168

FLUIDITY AND PLASTICITY

which have been studied lately. Kendall and Wright and many
others have done valuable service; they have chosen inert liquids
whose individual fluidities are widely separated, hence these
mixtures are suited to give a crucial test of the mixture formulas.
DelbertF. Brown has studied this data to determine (1) whether
the volume difference Av is greatest when the specific gravities
of the components are most widely different, (2) whether the
fluidity difference A<? is greatest in the same mixtures in which the
volume difference is greatest, (3) whether those pairs of liquids
showing the greatest volume difference also show the greatest
fluidity divergence, and (4) whether the fluidities of the mixtures
can be calculated from the fluidities and volumes of the compo-
nents. Table XLIII gives a summary of part of his results.
The table is so arranged that the differences between the specific
volumes of the components, column 2, are in the order of increas-

TABLE XLIII.—FLUIDITY AND VOLUME RELATIONS IN CERTAIN IDEAL
MIXTUBES (USING DATA OF KENDALL AND WRIGHT)

Specific vol-

Components
ume difference of com-
Specific volume differ-
Fluidity dif-
Average deviation in

ponents
ence Av
<f>
per cent

. va — «:

Ethyl benzoate and benzyl

benzoate .....................
0 . 0594
0.0010
5 04
1.0

Phenetol and diphenyl ether ___
0.1056
0.0028
5.58
0.56

Ethyl acetate and ethyl benzoate
0.1616
0.0062
25.9
1.2

Ethyl acetate and benzyl benzoate
0.2183
0.0118
55.05
9.2

Diethyl ether and phenetol ......
0.3610
0.0268
60.3
1.2

Diethyl ether and diphenyl ether
0.4666
0.0458
110.5
3.8

ing magnitude. The third column shows that the sag in the
volume-volume concentration curve follows exactly this order
of increase, and column 4 shows that the fluidity divergence Acp
follows the same order of increase. Moreover, the maximum
divergence in both the volumes and the fluidities occurs in the
same mixture in every case, except that of diethyl ether and
diphenyl ether, although it is not possible to bring this out in
the table. The last column shows the average deviation of the
values of the fluidity, as calculated by Brown from the data of
Kendall and Wright by the formula (61). In only two cases is