become acquainted with another acid, the nitric,
which, though it produces less heat on the skin, destroys it still
quicker, and makes upon it an indelible stain. You should never handle
any substances of this kind, without previously dipping your fingers in
water, which will weaken their caustic effects. But, since you will not
repeat the experiment, I must put in the stopper, for the acid attracts
the moisture from the atmosphere, which would destroy its strength and
purity.

EMILY.

Pray, how can sulphuric acid be extracted from sulphat of iron by
distillation?

MRS. B.

The process of distillation, you know, consists in separating substances
from one another by means of their different degrees of volatility, and
by the introduction of a new chemical agent, caloric. Thus, if sulphat
of iron be exposed in a retort to a proper degree of heat, it will be
decomposed, and the sulphuric acid will be volatilised.

EMILY.

But now that the process of forming acids by the combustion of their
radicals is known, why should not this method be used for making
sulphuric acid?

MRS. B.

This is actually done in most manufactures; but the usual method of
preparing sulphuric acid does not consist in burning the sulphur in
oxygen gas (as we formerly did by the way of experiment), but in heating
it together with another substance, nitre, which yields oxygen in
sufficient abundance to render the combustion in common air rapid and
complete.

CAROLINE.

This substance, then, answers the same purpose as oxygen gas?

MRS. B.

Exactly. In manufactures the combustion is performed in a leaden
chamber, with water at the bottom, to receive the vapour and assist its
condensation. The combustion is, however, never so perfect but that a
quantity of _sulphureous_ acid is formed at the same time; for you
recollect that the sulphureous acid, according to the chemical
nomenclature, differs from the sulphuric only by containing less oxygen.

From its own powerful properties, and from the various combinations into
which it enters, sulphuric acid is of great importance in many of the
arts.

It is used also in medicine in a state of great dilution; for were it
taken internally, in a concentrated state, it would prove a most
dangerous poison.

CAROLINE.

I am sure it would burn the throat and stomach.

MRS. B.

Can you think of any thing that would prove an antidote to this poison?

CAROLINE.

A large draught of water to dilu