1916] SHULL—SOILS 17 
The general situation is strikingly illustrated by table VI, which 
combines the results of the 4 experiments of table V. While there 
are a number of discrepancies, as one might expect, it is evident 
that the method can be used in measuring approximately the forces 
residing on the surfaces of soil particles at various soil moisture 
contents. For instance, when this soil contains about 9.36 per 
a 
45 
40 + 
35:4 
30 5 
—_ 
, 
a 
~ 
re . ——y n - ~— 
5 10 15 20% 
Fic. 4.—Curves showing relation of moisture intake by seeds to increasing soil 
moisture, plotted from experiment 4, table V; abscissae, percentage of soil moisture 
in terms of absolute dry weight; ordinates, percentage of increase of soil moisture 
above air-dry weight for the soil moisture curve (straight), and percentage of intake 
by seeds in terms of their air-dry weight. 
cent of moisture (3.5 per cent above air-dry), it is in moisture 
equilibrium with seeds at 6.47 per cent above their air-dry weight. 
The seeds attain about the same equilibrium point with saturated 
NaCl solution, which has an osmotic pressure of 375 atmospheres, 
