THE CHEMICAL COMPOSITION OF SOIL COLLOIDS 
15 
Table 3. — Chemical analysis of celloicls from various soils and subsails — Con. 
No. 
Soil type from which colloid was 
extracted 
Depth 
P2O5 
S0 3 
CI 
CO2 
Igni- 
tion 
loss 
Com- 
bined 1 
H 2 
H 2 
110° 
Or- 
ganic 2 
mat- 
ter 
N . 
P.ct. 
P.ct. 
P.ct. 
P.ct. 
P.ct. 
P.ct. 
P.ct. 
P.ct. 
P.ct. 
1 
Carrington loam, Iowa 
0"-12" 
15"-36" 
0.28 
.14 
0.19 
.08 
0.065 
.037 
0.00 
.00 
20.15 
8.56 
11.22 
10.98 
11.59 
4.52 
0.61 
2 
Carrington loam, Iowa 
13. 75 9. 23 
.20 
3 
Cecil clay loam, "Maryland 
0"- 7" 
.19 
( 3 ) 
( 3 ) 
17.24! 12.61 
4.33 
4.63 
.26 
4 
Cecil clay loam, Georgia 
0"- 9" 
.25 
.06 
.036 
"""."66 
16.671 14.42 
3.23 
2.25 
.22 
5 
Cecil clay loam, Georgia 
9"-18" 
. 11 
.02 
.023 
.00 
18.00! 16.56 
4.93 
1.44 
. 11 
6 
Chester loam, Virginia 
0"- 7" 
.31 
.07 
( 3 ) 
.00 
17.44' 11.90 
3.86 
5.54 
.36 
Chester loam, Maryland 
0"- 8" 
.20 
.09 
.028 
.00 
15.88! 11.77 
3.76 
4.11 
.28 
8 
Chester loam, Maryland 
8"-32" 
.15 
.05 
.036 
.00 
15.25! 10.26 
5.90 
4.99 
.22 
9 
Clarksville silt loam, Kentucky.. 
0"-10" 
.65 
.21 
.045 
.00 
15. 60| 9. 89 
10.21 
5.71 
.38 
10 
Clarksville silt loam, Kentucky.. 
10"-36" 
.38 
.09 
.031 
.00 
12.79; 10.51 
8.00 
2.28 
.20 
11 
Crowley silt loam, Louisiana 
0"-10" 
. 14 
.14 
( 3 ) 
( 3 ) 
13. 35 1 10.63 
1.38 
2.72 
.34 
12 
Dunkirk clay loam, New York.. 
0"- 8" 
.46 
.08 
( 3 ) 
.00 
7.52 
5.02 
8.16 
2.50 
.30 
13 
Fallon loam , Nevada 
0"-12" 
.26 
. 11 
( 3 ) 
( 3 ) 
8.87 
7.04 
11.78 
1.83 
.09 
14 
Hagerstown loam, Maryland 
0"- 8" 
.30 
.11 
.033 
.00 
16.91 
9.94 
3.69 
6.97 
.24 
15 
Hagerstown loam, Maryland 
8"-30" 
.20 
.07 
.032 
.00 
13.20 
10.51 
4.16 
2.69 
.10 
16 
Houston black clay, Texas 
0"-12" 
( 3 ) 
( 3 ) 
( 3 ) 
.00 
11.44 
9.60 
9.16 
1.84 
.09 
17 
Huntington loam, Maryland 
0"- 8" 
.64 
.27 
.033 
.00 
17.96 
8.14 
5.33 
9.82 
.55 
IS 
Huntington loam, Maryland 
8"-30" 
.35 
.08 
.032 
.00 
14.35 
8.24 
4.89 
6.11 
.20 
19 
Iredell clay, North Carolina 
6"-24" 
.50 
Trace 
( 3 ) 
.00 
14.47 
13.58 
3.98 
.89 
( 3 ) 
20 
Lufkin clay, Mississippi 
5"-36" 
.09 
.02 
( 3 ) 
.00 
7.77 
7.06 
13.45 
.71 
.07 
21 
Manor loam, Maryland 
0"_ 7" 
.28 
.09 
.029 
.00 
15.63 
11.94 
4.63 
3. 69 
.21 
22 
Manor loam, Maryland 
0"-20" 
.46 
. 11 
.020 
.00 
13.91 
11.35 
5.34 
2.56 
.15 
23 
Marshal silt loam, Nebraska..:.. 
0"-14" 
.46 
.21 
.060 
.00 
16.47 
7.92 
7.75 
8.55 
.51 
24 
Marshal silt loam, Nebraska 
14"-36" 
.21 
.06 
.032 
.00 
13. 28 9. 32 
11.00 
3.96 
.22 
25 
Miami silty clay loam, Indiana. . 
