:&>8 Process for Refining Lead . 
ble quantity of silver with them ; this is generally reduced 
by itself and again refined. 
The litharge as it falls upon the floor of the refinery 
is occasionally removed ; it is in clots at first, hut after 
a short time as it cools it falls for the most part like 
slacked lime, and appears in the brilliant scales it is met 
with in commerce: if it is intended as an article for 
sale, nothing more is necessary than to sift it from 
the clots which have not fallen and pack it in bar- 
rels. 
If, on the contrary, it is intended to be manufac- 
tured into pure lead, it is placed in a reverberatory 
furnace, mixed with clean small-coal, and exposed to 
a heat just sufficient to fuse the litharge. The metal 
as it is reduced flows through an aperture into an 
iron pot, and is cast into pigs for sale. During the re- 
ducing, care is taken to keep the whole surface of the li- 
tharge in the furnace covered with small-coal. 
In some smelt works, instead of a reverberatory fur- 
nace for reducing, a blast furnace is made use of, on ac- 
count of the greater produce, but the lead so reduced is 
never so pure as that made in the wind furnace. The 
oxides of the metals, which require a greater heat to re- 
duce than the lead, are in the blast furnace generally re- 
duced with it. 
The volatile oxides, as zinc, antimony, and arsenic, 
are mostly carried off by evaporation during refining; 
a considerable portion of the oxide of lead itself is 
carried off by evaporation, making the interior of the fur- 
nace so misty and obscure that a person unused to refi- 
ning cannot see more than a few inches into it. 
A considerable portion of these oxides are driven by 
the blast of the bellows through the feeding aper- 
ture, and would be dissipated in the refining- house, to 
the great injury of the workmen’s healths ; to prevent 
