312 University of California Publications in Agricultural Sciences [Vol. 1 



compounds, which resemble most natural silicates in possessing a 

 comparatively inert chemical nature, and which suffer but slight 

 decomposition when in contact with water or are scarcely more 

 than appreciably soluble in water. This hypothesis receives 

 further confirmation in the contention of R. Gans^^ that artificial 

 aluminum silicates behave like natural zeolitic silicates. More- 

 over, Way^** clearly recognized the formation of .such compounds, 

 and Van Bemmelen^' is inclined to consider the absorbed salts as 

 fixed in loosely bound chemical combination. 



It was originally considered that the substitution of sodium for 

 calcium and magnesium in the soil was a potent factor in bring- 

 ing about the diffusion of the salt-treated, water-washed soils. 

 However, this first conception attributed the possible effect of 

 the chemical exchange to the double decomposition of the organic 

 salts of calcium and magnesium by the NaCl, which would result 

 in the formation of CaCla and MgCL and organic compounds of 

 sodium. Since these end-products are all soluble in water, a 

 continuous leaching of the soil with that solvent would be likely 

 to deprive the soil of a portion of its organic matter and of a 

 certain amount of calcium and magnesium. If the organic matter 

 herein referred to can be properly catalogued under those elastic 

 and indefinite terms, humus or humates, then it appears reason- 

 able in the light of Schloesing's work^^" to expect that the physical 

 condition of the soil, depleted of such organic matter, would be 

 seriously affected in the direction already suggested. The loss 

 of such well-known flocculating agents as calcium and magnesium 

 might also be reflected in the changed physical aspect of the 

 soil. 



But the cogency of the argument just presented is consider- 

 ably lessened by the results of the experiment to be described 

 next. Twenty-five gram portions of the Davis soil were subjected 

 to the treatments outlined in Table VI. The soils were then 

 allowed to dry, after which 10 grams of each soil were sus- 

 pended in 100 cc. of distilled water for 48 hours before the sus- 



15 Cited from Exp. Sta. Eec, vol. 31, no. 1, p. 22, 1914. 

 i« Journ. R. Agric. Soc, vol. 13, p. 123, 1852. 



17 Loc. cit.; also in Landw. Vers. Stat., vol. 35, p. 121, 1888. 



18 Cited from Ililgard, Soils (1911), p. 111. 