0"-40" 
. 11 
.07 
.047 
.00 
11. 76| 8. 09 
7.10 
3.67 
.27 
26 
Miami silty clay loam, Indiana. _ 
10"-30" 
.21 
.03 
.034 
.22 
8.57 
7.64 
5.89 
.93 
.10 
27 
Norfolk fine sandy loam, North 
C arolina 
0"- 8" 
.23 
.08 
.047 
.00 
16.51 
11.92 
4.45 
4.69 
.22 
28 | Norfolk tine sandy loam, North 
Carolina 
12"-36" 
.26 
.05 
.028 
.00 
13.81 
11.50 
3.25 
1.60 
.25 
29 
Ontario loam, New York 
0"-12" 
.44 
.37 
.033 
.00 
20.46 
3.33 
9.95 
17.13 
.70 
30 
Ontario loam, New York 
12"-22" 
.25 
.06 
.028 
.00 
10.71 
7.22 
9.50 
3.49 
.23 
31 
Orangeburg fine sandy loam, 
Mississippi 
0"-10" 
.42 
.10 
.026 
.00 
14.89 
10.63 
4.34 
4.26 
.26 
32 
Orangeburg fine sandy loam, 
M ississippi 
]0"-36" 
.17 
.09 
.024 
.00 
13.60 
11.92 
5.44 
1.68 
.25 
33 
Sassafras silt loam, Maryland 
0"- 8" 
.47 
.20 
.035 
.00 
17.29 10.97 
5.44 
6.32 
.43 
34 
Sassafras silt loam, Maryland 
S"-22" 
.08 
.07 
.020 
.00 
14.08! 12.49 
5.32 
1.59 
.32 
35 
Sharkey clay, Mississippi 
N o.t cer- 
tain. 
,0"_ 4" 
.28 
.12 
( 3 ) 
.00 
12.28 
8.81 
7.91 
3.47 
.21 
36 
Sharkey clay, Mississippi 
( 3 ) 
( 3 ) 
( 3 ) 
( 3 ) 
10.93 
7.45 
9.30 
3.48 
.57 
37 
Stockton clay adobe, California.. 
0"-12" 
.25 
.12 
( 3 ) 
.00 
11.44 
9.56 
11.91 
1.88 
.16 
38 
Stockton clay adobe, California.. 
0"-38" 
.06 
.03 
.020 
.00 
11.95 
10.75 
10.70 
1.20 
.05 
39 
Stockton clay adobe, California.. 
38"-50" 
.20 
.04 
.019 
.00 
12.51 
9.69 
8.76 
2.82 
.07 
40 
Susquehanna clay, Mississippi... 
0"- 4" 
.02 
Trace 
( 3 ) 
.00 
11.30 
8.75 
1.56 
2.55 
.14 
41 
Susquehanna clay, Maryland 
5'- 6' 
.27 
.09 
( 3 ) 
.00 
11.87 
11.12 
2.65 
. 75 
( 3 ) 
42 
Vega Baja clay loam, Porto Rico. 
0"-12" 
.36 
( 3 ) 
( 3 ) 
( 3 ) 
16.88 
12.73 
2.63 
4.15 
.31 
43 
Wabash silt loam, Nebraska 
0"-15" 
.25 
.16 
.037 
.00 
11.73 
6.18 
10.19 
5.55 
.31 
44 
Wabash silt loam, Nebraska 
15"-36" 
.24 
.14 
.034 
.00 
12.34 
6.74 
10.24 
5.60 
.27 
45 
Yolo clay, California 
0"-18" 
.49 
.17 
( 3 ) 
.00 
15.61 
13.42 
7.39 
2.19 
.10 
1 The number given for combined water is the difference between ignition loss and organic matter. 
2 Calculated by multiplying the CO2 evolved by combustion by .471. 
3 Not determined. 
It can be seen from Table 3 that the colloidal matter of soils is 
composed mainly of silica, alumina, iron oxide, and combined water. 
There is quite a wide variation in the quantities of these constitu- 
ents present, though a considerable number of the different colloids 
have almost a constant composition so far as these main constituents 
are concerned. 
In the whole series silica varies between 31.84 and 55.44 per cent, 
alumina varies between 16.42 and 38.28 per cent, iron oxide varies 
between 4 66 per cent and 16.67 per cent, and combined water varies 
between 3.33 and 16.56 per cent. 
Ten colloids, however, can be picked out which show only small 
variations in all four constituents : SiO, 38.25 to 41.63 per cent ; 
ALO3, 28.64 to 31.21 per cent; Fe 2 3 , 9.45 to 11.63 per cent; and 
