512 A. B. BEAUMONT 
adsorption method. The Dunkirk subsoil shows a decrease in adsorptive 
capacity due to one air-drying, and the Vergennes soil shows no effect. 
The differences between successive dryings are in many cases significant, 
but the results are so erratic as to justify no conclusions. With the two 
surface soils the cumulative effect of thirty-two dryings is nil, but with the 
two subsoils the cumulative effect is great enough to be significant in one 
case. This last observation is not in accord with the one on the same 
point under hygroscopicity. 
The effects of oven-drying and ignition are very marked in all cases, 
there being a decrease in adsorption in going from the air-dry to the oven- 
dry and to the ignited conditions. The differences are more marked 
with the subsoils than with the surface soils. 
A point which stands out in comparing the results obtained by this 
method with those obtained from the water-vapor-adsorption method is 
that the Clyde soil shows the least changes in its adsorptive capacity due 
to drying. Even the ignited Clyde soil adsorbs nearly as much as the 
same soil under other conditions. 
As already stated, a glacial clay subsoil was thrown out of the hygro- 
scopicity experiments because of its unusual adsorptive capacity. This soil 
was subjected to dye-adsorption tests. The results are given in table 18: 
TABLE 18. AvsorpTion oF METHYLENE BLUE By A GLACIAL CLAY SUBSOIL VARIOUSLY 
TREATED 
Corrected Milligrams of 
Soil treatment colorimetric dye adsorbed Difference 
reading pee 
of soil 
Continuouslysmoist;4-5- eee ae 50.0 +0.1 19.880.002 
0.05+0.002 
AIT -CTiCds alatime ses se ee ae 35.6 +0.5 19.83+0.002 
0.030.002 
Sa wash Rete pees pe ineere een. 30.25+0.3 19.80+0.002 
0.01+0.002 
TGP ie eet a8 eee, eee 30.9 +0.3 19.81+0.002 
0.02+0.004 
5 VaR ies See fete Tae a Sed © Ge a ee 28.5 +0.6 19.79+0.004 
0.00+0.004 
Oven-driedionces += pee eee 20.25+0.1 19.79+0.002 
Difference between 1 drying and 32 
drying. 2 5 erie! Re Bee RY Pn Re re eee Soe te ee 0.04+0.004 
