of the alloy there is a bes or three-quarters of silver. In this way every week,
if the work is for six days, thirty-six centutnpondia of cakes are made and
three centutnpondia of alloy, in all of which there is often almost twenty-four
librae of silver. The second smelter separates from the primary cakes the
greater part of the silver by absorbing it in lead. To eighteen centumpondia
of cakes made from crude copper ore, he adds twelve centumpondia of hearthlead and litharge, three centumpondia of stones from which lead is smelted,
five centumpondia of hard cakes rich in silver, and two centumpondia of
exhausted liquation cakes45 ; he adds besides, some of the slags resulting
from smelting crude copper, together with a small quantity of concentrates
made from accretions, all of which he melts for the space of twelve hours,
and makes eighteen centumpondia of secondary cakes, and twelve centumpondia of copper-lead-silver alloy ; in each centumpondium of the latter
there is half a libra of silver. After he has taken off the cakes with a
hooked bar, he pours the alloy out into copper or iron moulds ; by this
method they make four cakes of alloy, which are carried to the works in
which silver is parted from copper. On the following day, the same smelter,
taking eighteen centumpondia of the secondary cakes, again adds twelve
centumpondia of hearth-lead and litharge, three centumpondia of stones
from which lead is smelted, five centumpondia of hard cakes rich in silver,
together with slags from the smelting of the primary cakes, and with concentrates washed from the accretions which are usually made at that time.
This charge is likewise smelted for the space of twelve hours, and he makes as
many as thirteen centumpondia of tertiary cakes and eleven centumpondia
of copper-lead-silver alloy, each centumpondium of which contains onethird of a libra and half an uncia of silver. When he has skimmed off the
tertiary cakes with a hooked bar, the alloy is poured into copper moulds, and
by this method four cakes of alloy are made, which, like the preceding four
cakes of alloy, are carried to the works in which silver is parted from copper.
By this method the second smelter makes primary cakes on alternate days
and secondary cakes on the intermediate days. The third smelter takes
eleven cartloads of the tertiary cakes and adds to them three cartloads of
hard cakes poor in silver, together with the slag from smelting the secondary
cakes, and the concentrates from the accretions which are usually made
at that time. From this charge when smelted, he makes twenty centumpondia of quaternary cakes, which are called " hard cakes," and also
fifteen centumpondia of those " hard cakes rich in silver," each centumpondium of which contains a third of a libra of silver. These latter cakes the
second smelter, as I said before, adds to the primary and secondary cakes
when he re-melts them. In the same way, from eleven cartloads of quaternary cakes thrice roasted, he makes the " final " cakes, of which one
centumpondinm contains only half an uncia of silver. In this operation he
also makes fifteen centumpondia of " hard cakes poor in silver," in each
centumpondium of which is a sixth of a libra of silver. These hard cakes the
"Exhausted liquation cakes (panes aerei fathiscentes). This is the copper sponge resulting
from the first liquation of lead, and still contains a considerable amount of lead. The liquation
process is discussed in great detail in Book XI.
