and a quarter of a libra of argol ; they should be melted in a crucible on a
slow fire for three hours, then the alloy is put into molten silver that it
may melt more rapidly. Or a libra of the same crude gold, crushed up, is
mixed together with half a libra of stibium likewise crushed, and put
into a crucible with half an uncia of copper filings, and heated until they
melt, then a sixth part of granulated lead is thrown into the same crucible.
As soon as the mixture emits an odour, iron-filings are added to it, or if these
are not at hand, iron hammer-scales, for both of these break the strength of
the stibium. When the fire consumes it, not alone with it is some strength
of the stibium consumed, but some particles of gold and also of silver, if it
be mixed with the gold29. When the button has been taken out of the
crucible and cooled, it is melted in a cupel, first until the antimony is exhaled,
and thereafter until the lead is separated from it.
Crushed pyrites which contains gold is smelted in the same way ; it
and the stibium should be of equal weight, and in truth the gold may be
made from them in a number of different ways30. One part of crushed
material is mixed with six parts of copper, one part of sulphur, half a part of
salt, and they are all placed in a pot and over them is poured wine distilled
by heating liquid argol in an ampulla. The pot is covered and smeared
over with lute and is put in a hot place, so that the mixture moistened with
wine may dry for the space of six days, then it is heated for three hours over
a gentle fire that it may combine more rapidly with the lead. Finally it is put
into a cupel and the gold is separated from the lead31.
Or else one libra of the concentrates from washing pyrites, or other stones
to which gold adheres, is mixed with half a libra of salt, half a libra of argol,
a third of a libra of glass-galls, a sixth of a libra of gold or silver slags, and a
sicilicus of copper. The crucible into which these are put, after it has been
covered with a lid, is sealed with lute and placed in a small furnace that is
provided with small holes through which the air is drawn in, and then it is
heated until it turns red and the substances put in have alloyed ; this should
take place within four or five hours. The alloy having cooled, it is again
crushed to powder and a pound of litharge is added to it ; then it is heated
again in another crucible until it melts. The button is taken out, purged of
slag, and placed in a cupel, where the gold is separated from the lead.
t9Quod cum ignis consumit non modo una cum eo, quae ipsius stibii vis est, aliqua auri
particula, sei etiam argenti, si cum auro fuerit permistum, consumitur. The meaning is by no
means clear. On p. 451 is set out the old method of parting silver from gold with antimony
sulphide, of which this may be a variation. The silver combines with sulphur, and the reduced
antimony forms an alloy with the gold. The added iron and copper would also combine with
the sulphur from the antimony sulphide, and no doubt assist by increasing the amount of free
collecting agent and by increasing the volume of the matte. (See note 17, p. 451.)
s There follow eight different methods of treating crude bullion or rich concentrates.
In a general way three methods are involved,—ist, reduction with lead or antimony, and
cupellation ; 2nd, reduction with silver, and separation with nitric acid ; 3rd, reduction
with lead and silver, followed by cupellation and parting with nitric acid. The use of sulphur
or antimony sulphide would tend to part out a certain amount of silver, and thus obtain
fairly pure bullion upon cupellation. But the introduction of copper could only result
deleteriously, except that it is usually accompanied by sulphur in some form, and would thus
probably pass off harmlessly as a matte carrying silver. (See note 33 below.)
81It is not very clear where this lead comes from. Should it be antimony ? The
German translation gives this as "silver."
