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 accelerates 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°. 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.