At one end of each furnace is the fire chamber,
which may be nine cubic feet inside; next to that is the ore chamber of
about the same size; and beyond that is the condensing chamber, in
which there are a number of partitions alternately running up from the
bottom and down from the top, with a space for the fumes to pass, their
course being up and down, and up and down again, and so on, for a
distance of thirty feet to the chimney, which is forty feet high. In
the bottom of the condensing chamber is water. The walls between the
fire chamber and the ore chamber, and between the latter and the
condensing chamber, are built with open spaces, so that the heat, smoke
and fumes can pass through. The ore is placed in the ore chamber in
such a manner as to leave many open spaces. The heat drives off the
sulphur and mercury of the ore in fumes, which in passing through the
condensing chambers, deposit the mercury, and the smoke and sulphur
escape through the chimney. In the Enriqueta and Guadalupe mines the
quicksilver is condensed in a close iron retort, and the sulphur is
absorbed by quicklime.

Copper ore is dug from several mines in California, but it is all
exported to be smelted elsewhere.

_Platinum._--Platinum, iridium and osmium, three white metals of about
the same specific gravity with gold, are found with the latter metal in
the placers in the basin of the Klamath and Trinity Rivers. Their
particles are usually fine scales, very rarely reaching a quarter of an
ounce in weight, and the largest piece of either ever found was less
than an ounce and a half. They cannot be separated from the gold by
washing, but they do not unite with quicksilver, and therefore they are
separated from the more precious metal by amalgamation. They have no
regular market in the state; miners never make them the chief object of
search, and they have not been studied, so it is not known to what
extent they might be obtained.

_Del Norte and Klamath._--Del Norte county in the north-western corner
of the state, is about forty miles long from east to west by thirty
from north to south. The mining population in it is small. Most of the
mining is done along the banks of the Klamath River, which runs about
twenty miles through the south-eastern portion of the county. There are
some miners on the head-waters of Althouse Creek, which runs northward
into Oregon. The county assessor, in his report for 1860, does not
mention the existence of any qua