48

FLUIDITY AND PLASTICITY

(2) The mean velocity at the lower limit of the oscillations is
inversely proportional to the radius of the tube.

TABLE XVI.—LAW OF RADII

R
Temperature
V
• v
E

0.04998
12.7
103.6
2,073

0.09036
13.6
214.9
2,378

0.13070
13.6
344.0
2,632

0.17780
13.6
377.0
2,121

0.21080
13.6
542.0
2,570

0,27620
13.6
701.0
2,538

0.29690 (Copper)
15.0
648.0
2,182

0.45000
15.0
1,205.0
2,678

(3) The mean velocity at the lower limit of the oscillations is
inversely proportional to the fluidity. For both mercury and
water an elevation of the temperature caused a lowering of the
mean velocity at the lower limit of the oscillations. The in-
crease in the temperature causes an increase in the fluidity in
both cases,

(4) Experiments with air and water confirm the law that the
mean velocity at the lower limit of the oscillations is inversely
proportional to the density of the medium. The number of
tarns of the outer cylinder per minute is taken as proportional
to the mean velocity, a being a constant.

TABLE X"VII.—LAW OF DENSITIES

Substance
*7
P
al
Ckppl

Water ..........
0 01096
1 0000
56
5 100

Mi ........
0 00018
0 0012
&on
^ 3Oft

There would be still some doubt whether the critical velocity
is inversely proportional to the fluidity, but this doubt is re-
moved by the work of Coker and Clement (1903) to test this
very point. They used a single tube I = 6 ft. R = 0.38 in.
measuring the flow of water over a range of temperatures from