216 
Lead, 
quantity of lead should always be left in the alloy to make 
it fuse easily in the iron pot. 
When the test is removed from the furnace and broken 
up, the litharge will be found to have penetrated to an in- 
considerable but equal depth in the ashes ; that part not 
impregnated with litharge may be pulverised, mixed with 
fresh ashes, and again used for another test. 
The operation of taking off the silver pure, differs in no 
respect from the foregoing, only more care is observed in 
the working, not to suffer the escape of any metallic parti- 
cles with the litharge, as that would occasion considera- 
ble waste of silver. As the process advances, and the pro- 
portion of silver to lead increases, the litharge assumes a 
darker colour, a greater heat becomes necessary, and at 
last the brightening takes place ; the interior of the fur- 
nace, which during the whole of the process had been very 
obscure and misty, clears up. When the operator ob- 
serves the surface of the silver to be free from litharge, he 
removes the blast of the bellows, and suffers the furnace to 
cool gradually ; as the silver cools many protuberances 
arise on the surface, and fluid silver is ejected from them 
with considerable force, which falling again on the plate 
spots it very fantastically with small globules. 
The latter portions of litharge bring over a considera- 
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, but 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 barrels* 
If, on the contrary, it is intended to be manufactured 
into pure lead, it is placed in a reverberatory furnace, 
