204

FLUIDITY AND PLASTICITY

measurement of the fluidity of suspensions is rendered difficult
by the fact that partial clogging of the capillary gives too low
fluidities, and settling out of the solid gives too high fluidities.
In reference to the discordant observation at 5°C, Oden remarks
that the suspension was strongly flocculated.

130

I

1201-^

110
100
90
80
TO
60
50
4-0
50

10

25

10 15
Per Cent*
PIG. 74.—Fluidities of suspensions of sulfur in water at various volume per-
centages, at 5°, 20°, and 30°C. (After Oden.)
It is interesting to find that Trinidad Lake asphalt, treated
with benzene gives suspensions which according to measurements
of Clifford Richardson (1916) indicate a zero fluidity at 24.6
volume per cent. The fluidities of the suspensions agree well
with our formula, which is surprising, since each solution was
centrifuged to remove that portion of the suspended matter
which would not remain in suspension at that particular con-
centration.