A Manual of the Chemistry of the Carbon Compounds

42 THE CHEMISTJ17 OF
Acetic Acid CtlLfiv d = 1053. n = 1-H72.
^=-^ « 0-3533. 60 x 0-3533 = 21-2.
a
Calculated from the composition—
2x5 + 4x1-3 + 2x3 = 21-2.
Ethyl Acetate C4H8O2. d = 08977. n = 1-3715.
^ 1 « 0-4138. 88 x 0-4138 = 364.
Butyric Acid 0^0^. d = 0-9608. n = 1-3973.
^-i = 0-4135. 88 x 0-4135 = 3«-4.
The two latter compounds are metameric, and have therefore the
same specific and molecular refractive energy, which latter found
by calculation is—
4x5 + 8x1-3 + 2x3 = 36-4.
The specific refractive power of mixtures is the mean of that of
their constituents, and if we know what compounds are present in a
mixture of liquids, we are able to find by means of this optical
analysis the quantity of each, which by chemical analysis can only
be done when the composition of the two bodies is widely different.
It often happens that such mixtures containing two alcohols, or two
hydrocarbons, &c, cannot be completely separated, either by chemical
or by physical means, but yet by means of an optical analysis we cau
find the quantity of each.
Mixture of Ethyl Alcohol, and Water.
n-_L
d
TAhjl Alcohol 04528
Water 0-3324
Mixture 0-4225
Calling the quantity of alcohol contained in 100 parts a;, and that of
the water y, we have the simultaneous equations—
(1) to + y«. 100.
(2) 0-4528S+ O-3324y= 0-4225 x 100.
From this we find—
a; = 74-84
y - 25-16
100-00
which agrees as nearly as possible with the real composition—
Alcohol 74-9
Water 25-1
1000