1917] SOILS — FERTILIZERS. 117 



an atmosphere of oxygen and hydrogen. Colonies developed of which a large 

 number proved to possess the pov^^er of oxidizing hydrogen in the presence of 

 soluble nitrogenous organic matter and which were found to consist of the 

 larger nonmotile bacterium previously referred to." 



The characteristics of the bacterium are described in detail, together with 

 the experimental details of the work. 



Relations between water and soil, H. Fischer {Internat. Mitt. Bodenk., 5 

 (1915), No. 5-6, pp. 517-576, fig. 1; abs. m Chem. Abs., 10 {1916), No. 10, p. 

 1391). — Analyses of a number of soils, especially swamp soils, and soil waters 

 which had undergone different natural changes and fertility k'eatments are 

 reported and discussed with special reference to the judgment o£ the value of 

 the* soils. It is concluded that in judging the productiveness of a soil it is 

 necessary, not only to analyze the soil and soil water and to conduct plat and 

 pot tests and fertilizer experiments, but also to classify the soil with reference 

 to regional and climatic conditions and thereby compare the results of natural 

 and artificial changes. 



Comparative tests of methods for determining cohesion, with special 

 reference to marsh soils, C. Makquis (Internat. Mitt. Bodenk., 5 (1915), No. 

 5-6, pp. 381-516, figs. U; abs. in Chem. Abs., 10 (1916), No. 10, p. 13S1).—A com- 

 parison of methods of measuring cohesion in soils with different moisture and 

 lime contents, including experiments on the draft of plows under varying soil 

 conditions, is reported. It was found that moisture content was the most 

 important factor determining the variation in cohesion values, and minimum 

 cohesion was observed in each soil at a moisture content corresponding to its 

 character. 



Acidity and adsorption in soils as measured by the hydrogen electrode, 

 L. T. Sharp and D. R. Hoagland (U. S. Dept. Agr., Jour. Agr. Research, 7 

 (1916), No. 3, pp. 123-145, fig. 1). — Experiments conducted at the California Ex- 

 periment Station with silty clay loam, fine sandy loam, sandy loam, gravelly 

 loam, clay adobe, silty loam, and peat soils on the relation between soil reaction 

 and the concentration of the hydrogen ion in soil suspensions and extracts are 

 reported, together with the progress results of experiments on the influence of 

 varying proportions of soil to water, grinding the soil, heating it at various 

 temperatures, and of the addition of salts on the H-ion concentration. " Con- 

 sideration has also been given to the relation of HCO-^ CO-^ and CO2 to soil 

 reaction as measured by the electrometric method. Experimental data have 

 likewise been secured with respect to the lime requirement of soils and the so- 

 called ' adsorption of bases.' " A hydrogen electrode apparatus for determin- 

 ing small differences in potential was used to measure hydrogen-ion concentra- 

 tions in soil suspensions. 



Hydrogen electrode measurements gave direct evidence that soil acidity is 

 due to the presence of an excess of hydrogen ions in the soil solution. " The 

 hydrogen-ion concentration of different soil suspensions was found to vary 

 within wide limits, from a condition of high acidty to one of high alkalinity. 

 Soils containing calcium in equilibrium with HCO-3 and CO2 have a very slightly 

 alkaline reaction." 



With one exception, grinding did not materially alter the hydrogen-ion con- 

 centration of the soil suspensions. Varying the proportion of soil to water 

 produced only slight fluctuations in hydrogen-ion concentration in soil sus- 

 pensions. 



" The intensity of acidity decreases when the soils are heated at high tem- 

 peratures. The insufliciency of the data concerning heating at 140° C. does 

 not admit of positive conclusions, though there is indication that the H-ion con- 

 centration may be slightly increased by this treatment. . . . 



