Because lead and copper ores and their metals have much in common
with silver ores, it is fitting that I should say a great deal concerning them,
both now and later on. Also in the same manner, pyrites are smelted separ
ately if there be much of them. To three parts of roasted lead or copper
ore and one part of crude ore, are added concentrates if they were made by
washing the same ore, together with slags, and all are put in the third furnace
whose tap-hole is always open. Cakes are made from this charge, which,
when they have been quenched with water, are roasted. Of these roasted
cakes generally four parts are again mixed with one part of crude pyrites
and re-melted in the same furnace. Cakes are again made from this charge,
and if there is a large amount of copper in these cakes, copper is made
immediately after they have been roasted and re-melted; if there is little
copper in the cakes they are also roasted, but they are re-smelted with a little
soft slag. In this method the molten lead in the forehearth absorbs the
silver. From the pyritic material which floats on the top of the forehearth
are made cakes for the third time, and from them when they have been
roasted and re-smelted is made copper. Similarly, three parts of roasted
cadmia38 in which there is silver, are mixed with one part of crude pyrites,
together with slag, and this charge is smelted and cakes are made from it;
these cakes having been roasted are re-smelted in the same furnace. By this
method the lead contained in the forehearth absorbs the silver, and the silver
lead is taken to the cupellation furnace. Crude quartz and stones which
easily fuse in fire of the third order, together with other ores in which there
is a small amount of silver, ought to be mixed with crude roasted pyrites or
cadmía, because the roasted cakes of pyrites or cadmía cannot be
profitably smelted separately. In a similar manner earths which contain
little silver are mixed with the same; but if pyrites and cadmia are not
available to the smelter, he smelts such silver ores and earths with litharge,
hearth-lead, slags, and stones which easily melt in the fire. The concentrates39
originating from the washing of rudis silver, after first being roasted40 until
they melt, are smelted with mixed litharge and hearth-lead, or else, after
being moistened with water, they are smelted with cakes made from pyrites
and cadmia. By neither of these methods do (the concentrates) fall
back in the furnace, or fly out of it, driven by the blast of the bellows and the
agitation of the fire. If the concentrates originated from galena they are
smelted with it after having been roasted; and if from pyrites, then with
pyrites.
with silver ores, it is fitting that I should say a great deal concerning them,
both now and later on. Also in the same manner, pyrites are smelted separ
ately if there be much of them. To three parts of roasted lead or copper
ore and one part of crude ore, are added concentrates if they were made by
washing the same ore, together with slags, and all are put in the third furnace
whose tap-hole is always open. Cakes are made from this charge, which,
when they have been quenched with water, are roasted. Of these roasted
cakes generally four parts are again mixed with one part of crude pyrites
and re-melted in the same furnace. Cakes are again made from this charge,
and if there is a large amount of copper in these cakes, copper is made
immediately after they have been roasted and re-melted; if there is little
copper in the cakes they are also roasted, but they are re-smelted with a little
soft slag. In this method the molten lead in the forehearth absorbs the
silver. From the pyritic material which floats on the top of the forehearth
are made cakes for the third time, and from them when they have been
roasted and re-smelted is made copper. Similarly, three parts of roasted
cadmia38 in which there is silver, are mixed with one part of crude pyrites,
together with slag, and this charge is smelted and cakes are made from it;
these cakes having been roasted are re-smelted in the same furnace. By this
method the lead contained in the forehearth absorbs the silver, and the silver
lead is taken to the cupellation furnace. Crude quartz and stones which
easily fuse in fire of the third order, together with other ores in which there
is a small amount of silver, ought to be mixed with crude roasted pyrites or
cadmía, because the roasted cakes of pyrites or cadmía cannot be
profitably smelted separately. In a similar manner earths which contain
little silver are mixed with the same; but if pyrites and cadmia are not
available to the smelter, he smelts such silver ores and earths with litharge,
hearth-lead, slags, and stones which easily melt in the fire. The concentrates39
originating from the washing of rudis silver, after first being roasted40 until
they melt, are smelted with mixed litharge and hearth-lead, or else, after
being moistened with water, they are smelted with cakes made from pyrites
and cadmia. By neither of these methods do (the concentrates) fall
back in the furnace, or fly out of it, driven by the blast of the bellows and the
agitation of the fire. If the concentrates originated from galena they are
smelted with it after having been roasted; and if from pyrites, then with
pyrites.
Pure copper ore, whether it is its own colour or is tinged with chrysocolla
or azure, and copper glance, or grey or black rudis copper, is smelted in a
furnace of which the tap-hole is closed for a very short time, or else is always
or azure, and copper glance, or grey or black rudis copper, is smelted in a
furnace of which the tap-hole is closed for a very short time, or else is always