1the older they are, the dryer and
better they are.
The moulds in which the
cupels are moulded are of two kinds, that is, a smaller size and a larger size.
In the smaller ones are made the cupels in which silver or gold is purged
from the lead which has absorbed it; in the larger ones are made cupels in
which silver is separated from copper and lead. Both moulds are made out
of brass and have no bottom, in order that the cupels can be taken out of
them whole. The pestles also are of two kinds, smaller and larger, each
likewise of brass, and from the lower end of them there projects a round
knob, and this alone is pressed into the mould and makes the hollow part of
the cupel. The part which is next to the knob corresponds to the upper
part of the mould.
cupels are moulded are of two kinds, that is, a smaller size and a larger size.
In the smaller ones are made the cupels in which silver or gold is purged
from the lead which has absorbed it; in the larger ones are made cupels in
which silver is separated from copper and lead. Both moulds are made out
of brass and have no bottom, in order that the cupels can be taken out of
them whole. The pestles also are of two kinds, smaller and larger, each
likewise of brass, and from the lower end of them there projects a round
knob, and this alone is pressed into the mould and makes the hollow part of
the cupel. The part which is next to the knob corresponds to the upper
part of the mould.
A—LITTLE MOULD. B—INVERTED MOULD. C—PESTLE. D—ITS
KNOB. E—SECOND
PESTLE.
PESTLE.
So much for these matters.
I will now speak of the preparation of the
ore for assaying. It is prepared by roasting, burning, crushing, and wash
ing. It is necessary to take a fixed weight of ore in order that one may
determine how great a portion of it these preparations consume. The
hard stone containing the metal is burned in order that, when its hardness
has been overcome, it can be crushed and washed; indeed, the very hardest
kind, before it is burned, is sprinkled with vinegar, in order that it may more
rapidly soften in the fire. The soft stone should be broken with a hammer,
crushed in a mortar and reduced to powder; then it should be washed
and then dried again. If earth is mixed with the mineral, it is washed in a
basin, and that which settles is assayed in the fire after it is dried. All mining
products which are washed must again be dried. But ore which is rich in
metal is neither burned nor crushed nor washed, but is roasted, lest that
method of preparation should lose some of the metal. When the fires have
ore for assaying. It is prepared by roasting, burning, crushing, and wash
ing. It is necessary to take a fixed weight of ore in order that one may
determine how great a portion of it these preparations consume. The
hard stone containing the metal is burned in order that, when its hardness
has been overcome, it can be crushed and washed; indeed, the very hardest
kind, before it is burned, is sprinkled with vinegar, in order that it may more
rapidly soften in the fire. The soft stone should be broken with a hammer,
crushed in a mortar and reduced to powder; then it should be washed
and then dried again. If earth is mixed with the mineral, it is washed in a
basin, and that which settles is assayed in the fire after it is dried. All mining
products which are washed must again be dried. But ore which is rich in
metal is neither burned nor crushed nor washed, but is roasted, lest that
method of preparation should lose some of the metal. When the fires have