ith the alcohol in
which the resin is dissolved, and the latter will be precipitated in the
form of a white cloud--

EMILY.

It is so. And yet how is it that pictures or drawings, varnished with
this solution, may safely be washed with water?

MRS. B.

As the varnish dries, the alcohol evaporates, and the dry varnish or
resin which remains, not being soluble in water, will not be acted on
by it.

There is a class of compound resins called _gum-resins_, which are
precisely what their name denotes, that is to say, resins combined with
mucilage. Myrrh and assafoetida are of this description.

CAROLINE.

Is it possible that a substance of so disagreeable a smell as assafoetida
can be formed from a volatile oil?

MRS. B.

The odour of volatile oils is by no means always grateful. Onions and
garlic derive their smell from volatile oils, as well as roses and
lavender.

There is still another form under which volatile oils present
themselves, which is that of _balsams_. These consist of resinous juices
combined with a peculiar acid, called the benzoic acid. Balsams appear
to have been originally volatile oils, the oxygenation of which has
converted one part into a resin, and the other part into an acid, which,
combined together, form a balsam; such are the balsams of Peru, Tolu,
&c.

We shall now take leave of the oils and their various modifications, and
proceed to the next vegetable substance, which is _caoutchouc_. This is
a white milky glutinous fluid, which acquires consistence, and blackens
in drying, in which state it forms the substance with which you are so
well acquainted, under the name of gum-elastic.

CAROLINE.

I am surprised to hear that gum-elastic was ever white, or ever fluid!
And from what vegetable is it procured?

MRS. B.

It is obtained from two or three different species of trees, in the
East-Indies, and South-America, by making incisions in the stem. The
juice is collected as it trickles from these incisions, and moulds of
clay, in the form of little bottles of gum-elastic, are dipped into it.
A layer of this juice adheres to the clay and dries on it; and several
layers are successively added by repeating this till the bottle is of
sufficient thickness. It is then beaten to break down the clay, which is
easily shaken out. The natives of the countries where this substance is
produced sometimes make shoes and boots of it by a similar process, and
they are said to be extremely pleas