452 
Journal of Agricultural Research 
Vol. VII, No. io 
that they could be kept uniform in temperature to within about one 
degree. Twenty-five gm. of soil were moistened and then put in flat- 
bottomed aluminum cans 7 cm. in diameter and 3 cm. deep, the cans 
being about one-fourth full. In order to bring the temperature of the 
soil quickly to the temperature of the water, these cans were allowed to 
float on water in the water baths. The baths were maintained at 20, 
30, 40, 50, 60, 70, 80, and 90° C. It was almost impossible to maintain 
a uniform temperature when the hath was hotter than 90°; and when it 
was colder than 20° the 
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loff 
evaporation was too 
slow to give noticeable 
results. 
Two soils were in¬ 
vestigated. The first 
was Greenville loam 
with an initial moisture 
content of 12 per cent 
of the dry weight of 
the soil and the second 
was a coarse sand with 
20 per cent of initial 
moisture on the dry 
basis. 
Hundreds of weigh¬ 
ings were made to de¬ 
termine the rate of loss 
with each temperature. 
90 c These weighings gave 
the results contained in 
figures 8 and 9. 
The loam containing 
12 per cent of moisture required 265 minutes at 20° C. to lose half of 
its moisture and 510 minutes to become practically dry. At 30°, 89 
and 312 minutes were required to make it half and completely dry, 
respectively; at 40°, 46 and 143; at 50°, 23 and 88; at 6o°, 17 and 56; at 
70°, 12% and 45; at 8o°, and 38; and at 90°, 7 and 27. 
In sand containing 20 per cent of moisture, the number of minutes re¬ 
quired to become half and completely dry respectively at the various 
temperatures was as follows: At 20°, 315 and 819; at 30°, 90 and 240; 
at 40°, 45 and 100; at 50°, 30 and 72; at 6o°, 13 and 35; at 70°, 9 and 24; 
at 8o°, 6 and 18; and at 90°, and 13 minutes. 
In the loam containing 12 per cent of water as an average, it required 
nearly three times as long to drive off the last 6 per cent of w ater as it did 
for the first 6. In the sand containing 20 per cent, it required more than 
50 40 SO 60 
TEMPERATURE 
60 
Fig . 8 .—Time required at different temperatures to drive off half and 
all the water from Greenville loam containing 12 per cent moisture. 
