AGRONOMY: L. T. SHARP 
565 
ride and barium chloride, when similarly leached from it, seem to leave 
the soil in its original condition. Not only were various salts tried, 
but also various soils with the same salt. Thus the washing out of 
sodium chloride from the Davis clay loam, the Berkeley adobe, the 
Anaheim sandy and the Oakley blow sand brought about a marked 
increase in the diffusion of the soil colloids. Apparently, then, we are 
dealing with a phenomenon of general application. 
Turning to the Hterature we find reports of some interesting observa- 
tions which concern the phenomenon under consideration, Adolph 
Maye/T^ noted a decrease in percolation when certain salts are washed 
from soil; and according to Van Bemmelen^ the same thing occurs 
when clays or the hydrated oxides of tin, silica, and manganese are 
treated in the same manner. He also calls attention to the turbidity 
of the filtrate which appears as the salts are washed out. A similar 
turbidity has been observed by us in the filtrates from soils being washed 
free of salts. Warington^ also refers in a general way to the appear- 
ance of somewhat similar phenomena when soils previously treated with 
acids are v/ashed with water. Some further observations pertaining to 
this subject have also been recorded by Warington,^ Hall,^^ Kriiger,^^ 
McGeorge,^^ and others. Their observations dealt in the main with 
fertilizer salts and particularly with the after effects of sodium nitrate. 
In general, the ill effects of long continued use of this salt, are attributed 
to the formation of sodium carbonate. 
Finding that the salt and water treatment of soils referred to brought 
about such striking results, some experiments were undertaken with the 
view of studying the mechanism by which these effects are produced. 
These investigations followed certain theories which had been advanced 
to account for the soil conditions noted above. 
If a soil which has been treated as outlined above is suspended in 
water it yields a suspension much richer in soHd matter than a suspen- 
sion similarly formed from the untreated soil. Boiling the normal soil 
in distilled water produces a somewhat similar effect. Likewise, the 
same general condition of diffusion appears if NaOH in certain concen- 
trations is added to a suspension of the normal soil. We also found 
that it required more NaCl to flocculate the suspension of a soil from 
which this salt had been previously leached than to flocculate a sus- 
pension of the normal soil. Evidently the colloids of the salt- treated 
soil are in a high state of diffusion. Furthermore, there is some indica- 
tion that colloids of a new type, or perhaps additional colloids of the 
same general type, have been formed. 
In either case an increase in the internal surface of the soil would 
