24 
Table X. — Effect of salts on cohesion in soils under various percentages of moisture- 
Continued. 
SOIL NO, 516. 
Check. 
Potassittm 
Calcium 
Superphos- 
Ammonium 
Sodium 
Sodium 
sulphate. 
oxid. 
phate. 
sulphate. 
nitrate. 
carbonate. 
© 
fl 
<D 
^ 
<D 
Pi 
<D 
a 
® 
^ 
<D 

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a 
>H • 
U • 
ii • 
^^ • 
^"3 
4J CO 
00 ■g 
C3rd 
5| 
11 
'=''3 
05 iD 
5S 
is 
51 
1.1 
11 
o § 
^^ 
o § 
n^^ 
og 
g^ 
o^ 
g^ 
o^ 
g^ 
o^ 
g^ 
Z^ 
g^ 
^ 
Ph 
s 
^ 
^ 
(^ 
^ 
(^ 
!^ 
^ 
1^ 
Ph 
§ 
^ 
Per ct. 
Gm. 
Perci. 
Gm. 
Perct. 
Gm. 
Perd. 
Gm. 
Perct. 
Gm. 
Perrt. 
Gm. 
Per cf . 
(?TO. 
10.95 
38.5 
36.65 
15.14 
14.19 
35.95 
12.33 
39.4 
13.09 
35.90 
11.49 
35.3 
10.19 
37.15 
12.18 
35.6 
18.54 
36.3 
17.77 
37.15 
15.96 
38.3 
16.51 
35.9 
15.01 
39.8 
13.98 
39.30 
15.62 
36.9 
21.26 
38.45 
21.16 
35.0 
19.12 
38.35 
19.11 
36.2 
18.22 
37.45 
17.46 
36.5 
18.79 
35.65 
24.13 
37.5 
23.67 
33.3 
21.71 
40.05 
22.46 
39.55 
21.86 
39.5 
20.90 
36.95 
21.25 
37.45 
26.71 
33.9 
26.11 
32.55 
24.77 
35.60 
24.95 
34 
22.21 
37.45 
22.79 
36.1 
23.37 
37.05 
SOIL NO. 428. 
11.23 
37.85 
35.40 
31.6 
31.75 
30.3 
28.4 
15.11 
12.97 
16.42 
19.10 
21.98 
24.96 
34.6 
35.95 
35.0 
33.1 
31.15 
14.44 
18.39 
20.00 
22.75 
26.62 
35.1 
32.95 
34.5 
31.25 
30.5 
13.14 
17.30 
19.50 
22.42 
25.34 
36.6 
35.25 
34.4 
33.05 
32.75 
14.18 
18.08 
20.76 
23.25 
25.87 
37.05 
17.96 
33.95 
18.50 
34.7 
21.90 
. 
35.25 
25.33 
32.1 
Soil No. 573; given in Table X, is the silty organic soil. The weight 
required for penetration increased at first and then decreased with 
increase in moisture content, reaching a minimum at 25 per cent, 
which is apparently the optimum moisture content for this type of 
soil. The effect of the addition of salts is to increase the weight nec- 
essary for penetration at the optimum moisture content, that is, salts 
increase the cohesion of the soil particles. This is especially true of 
lime. The cohesion apparently does not vary with change in moisture 
content in the presence of sodium carbonate. 
Soil No. 530. — Table X shows the relation between moisture con- 
tent and cohesion for the predominating red type of clay soil. Nine- 
teen per cent moisture represents the point above which it is impossi- 
ble to work with this type, due to the fact that the soil will not pass 
through the screen used in the apparatus. The figures obtained 
show an optimum moisture content of about 1 per cent if conclusions 
are to be drawn from the theories advanced by previous investigators. 
However, 10 per cent is rather low for this type of soil and it is prob- 
able that the optimum point for plant growth is above the range of 
the experiment. The cohesion of this soil decreases at first, then 
increases up to 16 per cent moisture, followed by a second decrease. 
The remarkable effect of sodium carbonate (and this would apply in 
more or less degree to all deflocculating agents) is clearly shown in the 
table. Regarding the effect of other salts, little can be concluded from 
the data at hand. That they do affect cohesion there is no doubt, but 
it is impossible to definitely classify these effects. 
