158

FLUIDITY AND PLASTICITY

multiplying by the same factor. Since the fluidity vapor-pressure

curves pass through the origin and we by this process bring them

800

700

400

500

O 100 2OO 30O
Fluidity
FIG. 59.—The vapor-pressure curves of some associated substances compared
with heptane.
together at the boiling-point, a comparison of the reduced values
for other temperatures with the values for heptane will show
how nearly similar are the curves for different substances, even