on from being so conspicuous.

CONVERSATION XVII.

OF THE SULPHURIC AND PHOSPHORIC ACIDS; OR THE COMBINATIONS OF OXYGEN
WITH SULPHUR AND PHOSPHORUS; AND OF THE SULPHATS AND PHOSPHATS.

MRS. B.

In addition to the general survey which we have taken of acids, I think
you will find it interesting to examine individually a few of the most
important of them, and likewise some of their principal combinations
with the alkalies, alkaline earths, and metals. The first of the acids,
in point of importance, is the SULPHURIC, formerly called _oil of
vitriol_.

CAROLINE.

I have known it a long time by that name, but had no idea that it was
the same fluid as sulphuric acid. What resemblance or connection can
there be between oil of vitriol and this acid?

MRS. B.

Vitriol is the common name for sulphat of iron, a salt which is formed
by the combination of sulphuric acid and iron; the sulphuric acid was
formerly obtained by distillation from this salt, and it very naturally
received its name from the substance which afforded it.

CAROLINE.

But it is still usually called oil of vitriol?

MRS. B.

Yes; a sufficient length of time has not yet elapsed, since the
invention of the new nomenclature, for it to be generally disseminated;
but, as it is adopted by all scientific chemists, there is every reason
to suppose that it will gradually become universal. When I received this
bottle from the chemists, _oil of vitriol_ was inscribed on the label;
but, as I knew you were very punctilious in regard to the nomenclature,
I changed it, and substituted the words _sulphuric acid_.

EMILY.

This acid has neither colour nor smell, but it appears much thicker than
water.

MRS. B.

It is nearly twice as heavy as water, and has, you see, an oily
consistence.

CAROLINE.

And it is probably from this circumstance that it has been called an
oil, for it can have no real claim to that name, as it does not contain
either hydrogen or carbon, which are the essential constituents of oil.

MRS. B.

Certainly; and therefore it would be the more absurd to retain a name
which owed its origin to such a mistaken analogy.

Sulphuric acid, in its purest state, would probably be a concrete
substance, but its attraction for water is such, that it is impossible
to obtain that acid perfectly free from it; it is, therefore, always
seen in a liquid form, such as you here find it. One of the most
striking properties of sulphuric acid i