. The
_caoutchouc_, though originally white, becomes black from the smoke to
which it is exposed while drying. It is in this state brought down to
the coast and sold to the traders.

"Oh yes," said David. "This is the material with which Mr Mackintosh
makes his waterproof coats. He found that it could be re-dissolved in
petroleum; and by covering two pieces of woollen or cotton stuff with
the liquid, and uniting them by a strong pressure, he formed a material
through which no water can penetrate. Some time afterwards, Messrs.
Handcock and Broding discovered that, by the addition of a small
quantity of sulphur to the _caoutchouc_, it acquired the property of
retaining the same consistency in every temperature without losing its
elasticity. A further discovery was made by Mr Goodyear, who, by
adding about twenty per cent of sulphur, converted it into so hard a
substance that all sorts of articles can be manufactured from it for
which tortoise-shell had hitherto been chiefly used--indeed, it is
difficult to say what cannot be made out of it."

Besides india-rubber, the blacks had several huge lumps of ebony and a
small number of elephants' tusks, which they had either purchased from
other natives further in the interior, or were carrying down to the
coast to sell for the original owners on commission. The ebony was
brought from the hilly country, where alone the ebony-tree grows. It is
one of the finest and most graceful of African trees. The trunk, five
or six feet in diameter at the base, rises to the height of fifty or
sixty feet, when fine heavy boughs branch forth, with large dark green
and long and pointed leaves hanging in clusters. Next to the bark is a
white sap wood, and within that the black wood. This does not appear
till the tree has reached a growth of two or three feet in diameter, so
that young trees are not cut down. The trunk and even the branches of
the mature tree become hollow. It generally grows in clumps of three or
four together, scattered about the forest.

Nearly all the negro tribes on this part of the coast have the spirit of
trade strongly implanted in them; and I cannot help thinking that it is
so for the purpose of ultimately bringing about their civilisation,
which the nefarious slave-trade has so long retarded. That trade is one
of the sins which lies at England's door, and she should endeavour to
make amends for the crime, by using every means in her power for the
spread o