THE FLUIDITY OF SOLUTIONS

177

particularly good example as there is a very strongly pronounced
minimum in the fluidity curves. The greatest deviation from
the linear is in a mixture corresponding to the formula CVEI60.-
4H2O, containing 44.79 per cent alcohol by volume. To obtain
a fluidity of 200, ethyl alcohol requires an absolute temperature
of 343.6° and water a temperature of 328.9°, so if there were no
chemical change on mixing we should expect a temperature
corresponding to the fluidity of 200 in the 44.79 volume per cent

Pro. 06.— -Mixing solutions of ethyl alcohol in water (corresponding to the
composition OsHaO.SHvO) with solutions of acetic acid in water (corresponding
to the composition CaH^Os-HsO) brings about an increase in fluidity.

mixture of 0.4479 X 343.6 X 0.5521 X 328.9 = 335.5°. On the
other hand, from the constants already given, the temperature
required to give the pure hydrate C2H60.4H20 a fluidity of 200
would be 14 X 59.2 + 5 X 24.2 - 2 X 95.7 = 758.4°. But the
observed absolute temperature at which the 44.79 volume per
eeixt mixture has a fluidity of 200 is 362.3°. Hence, if we let
x represent the fraction by volume of the mixture combined as
C2H0O.4H20, the rest remaining unchanged, we have
335.5 (1 - a?) + 758.4s = 362.3
and x = 0.0634.
12 ^