Agricola, Georgius, De re metallica, 1912/1950

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1When the masses of lead are to be melted, the workman first places the wood
in
the hearth so that one end of each billet faces the wall, and the other end
the
dipping-pot.
Then, assisted by other workmen, he pushes the mass
of
lead forward with crowbars on to a low trolley, and draws it to the
crane
.
The trolley consists of planks fastened together, is two and one-half
feet
wide and five feet long, and has two small iron axles, around which at
each
end revolve small iron wheels, two palms in diameter and as many digits
wide
.
The trolley has a tongue, and attached to this is a rope, by which it is
drawn
to the crane.
The crane is exactly similar to those in the second part
of
the works, except that the crane-arm is not so long.
The tongs in whose
jaws
6 the masses of lead are seized, are two feet a palm and two digits long;
both
of the jaws, when struck with a hammer, impinge upon the mass and are
driven
into it.
The upper part of both handles of the tongs are curved back,
the
one to the right, the other to the left, and each handle is engaged in one
of
the lowest links of two short chains, which are three links long.
The upper
links
are engaged in a large round ring, in which is fixed the hook of a chain
let
down from the pulley of the crane-arm.
When the crank of the crane
is
turned, the mass is lifted and is carried by the crane-arm to the hearth and
placed
on the wood.
The workmen wheel up one mass after another and
place
them in a similar manner on the wood of the hearth; masses which
weigh
a total of about a hundred and sixty centumpondía7 are usually placed
upon
the wood and melted at one time.
Then a workman throws charcoal
on
the masses, and all are made ready in the evening.
If he fears that it may
rain
, he covers it up with a cover, which may be moved here and there; at the
back
this cover has two legs, so that the rain which it collects may flow down
the
slope on to the open ground.
Early in the morning of the following day,
he
throws live coals on the charcoal with a shovel, and by this method the
masses
of lead melt, and from time to time charcoal is added.
The lead, as
soon
as it begins to run into the dipping-pot, is ladled out with an iron ladle
into
copper moulds such as the refiners generally use.
If it does not cool
immediately
he pours water over it, and then sticks the pointed pick into
it
and pulls it out.
The pointed end of the pick is three palms long and
the
round end is two digits long.
It is necessary to smear the moulds with a
wash
of lute, in order that, when they have been turned upside down and
struck
with the broad round end of the pick, the cakes of lead may fall out
easily
.
If the moulds are not washed over with the lute, there is a risk that
they
may be melted by the lead and let it through.
Others take hold of a
billet
of wood with their left hand, and with the heavy lower end of it they
pound
the mould, and with the right hand they stick the point of the pick
into
the cake of lead, and thus pull it out.
Then immediately the workman
pours
other lead into the empty moulds, and this he does until the work of
melting
the lead is finished.
When the lead is melted, something similar to
litharge
is produced; but it is no wonder that it should be possible to make

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