nch chemist, Fourcroy, has classed two of them
(barytes and strontites) with the alkalies; but as lime and magnesia
have almost an equal title to that rank, I think it better not to
separate them, and therefore have adopted the common method of classing
them with the earths, and of distinguishing them by the name of
_alkaline earths_.

The general properties of alkalies are, an acrid burning taste,
a pungent smell, and a caustic action on the skin and flesh.

CAROLINE.

I wonder they should be caustic, Mrs. B., since they contain so little
oxygen.

MRS. B.

Whatever substance has an affinity for any one of the constituents of
animal matter, sufficiently powerful to decompose it, is entitled to the
appellation of caustic. The alkalies, in their pure state, have a very
strong attraction for water, for hydrogen, and for carbon, which, you
know, are the constituent principles of oil, and it is chiefly by
absorbing these substances from animal matter that they effect its
decomposition; for, when diluted with a sufficient quantity of water, or
combined with any oily substance, they lose their causticity.

But, to return to the general properties of alkalies--they change, as we
have already seen, the colour of syrup of violets, and other blue
vegetable infusions, to green; and have, in general, a very great
tendency to unite with acids, although the respective qualities of these
two classes of bodies form a remarkable contrast.

We shall examine the result of the combination of acids and alkalies
more particularly hereafter. It will be sufficient at present to inform
you, that whenever acids are brought in contact with alkalies, or
alkaline earths, they unite with a remarkable eagerness, and form
compounds perfectly different from either of their constituents; these
bodies are called _neutral_ or _compound salts_.

The dry white powder which you see in this phial is pure caustic POTASH;
it is very difficult to preserve it in this state, as it attracts, with
extreme avidity, the moisture from the atmosphere, and if the air were
not perfectly excluded, it would, in a very short time, be actually
melted.

EMILY.

It is then, I suppose, always found in a liquid state?

MRS. B.

No; it exists in nature in a great variety of forms and combinations,
but is never found in its pure separate state; it is combined with
carbonic acid, with which it exists in every part of the vegetable
kingdom, and is most commonly obtain