1holes, the ashes from the burning charcoal,
as I have stated, fall down, and
air blows into the furnace after passing through the openings in the walls of
the chamber. The furnace is rectangular, and inside at the lower part it is
three palms and one digit wide and three palms and as many digits long. At
the upper part it is two palms and three digits wide, so that it also grows
narrower; it is one foot high; in the middle of the back it is cut out at
the bottom in the shape of a semicircle, of half a digit radius. Not
unlike the furnace before described, it has in its forepart a mouth which is
rounded at the top, one palm high and a palm and a digit wide. Its door
is also made of clay, and this has a window and a handle; even the lid
of the furnace which is made of clay has its own handle, fastened on with iron
wire. The outer parts and sides of this furnace are bound with iron wires,
which are usually pressed in, in the shape of triangles. The brick furnaces
must remain stationary; the clay and iron ones can be carried from one
place to another. Those of brick can be prepared more quickly, while those
of iron are more lasting, and those of clay are more suitable. Assayers
also make temporary furnaces in another way; they stand three bricks
on a hearth, one on each side and a third one at the back, the fore-part lies
open to the draught, and on these bricks is placed an iron plate, upon which
they again stand three bricks, which hold and retain the charcoal.
air blows into the furnace after passing through the openings in the walls of
the chamber. The furnace is rectangular, and inside at the lower part it is
three palms and one digit wide and three palms and as many digits long. At
the upper part it is two palms and three digits wide, so that it also grows
narrower; it is one foot high; in the middle of the back it is cut out at
the bottom in the shape of a semicircle, of half a digit radius. Not
unlike the furnace before described, it has in its forepart a mouth which is
rounded at the top, one palm high and a palm and a digit wide. Its door
is also made of clay, and this has a window and a handle; even the lid
of the furnace which is made of clay has its own handle, fastened on with iron
wire. The outer parts and sides of this furnace are bound with iron wires,
which are usually pressed in, in the shape of triangles. The brick furnaces
must remain stationary; the clay and iron ones can be carried from one
place to another. Those of brick can be prepared more quickly, while those
of iron are more lasting, and those of clay are more suitable. Assayers
also make temporary furnaces in another way; they stand three bricks
on a hearth, one on each side and a third one at the back, the fore-part lies
open to the draught, and on these bricks is placed an iron plate, upon which
they again stand three bricks, which hold and retain the charcoal.
The setting of one furnace differs from another, in that some are placed
higher and others lower; that one is placed higher, in which the man who is
assaying the ore or metals introduces the scorifier through the mouth with the
tongs; that one is placed lower, into which he introduces the crucible
through its open top.
higher and others lower; that one is placed higher, in which the man who is
assaying the ore or metals introduces the scorifier through the mouth with the
tongs; that one is placed lower, into which he introduces the crucible
through its open top.
In some cases the assayer uses an iron hoop4 in place of a furnace;
this is placed upon the hearth of a chimney, the lower edge being daubed
with lute to prevent the blast of the bellows from escaping under it.
If the blast is given slowly, the ore will be smelted and the copper will melt in
the triangular crucible, which is placed in it and taken away again with the
tongs. The hoop is two palms high and half a digit thick; its diameter is
generally one foot and one palm, and where the blast from the bellows enters
into it, it is notched out. The bellows is a double one, such as goldworkers
use, and sometimes smiths. In the middle of the bellows there is a board in
which there is an air-hole, five digits wide and seven long, covered by a
little flap which is fastened over the air-hole on the lower side of the board;
this flap is of equal length and width. The bellows, without its head, is
three feet long, and at the back is one foot and one palm wide and
somewhat rounded, and it is three palms wide at the head; the head itself
is three palms long and two palms and a digit wide at the part where it joins
the boards, then it gradually becomes narrower. The nozzle, of which there
is only one, is one foot and two digits long; this nozzle, and one-half of the
head in which the nozzle is fixed, are placed in an opening of the wall, this
being one foot and one palm thick; it reaches only to the iron hoop on the
this is placed upon the hearth of a chimney, the lower edge being daubed
with lute to prevent the blast of the bellows from escaping under it.
If the blast is given slowly, the ore will be smelted and the copper will melt in
the triangular crucible, which is placed in it and taken away again with the
tongs. The hoop is two palms high and half a digit thick; its diameter is
generally one foot and one palm, and where the blast from the bellows enters
into it, it is notched out. The bellows is a double one, such as goldworkers
use, and sometimes smiths. In the middle of the bellows there is a board in
which there is an air-hole, five digits wide and seven long, covered by a
little flap which is fastened over the air-hole on the lower side of the board;
this flap is of equal length and width. The bellows, without its head, is
three feet long, and at the back is one foot and one palm wide and
somewhat rounded, and it is three palms wide at the head; the head itself
is three palms long and two palms and a digit wide at the part where it joins
the boards, then it gradually becomes narrower. The nozzle, of which there
is only one, is one foot and two digits long; this nozzle, and one-half of the
head in which the nozzle is fixed, are placed in an opening of the wall, this
being one foot and one palm thick; it reaches only to the iron hoop on the
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