Effects Of This Apparatus
Although the still might contain 400 gallons, there must be only 200
gallons put into it: the rest remaining empty, the vapors develops
themselves, and rise. In that state, the vinous liquor is about one foot
deep, on a surface of 20 feet square: hence two advantages--the first,
that being so shallow, it requires but little fuel to boil; the second,
that the extent of surface gives rise to a rapid evaporation, which
ac
elerates the work. This acceleration is such, that six distillations
might be obtained in one day. The spirit contained in the vinous liquor
rises in vapors to the lid of the still, there find the cap and its
pipe, through which they escape into the first urn, by the side pipe
above described, which conducts them to the bottom, where they are
condensed immediately.
But the vapors, continuing to come into the urn, heat it progressively:
the spirituous liquor that it contains rises anew into vapors, escapes
through the cap and pipe, and arrives into the second urn, where it is
condensed as in the first. Here again, the same cause produces the same
effect: the affluence of the heat drawn with the vapors, carries them
successively into the third urn, and from thence into the worm, which
condenses them by the effects of the cold water in which it is immersed.
The urns, receiving no other heat than that which the vapors coming out
of the still can transmit to them, raise the spirit; the water, at least
the greatest part of it, remains at the bottom: hence, what runs from
the worm is alcohol; that is, spirit at 35 deg.. It is easily understood how
the vapors coming out of the still are rectified in the urns, and that
three successive rectifications bring the spirit to a high degree of
concentration: it gets lower only when the vinous liquor draws towards
the end of the distillation. As soon as it yields no more spirit, the
fire is stopped, and the still is emptied in 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.