100 Brass', 
out shewing any east of yellow when polished, not very 
liable to tarnish, quite free from pores even when examine 
ed by a lens, of a certain coherence or toughness to bear 
the grinder, and for the convenience of working, as soft 
as may be consistent with the other requisites® 
Mr, Mudge, whose specula were celebrated for their 
goodness, observes, that the extreme of whiteness is giv- 
en by 32 parts of copper and 16 of tin, but this is excess- 
ively hard and brittle ; that 32 of copper with 14 1-2 of 
tin is still quite white and as hard as can be wrought. He 
also observed by many trials, that the metal to turn out 
free from pores should be twice fused, that is, the first 
time for the purpose of mixture (in which the copper is to 
be first melted separately) and then remelted with as little 
heat as possible, for casting. As there is always some 
loss by the calcination, chiefly of the tin, a little allowance 
in the proportion of this latter may be made on account 
of the double fusion. 
The most elaborate mixture hnd accurate directions ori 
this important subject are given by Mr. Edwards, whose 
specula are of extreme excellence, and are published in 
the nautical almanac for 1787, of which the following are 
the leading particulars. 
The quality of the copper should first be tried by add- 
ing successively from so much short of half its weight of 
tin that it proves a little yellow, to the full half of tin, and 
by comparison ascertaining the maximum of whiteness, 
observing that beyond this point the alloy begins to lose 
part of the brilliance of fracture and to become bluish. 
When this is found, take 32 parts of the copper, melt it, 
add one part of brass and as much silver, with a little 
black flux* to cover the surface ; when these are melted,, 
stir with a wooden rod, and pour in from 15 to 16 parts 
of tin (according as found necessary by previous experi- 
ment) fused in a separate crucible with a low heat, stir the 
f Crude Tartar deflagrated with nitre® T. C. 
