The bellows which this master uses differ in size from the others, for the
boards are seven and a half feet long; the back part is three feet wide;
the front, where the head is joined on is a foot, two palms and as many digits.
The head is a cubit and a digit long ; the back part of it is a cubit and a
palm wide, and then becomes gradually narrower. The nozzles of the bellows
are bound together by means of an iron chain, controlled by a thick
bar, one end of which penetrates into the ground against the back of the long
wall, and the other end passes under the beam which is laid upon the
foremost perforated beams. These nozzles are so placed in a copper pipe
that they are at a distance of a palm from the mouth ; the mouth should be
made three digits in diameter, that the air may be violently expelled through
this narrow aperture.
There now remain the liquation thorns, the ash-coloured copper, the
" slags," and the codmiaP Liquation cakes are made from thorns in the
following manner.28 There are taken three-quarters of a centumpondium of
thorns, which have their origin from the cakes of copper-lead alloy when
lead-silver is liquated, and as many parts of a centumpondium of the thorns
derived from cakes made from once re-melted thorns by the same method,
and to them are added a centumpondium of de-silverized lead and half a
centumpondium of hearth-lead. If there is in the works plenty of litharge, it
is substituted for the de-silverized lead. One and a half centumpondia of
litharge and hearth-lead is added to the same weight of primary thorns,
and half a centumpondium of thorns which have their origin from liquation
cakes composed of thorns twice re-melted by the same method (tertiary
thorns), and a fourth part of a centumpondium of thorns which are pro-
" made from the cakes of copper. All these methods are carried on in the works of Cyprus ;
" the difference between these substances is that the squamae (copper scales) are detached from
" hammering the cakes, while the flower falls off spontaneously." Agricola (De Nat. Fos.,
p. 352) notes that " flowers of copper (flos ceris) have the same properties as ' roasted
" copper.' "
"It seems scarcely necessary to discuss in detail the complicated " flow scheme " of the
various minor bye-products. They are all re-introduced into the liquation circuit, and thereby
are created other bye-products of the same kind ad infinitum. Further notes are given on:—
There are no data given, either by Agricola or the later authors, which allow satisfactory calculation of the relative quantities of these products. A rough estimate from the
data given in previous notes would indicate that in one liquation only about 70% of the
original copper came out as refined copper, and that about 70% of the original lead would go
to the cupellation furnace, i.e., about 30% of the original metal sent to the blast furnace
Would go into the ' " thorns," " slags," and " ash-coloured copper." The ultimate losses
were very great, as given before (p. 491), they probably amounted to 25% of the silver, 9%
copper, and 16% of the lead.
**There were the following classes of thorns :—
In a general way, according to the later authors, they were largely lead oxide, and
contained from 5% to 20% cuprous oxide. If a calculation be made backward from the
products given as the result of the charge described, it would appear that in this case they must
have contained at least one-fifth copper. The silver in these liquation cakes would run about
24 ozs. per ton, in the liquated lead about 36 ozs. per ton, and in the liquation thorns 24 ozs.
per ton. The extraction into the liquated lead would be about 80% of the silver.