Nov. 20,1916 Determination of Hygroscopic Coefficients of Soils 355 
and 3.3. The averages for the 15 samples of each were 8.9 for S and 3.5 
for La. The ratio was accordingly 2.47 for S and 2.74 for La, the hygro¬ 
scopic coefficients being 22.0 and 9.6 per cent, respectively. 
Table} VIII .—Comparison of the determined hygroscopic coefficients with those computed 
from the hygroscopic moisture in a series of residual soils from southwestern Nebraska 
Soil. 
Hygroscopic 
moisture. 
Hygroscopic coefficient. 
Ratio of 
hygroscopic 
coefficient 
to hygro¬ 
scopic 
moisture. 
Determined. 
Computed. 
Departure. 
Per cent . 
H (control). 
I. 0 
5-6 
S (control).. 
10. 2 
O v) 
y 
1.,. 
•3 
.8 
0.9 
0. I 
2.7 
2. 
•3 
.8 
•9 
. I 
2. 7 
3 . 
. -3 
.8 
•9 
. I 
2.7 
4 . 
•3 
■9 
•9 
. O 
3 -o 
5 . 
•4 
1. 1 
* I. 2 
. I 
2. 8 
6. 
• 4 
1. 1 
I. 2 
. I 
2.8 
7 .. 
.4 
1.4 
I. 2 
— . 2 
3 - 5 
8. 
* 5 
1.4 
I.4 
. O 
2.8 
. 7 
2. 2 
2. 0 
— . 2 
1. T 
10. 
.8 
2. 2 
2-3 
. I 
O ' A 
2. 8 
11. 
i* 7 
4.4 
4*9 
•5 
2. 6 
12.:. 
i *3 
4-5 
3-8 
- -7 
3-5 
13 . 
1.8 
5-4 
5*2 
— . 2 
3 *o 
14 . 
i -7 
5-9 
4.9 
— 1. 0 
3 * 5 
15 . 
2.4 
6. 6 
7.0 
•4 
2. 7 
16.. 
2-5 
8.0 
7.2 
- .8 
3 - 2 
17 . 
2.9 
8-3 
8.4 
. 1 
2.8 
18. 
2.7 
8.4 
7.8 
- .6 
3 *i 
19 . 
3 - 5 
9-7 
10.1 
•4 
2.8 
3-6 
9.8 
10. 4 
.6 
2. 7 
3-6 
10. 7 
10. 4 
- -3 
3 *o 
3-6 
10. 8 
10. 4 
- -4 
3 *o 
23. 
5-7 
14.4 
16. 5 
2. 1 
2. 6 
24. 
5-2 
14.9 
i 5 - 1 
. 2 
2.9 
At this point the removal of the junior author to California interrupted 
the work, but during the following year Mr. A. Skudma made single 
determinations of the hygroscopic coefficients in the usual manner, 
using also the same control samples. In Table IX are shown the ratios 
of typical sets for various fields, the others being similar. It will be 
seen that the ratio is not affected by the presence of organic matter, as 
in the surface 6 inches it is similar to that in the subsoil. 
This set serves well to illustrate the advantage of the indirect method 
of determination. During the early part of May the samples had been 
collected from 23 fields in western Nebraska for the study of field mois¬ 
ture conditions, which happened to be of unusual interest at that time, 
a wet winter and early spring having succeeded an exceptionally dry 
summer and autumn. The moisture samples had been weighed into 
light cotton sacks and dried at no 0 C. to constant weight, and then left 
exposed to the air for a week or two before being placed on the plates 
in the so-called “ constant temperature room.” By the middle of June, 
as it later proved, reliable data on the unusual field moisture conditions 
