81 
is fit for use. For this purpose the same crucibles are 
again employed and are filled, first with three handfuls of 
the mixture of calamine and charcoal, over which are put 
two or three pounds of the impure brass broken in pieces^ 
then more calamine and charcoal, with a lump of the ar~ 
best, and over all, calamine and charcoal powder. The 
crucible is then strongly heated for two hours, after which 
the brass is fit to be cast into plates, which is done here in 
the following manner. 
A mould is formed of two blocks of granite, five feet 
long, three and a half broad, and eight inches thick. They 
are placed one above the other, the upper one being only 
moveable, and furnished with a tackle and pullies for that 
purpose, and before casting, the surface is smeared with 
cow-dung. To give the plate the requisite thickness* 
hoops of iron of different dimensions are adapted to the 
under stone, so as to confine a determinate quantity of 
melted metal. The stones are then gently inclined and 
the melted brass let in between them. These plates are 
afterwards laminated i some of them are cut into slips by 
strong shears, for the further purpose of being drawn into 
wire, and otherwise manufactured in various ways^ 
A single process, where the fire is kept up long enough 
and the materials are good, is certainly sufficient to make 
good malleable brass, but it is probable that the excel- 
lence and beauty of the article are improved by mak- 
ing it undergo a second cementation with fresh calamine 
and charcoal. 
In the laboratory brass may be made very well in the 
small way in a much shorter time. Put into a crucible a 
mixture of calamine and charcoal, bury it in the requisite 
proportion of copper shot, cover the whole with charcoal 
powder, lute on a cover to the crucible, and heat slowly 
in a wind-furnace for half an hour, till the zinc begins to 
burn off in a blue flame round the top of the crucible,, 
L 
