Pyrites, when they contain not only copper, but also silver, are smelted
in the manner I described when I treated of ores of silver. But if they are
poor in silver, and if the copper which is melted out of them cannot easily be
treated, they are smelted according to the method which I last explained.
Finally, the copper schists containing bitumen or sulphur are roasted,
and then smelted with stones which easily fuse in a fire of the second order,
and are made into cakes, on the top of which the slags float. From
these cakes, usually roasted seven times and re-melted, are melted out
slags and two kinds of cakes ; one kind is of copper and occupies the
bottom of the crucible, and these are sold to the proprietors of the works in
which silver is parted from copper ; the other kind of cakes are usually
re-melted with primary cakes. If the schist contains but a small amount of
copper, it is burned, crushed under the stamps, washed and sieved, and
the concentrates obtained from it are melted down ; from this are made
cakes from which, when roasted, copper is made. If either chrysocolla or azure,
or yellow or black earth containing copper and silver, adheres to the schist,
it is not washed, but is crushed and smelted with stones which easily
fuse in fire of the second order.
Lead ore, whether it be molybdaena^, pyrites, (galena ?) or stone from
which it is melted, is often smelted in a special furnace, of which I have
spoken above, but no less often in the third furnace of which the tap-hole
is always open. The hearth and forehearth are made from powder containing
a small portion of iron hammer-scales ; iron slag forms the principal flux
for such ores ; both of these the expert smelters consider useful and to
the owner's advantage, because it is the nature of iron to attract lead. If
it is molybdaena or the stone from which lead is smelted, then the lead runs
down from the furnace into the forehearth, and when the slags have been
skimmed off, the lead is poured out with a ladle. If pyrites are smelted,
the first to flow from the furnace into the forehearth, as may be seen at
Goslar, is a white molten substance, injurious and noxious to silver, for it
consumes it. For this reason the slags which float on the top having been
skimmed off, this substance is poured out ; or if it hardens, then it is taken
out with a hooked bar ; and the walls of the furnace exude the same substance48.
*7This expression is usually used for hearth-lead, but in this case the author is apparently
confining himself to lead ore, and apparently refers to lead carbonates. The German Translation gives pleyschweiss. The pyrites mentioned in this paragraph may mean galena, as
pyrites was to Agricola a sort of genera.
ia(Excoquitur) . . . "si vero pyrites, primo è fornace, ut Goselariae videre licet, in
" catinum defluii liquor quidam candidus, argento inimicus et nocivus ; id enìm comburit :
" quo circa recrementis, quae supernatant, detractis effunditur : vel induratus conto uncinato
" extrahitur : eundem liquorem parietes fornacis exudant." In the Glossary the following
statement appears : " Liquor candidus primo è fornace defluens cum Goselariae excoquitur
" pyrites,— kobelt ; quem parietes fornacis exudant,—conterrei." In this latter statement
Agricola apparently recognised that there were two different substances, i.e., that the substance found in the furnace walls—conterfei—was not the same substance as that which
first flowed from the furnace—kobelt. We are at no difficulty in recognizing conterfei as
metallic zinc ; it was long known by that term, and this accidental occurrence is repeatedly
mentioned by other authors after Agricola. The substance which first flowed into the forehearth presents greater difficulties ; it certainly was not zinc. In De Natura Fossilium (p.
347), Agricola says that at Goslar the lead has a certain white slag floating upon it, the
" colour derived from the pyrites (pyriten argenteum) from which it was produced." Pyriten
argenteum was either marcasite or mispickel, neither of which offers much suggestion ; nor are
we able to hazard an explanation of value.
Historical Note on Zinc. The history of zinc metallurgy falls into two distinct
