ese conversations. Unless you follow some
such plan, you cannot expect to retain nearly all that you learn, how
great soever be the impression it may make on you at first.

EMILY.

I will certainly follow your advice. --Hitherto I have found that I
recollected pretty well what you have taught us; but the history of
carbon is a more extensive subject than any of the simple bodies we have
yet examined.

MRS. B.

I have little more to say on carbon at present; but hereafter you will
see that it performs a considerable part in most chemical operations.

CAROLINE.

That is, I suppose, owing to its entering into the composition of so
great a variety of substances?

MRS. B.

Certainly; it is the basis, you have seen, of all vegetable matter; and
you will find that it is very essential to the process of animalization.
But in the mineral kingdom also, particularly in its form of carbonic
acid, we shall often discover it combined with a great variety of
substances.

In chemical operations, carbon is particularly useful, from its very
great attraction for oxygen, as it will absorb this substance from many
oxygenated or burnt bodies, and thus deoxygenate, or _unburn_ them, and
restore them to their original combustible state.

CAROLINE.

I do not understand how a body can be _unburnt_, and restored to its
original state. This piece of tinder, for instance, that has been burnt,
if by any means the oxygen were extracted from it, would not be restored
to its former state of linen; for its texture is destroyed by burning,
and that must be the case with all organized or manufactured substances,
as you observed in a former conversation.

MRS. B.

A compound body is decomposed by combustion in a way which generally
precludes the possibility of restoring it to its former state; the
oxygen, for instance, does not become fixed in the tinder, but it
combines with its volatile parts, and flies off in the shape of gas, or
watery vapour. You see, therefore, how vain it would be to attempt the
recomposition of such bodies. But, with regard to simple bodies, or at
least bodies whose component parts are not disturbed by the process of
oxygenation or deoxygenation, it is often possible to restore them,
after combustion, to their original state. --The metals, for instance,
undergo no other alteration by combustion than a combination with
oxygen; therefore, when the oxygen is taken from them, they return to
their pure metallic state