Brass. 
cable to a vast variety of purposes and capable of being 
wrought with the greatest facility,, 
It is not easy to obtain a perfect union of zinc and cop- 
per by mere fusion in open vessels, for at a heat less than 
is required to melt the copper, the zinc readily takes fire 
and much of it burns off before it has time to mix with 
the other metals, so that the proportion of zinc is con- 
stantly lessening by volatilization. Even after both me- 
tals are fused, the zinc continues to burn off in uncovered 
vessels, and at last scarcely any thing but copper would 
be left. In order therefore to combine copper most inti- 
mately with zinc, and yet to preserve its malleability, 
the ingenious process of cementation has been resorted to 
an the manufacture of brass, which is performed by heat- 
ing in a covered pot alternate layers of copper in small 
pieces, with zinc ore and charcoal, and continuing the fire 
till the copper is thoroughly impregnated with the zinc. 
Zinc being a volatile metal can only be procured from 
its ores by sublimation ; the process for obtaining it 
(which will be described more at length under that article) 
being to heat strongly a mixture of its ore with charcoal 
in a vessel closed on all sides, except where it admits a 
tube, the lower end of which dips in water : as soon as 
the charcoal reduces the oxyd, the metal rises in vapour 
through the tube and condenses in the water below. A 
similar reduction takes place in brass- making, only the 
vapour of the zinc instead of being conveyed out of the 
crucible in which it is formed, unites with the copper en- 
closed in the same vessel, and the whole melts down into 
brass. A less heat is required in brass- making than that 
which fuses copper, the zinc being able to penetrate the 
copper when thoroughly red hot, and melting it down as 
soon as it becomes brass. 
Brass is manufactured in many countries, but no where 
more extensively and better than in England, where 
