448 
Journal of Agricultural Research 
Vol. VII, No. io 
Initi&l Percent Moisture In Cl&y 
Fig. 3.—Evaporation from clay containing different initial per¬ 
centages of moisture. 
cheesecloth and connected by a perpendicular wick to a water container 
on top. The wick kept all the cheesecloth covers saturated. To make 
sure no vapor escaped at the door, pieces of cloth kept constantly drip¬ 
ping were hung in front of the door. Tested thermometers showed 
throughout the experi¬ 
ment an almost constant 
temperature of i9.5°C., 
about one degree lower 
than that of the labora¬ 
tory. Each day for 10 
days the vessels were 
weighed to 0.01 gm. 
and made up by 
adding the water lost. 
The lower percent¬ 
ages, however, gained 
and were left at the 
wetness reached, which 
was about 7 per cent. 
Fairly comparable 
with this test was another in which the same vessels, made up as before, 
were surrounded with cheesecloth 24 inches high to prevent drafts and 
to maintain a uniform temperature. Possible variations were elimi¬ 
nated by shifting the vessels in such a way that each occupied all 
sections of the cloth 
box some time during 
the 20 days of the 
experiment. The top 
was left open to permit 
vapor to escape upward. 
The relative humidity 
of the air was almost 
constantly at 76 per 
cent, whereas it was 
about 68 in the open 
laboratory. The tem¬ 
perature averaged 19 0 
C. during the 20 days. 
Completely dried 
soil gained to 4 per 
cent, then remained constant. Weighings were made each day to the 
nearest 0.01 gm. and the losses made up as with the test in the germi- 
nator. 
Figure 5 shows the losses for each 1 per cent in the saturated atmosphere 
of the germinator and for the slightly overraoist air of the cloth boxes. 
40 €0 to too tzo 140 160 
Initi&l Per Cent Moisture InMucfe 
Fig. 4.—Evaporation from muck containing different initial per¬ 
centages of moisture. 
