of the same size and shape, and without a spout, but having three holes, two of
which are below the mouth and receive the spouts of the two first pots ; the
third hole is on the opposite side at the bottom, and through it the sulphur
flows out. In each furnace are placed two pots with spouts, and the furnace
must be covered by plates of iron smeared over with lute two digits thick ; it is
thus entirely closed in, but for two or three ventholes through which the mouths
of the pots project. Outside of the furnace, against one side, is placed the pot
without a spout, into the two holes of which the two spouts of the other pots
penetrate, and this pot should be built in at both sides to keep it steady. When
the sulphur ore has been placed in the pots, and these placed in the furnace,
they are closely covered, and it is desirable to smear the joint over with lute,
so that the sulphur will not exhale, and for the same reason the pot below is
covered with a lid, which is also smeared with lute. The wood having been
kindled, the ores are heated until the sulphur is exhaled, and the vapour,
arising through the spout, penetrates into the lower pot and thickens into
sulphur, which falls to the bottom like melted wax. It then flows out
through the hole, which, as I said, is at the bottom of this pot ; and the workman makes it into cakes, or thin sticks or thin pieces of wood are dipped in it.
Then he takes the burning wood and glowing charcoal from the furnace, and
when it has cooled, he opens the two pots, empties the residues, which, if the
ores were composed of sulphur and earth, resemble naturally extinguished
ashes ; but if the ores consisted of sulphur and earth and stone, or sulphur
and stone only, they resemble earth completely dried or stones well roasted.
Afterward the pots are re-filled with ore, and the whole work is repeated.
The sulphurous mixture, whether it consists of stone and sulphur only,
or of stone and sulphur and metal, may be heated in similar pots, but with
perforated bottoms. Before the furnace is constructed, against the " second "
wall of the works two lateral partitions are built seven feet high, three feet
long, one and a half feet thick, and these are distant from each other twentyseven feet. Between them are seven low brick walls, that measure but
two feet and the same number of digits in height, and, like the other walls,
are three feet long and one foot thick; these little walls are at equal
distances from one another, consequently they will be two and one half feet
apart. At the top, iron bars are fixed into them, which sustain iron plates
three feet long and wide and one digit thick, so that they can bear not only
the weight of the pots, but also the fierceness of the fire. These plates have
in the middle a round hole one and a half digits wide ; there must not be
more than eight of these, and upon them as many pots are placed. These
pots are perforated at the bottom, and the same number of whole pots are
placed underneath them ; the former contain the mixture, and are covered
with lids ; the latter contain water, and their mouths are under the holes
in the plates. After wood has been arranged round the upper pots and
ignited, the mixture being heated, red, yellow, or green sulphur drips
from it and flows down through the hole, and is caught by the pots placed
underneath the plates, and is at once cooled by the water. If the mixture
contains metal, it is reserved for smelting, and, if not, it is thrown away.
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