THE CHEMICAL COMPOSITION OF SOIL COLLOIDS 
35 
Table 10. — Hypothetical quantities of kaolinite, iwntronite. silica, iron, and 
aluminum oxides in soil colloid* 
Source of colloid 
Color of colloid 
Kaoli- 
nite 
Non- 
tro- 
nite 
Ex- 
cess 
Si0 2 
Ex- 
cess 
AI2O3 
Ex- 
cess 
Fe 2 3 
Com- 
bined 
H 2 
in 
kaoli- 
nite 
and 
non- 
tronite 
De- 
ter- 
mined 
com- 
bined 
wa- 
ter 1 
Carrington loam, Iowa 
Carrington loam, Iowa 
Cecil clay loam, Maryland-. 
Cecil clay loam, Georgia 
Cecil clay loam, Georgia 
Chester loam, Virginia 
Chester loam, Maryland 
Chester loam, Maryland 
Clarksville silt loam, Ken- 
tucky. 
Clarksville silt loam, Ken- 
tucky. 
Crowley silt loam, Louisiana. 
Dunkirk clav loam, New 
York. 
Fallon loam, Nevada 
Hagerstownloam, Mars'land 
Hagerstownloam, Maryland 
Houston black clay, Texas . . 
Huntington loam, Maryland 
Huntington loam, Maryland 
Iredell clay, North Carolina. 
Lufkin clay, Mississippi 
Manor loam, Maryland 
Manor loam, Maryland 
Marshall silt loam," Nebraska 
Marshall silt loam, Nebraska. 
Miami silty clay loam, In- 
diana. 
Miami silty clay loam, In- 
diana. 
Norfolk fine sandy loam, 
North Carolina. 
Norfolk fine sandy loam, 
North Carolina. 
Ontario loam, New York 
Ontario loam, New York 
Orangeburg fine sandy loam, 
Mississippi. 
Orangeburg fine sandy loam, 
Mississippi. 
Sassafras silt loam, Maryland. 
Sassafras silt loam, Maryland. 
Sharkey clay, Mississippi 
Sharkey clay, Mississippi 
Stockton clay adobe, Cali- 
fornia. 
Stockton clay adobe, Cal- 
ifornia. 
Stockton clay adobe, Cal- 
ifornia. 
Susquehanna clay, Missis- 
sippi. 
Susquehanna clay, Maryland. 
Vega Baja clay loam, Porto 
Rico. 
Wabash silt loam, Nebraska . 
Wabash silt loam, Nebraska. 
Yolo clay, California 
Black 
Dark grayish brown . 
Red 
Red 
Red 
I Brown 
1 Yellowish brown 
j Light reddish brown. 
I Dark brown. 
I Reddish brown : 
Grayish brown . 
Yellowish olive. 
Light gray 
Dark reddish brown. 
! Brownish red 
[ Gray 
! Dark brown... 
Light reddish brown. 
Cream 
Yellowish brown 
Yellowish brown 
Very dark grayish 
brown. 
Dark grayish brown.. 
Grayish brown 
Brown 
Yellowish brown. 
Yellow. 
Dark grayish brown.. 
Dark reddish brown. . 
Dark brownish red. .. 
Red 
Brown 
I Reddish brown 
Grayish brown 
Dark grayish brown.. 
Dary gray... 
Grayish brown 
Light yellowish brown 
Brilliant red 
Yellowish red.. 
Yellowish red.. 
I Black 
j Black 
1 Light yellowish brown 
Per 
cent 
57.7 
64.3 
73.0 
72.2 
67.7 
71.2 
76.4 
78.0 
67.6 
70.7 
71.2 
43.3 
74.0 
76.3 
53.0 
69.3 
68.3 
87.4 
57.8 
79.4 
79.6 
55.4 
56.1 
61.1 
61.6 
59.5 
63.1 
79.2 
84.9 
73.1 
74.7 
52.8 
57.7 
55,0 
57.4 
56.7 
78.6 
72.6 
77.1 
51.8 
53.3 
41.9 
Per Per 
cent i cent 
15.5 11. S 
17.1 
5.0 
None.j 
Xone. : 
8.1 
8.8 
20.7 
25.6 
17.5 
25.3 
21.7 
13.6 
15.6 
14.3 
13.8 
19.7 
3.9 
17.9 
4.1 
7.8 
17.8 
20.0 
22.9 
20.8 
2.1 
11.2 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
3.1 
1.5 
7. 5 
0.0 
23.6 
0.0 
0.0 
23.1 
0.0 
0.0 
0.0 
21.5 
0.0 
0.0 
13.2 
14.3 
9.0 
11.7 
0.0 
12.3 
0.0 
21.7 
30.5 
8.2 
1.9 
1.3 
0.0 
1.1 
0.0 
13.0 
16.0 
18.1 
17.5 
27.4 
0.0 
0.0 
19.0 
17.6 
12.8 
21.1 
14.6 
20.2 
14.3 
None. 
0.0 
21.4 
None. 
1.5 
0.0 
19.5 
19.1 
20.0 
19.6 
18.3 
19.1 
Per 
cent 
0.0 
0.0 
0.0 
8.3 
11.8 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
6.1 
0.0 
2.6 
0.0 
0.0 
0.0 
Per 
cent 
0.0 
0.0 
14.2 
11.0 
10.0 
14.1 
7.2 
6.9 
0.0 
0.0 
0.0 
0.0 
2.7 
3.6 
0.0 
4.4 
3.4 
2.6 
0.0 
8.3 
6.4 
0.0 
0.0 
0.0 
0.0 
10.2 
5.5 
0.0 
0.0 
6.0 
0. I 9. 5 
3.7 
4.7 
0.0 
0.0 
0.0 
0.0 
0.0 
10.4 
0.0 
12.4 
0.0 
0.0 
0.0 
Per 
cent 
9.84 
10.97 
10.74 
9.96 
9.34 
10.26 
11.55 
11.84 
11.78 
12.67 
11.78 
12.94 
11.87 
12.62 
9.06 
11.26 
11.84 
12.54 
10.17 
11.44 
11.93 
9.82 
10.19 
11.24 
11.04 
11.24 
12.07 
10.86 
12.43 
11.93 
12. So 
11.30 
12.27 
9.50 
10.10 
10.95 
10.51 
10.30 
10.84 
12.63 
10.63 
52 
Per 
cent 
8.56 
9.23 
12.61 
14.42 
16. 56 
11.90 
11.77 
10.26 
10.51 
10.63 
5.02 
7.04 
9.94 
10.51 
9.60 
8.14 
8.24 
13.58 
7.06 
11.94 
11. 35 
7.92 
9.32 
7.64 
11.92 
11.50 
3.33 
7.22 
10.63 
11.92 
10.97 
12.49 
8.81 
7.45 
9.56 
10.75 
8.75 
11.12 
12.73 
6.18 
6.74 
13.42 
1 This is comparable to the H2O+ of the mineralogists. It does not include organic matter. 
It can be seen from the table that soil colloids are not entirely 
made up of Al 2 3 .2Si0 2 .2H 2 and Fe 2 3 .2Si0 2 .2H 2 ; since in 31 
cases the excesses of silica, alumina, and iron oxide are appreciable; 
that is, greater than 5 per cent, which may be allowed for additive 
