1the other on the left.
Finally, outside the hearth is the receiving-pit, which
is a foot wide and three palms deep; when this is worn away it is restored
with lute alone, which easily retains the lead alloy.
is a foot wide and three palms deep; when this is worn away it is restored
with lute alone, which easily retains the lead alloy.
If four liquation cakes are placed on the plates of each furnace, then the
iron blocks are laid under them; but if the cakes are made from copper
“bottoms,” or from liquation thorns, or from the accretions or “slags,” of
which I have partly written above and will further describe a little later,
there are five of them, and because they are not so large and heavy, no blocks
are placed under them. Pieces of charcoal six digits long are laid between the
cakes, lest they should fall one against the other, or lest the last one should
fall against the wall which protects the third long wall from injury by fire. In
the middle empty spaces, long and large pieces of charcoal are likewise laid.
Then when the panels have been set up, and the bar has been closed, the
furnace is filled with small charcoal, and a wicker basket full of charcoal is
thrown into the receiving-pit, and over that are thrown live coals; soon
afterward the burning coal, lifted up in a shovel, is spread over all parts of
the furnace, so that the charcoal in it may be kindled; any charcoal which
remains in the receiving-pit is thrown into the passage, so that it may likewise
be heated. If this has not been done, the silver-lead alloy liquated from the
cakes is frozen by the coldness of the passage, and does not run down into the
receiving-pit.
iron blocks are laid under them; but if the cakes are made from copper
“bottoms,” or from liquation thorns, or from the accretions or “slags,” of
which I have partly written above and will further describe a little later,
there are five of them, and because they are not so large and heavy, no blocks
are placed under them. Pieces of charcoal six digits long are laid between the
cakes, lest they should fall one against the other, or lest the last one should
fall against the wall which protects the third long wall from injury by fire. In
the middle empty spaces, long and large pieces of charcoal are likewise laid.
Then when the panels have been set up, and the bar has been closed, the
furnace is filled with small charcoal, and a wicker basket full of charcoal is
thrown into the receiving-pit, and over that are thrown live coals; soon
afterward the burning coal, lifted up in a shovel, is spread over all parts of
the furnace, so that the charcoal in it may be kindled; any charcoal which
remains in the receiving-pit is thrown into the passage, so that it may likewise
be heated. If this has not been done, the silver-lead alloy liquated from the
cakes is frozen by the coldness of the passage, and does not run down into the
receiving-pit.
After a quarter of an hour the cakes begin to drip silver-lead alloy,18
which runs down through the openings between the copper plates into the
passage. When the long pieces of charcoal have burned up, if the cakes
lean toward the wall, they are placed upright again with a hooked bar, but
if they lean toward the front bar they are propped up by charcoal; more
over, if some cakes shrink more than the rest, charcoal is added to the former
and not to the others. The silver drips together with the lead, for both melt
more rapidly than copper. The liquation thorns do not flow away, but remain
in the passage, and should be turned over frequently with a hooked bar, in
order that the silver-lead may liquate away from them and flow down into
the receiving pit; that which remains is again melted in the blast furnace,
while that which flows into the receiving pit is at once carried with the remain
which runs down through the openings between the copper plates into the
passage. When the long pieces of charcoal have burned up, if the cakes
lean toward the wall, they are placed upright again with a hooked bar, but
if they lean toward the front bar they are propped up by charcoal; more
over, if some cakes shrink more than the rest, charcoal is added to the former
and not to the others. The silver drips together with the lead, for both melt
more rapidly than copper. The liquation thorns do not flow away, but remain
in the passage, and should be turned over frequently with a hooked bar, in
order that the silver-lead may liquate away from them and flow down into
the receiving pit; that which remains is again melted in the blast furnace,
while that which flows into the receiving pit is at once carried with the remain
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