620 EXPERIMENT STATION EECORD. 



The flocculating power of some soluble salts on the clay substances of the 

 soil, G. Masoni (Stas. Sper. Agr. Ital., 45 {1912), No. 2, pp. 113-159; abs. in 

 Chem. ZeniU., 1912, I, No. 18, p. U96; Jour. Soc. Chem. Indus., 31 {1912), No. 

 10, p. 504; Jour. Chem. Soc. [London], 102 {1912), No. 591, II, pp. 677, 678).— 

 " From the results of a large number of experiments the author concludes that 

 chlorids have a greater flocculating power than nitrates and sulphates. Cal- 

 cium salts are more active than potassium and ammonium salts, and the latter 

 are more active than sodium salts. There appears to be no simple relation 

 between the quantity of a salt and its flocculating power, but the flocculating 

 power of the solution of a salt depends upon the ionic concentration and the 

 degree of dissociation. . . . 



" The flocculating power is a function of the cation, the anion being without 

 influence. The flocculating power depends ujion the valency of the cation, but 

 not upon its atomic weight. If the value of the flocculating power for the 

 sodium ion be taken as 1, then for the potassium or ammonium ion it is 2.4 

 and for the calcium ion 5.7, The flocculating power of a salt on the clay sub- 

 stance of a soil is dii'ectly connected with the absorptive power of the soil for 

 the salt, and may be regarded as due to an interchange of radicals between the 

 salt and the soil." 



Biochemical studies on soils subjected to dry heat, F. J. Seaver and E. D. 

 Clark {BiocJiem. Bui, 1 {1912), No. 3, pp. 413-427, pi. 1).—A study of extracts 

 from soils subjected to different temperatures showed that the color and soluble 

 matter varied with the temperature but not with the length of time of heating. 

 The growth of oats was slightly increased in soils heated at low temperatures, 

 90 to 120° C, but was retarded progressively as the temperatures increased 

 above this point. 



" Retardation seems not to be due to the toxic effects of the substances ren- 

 dered soluble, but to the fact that they are present in such large quantities 

 that the plant is unable to absorb them. The influence of heated soils on the 

 growth of fungi is the opposite of that on the growth of green plants, the 

 growth becoming more luxuriant as the temperature is increased. This can be 

 explained by the fact that fungi, unlike most gi-een plants, have the power of 

 adapting themselves to nutrient media of a comparatively high degree of con- 

 centration. The beneficial or harmful results, therefore, of the heating of a 

 soil for the growth of plants depends upon the temperature to which the soil 

 has been heated as well as upon the nature of the soil and the plant. The 

 preference of certain plants for burned-over areas or for peaty soils may be 

 explained by the acidity of such situations, a supposition we are testing by 

 blueberry-culture experiments now under way." 



Bacterial slimes in soil, R. Greig-Smith {Proc. Linn. Soc. N. S. Wales, S6 

 {1911), pt. 4, pp. 609-612; CentU. Bakt. [etc.], 2. Aht., 34 {1912), No. 8-9, pp. 

 226, 227). — This note briefly presents evidence which is thought to indicate the 

 presence of bacterial slimes in soils. 



The determination of Bhizobia in the soil, R. Greig-Smith {Proc. Linn. Soc. 

 N. S. Wales, 36 {1911), pt. 3, pp. 492-503; Centbl. Bakt. [etc.], 2. AM., 34 

 (1912), No. 8-9, pp. 227-229). — A medium specially suited to this purpose is 

 described. 



The role of Streptothrix in the soil, A. Fousek (Mitt. Landw. LehrTcanz. K. 

 K. Hochsch. Bodenkul. Wien, 1 {1912), No. 2, pp. i2i7-2-J^).— Determinations of 

 the number of Streptothrix chromogena and S. alha In different soil types and 

 studies of the assimilation of nitrate, ammoniacal, and amid nitrogen, and 

 free nitrogen of the air by these organisms and their effect on the decomposi- 

 tion of peptone, dried blood, bone meal, and straw, and on the growth of plants 

 are reported. 



