; Disiillation of Ardent Spirit. 261 
of the whole of the fermenting mass; from the con- 
sideration of which we shall not be surprised that 
Chaptal made vinegar from the fluids thrown off 
by fermentation.* 
This part of the subject appeared too jnterdsiing 
to be left without a little farther investigation, as 
some chemical writers of eminence have stated, that 
it was pure unadulterated carbonic acid gas which 
was thrown off by fermentation; others, that it was 
carbonic acid gas combined with pure alcohol ; while 
many have supposed to be an union of gas, alcohol, 
and water;t but none, whose opinion I have seen, 
have stated it to-be what it is:—all the elementary 
* M.I. A. Chaptal communicated to the Academy at 
Paris (1786) an observation of some curiosity respecting 
the formation of vinegar. He placed some distilled wa- 
ter above the vinous fluid in fermentation, to impregnate 
it with carbonic acid. The water, thus impregnated, 
afforded vinegar; and, at the end of some months, a depo- 
sition was made of a substance in flocks, which was ana- 
logous to the fibrous matter of vegetables. 
+ Lavoisier says, “* when this gas is carefully gathered, 
it is found to be carbonic acid perfectly pure, and free 
from admixture with any other species of air or gas;” 
but his translator observes, * that the perfect purity 
must be taken with some allowance; for it almost always 
(I believe constantly) contains some alcohol, besides a con-, 
siderable quantity of aqueous gas or water, in solution, 
The latter does not affect its purity, the former does in 
some degree.” 
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