order to fill it up again,
to begin a new distillation.

Each time that the vinous liquor is renewed in the still, the water
contained in the urns must be emptied, through the pipes of discharge at
the bottom.

Metals are conductors of the _caloric_. The heat accumulated in the
still, rises to the cap, from whence it runs into the urns: with this
difference--that the pewter, of which the cap and pipes are made,
transmits less caloric than copper, because it is less dense: and that
bodies are only heated in reason of their density.

However, a great deal of heat is still communicated to the worm, and
heats the water in which it is immersed. I diminish this inconvenience
by putting a wooden pipe between the worm and the pipe of the third urn.
Wood being a bad conductor of caloric, produces a _solution of
continuity_, or interruption between the metals. The wood of this pipe
must be soft and porous, and not apt to work by the action of the fire:
however, to avoid its splitting, I wrap it up in two or three doubles of
good paper, well pasted, and dried slowly. This pipe is one foot long,
and hollowed in its length, so as to receive the pewter pipe of the
third urn at one end, and to enter the worm at the other; thereby the
worm is not as hot, since it only receives the heat of the vapors which
it condenses.

Notwithstanding all these precautions, it heats the water in which it is
immersed after a length of time; and whatever care may be taken to renew
it, all the vapors are not condensed, and this occasions a loss of
spirit. I obviate this accident, by adding a second worm to the first:
they communicate by means of a wooden pipe like the above. The effect of
this second worm, rather smaller than the first, is such, that the water
in which it is plunged remains cold, while that of the first must be
renewed very often. By these means, no portion of vapors escape
condensation. The liquor running from the worm is received into a small
barrel, care being taken that it may not lose by the contact of the air
producing evaporation.

CHAPTER XIII.

OF FERMENTS.

They are of two kinds; the very putrescent bodies, and those supplied by
the _oxigen_. Animal substances are of the first kind: _acids_, neutral
salts, rancid oils, and metallic _oxids_, are of the second.

Were I obliged to make use of a ferment of the first class, I would
choose the glutinous part of wheat flour. This vegeto-animal substance
is formed in