Lead 1 
241 
lead however, is not converted into oxyd. There are al- 
ways some refractory lumps remaining, which are col- 
lected, melted over again, and worked up in the next 
charge. (These are probably parts of the lead, alloyed 
with silver, zinc or antimony, or all three.) 
The fire is well kept up during the whole time; but as 
the mouths of the furnace and also of the lire places are 
kept constantly open to expose the surface of the lead to 
the air, the heat never exceeds a full cherry-red. The 
smoke and dust passes up the chimney situated over the 
mouth of the furnace. 
At the end of about 5 hours the lead is converted into 
grey ashes, but it takes a continued heat of about 24 hours 
to convert it into massicot ; during this time, it is raked 
just enough to prevent its clotting, and forming lumps, 
as well as any tendency to fusion. It is then raked out 
upon the floor of the apartment which is well and neatly 
paved with hard brick. In this state while on the floor, 
it is wetted with water and raked ; and when cold it as- 
sumes the colour of yellow ochre. In this wet state it is 
taken away and ground between two mill- stones. But 
this operation does not grind it fine enough. Kence, af- 
ter it has been discharged from the mill-stones into the tub 
placed to receive it, a man takes it up in a copper basin, 
and agitates it under water in another vessel, until by 
turning the basin round backward and forward in a half 
circle, all the fine part is washed out of the basin and falls 
into the tub of water, while the coarse sediment in the ba- 
sin, is thrown aside, either to be ground or remelted. It 
is this sediment which is employed to form the dam or 
ledge in front of the furnace, used to keep in the charge 
of melted lead. The massicot so ground and washed, 
subsides ; the water is turned off from it, and it is then 
carried to the furnace again for the next operation. Some 
manufacturers use the same furnace ; others more con- 
Vo i,. Ill, Hh 
