B.

By its combustion. Water is composed of eighty-five parts, by weight, of
oxygen, combined with fifteen parts of hydrogen; or of two parts, by
bulk of hydrogen gas, to one part of oxygen gas.

CAROLINE.

Really! is it possible that water should be a combination of two gases,
and that one of these should be inflammable air! Hydrogen must be a most
extraordinary gas that will produce both fire and water.

EMILY.

But I thought you said that combustion could take place in no gas but
oxygen?

MRS. B.

Do you recollect what the process of combustion consists in?

EMILY.

In the combination of a body with oxygen, with disengagement of light
and heat.

MRS. B.

Therefore when I say that hydrogen is combustible, I mean that it has an
affinity for oxygen; but, like all other combustible substances, it
cannot burn unless supplied with oxygen, and also heated to a proper
temperature.

CAROLINE.

The simply mixing fifteen parts of hydrogen, with eighty-five parts of
oxygen gas, will not, therefore, produce water?

MRS. B.

No; water being a much denser fluid than gases, in order to reduce these
gases to a liquid, it is necessary to diminish the quantity of caloric
or electricity which maintains them in an elastic form.

EMILY.

That I should think might be done by combining the oxygen and hydrogen
together; for in combining they would give out their respective
electricities in the form of caloric, and by this means would be
condensed.

CAROLINE.

But you forget, Emily, that in order to make the oxygen and hydrogen
combine, you must begin by elevating their temperature, which increases,
instead of diminishing, their electric energies.

MRS. B.

Emily is, however, right; for though it is necessary to raise their
temperature, in order to make them combine, as that combination affords
them the means of parting with their electricities, it is eventually the
cause of the diminution of electric energy.

CAROLINE.

You love to deal in paradoxes to-day, Mrs. B. --Fire, then, produces
water?

MRS. B.

The combustion of hydrogen gas certainly does; but you do not seem to
have remembered the theory of combustion so well as you thought you
would. Can you tell me what happens in the combustion of hydrogen gas?

CAROLINE.

The hydrogen combines with the oxygen, and their opposite electricities
are disengaged in the form of caloric. --Yes, I think I understand it
now--by the loss of this caloric, the ga