g fixed the glass tube EF, (Pl. vii. fig. 11.) of from 8 to 12
lines diameter, across a furnace, with a small inclination from E to F,
lute the superior extremity E to the glass retort A, containing a
determinate quantity of distilled water, and to the inferior extremity
F, the worm SS fixed into the neck of the doubly tubulated bottle H,
which has the bent tube KK adapted to one of its openings, in such a
manner as to convey such aeriform fluids or gasses as may be disengaged,
during the experiment, into a proper apparatus for determining their
quantity and nature.

To render the success of this experiment certain, it is necessary that
the tube EF be made of well annealed and difficultly fusible glass, and
that it be coated with a lute composed of clay mixed with powdered
stone-ware; besides which, it must be supported about its middle by
means of an iron bar passed through the furnace, lest it should soften
and bend during the experiment. A tube of China-ware, or porcellain,
would answer better than one of glass for this experiment, were it not
difficult to procure one so entirely free from pores as to prevent the
passage of air or of vapours.

When things are thus arranged, a fire is lighted in the furnace EFCD,
which is supported of such a strength as to keep the tube EF red hot,
but not to make it melt; and, at the same time, such a fire is kept up
in the furnace VVXX, as to keep the water in the retort A continually
boiling.

In proportion as the water in the retort A is evaporated, it fills the
tube EF, and drives out the air it contained by the tube KK; the aqueous
gas formed by evaporation is condensed by cooling in the worm SS, and
falls, drop by drop, into the tubulated bottle H. Having continued this
operation until all the water be evaporated from the retort, and having
carefully emptied all the vessels employed, we find that a quantity of
water has passed over into the bottle H, exactly equal to what was
before contained in the retort A, without any disengagement of gas
whatsoever: So that this experiment turns out to be a simple
distillation; and the result would have been exactly the same, if the
water had been run from one vessel into the other, through the tube EF,
without having undergone the intermediate incandescence.

_Experiment Second._

The apparatus being disposed, as in the former experiment, 28 grs. of
charcoal, broken into moderately small parts, and which has previously
been exposed