If the lead is to be liquated and then brought to a bright-red heat, both operations are carried on in the same reverberatory furnace.
The liquated zinc-silver-lead crust contains 5-10% silver, 30-40% zinc and 65-50% lead.
The retort is pear-shaped, and holds1000-1500lb of charge, consisting of liquated crust mixed with 1-3% of charcoal.
This method is rarely practised except by the rollers of zinc. A certain amount of refined zinc can be dipped from the furnace; a further amount, nearly free from iron, can be liquated out of the ingots cast from the bottom of the bath in a subsequent slow remelting, and it is sometimes possible to eliminate a zinciferous lead which collects in the sump of the furnace.
It is also manufactured by the latter process from the metallic zinc liquated out of galvanizer's dross.