ashes fall from the burnt wood, which is supported by iron rods, arranged to
form a grating. The middle chamber is two feet high, and the wood is pushed
in through its mouth. The wood ought to be oak, holmoak, or turkey-oak,
for from these the slow and lasting fire is made which is necessary for this
operation. The upper chamber is open at the top so that the pots, for which
it has the depth, may be put into it ; the floor of this chamber consists of iron
rods, so strong that they may bear the weight of the pots and the heat of the
fire ; they are sufficiently far apart that the fire may penetrate well and may
heat the pots. The pots are narrow at the bottom, so that the fire entering
into the space between them may heat them ; at the top the pots are wide,
so that they may touch and hold back the heat of the fire. The upper part
of the furnace is closed in with bricks not very thick, or with tiles and lute,
and two or three air-holes are left, through which the fumes and flames may
escape.
The gold granules or leaves and the cement, alternately placed in the pots,
are heated by a gentle fire, gradually increasing for twenty-four hours, if the
furnace was heated for two hours before the full pots were stood in it, and if
this was not done, then for twenty-six hours. The fire should be increased
in such a manner that the pieces of gold and the cement, in which is the
potency to separate the silver and copper from the gold, may not melt, for in
this case the labour and cost will be spent in vain ; therefore, it is ample to
have the fire hot enough that the pots always remain red. After so many
hours all the burning wood should be drawn out of the furnace. Then the
refractory bricks or tiles are removed from the top of the furnace, and the
glowing pots are taken out with the tongs. The Hds are removed, and
if there is time it is well to allow the gold to cool by itself, for then there is
less loss ; but if time cannot be spared for that operation, the pieces of gold
are immediately placed separately into a wooden or bronze vessel of water
and gradually quenched, lest the cement which absorbs the silver should
exhale it. The pieces of gold, and the cement adhering to them, when cooled
or quenched, are rolled with a little mallet so as to crush the lumps and free
the gold from the cement. Then they are sifted by a fine sieve, which is
placed over a bronze vessel ; in this manner the cement containing the
silver or the copper or both, falls from the sieve into the bronze vessel, and the
gold granules or leaves remain on it. The gold is placed in a vessel and
again rolled with the little mallet, so that it may be cleansed from the cement
which absorbs silver and copper.
The particles of cement, which have dropped through the holes of the
sieve into the bronze vessel, are washed in a bowl, over a wooden tub, being
shaken about with the hands, so that the minute particles of gold which have
fallen through the sieve may be separated. These are again washed in a
little vessel, with warm water, and scrubbed with a piece of wood or a twig
broom, that the moistened cement may be detached. Afterward all the gold
is again washed with warm water, and collected with a bristle brush, and should
be washed in a copper full of holes, under which is placed a little vessel.
Then it is necessary to put the gold on an iron plate, under which is a vessel,
