124 EXPERIMENT STATION RECORD. 



results of original investigations on the influence of bumus substances on the 

 weathering of silicates, a brief account of which is given in an article pre- . 

 viously noted (E. S. R., 28, p. 322). The paper contains in addition extensive 

 reviews of present knowledge and a bibliography of the subject. 



Investigations on humus acids, E. Gully (Landw. Jahrh. Baycrn, 2 (1912), 

 Nos. 12, pp. 9Jfl-102Jf, figs. 2; IS, pp. 1025-1074; Mitt. K. Bayr. Moorkiilturanst., 

 1913, No. 5, pp. 135, figs. 2). — A continuation and extension of previous work 

 (E. S. R., 23, p. 715) on the chemical composition and absorptive power of 

 sphagnum in relation to the formation of upland moors is reported in detail. 

 The results are discussed in their bearing upon the conclusions of Rindell 

 (E. S. R., 26, p. 123) and Tacke and Slichting (E. S. R., 26, p. 720), who hold, in 

 opposition to the author, that there are free humus acids in the soil. 



The chemical study of sphagnums showed that these plants took up more plant 

 food than was needed for normal growth. The live sphagnums were always 

 richer in plant food (potash, phosphoric acid, and nitrogen, as well as mag- 

 nesia) than the dead. There was either no difference in lime or an increase 

 in case of forest or meadow moors. The peat moss of the upland moors con- 

 tained the least plant food, that of the low moors the most, while that of forest 

 moors contained an intermediate amount, but the relative proportions in any 

 case A-aried widely with the kind of sphagnums predominating. The absorptive 

 power of the sphagnums for different salts varied with the plant food they 

 already contained. 



The author's further investigations confirm his previous conclusion that there 

 are no humus acids, strictly so-called, and that Tacke and Siichting's results can 

 not be properly held to lead to the opposite conclusion. 



Behavior of amino acids in the soil, S. L. Jodidi (Orig. Comniun. 8. Internat. 

 Cong. AppL Chem. [Washington and Neic York], 26 {1912), Sects. Vla^XIb, 

 App., pp. 119-13Ji). — The author found that amino acids, like acid amids (E. 

 S. R., 28, p. 813), readily undergo ammonification in the soil, glycocoU yielding 

 under the conditions of the experiments 81.03 per cent of ammonia, alanin 75.58, 

 leucin 59.62, aspartic acid 72.74, glutamic acid 72.19, phenylalanin 54.31, tyrosin 

 59.65, and asparagin 77.47. "All other things being equal, the rate of trans- 

 formation of the amino acid nitrogen into ammonia is greatly influenced ^by 

 the chemical structure of the amino acids so that amino acids of equal structure 

 yield about the same proportion of ammonia and vice versa." 



Osmosis in soils. — Soils act as semipermeable membranes, I and II, C. J. 

 Lynde and F. W. Bates {Jour. Phys. Chan., 16 {1912), No. 9, pp. 759-781, flgs. 

 5; Proc. Afner. 8oc. Agron., // {1912), pp. 102-121, figs. 5; ahs. in Chem. ATjs., 7 

 {1913), No. 5, p. 851,; Jour. Soc. Chem. Indus., 32 {1913), No. 2. pp. 99. 100; 

 Jour. Chem. Soc. [London], lOJ, {1913), No. 601,, I, pp. 237, 238).— From a series 

 of experiments in which air-dried subsoil was allowed to stand in water for 

 about a week, then disintegrated, the mixture of soil and water sterilized, cen- 

 trifuged, and the column of settled soil used in place of a membrane in an 

 apparatus for measuring osmotic pressure, the authors conclude that a heavy 

 clay subsoil acts as a semipermeable membrane and that water moves through 

 such a subsoil from points of low concentration to points of high concentration, 

 thus developing a certain osmotic pressure. The efficiency of the subsoil as a 

 semipermeable membrane increased with the depth, and the osmotic pressure 

 increased with the temperature. 



The experiments substantiate the " theory that the soil acts as a semiper- 

 meable membrane only for the case of a heavy subsoil prepared in a certain 

 way. It remains to be shown that it holds for soils under field conditions." 



The application of the theory to tillage, drainage, fertilizing, and temperature 

 of the soil is briefly discussed. 



