11 
all inorganic salts increase the surface tension of water while organic 
substances decrease it. On the other hand, the opposite relation 
exists with regard to viscosity. A series of experiments made at the 
Maryland Experiment Station ^ upon the surface tension of soil 
extracts show it to be considerably less than pure water. These and 
many other facts indicate the complexity of the application of theo- 
retic principles to soils. 
The capillary power of a soil is generally measured by the height 
to which water will rise in a soil column, although it may take place 
in all directions in soils and varies greatly according to the mechanical 
composition. The present study of capillarity was carried out in 
1-inch glass tubes. Experiments were made not only with soils 
but also with silica sand and kaolin to ascertain the relation of 
these materials to soils. In aU about 40 salts, fertilizer materials, 
and mixtures were used, including several organic manures. As a 
means of studying the effect of these salts, comparisons were made 
both when added in amounts proportional to their molecular weights 
and when added in equal amounts. Also measurements were made 
upon the variation in height to which the water would rise as 
affected by amounts of the salt varying from 0.06 to 6.66 per cent. 
In all cases the salts were added in small amounts. 
Before presenting the data obtained in these experiments it is of 
interest to know the relative capillary activity of the soils in ques- 
tion. This is shown in Table IV, in which the figures were obtained 
by allowing the soil column to stand in about one-half inch of water 
for 78 days. 
Table IV. — Capillary rise of water in the soils. 
Soil No. 
6 
hours. 
24 
hours. 
48 
hours. 
4 
days. 
5 
days. 
6 
days. 
7 
days. 
9 
days. 
11 
days. 
19 
days. 
32 
days. 
43 
days. 
78 
days. 
44S 
Cm. 
26.8 
22.4 
31.6 
39. S 
36.8 
41.0 
33.7 
Cm. 
35.5 
29.1 
38.1 
51.3 
47.8 
56.6 
40.1 
Cm. 
40.9 
34.4 
42.9 
57.3 
Cm. 
46.0 
40.0 
47.3 
62.7 
Cm. 
47.8 
41.6 
49.0 
64.6 
64.0 
79.0 
45.1 
Cm. 
49.1 
42.5 
50.4 
65.9 
65.0 
81.6 
45.1 
Cm. 
50.3 
43.8 
51.5 
67.8 
66.8 
83.5 
45.1 
Cm. 
52.1 
45.2 
53.8 
70.6 
69.2 
88.4 
45.1 
Cm. 
54.0 
46.7 
55.6 
72.8 
71.2 
91.6 
Cm. 
60.4 
51.0 
58.4 
79.3 
76.4 
100.8 
Cm. 
67.0 
55.3 
62.1 
86.6 
84.8 
109.8 
50.5 
Cm. 
70.8 
■"64.' 8' 
89.8 
88.7 
1115.6 

Cm. 
82.5 
530 
71.5 
428 
76.5 
542 
100.0 
516 
55.2 62.0 
64.2 69.9 
44. 45. 1 
100.0 
573 
574 
63.0 
1 Top of column. 
The highly organic silty soil showed the greatest capillary rise, the 
clay soils least, while the sandy soils were intermediate. 
In filling the tubes it is necessary to exercise considerable care in 
order to obtain a uniform mixture. This is made possible by pro- 
jecting a long mre with a loop on the end into the tube and withdraw- 
ing it with a rotary motion. 
1 U. S. Dept. Agr., Weather Bur. Bui. 4 (1892), p. 16. 
