orce;
and if we place the flame of a lamp in the current, you will see how
violently the flame is driven in that direction.

CAROLINE.

It seems to be exactly the same effect as that of a blow-pipe worked by
the mouth, only much stronger.

EMILY.

Yes; and this new instrument has this additional advantage, that it does
not fatigue the mouth and lungs like the common blow-pipe, and requires
no art in blowing.

MRS. B.

Unquestionably; but yet this blow-pipe would be of very limited utility,
if its energy and power could not be greatly increased by some other
contrivance. Can you imagine any mode of producing such an effect?

EMILY.

Could not the reservoir be charged with pure oxygen, instead of common
air, as in the case of the gas-holder?

MRS. B.

Undoubtedly; and this is precisely the contrivance I allude to. The
vessel need only be supplied with air from a bladder full of oxygen,
instead of the air of the room, and this, you see, may be easily done by
screwing the bladder on the upper part of the syringe, so that in
working the syringe the oxygen gas is forced from the bladder into the
condensing vessel.

CAROLINE.

With the aid of this small apparatus, therefore, we could obtain the
same effects as those we have just produced with the gas-holder, by
means of a column of water forcing the gas out of it?

MRS. B.

Yes; and much more conveniently so. But there is a mode of using this
apparatus by which more powerful effects still may be obtained. It
consists in condensing in the reservoir, not oxygen alone, but a mixture
of oxygen and hydrogen in the exact proportion in which they unite to
produce water; and then kindling the jet formed by the mixed gases. The
heat disengaged by this combustion, without the help of any lamp, is
probably the most intense known; and various effects are said to have
been obtained from it which exceed all expectation.

CAROLINE.

But why should we not try this experiment?

MRS. B.

Because it is not exempt from danger; the combustion (notwithstanding
various contrivances which have been resorted to with a view to prevent
accident) being apt to penetrate into the inside of the vessel, and to
produce a dangerous and violent explosion. --We shall, therefore, now
proceed in our subject.

CAROLINE.

I think you said the oxyds of metals could be restored to their metallic
state?

MRS. B.

Yes; this is called _reviving_ a metal. Metals are in general capable of