that contains it.

EMILY.

This, then, is one of the bodies that oxydates spontaneously without the
application of heat?

MRS. B.

Yes; and it has this remarkable peculiarity that it attracts oxygen much
more rapidly from water than from air; so that when thrown into water,
however cold, it actually bursts into flame. I shall now throw a small
piece, about the size of a pin's head, on this drop of water.

CAROLINE.

It instantaneously exploded, producing a little flash of light! this is,
indeed, a most curious substance!

MRS. B.

By its combustion it is reconverted into potash; and as potash is now
decidedly a compound body, I shall not enter into any of its properties
till we have completed our review of the simple bodies; but we may here
make a few observations on its basis, potassium. If this substance is
left in contact with air, it rapidly returns to the state of potash,
with a disengagement of heat, but without any flash of light.

EMILY.

But is it not very singular that it should burn better in water than in
air?

CAROLINE.

I do not think so: for if the attraction of potassium for oxygen is so
strong that it finds no more difficulty in separating it from the
hydrogen in water, than in absorbing it from the air, it will no doubt
be more amply and rapidly supplied by water than by air.

MRS. B.

That cannot, however, be precisely the reason, for when potassium is
introduced under water, without contact of air, the combustion is not so
rapid, and indeed, in that case, there is no luminous appearance; but a
violent action takes place, much heat is excited, the potash is
regenerated, and hydrogen gas is evolved.

Potassium is so eminently combustible, that instead of requiring, like
other metals, an elevation of temperature, it will burn rapidly in
contact with water, even below the freezing point. This you may witness
by throwing a piece on this lump of ice.

CAROLINE.

It again exploded with flame, and has made a deep hole in the ice.

MRS. B.

This hole contains a solution of potash; for the alkali being extremely
soluble, disappears in the water at the instant it is produced. Its
presence, however, may be easily ascertained, alkalies having the
property of changing paper, stained with turmeric, to a red colour; if
you dip one end of this slip of paper into the hole in the ice you will
see it change colour, and the same, if you wet it with the drop of water
in which the first piece of