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Lead. 
Previous to the ore being smelted, it requires to be se- 
parated as much as possible from the earthy matter in 
which it is imbedded. Although galena, which is the ore 
used for smelting, is most frequently accompanied by 
sulphat of barytes, fluats and carbonat of lime, it is found 
to exist in crystallized distinct masses, and can be sepa- 
rated from it by mechanical means to a tolerable extent. 
The whole of the ore, with the earthy matter, is pounded 
to a certain degree with hammers ; this is chiefly perform- 
ed by women. In some places, however, it is broken 
down by passing it through iron rollers pressed together 
by great weights. After the ore has been thus reduced, 
the earthy matter is separated by washing. The powder 
to be washed is introduced into a sieve or riddle, and 
placed in a large tub full of water. By a certain motion 
given to the riddle, the lighter or earthy parts are thrown 
over the edge of the same, while the galena, by its greater 
specific gravity, is retained. This process requires great 
dexterity, which can be acquired by experience only. 
There are, however, some impurities which cannot be 
separated by this mechanical process, and are generally 
smelted with the ore. These are blind * or black-jack , ; 
called by the smelter mock ore, pyrites, or sulphuret of 
iron, named brazil by the workmen. When the ore 
abounds much with these substances, the process of 
smelting is more difficult, and requires an extra assistance 
of flux to reduce it. 
In the state above described, the ore is introduced at the 
hopper in the middle of the roof of the furnace, and spread 
upon the concave hearth, to expose it as much to the flame 
as possible, in order to facilitate the escape of the sulphur. 
This should be performed by a long continued heat which 
is not violent , in order that the sulphuret itself may not 
be volatilized, an effect which, more or less, always takes 
place. The moment the sulphur has left the lead, it be- 
* Blende. Sulphuret of zinc. — -T. C. 
