110 EXPEKIMENT STATION EECOED. 



phosphates, titrating first with methyl orange and then with phenolphthalein. 

 It is stated that as a rule the amount of free sulphuric acid in superphosphates 

 is negligible, and therefore the whole of the sodium hydroxid consumed may 

 be regarded as neutralizing only free phosphoric acid. 



A short scheme of water analysis, J. A. Hughes (Merck's Rpt., 16 (1907), 

 No. 5, pp. 12S. 129). — A simple scheme, which is considered sufficient to enable 

 one to quiclvly form a very good opinion of the ])otabillty of a given water, is 

 'described. 



Chemical soil analysis for investigations in plant physiology, E. A. INIit- 

 SCHERLICH (LaiKlir. Juhrh., 36 (1901), A'o. 2, pp. 309-369, pi. 1, figs. 10).— The 

 method proposed by the author (see also E. S. R., 18, p. 417), is based upon the 

 assumption that solubility in water saturated with carbon dioxid is a measure 

 of the plant food in the soil at the disposal of cultivated plants. Studies of 

 the influence of the elements of time, carbon dioxid content of the solvent, 

 amount of solvent, and temperature are reported and the details of the method 

 recommended are given. 



The extract is prepared by digestion of the soil with 10 or 25 times its amount 

 of solvent for Hi hours at 30° C. in a flask provided with a constant stirring 

 apparatus and connected with a cylinder of compressed carbon dioxid which 

 keeps the solution in the flask saturated with carbon dioxid. The extract is 

 clarified by suction through a clay filter and aliquot portions are taken for 

 determination of nitrogen by the phenol-sulpluu-ic acid method, potash by the 

 ordinary i)roc«lure. final weighing being made of reduced ]>latimnn according 

 to Kegel (E. S. K., IS, i». loS). phosphoric acid by the Waguer-Stutzer molybdic 

 method, and lime by precipitation with ammonium oxalate as usual. 



The errors inherent in the various deternnnatious are discussed and a series 

 of tests are reported which show that the method is capable of detecting small 

 variations in the composition of soils due to ajtplications of fertilizers. 



On the question of the method of determining nitric acid in soils ( Vi/cst- 

 nili Sakh. Prom., 1906, A"o. ////, p. 652; abs. in Venthl. Znckcriiidus., 1-', (1907), 

 No. S.'t, pp. 923, 92.i).— Thin is a brief note on work of Welbel, Frankfurt, and 

 Duschetschkin on this subject, which led to the conclusion that the methods 

 of determining nitric acid in soils in which the soil is digested with water for 

 48 hours give too low results, due to reduction of nitrates. Two hours' digestion 

 is fully suSicient to extract the nitric acid of soils. If longer treatment is 

 necessary, accurate results can be obtained by adding chloroform, thymol, or 

 other substances which check the activity of the lower organisms that reduce 

 nitrates. 



Notes on the determination of nitric acid in chernozem soils, V. I. Sazanov 

 (Zhur. Opuitii. Ai/roit. (Riiss. Jour. Expt. Laiidw.), 7 (1906), No. Jf, pp. 381- 

 387). — The experiments of the author show that for the estimation of the 

 nitrates it is necessary not to allow the soil to remain in contact with the 

 water, in the extraction, any longer than is required for the settling of the 

 greater part of the fine particles. Longer contact causes a rapid diminution 

 of the nitrates. Chloroform prevents this decrease of the nitrates. In keeping 

 soils, the amount of nitrates increases with the time if the soils are preserved 

 in the humid state. Chloroform does not prevent this increase. A quick dry- 

 ing (in the sun) prevents (4iange in the nitr.-ite content. ^ — p. fireman. 



Anew calcinxeter, T. P>ieler-Chatelan (Citron. Ayr. Vaiid, 20 (1907), No. 6, 

 pp. 114-120, flg. 1). — A simple apparatus for the I'apid determination of calcium 

 carbonate in soils is described and its practical use explained. 



The use of biological methods in the analysis of food stufEs, A. J. J. 

 Vandfvelde (Biochem. Ztschr., 1 (1906), No. 1-2, pp. 1-7). — From his investiga- 



