1Mix one part of this ore, when it has been roasted,
crushed, and washed, with
three parts of some powder compound which melts ore, and six parts of lead.
Put the charge into the triangular crucible, place it in the iron hoop to which
the double bellows reaches, and heat first in a slow fire, and afterward
gradually in a fiercer fire, till it melts and flows like water. If the ore does
not melt, add to it a little more of these fluxes, mixed with an equal portion
of yellow litharge, and stir it with a hot iron rod until it all melts. Then
take the crucible out of the hoop, shake off the button when it has cooled,
and when it has been cleansed, melt first in the scorifier and afterward in
the cupel. Finally, rub the gold which has settled in the bottom of the cupel,
after it has been taken out and cooled, on the touchstone, in order to find out
what proportion of silver it contains. Another method is to put a centum
pondium (of the lesser weights) of gold ore into the triangular crucible, and
add to it a drachma (of the larger weights) of glass-galls. If it resists melting,
add half a drachma of roasted argol, and if even then it resists, add the
same quantity of roasted lees of vinegar, or lees of the aqua which separates
gold from silver, and the button will settle in the bottom of the crucible.
Melt this button again in the scorifier and a third time in the cupel.
three parts of some powder compound which melts ore, and six parts of lead.
Put the charge into the triangular crucible, place it in the iron hoop to which
the double bellows reaches, and heat first in a slow fire, and afterward
gradually in a fiercer fire, till it melts and flows like water. If the ore does
not melt, add to it a little more of these fluxes, mixed with an equal portion
of yellow litharge, and stir it with a hot iron rod until it all melts. Then
take the crucible out of the hoop, shake off the button when it has cooled,
and when it has been cleansed, melt first in the scorifier and afterward in
the cupel. Finally, rub the gold which has settled in the bottom of the cupel,
after it has been taken out and cooled, on the touchstone, in order to find out
what proportion of silver it contains. Another method is to put a centum
pondium (of the lesser weights) of gold ore into the triangular crucible, and
add to it a drachma (of the larger weights) of glass-galls. If it resists melting,
add half a drachma of roasted argol, and if even then it resists, add the
same quantity of roasted lees of vinegar, or lees of the aqua which separates
gold from silver, and the button will settle in the bottom of the crucible.
Melt this button again in the scorifier and a third time in the cupel.
We determine in the following way, before it is melted in the muffle
furnace, whether pyrites contains gold in it or not: if, after being three times
roasted and three times quenched in sharp vinegar, it has not broken nor
changed its colour, there is gold in it. The vinegar by which it is quenched
should be mixed with salt that is put in it, and frequently stirred and dissolved
for three days. Nor is pyrites devoid of gold, when, after being roasted and
then rubbed on the touchstone, it colours the touchstone in the same way that
it coloured it when rubbed in its crude state. Nor is gold lacking in that,
whose concentrates from washing, when heated in the fire, easily melt, giving
forth little smell and remaining bright; such concentrates are heated in the
fire in a hollowed piece of charcoal covered over with another charcoal.
furnace, whether pyrites contains gold in it or not: if, after being three times
roasted and three times quenched in sharp vinegar, it has not broken nor
changed its colour, there is gold in it. The vinegar by which it is quenched
should be mixed with salt that is put in it, and frequently stirred and dissolved
for three days. Nor is pyrites devoid of gold, when, after being roasted and
then rubbed on the touchstone, it colours the touchstone in the same way that
it coloured it when rubbed in its crude state. Nor is gold lacking in that,
whose concentrates from washing, when heated in the fire, easily melt, giving
forth little smell and remaining bright; such concentrates are heated in the
fire in a hollowed piece of charcoal covered over with another charcoal.
We also assay gold ore without fire, but more often its sand or the
con
centrates which have been made by washing, or the dust gathered up by
some other means. A little of it is slightly moistened with water and heated
until it begins to exhale an odour, and then to one portion of ore are placed
two portions of quicksilver28 in a wooden dish as deep as a basin. They are
mixed together with a little brine, and are then ground with a wooden pestle
for the space of two hours, until the mixture becomes of the thickness of dough,
and the quicksilver can no longer be distinguished from the concentrates
made by the washing, nor the concentrates from the quicksilver. Warm, or
at least tepid, water is poured into the dish and the material is washed until
the water runs out clear. Afterward cold water is poured into the same dish,
and soon the quicksilver, which has absorbed all the gold, runs together
into a separate place away from the rest of the concentrates made by
washing. The quicksilver is afterward separated from the gold by means
of a pot covered with soft leather, or with canvas made of woven
threads of cotton; the amalgam is poured into the middle of the cloth or
centrates which have been made by washing, or the dust gathered up by
some other means. A little of it is slightly moistened with water and heated
until it begins to exhale an odour, and then to one portion of ore are placed
two portions of quicksilver28 in a wooden dish as deep as a basin. They are
mixed together with a little brine, and are then ground with a wooden pestle
for the space of two hours, until the mixture becomes of the thickness of dough,
and the quicksilver can no longer be distinguished from the concentrates
made by the washing, nor the concentrates from the quicksilver. Warm, or
at least tepid, water is poured into the dish and the material is washed until
the water runs out clear. Afterward cold water is poured into the same dish,
and soon the quicksilver, which has absorbed all the gold, runs together
into a separate place away from the rest of the concentrates made by
washing. The quicksilver is afterward separated from the gold by means
of a pot covered with soft leather, or with canvas made of woven
threads of cotton; the amalgam is poured into the middle of the cloth or