44 
Pehr Olsson-Sefter. 
present in the soil air, thus increasing the amount of hygroscopic 
water, and bringing about to some depth a continuity which assists 
in a more rapid establishing of equilbrium. 
Here we must not overlook the influence of changes in 
temperature on the coefficient of viscosity, which is known to 
decrease with higher temperature, and which largely determines 
the rate of flow of the water, as certain experiments by King 1 
indicate. He found that— 
At 9-01°C the flow was 6453 grams per minute. 
9-23 
11 
6-27 
9-38 
11 
6-384 
12-6 
11 
7.046 
23-8 
11 
9-014 
32-46 
11 
10-554 
These experiments refer to a 1 saturated soil, and although 
other factors have to be taken into consideration in regard to the 
rate of movement of water in a soil, in which saturation is not 
complete, it remains without doubt that temperature changes, both 
diurnal and seasonal oscillations, greatly affect the rate of adjust¬ 
ment of soil moisture. 
Effects of Salts on Movement of Soil Water. 
The above statement (4) (p. 42) in relation to the effect on surface 
tension by salts, is of some importance in a discussion of the hydro- 
dynamic factors on coastal sands. It is well-known that the 
atmosphere on the seacoast has a certain percentage of salinity, and 
that this salt, under certain circumstances, is deposited, even in 
crystallized form, on the ground and on objects on the shore. 
Whitney 2 gives the surface tension of a solution of common salt, 
of a specific gravity of 14, as 7-911 gram-meters per square meter, 
that is on a square meter of liquid surface there is sufficient energy 
to raise so many grams to the height of one meter. The corres¬ 
ponding surface tension of pure water was 7-532. This difference in¬ 
dicates that on coastal sands, where salt is frequently deposited on 
the surface, the tension must be increased and consequently water 
drawn from below. In agricultural practice it is also well known 
that application of salts tends to keep the soil more moist during 
dry weather. We can therefore assume as certain that on coastal 
sands the amount of moisture in the surface soil is larger than on 
inland sand formations, and this helps considerably in replacing the 
water that has evaporated or been used by the vegetation. 
1 U.S. Weather Bur. Bull. 5, 1892, p. 66. 
2 Ibidem 4, 1892, p. 16, 
