ISO 
ON THE SEPARATION OF SOME ACIDS. 
with alkali must be measured by the amount of the valeri- 
anic acid supposed to exist in the mixture ; for instance, 
assuming 10 per cent, of valerianic acid, then one-tenth of 
the mixture is neutralized ; but supposing it to be a valeri- 
anic acid containing 10 per cent, of butyric acid which it is 
wished to separate, then nine-tenths of the acid must be 
neutralized. 
It is readily perceived that by a single operation one of 
the acids is always obtained pure. Either the distillate is 
pure butyric acid, and then the residue consists of a mixture 
of valerianic and butyric acids, or the distillate contains 
butyric and valerianic acids at the same time, and in this 
case the residue contains pure valerianic acid. By con- 
tinuing the same treatment of the mixed residue or of the 
mixed distillate, i. e. partial saturation and distillation, it is 
possible to obtain from the residue another portion of one 
or other of the acids pure; and finally a perfect separation 
is effected, such as is scarcely possible by mere distillation 
of the acids. 
As the boiling points of these two acids differ, it will be 
imagined that the soda, on combining with the least volatile 
of the acids, in this case the valerianic, deprives it of its 
volatility at the temperature at which the other boils. 
When, in a mixture of valerianic and butyric acids, the lat- 
ter can naturally be distilled off in a pure state. 
A mixture of valerianic with acetic acid, or of butyric 
with acetic acid, behaves in a totally different manner 
under the same circumstances. When such a mixture is 
partially neutralized with potash, and then submitted to. 
distillation, it would be expected that acetic acid would 
principally pass over ; such however is not the case, but 
the two other acids distil over, although the boiling point 
of acetic acid is more than 90° lower than that of butyric 
acid, and more than 126° lower than that of valerianic acid. 
This is owing to the formation of an acid acetate, which 
does not appear to be decomposed by either of the other 
wo acids. 
