it is the sudden evolution
of these which occasions the sound.

EMILY.

Would not oxy-muriat of potash make stronger gunpowder than nitrat of
potash?

MRS. B.

Yes; but the preparation, as well as the use of this salt, is attended
with so much danger, that it is never employed for that purpose.

CAROLINE.

There is no cause to regret it, I think; for the common gunpowder is
quite sufficiently destructive.

MRS. B.

I can show you a very curious experiment with this salt; but it must
again be on condition that you will never attempt to repeat it by
yourselves. I throw a small piece of phosphorus into this glass of
water; then a little oxy-muriat of potash; and, lastly, I pour in (by
means of this funnel, so as to bring it in contact with the two other
ingredients at the bottom of the glass) a small quantity of sulphuric
acid--

CAROLINE.

This is, indeed, a beautiful experiment! The phosphorus takes fire and
burns from the bottom of the water.

EMILY.

How wonderful it is to see flame bursting out under water, and rising
through it! Pray, how is this accounted for?

MRS. B.

Cannot you find it out, Caroline?

EMILY.

Stop--I think I can explain it. Is it not because the sulphuric acid
decomposes the salt by combining with the potash, so as to liberate the
oxy-muriatic acid gas by which the phosphoric is set on fire?

MRS. B.

Very well, Emily; and with a little more reflection you would have
discovered another concurring circumstance, which is, that an increase
of temperature is produced by the mixture of the sulphuric acid and
water, which assists in promoting the combustion of the phosphorus.

I must, before we part, introduce to your acquaintance the
newly-discovered substance IODINE, which you may recollect we placed
next to oxygen and chlorine in our table of simple bodies.

CAROLINE.

Is this also a body capable of maintaining combustion like oxygen and
chlorine?

MRS. B.

It is; and although it does not so generally disengage light and heat
from inflammable bodies, as oxygen and chlorine do, yet it is capable of
combining with most of them; and sometimes, as in the instance of
potassium and phosphorus, the combination is attended with an actual
appearance of light and heat.

CAROLINE.

But what sort of a substance is iodine: what is its form, and colour?

MRS. B.

It is a very singular body, in many respects. At the ordinary
temperature of the atmosphere, it commonly ap