304 University of California Puhlications in Agricultural Sciences [Vol. 1 



positit)!! that the hitter treatment has increased the colloidal 

 matter of the soil. On the other hand, boiling the soil in water 

 may bring about a more profound change in the physical condi- 

 tion of the soil than was formerly attributed to it by soil 

 physicists. Some data withheld from publication at this time 

 indicate that the effect of the boiling treatment is of a different 

 nature from that of the salt-and-water treatment, though the 

 soils receiving the two different treatments yield about the same 

 quantity of colloidal matter. On the other hand, the similarity 

 of the colloidal contents of the boiled soil and the soil suspended 

 in NaOH admits of a more plausible explanation on the basis 

 of NaOH as a deflocculating agent. 



It was thought that the quantitative data reported above 

 might show sutBeient dissimilarity to indicate an actual increase 

 in the soil colloids, but a second series of determinations, reported 

 in a later paragraph, are somewhat contradictory to the above, in 

 that the boiled soil yields a suspension slightly richer in colloidal 

 matter than that derived from a XaCl -|- HoO soil. This point, 

 however, deserves more investigation before a final conclusion is 

 reached. 



In the light of certain theories more properly discussed in 

 connection with the third hypothesis, it is of great interest to 

 note the general similarity between the NaCl -|- H._,0 soil when 

 suspended in HoO and the normal soil when suspended in NaOH. 

 One might infer that this peculiar agreement in the behavior of 

 the soils in response to two widely different treatments is not 

 accidental. It is also to be observed further that the data under 

 consideration indicates that XaOH and NaoCO, are not pro- 

 ductive of like results on soil suspensions. 



The failure of the suspension method to secure trustworthy 

 results on the quantity of colloidal matter present prompted the 

 adoption of other means for this purpose. But thus far the 

 determination of the hygroscopic coefficient and the dye- 

 adsorption capacity have given negative results, in that they have 

 not indicated any increase in the total interior surface of the 

 soils which have been subjected to the salt treatments. From a 

 theoretical consideration, a soil rich in colloids, or containing 

 colloids in a high state of diffusion, should expose more interior 



