ESTIMATION OF COLLOIDAL MATERIAL IX SOILS. 
13 
have been calculated for the different soils. The percentages of col- 
loidal material present in the soils as indicated by the adsorptions of 
dye. water, and ammonia (ratio X 100) are given in Table 2. 
Table 2. — Colloidal content of soils calculated by dye, water, and ammonia adsorption 
ratios. 
Colloidal material in soil 
Colloidal material in soil 
indicated by 
adsorp- 
indicated by adsorp- 
uon 
ratios, substance 
tion ratios, substance 
Tyr-e of soil. 
adsorbed being- 
Type of soil. 
adsorbed being — 
Dye. 
H 2 0. 
NH.,. 
Dye. 
H 2 0. 
NH3. 
Per 
Per 
Per 
Per 
Per 
Per 
Carrington loam: 
cent. 
cent. 
cent. 
Miami siltv day loam: 
cent. 
cent. 
cent. 
Soil 
19.4 
32.4 
32.1 
Soil 
15.1 
22.7 
25.1 
15.7 
29.4 
25.6 
Subsoil 
Norfolk fine sandv loam: 
54.8 
50.1 
54.2 
Cecil clav loam: 
Soil 
10.1 
10.2 
14.8 
Soil 
11.4 
10.7 
18.2 
Subsoil 
25.4 
31.5 
26.0 
Subsoil : 
23.7 
20.5 
18.6 
Chester loam: 
Ontario loam: 
Soil 
11.0 
16.7 
Soil 
15.9 
18.5 
IN 5 
Subsoil 
17.2 
24.8 
34.0 
Subsoil 
12.0 
11.4 
16.5 
Clarksrille silt loam: 
Orangeburg fine sandy 
Soil 
24.8 
23.3 
21.4 
loam: 
Subsoil, 
23.5 
25.5 
26.0 
SoU 
Subsoil 
7.4 
16.5 
6.2 
21.5 
6.1 
Hagerstown loam: 
16.3 
Soil 
13.4 
16.7 
23.7 
Sassafras silt loam: 
Subsoil 
1SL4 
32.0 
29. S 
Soil 
13.6 
8.0 
14.3 
Huntington loam: 
Subsoil 
13.2 
18.9 
21.8 
Sou 
13.5 
23.1 
32.6 
Sharker clav. soil 
56.6 
61.2 
58.8 
Subsoil 
1L8 
20.8 
30.3 
Stockton clav adobe: 
Manor loam: 
Soil 
50.3 
43.1 
51.9 
Soil 
11.5 
In 4 
20. S 
Subsoil 
14.9 
23.3 
33.8 
Subsoil 
12.1 
I&6 
21.6 
\ ega Baja clay loam, soil 
63.2 
57.8 
71.4 
Marshall silt loam: 
Wabash silt loam: 
Soil ': 
26.3 
27.3 
33.6 
Soil 
29.4 
29.8 
34.5 
Subsoil 
34.1 
34.3 ! 
37.3 
Subsoil 
27.2 
32.4 
32.1 
The dye, water, and ammonia adsorption ratios all substantially 
agree as to the quantity of colloidal material present in the 13 follow- 
ing soils: Cecil subsoil. Clarksville soil and subsoil, Marshall subsoil, 
Miami subsoil, Norfolk subsoil, Ontario soil. Orangeburg soil, Sharkey 
soil. Stockton soil, Vega Baja soil and Wabash soil and subsoil. In 
the case of these soils the differences in the percentages of colloidal 
material calculated from the adsorption of the three subtances are 
about what would be produced by usual variations in individual 
adsorption determinations. 
In the case of five soils — Chester subsoil, Hagerstown soil, Hunting- 
ton soil and subsoil, and Stockton subsoil — widely different per- 
centages of colloidal matter are indicated by the adsorptions of all 
three substances, malachite green, water, and ammonia. 
In the case of the remaining 14 soils there is a good agreement 
between the quantities of colloidal matter indicated by the adsorptions 
of some two of the substances, but the adsorption of the third sub- 
stance indicates a percentage of colloidal matter one-third to one-half 
higher or lower than the other two. 
It will be noted that where there is a marked disagreement between 
all three adsorption ratios the dye ratio invariably shows the lowest 
percentage of colloidal matter and the ammonia ratio the highest 
percentage, the water ratio giving a mean value. Also, in those 
cases where two of the ratios agree and the third disagrees, the am- 
monia ratio is usually the highest and the dye ratio the lowest. 
Thus there seems to be a certain regularity in the disagreements. 
