SOILS FERTILIZERS. 421 



opposition to Wiegner's conclusioiis (E. S. li., 2S, p. 517), the iiulhor coiu-Iutles 

 that alkaline solutions of colloidal aluniinuiu silit-ites containing water and 

 also the zeolitic silicates of soils which may be decomposed liy water or acids 

 are chemical comi)ounds since they maintain the same constant equivalent rela- 

 tions and by decomposition with water and in the exchange of ions with neutral 

 salt solutions they act as chemical compounds. He further concludes that the 

 zeolitic silicates of the soil consist mainly of aluminum silicates which in a 

 fertile surface soil can only to a small degree disintegrate into mechanical 

 mixtures of the gels of silica and alumina. 



He also points out that Wiegner's adaptation of his experimental results to 

 Freundlich's formula does not indicate that the colloidal aluminum silicates are 

 ahst)rption compounds since this fornuila does not always conform to experi- 

 mental results. The terminologj^ of the formula is in sharp contrast to the 

 absorption maxinnim devised by Schmidt, and in the exchange process described 

 by Wiegner the values inserted for the molecular equivalent concentration of 

 the salt solution do not consider the existing exchanged matter of the silicates 

 in addition to the unabsorbed substances yet in solution. 



Considering the exchanged matter in the formula i^fc= — = ^ {F—iho unknown, 



U 

 A-=the absorption factor, C"'=the concentration of the absorbing body in 

 absorbed matter, and (7'=the concentration of the salt solution), in which 

 with an absorption compound no constant appears, the author obtained a con- 

 stant. This he considers to be further proof that the ammonia absorption 

 describeil by Wiegner is not physical surface attraction. 



The chemical or physical nature of colloidal aluminum silicates contain- 

 ing water, G. Wiegner {Ccntbl. Miu., Geol. u. Paldontol., No. 9 (1914), pp. 

 262-272; abs. in Chcm. ZcntbJ., IOI4, I, ^'o. 26, p. 2200).— In replying to the 

 above criticism by Gans, the author questions the validity of the grounds upon 

 which the Freundlich formula is challenged. He is also of the opinion that 

 the chemical conception of the composition of aluminum silicates which he 

 regards from a colloidal-physical viewpoint is inadequate. 



The chemical or physical nature of colloidal alviminum silicates contain- 

 ing water, R.. Gans {Centbl. Min., Geol. m. PalaonioL, 1914, Nos. 0, pp. 213- 

 279; 10, pp. 299-306; abs. in Chem. Zentbh, 191.',, I, No: 26, p. 2200).— The 

 author deduces further data to show that the assumption by W^iegner of an 

 absorption process between aluminum silicates and neutral salt solutions is 

 incorrect. He is of the opinion that the fact that the aluminum silicate 

 absorbs the same quantity of the neutral salt out of solutions of dilferent con- 

 centrations is sufficient proof of the chemical nature of aluminum silicates. 

 This fact is thought also to contradict the assumption connected with the 

 Freundlich formula that for each variation of the equivalent molecular concen- 

 tration of the neutral salt solution there is a corresponding change in the 

 absorption by the aluminum silicate. 



Solution and absorption in the soil, E. A. Mitscherlich (Landiv. Jahrb., 

 J,6 {1914), A^o. 3, pp. 413-430, figs. 3; abs. in Chem. Zentbl., 1914, II, No. 10, 

 p. 655). — The author discusses those conditions of chemical reactions which 

 govern solution and absorption phenomena in the soil, and concludes that solu- 

 tion and absorption constitute in the soil a cyclic process and are subject to 

 the same laws. In proof of this he quotes the results of experiments by D. J. 

 Hissink in which water saturated with carbon dioxid constitute<l the solution 

 medium, clay soil the absorption medium, and ammoniacal nitrogen the body 



