 

 particles of soil less than 2 mm. in diameter fairly represent what should be 

 termed the soil from which the plant derives its food, it is evident that in 

 making determinations of the total phint food, the analysis if made on a sample 

 prepared through a sieve with perforations less than 2 mm. in diameter, i. e., 

 0.5 mm., will show the soil to contain considerably more plant food than the soil 

 from which the plant must derive its food and hence does not fairly represent 

 the composition of the soil." 



On methods of aqueous extraction, S. A. Zakhakov (Zhur. Opuitn. Agron. 

 [Russ. Jour. Expt. Londic], 10 (1909), No. 1, pp. 35-67, figs. 4)-— A systematic 

 study of the influence of the factors of time and mass of solvent was made by 

 the author, who conducted his experiments on a number of different kinds of soil. 



Eight soils were treated (200 gm. of soil and 800 gm. of water) during periods 

 of 2 minutes, 24 hours, 3 days, and 7 days. The results showed that with the 

 increase of the time of digestion a certain increase of the amount of dissolved 

 substances took place, the increase varying greatly with the nature of the soils. 

 The readily soluble compounds, however, always went into solution very rapidly. 

 Hence, in the opinion of the author, for certain practical purposes two-minute 

 shaking of the soil with water is sufficient. 



Tests were also made using water and soil in the ratios 4 : 1, S : 1, 16 : 1, 32 : 1, 

 and 64 : 1. The results obtained showed that an increase of the amount of the 

 solvent was accompanied by an increase of the amount of dissolved substances. 

 The solubility of the chlorids and other easily soluble compounds, however, was 

 very slightly or not at all dependent upon the amount of the solvent. 



The determination of potash in soils, P. de Sobnay (Bui. Assoc. Chim. Sucr. 

 et Distill, 26 (1909), No. 10, pp. 976-978; abs. in Chcm. Abs., 3 (1909), No. 15, 

 p. 1791). — In the method proposed oxalic acid is added to the nitric acid and 

 hydrochloric acid solution of the soil until frothing ceases and the calcium is 

 precipitated. The mass is then evaporated to dryness and heated strongly until 

 the oxalates are decomposed. The potash and soda are dissolved in water, 

 converted into chlorids. and determined as chloroplatinates. The method is 

 rapid and easily manipulated and gives results which agree well with those 

 obtained with older methods. 



Determination of potash in soils as phosphomolybdate, P. de Sornay (Bui. 

 Assoc. Chim. Sucr. et Distill., 26 (1909), No. 10, pp. 978-9S0; abs. in Chem. Abs., 

 3 (1909), No. 15, p. 1791). — On precipitation of known solutions of nitrate, 

 chlorid, and sulphate of potash with phosphomolybdic acid the author found 

 that the potash did not combine with the acid in constant proportions. He 

 concludes, therefore, that this method does not give accurate results in the 

 determination of potash in soils. 



Potash tests in mixed fertilizers, J. E. Breckenridge (Jour. Indus, and 

 Engin. Chcm., 1 (1909), No. 7, pp. Jt09-Jil3). — A comparison of the official method, 

 using water as a solvent, with other methods in which weak acid was used to 

 extract the potash, is reported. The author concludes from his tests that the 

 additional potash removed by extraction with dilute acid is a part of that which 

 was added in sToluble form but had become insoluble in water by mixture with 

 other constituents of the fertilizer, probably l)y the formation of zeolites. 



The determination of oxids of iron and alumina in Florida phosphates, 

 H. Herzog (Jour. Indus, and Engin. Chem., 1 (1909), No. 7, pp. 477, Jt78). — \ 

 modification of the Glaser method is described, the most important points of 

 which are special precautions to eliminate fluoiin and the use of very hot water 

 to wash the precipitate. 



