tters, p. 346.

"I have been inclined to think that the fluid _fire_, as well as the
fluid _air_, is attracted by plants in their growth, and becomes
consolidated with the other materials of which they are formed, and
makes a great part of their substance; that, when they come to be
digested, and to suffer in the vessels a kind of fermentation, part of
the fire, as well as part of the air, recovers its fluid active state
again, and diffuses itself in the body, digesting and separating it;
that the fire so re-produced, by digestion and separation, continually
leaving the body, its place is supplied by fresh quantities, arising
from the continual separation; that whatever quickens the motion of the
fluids in an animal, quickens the separation, and re-produces more of
the fire, as exercise; that all the fire emitted by wood, and other
combustibles, when burning, existed in them before in a solid state,
being only discovered when separating; that some fossils, as sulphur,
sea-coal, &c. contain a great deal of solid fire; and that, in short,
what escapes and is dissipated in the burning of bodies, besides water
and earth, is generally the air and fire, that before made parts of the
solid."

FOOTNOTES:

[8] I conclude from the experiments of M. Lavoisier, which were made
with a much better burning lens than I had an opportunity of making use
of, that there was no _real calcination_ of the metals, though they were
made to _fume_ in inflammable or nitrous air; because he was not able to
produce more than a slight degree of calcination in any given quantity
of common air.

SECTION IX.

_Of MARINE ACID AIR._

Being very much struck with the result of an experiment of the Hon. Mr.
Cavendish, related Phil. Trans. Vol. LVI. p. 157, by which, though, he
says, he was not able to get any inflammable air from copper, by means
of spirit of salt, he got a much more remarkable kind of air, viz. one
that lost its elasticity by coming into contact with water, I was
exceedingly desirous of making myself acquainted with it. On this
account, I began with making the experiment in quicksilver, which I
never failed to do in any case in which I suspected that air might
either be absorbed by water, or be in any other manner affected by it;
and by this means I presently got a much more distinct idea of the
nature and effects of this curious solution.

Having put some copper filings into a small phial, with a quantity of
spirit of sa