Pyrites, when they contain not only copper, but also silver, are smelted
in the manner I described when I treated of ores of silver. But if they are
poor in silver, and if the copper which is melted out of them cannot easily be
treated, they are smelted according to the method which I last explained.
in the manner I described when I treated of ores of silver. But if they are
poor in silver, and if the copper which is melted out of them cannot easily be
treated, they are smelted according to the method which I last explained.
Finally, the copper schists containing bitumen or sulphur are roasted,
and then smelted with stones which easily fuse in a fire of the second order,
and are made into cakes, on the top of which the slags float. From
these cakes, usually roasted seven times and re-melted, are melted out
slags and two kinds of cakes; one kind is of copper and occupies the
bottom of the crucible, and these are sold to the proprietors of the works in
which silver is parted from copper; the other kind of cakes are usually
re-melted with primary cakes. If the schist contains but a small amount of
copper, it is burned, crushed under the stamps, washed and sieved, and
the concentrates obtained from it are melted down; from this are made
cakes from which, when roasted, copper is made. If either chrysocolla or azure,
or yellow or black earth containing copper and silver, adheres to the schist,
it is not washed, but is crushed and smelted with stones which easily
fuse in fire of the second order.
and then smelted with stones which easily fuse in a fire of the second order,
and are made into cakes, on the top of which the slags float. From
these cakes, usually roasted seven times and re-melted, are melted out
slags and two kinds of cakes; one kind is of copper and occupies the
bottom of the crucible, and these are sold to the proprietors of the works in
which silver is parted from copper; the other kind of cakes are usually
re-melted with primary cakes. If the schist contains but a small amount of
copper, it is burned, crushed under the stamps, washed and sieved, and
the concentrates obtained from it are melted down; from this are made
cakes from which, when roasted, copper is made. If either chrysocolla or azure,
or yellow or black earth containing copper and silver, adheres to the schist,
it is not washed, but is crushed and smelted with stones which easily
fuse in fire of the second order.
Lead ore, whether it be molybdaena47, pyrites,
(galena?) or stone from
which it is melted, is often smelted in a special furnace, of which I have
spoken above, but no less often in the third furnace of which the tap-hole
is always open. The hearth and forehearth are made from powder containing
a small portion of iron hammer-scales; iron slag forms the principal flux
for such ores; both of these the expert smelters consider useful and to
the owner's advantage, because it is the nature of iron to attract lead. If
it is molybdaena or the stone from which lead is smelted, then the lead runs
down from the furnace into the forehearth, and when the slags have been
skimmed off, the lead is poured out with a ladle. If pyrites are smelted,
the first to flow from the furnace into the forehearth, as may be seen at
Goslar, is a white molten substance, injurious and noxious to silver, for it
consumes it. For this reason the slags which float on the top having been
skimmed off, this substance is poured out; or if it hardens, then it is taken
out with a hooked bar; and the walls of the furnace exude the same substance48.
which it is melted, is often smelted in a special furnace, of which I have
spoken above, but no less often in the third furnace of which the tap-hole
is always open. The hearth and forehearth are made from powder containing
a small portion of iron hammer-scales; iron slag forms the principal flux
for such ores; both of these the expert smelters consider useful and to
the owner's advantage, because it is the nature of iron to attract lead. If
it is molybdaena or the stone from which lead is smelted, then the lead runs
down from the furnace into the forehearth, and when the slags have been
skimmed off, the lead is poured out with a ladle. If pyrites are smelted,
the first to flow from the furnace into the forehearth, as may be seen at
Goslar, is a white molten substance, injurious and noxious to silver, for it
consumes it. For this reason the slags which float on the top having been
skimmed off, this substance is poured out; or if it hardens, then it is taken
out with a hooked bar; and the walls of the furnace exude the same substance48.