500 A. B. BEAUMONT 
The treatments consisted of keeping moist, air-drying, and oven-drying 
(105° C.). The results of the experiment are given in table 6: 
TABLE 6. AvbsorRPTION OF Dyes BY ARTIFICIALLY PREPARED So1Lt CoLioms 
Time | Moist Air-dried Oven-dried 
in S| 
contact 
(C-Ci). dye | Difference |(C—Ci)- dye Difference |(C—Ci) - dye | Difference 
1 day 81.3+2.4 88.4+0.1 88.5+0.8 
7.6+42.5 11.6+0.1 5.9+0.9 
Silica and 8 days 73.7+0.5 100ZOR ace 94.4+0.3 
methylene blue 14.5+0.9 Trace 5.6+0.3 
15 days 59.2+0.7 1OOZON eae 100.0 
1 day 89.8+0.1 85.8+0.4 86.3+40.0 
Humus and 0.2+0.1 1.2+0.5 0.4+0.2 
methylene blue] 8 days 90.0-0.0 84.6+0.2 85.9+0.2 
0.6+0.0 2.6+0.6 3.2+40.3 
15 days 96.6+0.0 87.2+0.6 89.1+0.2 
1 day LOOZOM wera 82.0-40.1 83.2+0.4 
Ferric oxide and OZ0RReE 2.2+0.5 4.5+0.7 
diamine sky-| 8 days T0020 84.2+0.5 87.7+0.6 
blue OX0 kar -7- 0.90.7 2.8+0.8 
5rdaysr | LOOLON ss. 85.1+0.6 90.5+0.6 
1 day 100500 79.9+0.1 80.4+0.3 
Alumina and OO vous 2.9+0.8 2.9+0.3 
diamine sky-| 8 days ODER OR es 82.8+0.7 83.3+0.0 
blue ORO haere 0.7+40.8 0.7+0.5 
ibid ayse=n|LCOROh sare 83.5+0.4 84.0+0.5 
It is seen that in the moist material, with the possible exception of 
humus, maximum adsorption was reached in one day, and with silica 
there was a reversal of the adsorption process as the time elapsed. In 
both the air-dried and the oven-dried materials, with two exceptions, the 
amount of adsorption increased with the lapse of time. In most eases 
the differences are significant. They show that the ecndition of these 
colloids caused by drying is reversed by their standing in water, and that 
the reversal requires time. 
Van Bemmelen (1909) has shown that the dried oxides of various metals 
will take up water vapor, and that there is a reversibility in this respect 
along some lines. The data in table 7 show the same thing for the com- 
monest soil colloids, and also give a comparison of their relative adsorption 
of water vapor in three days: 
