208 
Journal of Agricultural Research 
Vol. VIII, No. 6 
such as the quartz sand, sands, and sandy loams. In some of the clay 
loams and clays the amount of water that fails to freeze in the super¬ 
cooling of 3 0 is about 18 per cent less than in the supercooling of i°. 
Table; VI .—Effect of supercooling upon the amount of water that fails to freeze when 5 c.c. 
are added to various soils 
Degree of supercooling. 
Water in 
quartz sand 
failing to 
freeze. 
Water in 
sand failing 
to freeze. 
Water in 
silt loam 
failing to 
freeze. 
Water in heavy silt loam failing to 
freeze. 
First test. 
Second test. 
Third test. 
To i° C. 
To 3 °C. 
C.c. 
0.1 
0.1 
0 0 
K** 
C.c. 
0.4 
o -3 
P.cf. 
8.0 
6.0 
C.c. 
3-10 
2- 20 
P.cf. 
62.0 
44.0 
O.c. 
4 - IS 
3 -SO 
P. cf. 
83.0 
70.0 
C.c. 
3*70 
3 -io 
P. cf. 
74.0 
62.0 
C.c. 
3*30 
2.80 
P. cf. 
66.0 
56.0 
Attempts were made to obtain data at still greater supercoolings than 
3 0 C.; but it was found that if the temperature of the bath was increased 
above — 4 0 in order to obtain the greater supercoolings, the soil began to 
freeze when it was cooled only a few tenths of a degree below zero. The 
highest temperature that could be obtained at which premature solidifi¬ 
cation would not start was — 4 0 . Hence, the greatest supercooling that 
was possible at this temperature was 4 0 . For rapidity of operation, how¬ 
ever, the supercooling of 3 0 was employed. 
The decrease in the amount of the water that fails to freeze in the 
colloidal soils with the increase of supercooling is highly significant. It 
indicates that supercooling lends a certain amount of energy to the force 
of crystallization which overcomes the forces of the soils that cause the 
water to become unfree, and liberates this water so it can freeze. This 
decrease in the amount of water that fails to freeze with an increase in 
the supercooling bears an analogy to the increased quantity of the solid 
solvent that will separate from the solution with the increase in the 
degree of supercooling. It is a well-known fact that the amount of pure 
solvent separating into its solid phase upon freezing is increased with the 
degree of supercooling, and thus concentrates the remaining solution. 
The above results also go to bear out the statement already made that 
the unfree water does not exist in the soil in an unchangeable condition, 
but that it can be made free by various factors, and that the magnitude 
depends upon the empirical condition of the method employed for its 
determination. 
EFFECT OF THE AMOUNT OF MOISTURE PRESENT UPON THE AMOUNT OF 
WATER THAT FAILS TO FREEZE 
In the course of the development of the procedures of the dilatometer 
method it was noticed that the quantity of moisture present in the soil 
influenced somewhat the amount of water that failed to freeze. In order 
to obtain very definite data upon this subject a series of determinations 
was performed with soils at two different water contents, 5 and 10 c. c. 
of water in 25 gm. of soil. The data obtained are detailed in Table VII. 
