SOILS — FERTILIZERS. 215 



Comparative investigations of the cohesive power of different kinds of 

 soils, II. rucHNER {Iniernat. Mitt. BodcnJc, 3 (1913), No. 2-3, pp. 11,1-239, figs. 

 2). — The author describes methods and apparatus used and gives the results 

 of tests of the cohesive power of a large number of soil samples from different 

 depths. 



A summary of results indicates that the samples tested showed wide varia- 

 tions in cohesive power, which in the great majority of cases was more marked 

 in the upper strata of soil than in the deeper ones. Investigations on the 

 effect of mechanical composition of soils on their cohesive power showed that 

 coherence increased with a decrease of the coarse sand and an increase of fine 

 silt. The coarser silt (0.01 to 0.25 mm.) increased cohesive power in coarse- 

 grained soils with an excess of sand. On the other hand, too large a propor- 

 tion of the coarser silt in fine-grained soils decreased the cohesive power. The 

 sand separates of different grades (0.25 to 3 mm.) generally decreased co- 

 hesive power. The cohesive power of dry soils was affected to a consideral)le 

 extent by chemical and biological influences as well as by the physical properties 

 of the individual soil constituents. 



Physico-chemical studies of soils. — II, The hygroscopicity of soils, U. 

 Pratolongo {Staz. Sper. Agr. Ital., 46 {1913), No. 3, pp. 219-240, pis. 3, figs. 2).— 

 In a systematic study of the hygroscopicity of six soils, it was found by physi- 

 cal and mechanical analyses and by a determination of variations in water 

 vapor tension in the soil under fixed and variable temperatures that the physical 

 and chemical structure as well as the humus content of the soils directly 

 fiffected the processes of dehydration and rehydration. 



Relation between the hygroscopicity and the chemical composition of cer- 

 tain Java soils, J. Schuit {Meded. Proefstat. Java-Suikerindus., 4 (1913), No. 

 10, pp. 225, 226, table 1, pi. 1; Arch. Suikerindus. Nederland. Indie, 21 {1913), 

 No. 24, pp. 713, 714, pi. 1, table 1; abs. in Cheni. Abs., 7 {1913), No. 21, p. 3635).— 

 By hygroscopicity of the soil is here understood the number of grams of water 

 which 100 gm. of oven-dry soil absorbs in 14 days in vacuum over 10 per cent 

 sulphuric acid. With such of the soils as had hygroscopicity of less than 10.5 

 there was remarkable regularity in that the moisture, the organic matter, the 

 nitrogen, and the lime rose with the hygroscopicity and the phosphoric acid 

 soluble in hydrochloric acid and that soluble in citric acid fell, while the potash 

 dissolved by these two solvents first rose, then fell. With soils showing a 

 hygroscopicity above 10.5 the same relation was observed in the first named 

 constituents, while with the phosphoric acid and the potash there was less 

 regularity. 



Quantitative determination of the absorbed bases in the soil, D. Pri- 

 ANiscHNiKOW {Laudw. Vers. 8tat., 79-SO {1913), pp. 667-680, pi. 1, fig. 1; abs. 

 in Zentbl. Agr. Chem., 42 {1913), No. 5, pp. 296-298).— VnAer the assumption 

 that soil constituents are in the form of available plant food only when in an 

 absorbed condition, experiments were made to determine the efficiencies of 

 ammonium nitrite, acetate, hydroxid, carbonate, and chlorid for determining 

 the quantities of available potassium in soils. The nitrite showed a stronger 

 reaction than the chlorid, but was considered unsatisfactory on account of its 

 unstable character. In this respect the acetate and hydroxid gave better results 

 than the nitrite, although the energies of reaction were about the same. The 

 carbonate was less suitable on account of the organic matter in the soils. 



For determining quantities of available ammonia four methods were com- 

 pared, as already noted by Reschetnikov (E. S. R., 28, p. 111). 



A rich black soil, a loam, and a podzol soil were treated with ammonium 

 nitrate to determine the quantity of absorbed lime. The rich black soil was 



