ugh it, because the weight of the liquid serves the purpose
of an accurate cork.

To prevent any distillation of acid, especially in dissolutions
accompanied with heat, this tube is adapted to the retort A, Pl. VII.
Fig. 1. and a small tubulated recipient, M, is applied, in which any
liquor which may distill is condensed. On purpose to separate any gas
that is absorbable by water, we add the double necked bottle L, half
filled with a solution of caustic potash; the alkali absorbs any
carbonic acid gas, and usually only one or two other gasses pass into
the jar of the connected pneumato-chemical apparatus through the tube
NO. In the first chapter of this third part we have directed how these
are to be separated and examined. If one bottle of alkaline solution be
not thought sufficient, two, three, or more, may be added.

SECT. III.

_Apparatus necessary in Experiments upon Vinous and Putrefactive
Fermentations._

For these operations a peculiar apparatus, especially intended for this
kind of experiment, is requisite. The one I am about to describe is
finally adopted, as the best calculated for the purpose, after numerous
corrections and improvements. It consists of a large matrass, A, Pl. X.
fig. 1. holding about twelve pints, with a cap of brass a b, strongly
cemented to its mouth, and into which is screwed a bent tube c d,
furnished with a stop-cock e. To this tube is joined the glass
recipient B, having three openings, one of which communicates with the
bottle C, placed below it. To the posterior opening of this recipient is
fitted a glass tube g h i, cemented at g and i to collets of
brass, and intended to contain a very deliquescent concrete neutral
salt, such as nitrat or muriat of lime, acetite of potash, &c. This tube
communicates with two bottles D and E, filled to x and y with a
solution of caustic potash.

All the parts of this machine are joined together by accurate screws,
and the touching parts have greased leather interposed, to prevent any
passage of air. Each piece is likewise furnished with two stop-cocks, by
which its two extremities may be closed, so that we can weigh each
separately at any period of the operation.

The fermentable matter, such as sugar, with a proper quantity of yeast,
and diluted with water, is put into the matrass. Sometimes, when the
fermentation is too rapid, a considerable quantity of froth is produced,
which not only fills the neck of the matrass, but passes into the