critters
are up to their knees in wather all day, washing di'monds; so they
suffer much from rheumatiz and colds. Och, but it's murther entirely;
an' I've more than wance felt inclined to fill their pockets with
di'monds and set them all free! Jist look, now, there they are, hard at
it."

As he spoke they arrived at the mine. The ground in the vicinity was
all cut up and dug out to a considerable depth, and a dozen Negroes were
standing under a shed washing the earth, while others were engaged in
the holes excavating the material. While Martin watched them his friend
explained the process.

The different kinds of soil through which it is necessary to cut before
reaching the diamond deposit are, first about twenty feet of reddish
sandy soil; then about eight feet of a tough yellowish clay; beneath
this lies a layer of coarse reddish sand, below which is the peculiar
soil in which diamonds are found. It is called by the miners the
_cascalho_, and consists of loose gravel, the pebbles of which are
rounded and polished, having at some previous era been subject to the
action of running water. The bed varies in thickness from one to four
feet and the pebbles are of various kinds; but when there are many of a
species called _Esmerilo preto_, the cascalho is considered to be rich
in diamonds.

Taking Martin round to the back of the shed, Barney showed him a row of
troughs, about three feet square, close to the edge of a pond of water.
These troughs are called _bacos_. In front of each stood a Negro slave
up to his knees in water. Each had a wooden plate, with which he dashed
water upon the rough cascalho as it was thrown into the trough by
another slave. By this means, and by stirring it with a small hoe, the
earth and sand are washed away. Two overseers were closely watching the
process; for it is during this part of the operation that the largest
diamonds are found. These overseers were seated on elevated seats, each
being armed with a long leathern whip, to keep a sharp look-out, for the
slaves are expert thieves.

After the cascalho had been thus purified, it was carefully removed to
the shed to be finally washed.

Here seven slaves were seated on the side of a small canal, about four
feet broad, with their legs in the water nearly up to their knees. This
canal is called the _lavadeira_. Each man had a small wooden platter,
into which another slave, who stood behind him, put a shovelful of
purified casc