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2. Platina and copper, of each one ounce, and 
four ounces of tin, melted perfectly together, and 
without lofs. This compound filed freely and eafily, 
bore to be cut with a knife, but broke readily on the 
anvil, of an irregular furface, and dull whitifh co- 
lour. Polifiied, it looked like polifiied. iron. The 
fradture foon tarnifhed to a yellow ; the polifiied 
part grew dull, but retained its colour. \ 
3. A mixture of platina and copper, of each one 
part, and eight of tin, proved fofter than the fore- 
going ; and bore to be fattened a little under the 
hammer. It broke of a very irregular furface, com- 
peted of a great number of bright white plates. The 
fra&ure foon tarnifhed ; the polifiied part retained its 
colour. 
Remark. It is obfervable, that in the firfi: of thefe 
experiments, platina was perfectly taken up by lets 
than half its weight of a mixture of copper and tin ; 
though it could fcarce be made to melt with lels 
than its own weight of either of them feparately, in 
a fire equally, or rather more, intenfe. 
The l'pecific gravity of thefe mixtures turned out, 
upon experiment, a little lefs than by calculation ; 
though the copper and tin, melted together without 
platina, formed a compound fpecifically heavier than 
even the copper by itfelf. 
The feveral mixtures with zinc, bifmuth, regulus 
of antimony and brafs, were likewife weighed hy- 
drofiatically, and found all fomewhat lighter than 
they ought to have been by calculation. As few 
hydrofiatical experiments feem to have been made 
upon zinc and bifmuth, it may be proper to mention, 
