96 
Brass* 
In all, the copper was the purest Japanese, and the mix- 
ture was made in the way above mentioned. With 8 
drams of copper and as much zinc, much of the latter un- 
avoidably burnt off and the alloy only weighed 12 in- 
stead of 16 drams, the mixture was hard, brittle, yellow, 
and of a radiated texture. With 16 drams of copper and 
8 of zinc, the loss by burning was only one sixth of a 
dram. The alloy was softer than the last, still radiated, 
yellow, and began to be a little malleable. From this, 
successively diminishing the proportions of zinc, the al- 
loy became softer, more malleable, and of a colour more 
and more approaching to gold : and at last, with 11 or 
12 of copper and 1 of zinc, the finest golden tombac was 
produced. According to Wiegleb the Manheim gold 
is made by melting separately 3 parts of copper and 1 of 
zinc, mixing them, covering with charcoal, stirring with 
a stick and cooling immediately. These proportions 
scarcely differ from those of some kinds of brass. Beaume 
gives for the same metal 4 of copper and 1 of zinc, 
whence it is obvious that the proportions are quite arbi- 
trary, but it appears that the alloy is not made, as brass is 
by cementation, but by simple mixture of the metals, 
A very small quantity of tin is sometimes employed, but 
this metal has the disadvantage of remarkably diminish- 
ing the malleability of copper and its alloys. A fine mal- 
leable tombac is made, however, with 16 of copper, 1 of 
zinc, and 1 of tin. An alloy of 12 of brass and 1 of tin 
is scarcely malleable. 
A kind of tombac is the material of which a large pro- 
portion of the Roman coins was composed. Klaproth on 
analyzing several, struck during the first century of the 
emperors, found them all to consist either of pure copper, 
m of copper and zinc, in which the latter metal made ge- 
nerally from a fifth to a sixth of the mass® A little tin 
