into the water, but into the ground, there is created a sulphurous or a
bituminous substance resembling pompholyx1, and so light that it can be
blown away with a breath. Some employ a vaulted furnace, open at the
front and divided into two chambers. A wall built in the middle of the
furnace divides the lower chamber into two equal parts, in which are set pots
containing water, as above described. The upper chamber is again divided
into three parts, the middle one of which is always open, for in it the wood
is placed, and it is not broader than the middle wall, of which it forms the
topmost portion. The other two compartments have iron doors which are
closed, and which, together with the roof, keep in the heat when the wood
is lighted. In these upper compartments are iron bars which take the place
of a floor, and on these are arranged pots without bottoms, having in
place of a bottom, a grating made of iron wire, fixed to each, through
the openings of which the sulphurous or bituminous vapours roasted from
the ore run into the lower pots. Each of the upper pots holds a hundred
