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BOOK XI
foreman of the works mixes these thorns with other precious thorns. The
hearth-lead which remains in the middle of the crucible, and the hearth
material which absorbs silver-lead, is mixed with other hearth-lead which
remains in the cupellation furnace crucible ; and yet some cakes, made rich
in this manner, may be placed again in the cupellation furnaces, together
with the rest of the silver-lead cakes which the refiner has made.
The inhabitants of the Carpathian Mountains, if they have an abundance
of finely crushed copper35 or lead either made from "slags," or collected
from the furnace in which the exhausted liquation cakes are dried, or
litharge, alloy them in various ways. The " first " alloy consists of two
centumpondia of lead melted out of thorns, litharge, and thorns made
from hearth-lead, and of half a centumpondium each of lead collected in
the furnace in which exhausted liquation cakes are " dried," and of copper
minutum, and from these are made liquation cakes ; the task of the smelter is
finished when he has made forty liquation cakes of this kind. The
" second " alloy consists of two centumpondia of litharge, of one and a
quarter centumpondia of de-silverized lead or lead from " slags," and of half
a centumpondium of lead made from thorns, and of as much copper minutum.
The "third" alloy consists of three centumpondia of ütharge and of half a
centumpondium each of de-silverized lead, of lead made from thorns, and of
copper minutum contusum. Liquation cakes are made from all these alloys ; the
task of the smelters is finished when they have made thirty cakes.
The process by which cakes are made among the Tyrolese, from which
they separate the silver-lead, I have explained in Book IX.
Silver is separated from iron in the following manner. Equal portions of
iron scales and filings and of stibium are thrown into an earthenware crucible
which, when covered with a lid and sealed, is placed in a furnace, into
which air is blown. When this has melted and again cooled, the crucible
is broken ; the button that settles in the bottom of it, when taken out,
is pounded to powder, and the same weight of lead being added, is mixed
and melted in a second crucible ; at last this button is placed in a cupel
and the lead is separated from the silver.36
There are a great variety of methods by which one metal is separated
from other metals, and the manner in which the same are alloyed I have
explained partly in the eighth book of De Natura Fossilium, and partly I will
explain elsewhere. Now I will proceed to the remainder of my subject.
*sParticulis aeris tusï. Unless this be the fine concentrates from crushing the material
mentioned, we are unable to explain the expression.
8eThis operation would bring down a button of antimony under an iron matte, by
de-sulphurizing the antimony. It would seem scarcely necessary to add lead before cupellation. This process is given in an assay method, in the Probierbüchlein (folio 31) 50 years
before De Re Metallica : " How to separate silver from iron : Take that silver which is
" in iron filechen (filachmal), pulverize it finely, take the same iron or filec one part, spiesglasz
" (antimony sulphide) one part, leave them to melt in a crucible placed in a closed windtofen.
" When it is melted, let it cool, break the crucible, chip off the button that is in the bottom,
" and melt it in a crucible with as much lead. Then break the crucible, and seek from the
" button in the cupel, and you will find what silver it contains."
END OF BOOK XI
