s he has
particularly applied to some cristalized stones.

SECT. V.

_Of Simple Distillation._

As distillation has two distinct objects to accomplish, it is divisible
into simple and compound; and, in this section, I mean to confine myself
entirely to the former. When two bodies, of which one is more volatile
than the other, or has more affinity to caloric, are submitted to
distillation, our intention is to separate them from each other: The
more volatile substance assumes the form of gas, and is afterwards
condensed by refrigeration in proper vessels. In this case distillation,
like evaporation, becomes a species of mechanical operation, which
separates two substances from each other without decomposing or altering
the nature of either. In evaporation, our only object is to preserve the
fixed body, without paying any regard to the volatile matter; whereas,
in distillation, our principal attention is generally paid to the
volatile substance, unless when we intend to preserve both the one and
the other. Hence, simple distillation is nothing more than evaporation
produced in close vessels.

The most simple distilling vessel is a species of bottle or matrass, A,
Pl. III. Fig. 8. which has been bent from its original form BC to BD,
and which is then called a retort; when used, it is placed either in a
reverberatory furnace, Pl. XIII. Fig. 2. or in a sand bath under a dome
of baked earth, Pl. III. Fig. 1. To receive and condense the products,
we adapt a recipient, E, Pl. III. Fig. 9. which is luted to the retort.
Sometimes, more especially in pharmaceutical operations, the glass or
stone ware cucurbit, A, with its capital B, Pl. III. Fig. 12, or the
glass alembic and capital, Fig. 13. of one piece, is employed. This
latter is managed by means of a tubulated opening T, fitted with a
ground stopper of cristal; the capital, both of the cucurbit and
alembic, has a furrow or trench, r r, intended for conveying the
condensed liquor into the beak RS, by which it runs out. As, in almost
all distillations, expansive vapours are produced, which might burst the
vessels employed, we are under the necessity of having a small hole, T,
Fig. 9. in the balloon or recipient, through which these may find vent;
hence, in this way of distilling, all the products which are permanently
aeriform are entirely lost, and even such as difficultly lose that state
have not sufficient space to condense in the balloon: This apparatus is
not, theref