322 
CHARLES A. SHULL AND S. P. SHULL 
One typical example of the intake has been chosen to illustrate the 
behavior of the gelatin under the given conditions. The gelatin disks 
weighed 0.787 g. air-dry. The absorption data obtained during 47 days 
are given in table 4. 
Table 4. Ah:orption of Water by Gelatin in a Saturated Atmosphere. 
Time Intake in Water Gain Percent 
6.5 hrs 0.1292 g. 15.27 
16.5 hrs 0.2174 27.62 
i.oday 0.2698 34-28 
2.0 days 0-3796 48.23 
3- 0 days 0.4599 58.43 
4- 0 days 0.5332 67.75 
5.04 days 0.5884 ■ 74.76 
6.0 days 0.6260 79-54 
8.0 days 0.7109 90.20 
lo.o days 0.7754 9^-52 
12.0 days 0.8356 106.17 
14.0 days 0.8734 110.97 
18.0 days 0.9644 122.54 
22.0 days I-0374 131 -81 
26.0 days I-0979 139-50 
30.0 days 1. 1602 147-42 
35.0 days 1.2209 155-13 
40.0 days 1.2886 163.73 
47.0 days 1-3426 170-59 
After the last weighing recorded in table 4 was made, the disks were 
returned to the bottles and left undisturbed for two months, as they were 
hard to handle without breaking. On opening them at the close of two 
months, the disks were found in liquefied condition. No culturing was 
attempted to determine whether liquefying bacteria might have been 
present. But the thymol had inhibited development of molds, and it is 
usually considered that molds are less readily controlled than bacteria. 
It does not appear to us likely, therefore, that liquefaction was brought 
about by bacterial action. 
The contrast in behavior of gelatin as we have found it, and that reported 
by von Schroder, is shown graphically in figure I . The possible cause of this 
difiference will be considered later. 
One striking thing which has been noted in regard to water absorption 
is the regularity of intake. It usually begins rapidly, and becomes con- 
tinually less rapid as absorption increases, falling off in regular fashion till 
approaching saturation causes a more rapid decline in the rate of intake. 
The rate of absorption has been studied particularly with reference to seed 
colloids soaking in water, and mathematical analysis has given us a formula 
by which the intake can be closely approximated by calculation. 
The same kind of analysis was made of the gelatin absorption from 
saturated air, and the same formula that was derived from the absorption 
of water by seeds from liquid water can be used in calculating the curve 
of absorption of water by gelatin from a saturated atmosphere. 
