runs down on to the lower layer of wood ; and when this is consumed by
the fire, the metal is collected. If necessity demand, it is melted over and
over again in the same manner, but it is finally melted by means of wood
laid over the large crucible, the slabs of lead being placed upon it.
The concentrates from washing are smelted together with slags (fluxes ?)
in a third furnace, of which the tap-hole is always open.
It is worth while to build vaulted dust-chambers over the furnaces,
especially over those in which the precious ores are to be smelted, in order
that the thicker part of the fumes, in which metals are not wanting, may be
caught and saved. In this way two or more furnaces are combined under the
same vaulted ceiling, which is supported by the wall, against which the
furnaces are built, and by four columns. Under this the smelters of the
ore perform their work. There are two openings through which the fumes
rise from the furnaces into the wide vaulted chamber, and the wider this is the
more fumes it collects ; in the middle of this chamber over the arch is an opening
three palms high and two wide. This catches the fumes of both furnaces,
which have risen up from both sides of the vaulted chamber to its arch, and
have fallen again because they could not force their way out ; and they thus
pass out through the opening mentioned, into the chimney which the Greeks
call καπνοΰόχη, the name being taken from the object. The chimney has
thin iron plates fastened into the walls, to which the thinner metallic substances adhere when ascending with the fumes. The thicker metallic
substances, or cadmia,25 adhere to the vaulted chamber, and often
harden into stalactites. On one side of the chamber is a window in which
are set panes of glass, so that the light may be transmitted, but the fumes
kept in ; on the other side is a door, which is kept entirely closed while the
ores are being smelted in the furnaces, so that none of the fumes may escape.
It is opened in order that the workman, passing through it, may be enabled
to enter the chamber and remove the soot and pompholyx26 and chip off
t6Cadmia. In the German Translation this is given as kobelt. It would be of uncertain
character, but no doubt partially furnace calamine. (See note on p. 112.)
^Pompholyx (Interpretatio gives the German as Weisser hütten rauch als ober dem garherde
und ober dem kupfer of en). This was the impure protoxide of zinc deposited in the furnace
outlets, and is modern " tutty." The ancient products, no doubt, contained arsenical
oxides as well. It was well known to the Ancients, and used extensively for medicinal purposes, they dividing it into two species—pompholyx and spodos. The first adequate description is by Dioscorides (V, 46) : " Pompholyx differs from spodos in species, not in genus.
" For spodos is blacker, and is often heavier, full of straws and hairs, like the refuse that is
" swept from the floors of copper smelters. But pompholyx is fatty, unctuous, white and light
" enough to fly in the air. Of this there are two kinds—the one inclines to sky blue and is
" unctuous ; the other is exceedingly white, and is extremely light. White pompholyx is
" made every time that the artificer, in the preparation and perfecting of copper (brass ?)
" sprinkles powdered cadmia upon it to make it more perfect, for the soot which rises being
" very fine becomes pompholyx. Other pompholyx is made, not only in working copper
" (brass ?), but is also made from cadmia by continually blowing with bellows. The manner
" of doing it is as follows :—The furnace is constructed in a two-storied building, and there
" is a medium-sized aperture opening to the upper chamber ; the building wall nearest the
" furnace is pierced with a small opening to admit the nozzle of the bellows. The building must
" have a fair-sized door for the artificer to pass in and out. Another small building must
" adjoin this, in which are the bellows and the man who works them. Then the charcoal
" in the furnace is lighted, and the artificer continually throws broken bits of cadmia from
" the place above the furnace, whilst his assistant, who is below, throws in charcoals, until
" all of the cadmia inside is consumed. By this means the finest and lightest part of the
