to be passed over so slightly as the last.

Lime is strongly alkaline. In nature it is not met with in its simple
state, as its affinity for water and carbonic acid is so great, that it
is always found combined with these substances, with which it forms the
common lime-stone; but it is separated in the kiln from these
ingredients, which are volatilised whenever a sufficient degree of heat
is applied.

EMILY.

Pure lime, then, is nothing but lime-stone, which has been deprived, in
the kiln, of its water and carbonic acid?

MRS. B.

Precisely: in this state it is called _quick-lime_, and it is so
caustic, that it is capable of decomposing the dead bodies of animals
very rapidly, without their undergoing the process of putrefaction.
--I have here some quick lime, which is kept carefully corked up in a
bottle to prevent the access of air; for were it at all exposed to the
atmosphere, it would absorb both moisture and carbonic acid gas from it,
and be soon slaked. Here is also some lime-stone--we shall pour a little
water on each, and observe the effects that result from it.

CAROLINE.

How the quick-lime hisses! It is become excessively hot! --It swells,
and now it bursts and crumbles to powder, while the water appears to
produce no kind of alteration on the lime-stone.

MRS. B.

Because the lime-stone is already saturated with water, whilst the
quick-lime, which has been deprived of it in the kiln, combines with it
with very great avidity, and produces this prodigious disengagement of
heat, the cause of which I formerly explained to you; do you
recollect it?

EMILY.

Yes; you said that the heat did not proceed from the lime, but from the
water which was _solidified_, and thus parted with its heat of
liquidity.

MRS. B.

Very well. If we continue to add successive quantities of water to the
lime after being slaked and crumbled as you see, it will then gradually
be diffused in the water, till it will at length be dissolved in it, and
entirely disappear; but for this purpose it requires no less than 700
times its weight of water. This solution is called _lime-water_.

CAROLINE.

How very small, then, is the proportion of lime dissolved!

MRS. B.

Barytes is still of more difficult solution; it dissolves only in 900
times its weight of water: but it is much more soluble in the state of
crystals. The liquid contained in this bottle is lime-water; it is often
used as a medicine, chiefly, I believe, for