may
thus be obtained in its separate state.

CAROLINE.

I do not understand how a gas can be absorbed?

MRS. B.

It is only the oxygen, or basis of the gas, which is absorbed; and the
two electricities escaping, that is to say, the negative from the
oxygen, the positive from the burning body, unite and produce caloric.

EMILY.

And what becomes of this caloric?

MRS. B.

We shall make this piece of dry wood attract oxygen from the atmosphere,
and you will see what becomes of the caloric.

CAROLINE.

You are joking, Mrs. B--; you do not mean to decompose the atmosphere
with a piece of dry stick?

MRS. B.

Not the whole body of the atmosphere, certainly; but if we can make this
piece of wood attract any quantity of oxygen from it, a proportional
quantity of atmospherical air will be decomposed.

CAROLINE.

If wood has so strong an attraction for oxygen, why does it not
decompose the atmosphere spontaneously?

MRS. B.

It is found by experience, that an elevation of temperature is required
for the commencement of the union of the oxygen and the wood.

This elevation of temperature was formerly thought to be necessary, in
order to diminish the cohesive attraction of the wood, and enable the
oxygen to penetrate and combine with it more readily. But since the
introduction of the new theory of chemical combination, another cause
has been assigned, and it is now supposed that the high temperature, by
exalting the electrical energies of bodies, and consequently their force
of attraction, facilitates their combination.

EMILY.

If it is true, that caloric is composed of the two electricities, an
elevation of temperature must necessarily augment the electric energies
of bodies.

MRS. B.

I doubt whether that would be a necessary consequence; for, admitting
this composition of caloric, it is only by its being decomposed that
electricity can be produced. Sir H. Davy, however, in his numerous
experiments, has found it to be an almost invariable rule that the
electrical energies of bodies are increased by elevation of temperature.

What means then shall we employ to raise the temperature of the wood, so
as to enable it to attract oxygen from the atmosphere?

CAROLINE.

Holding it near the fire, I should think, would answer the purpose.

MRS. B.

It may, provided you hold it sufficiently close to the fire; for a very
considerable elevation of temperature is required.

CAROLINE.

It has actuall