10

FLUIDITY AND PLASTICITY
TABLE I.—CAPILLARY A'

Pressure in
Observed time

millimeters of
for transpiration
Calculated
Per cent

mercury at
of 13. 34085 cc
time
difference

10°C
of water

97.764
10,361.0

147.832
6,851.0
6,851.91
0.01

193.632
5,233.0
5,231.22
0.03

387.675
2,612.5
2,612.84
0.01

738.715
1,372.5
1,371.20
0.09

774.676
1,308.0
1,307.55
0.04

In the above case it is certainly true that the rate of flow is
proportional to the pressure, but it is equally certain that this
relation no longer holds when the capillary becomes sufficiently
shortened. Thus when the length of the tube used above is
shortened to 15.75 mm, the values given in Table II are obtained.

TABLE II.—CAPILLARY A.™

Pressure in
Observed time

millimeters of
for transpiration
Calculated
Per cent

mercury at
of 13. 34085 cc
time
difference

10°C
of water

24.661
8,646

49.591
4,355
4,299
-1.29

98.233
2,194
2,170
-1.09

148.233
1,455
1,438
-1.17

194.257
1,116
1,097
-1.63

388.000
571
549
-3.85

775.160
298
275
-7.72

Not only is there a marked deviation from the assumed law
of pressures as soon as the capillary is sufficiently shortened, but
the percentage difference between the observed and calculated
values increases quite regularly as the pressure increases. But
in either case, whether the capillary is shortened or the pressure
increased, we note that the velocity is decreased. Whether the
irregularity here observed is due to the use of some of the avail-
able work in imparting kinetic energy to the liquid, or it is due