MINES OF CREMNITZ. 36T 
fusion upon lead; because when the furnace is chap. 
tapped, and the metal begins to flow into a \. 
receiver made with charcoal and claij, they cast l^oni^eul 
lead upon it' : this, after melting, combines 
with the gold and silvery and falls to the bottom 
of the vessel. During this operation, the lighter 
metals — such as copper, iron, cobalt, bismuth, and 
arsenic — rise to the surface, and are raked off 
in the form of scoricr, which they carry, as lech, 
to be fused again in \he Jirst operation. The 
lead J thus combined with gold and silver, is col- 
lected into large crucibles, and carried to the 
fourth fusion, or fifth operation, for the separation 
of the lead, which process will now be described. 
V. The furnace used for the separation of the Purification 
Furnace. 
lead is called a purification furnace. The shape 
of it resembles a hollow sphere, of which the 
upper part is so contrived, that it may be taken 
off like an operculum, being raised by large 
chains*. Here the richest ores that can be 
(1) Sometimes, instead of casting ^urelead into the receiver, they 
wse for this purpose an otc of lead, as galena, which, by the intense heat, 
fuses in the same manner, amidst the other metals. 
(2) A beautiful morfe/ of the purification furnace is exhibited to the 
students at SchemniU, by Professor Muhling ; but even the model is of 
•Hormous size ; and without an engraved representation, flie description 
«>f it must be defective. 
