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



different quantities of calcium and magnesium in the percolate, 

 thus affording additional evidence that the increased solubility 

 and the consequent loss of these elements from the treated soils 

 is not the prime factor in causing the ultimate diffusion of the 

 soil colloids. The facts herein presented concerning the absorp- 

 tion of sodium and the formation of new colloidal substances cor- 

 responds in the main with the idea of unsaturated silicates and 

 absorption phenomena, as developed by Cameron,-^ Harris,-- and 

 Loew,-^ and others, in their work dealing with acid soils. 



The conception of the causes of the apparent deflocculation, 

 as discussed above, receives tangible substantiation in the results 

 of the following experiment. Twenty grams of Davis soil were 

 subjected to the treatments outlined in Table VII. After wash- 

 ing with water, the soils were dried at room temperature and 

 then 10 grams of each were suspended in 100 cc. of water to 

 secure the figures in the last column. Meanwhile the calcium 

 and magnesium in the total percolates were determined in the 

 usual fa.shion. 



No. 



1 

 2 



3 



4 

 5 



10 



TABLE VII 



Effects of Washing Various Sodium Salts from the Davis Soil 



Soil 

 (Davis) 

 20 grs. 

 20 grs. 



20 grs. 

 20 grs. 

 20 grs. 



20 



grs. 



Treatments 



H.O only 



100 cc N/10 NaOH fol- 

 lowed with water 



100 cc N/10 Na, CO, fol- 

 lowed with water 



100 cc. N/10 NaCl fol- 

 lowed with water 



100 cc. (approx.) N/10 

 NaHCO, followed with 

 water 



100 cc. N/10 NaNOj fol- 

 lowed with water 



It is clear that all of the sodium salts vised in the above ex- 

 periment produce approximately the same effects on the colloidal 

 matter of the soil when washed from it, as indicated bv the 



21 The Soil Solution (Chemical Publishing Co.), 1911. 



22 Journ. Phys. Chem., vol. 28, no. 4, p. 355; and Michigan Agric. 

 Exper. Sta. Tech. Bull. 19. 



23 Porto Rico Agric. Exper. Sta., Bull. 13, 1913. 



