Or to a líbra of the
powder prepared from such metalliferous
concentrates, is added a libra each of salt, of saltpetre, of argol, and of
glass-galls, and it is heated until it melts. When cooled and crushed, it is washed,
then to it is added a libra of silver, a third of copper filings, a sixth of litharge,
and it is likewise heated again until it melts. After the button has been
purged of slag, it is put into the cupel, and the gold and silver are separated
from the lead; the gold is parted from the silver with aqua valens. Or else
a líbra of the powder prepared from such metalliferous concentrates,
a quarter of a libra of copper filings, and two librae of that second powder32
which fuses ores, are heated until they melt. The mixture when cooled is again
reduced to powder, roasted and washed, and in this manner a blue powder is
obtained. Of this, and silver, and that second powder which fuses ores, a
libra each are taken, together with three librae of lead, and a quarter of a
libra of copper, and they are heated together until they melt; then the
button is treated as before. Or else a libra of the powder prepared from
such metalliferous concentrates, half a libra of saltpetre, and a quarter of a
líbra of salt are heated until they melt. The alloy when cooled is again
crushed to powder, one libra of which is absorbed by four pounds of molten
silver. Or else a líbra of the powder made from that kind of concentrates,
together with a libra of sulphur, a libra and a half of salt, a third of a libra of
salt made from argol, and a third of a líbra of copper resolved into powder
with sulphur, are heated until they melt. Afterward the lead is re-melted,
and the gold is separated from the other metals. Or else a líbra of the
powder of this kind of concentrates, together with two líbrae of salt, half a
líbra of sulphur, and one libra of litharge, are heated, and from these the
gold is melted out. By these and similar methods concentrates containing
gold, if there be a small quantity of them or if they are very rich, can be
smelted outside the blast furnace.
concentrates, is added a libra each of salt, of saltpetre, of argol, and of
glass-galls, and it is heated until it melts. When cooled and crushed, it is washed,
then to it is added a libra of silver, a third of copper filings, a sixth of litharge,
and it is likewise heated again until it melts. After the button has been
purged of slag, it is put into the cupel, and the gold and silver are separated
from the lead; the gold is parted from the silver with aqua valens. Or else
a líbra of the powder prepared from such metalliferous concentrates,
a quarter of a libra of copper filings, and two librae of that second powder32
which fuses ores, are heated until they melt. The mixture when cooled is again
reduced to powder, roasted and washed, and in this manner a blue powder is
obtained. Of this, and silver, and that second powder which fuses ores, a
libra each are taken, together with three librae of lead, and a quarter of a
libra of copper, and they are heated together until they melt; then the
button is treated as before. Or else a libra of the powder prepared from
such metalliferous concentrates, half a libra of saltpetre, and a quarter of a
líbra of salt are heated until they melt. The alloy when cooled is again
crushed to powder, one libra of which is absorbed by four pounds of molten
silver. Or else a líbra of the powder made from that kind of concentrates,
together with a libra of sulphur, a libra and a half of salt, a third of a libra of
salt made from argol, and a third of a líbra of copper resolved into powder
with sulphur, are heated until they melt. Afterward the lead is re-melted,
and the gold is separated from the other metals. Or else a líbra of the
powder of this kind of concentrates, together with two líbrae of salt, half a
líbra of sulphur, and one libra of litharge, are heated, and from these the
gold is melted out. By these and similar methods concentrates containing
gold, if there be a small quantity of them or if they are very rich, can be
smelted outside the blast furnace.
If there be much of them and they are poor, then they are smelted in the
blast furnace, especially the ore which is not crushed to powder, and particularly
when the gold mines yield an abundance of it33. The gold concentrates mixed
with litharge and hearth-lead, to which are added iron-scales, are smelted in the
blast furnace whose tap-hole is intermittently closed, or else in the first or the
second furnaces in which the tap-hole is always open. In this manner an
blast furnace, especially the ore which is not crushed to powder, and particularly
when the gold mines yield an abundance of it33. The gold concentrates mixed
with litharge and hearth-lead, to which are added iron-scales, are smelted in the
blast furnace whose tap-hole is intermittently closed, or else in the first or the
second furnaces in which the tap-hole is always open. In this manner an