2,0 2 Mr. mudge on the ConfiruBion 
All that is ncceiTary, therefore, to be done to procure 
a metal which fhall be white, as hard as it can be 
wrought, and perfectly compact, is to melt two pounds 
of Swedifh copper, and when fo melted, to add fourteen 
ounces and a half of grain-tin to it; then, having taken 
off the fcoria, to caft it into an ingot. This metal muft be 
a fecond time melted to caft the fpeculum ; but as it will 
fufe in this compound ftate with a fmall heat, and there- 
fore will not calcine the tin into putty, it flioukl be poured 
off asfoonas it is melted, giving it no more heat than isab- 
folutcly neceffary. It is to be obferved, however, that the 
fame metal, by frequent melting, lofes fomething of its 
hardnefs and whitenefs : when this is the cafe, it becomes 
neceffary to enrich the metal by the addition of a little 
tin, perhaps in the proportion of half an ounce to a 
pound. And indeed when the metal is firft made, if in- 
ftead of adding the fourteen ounces and a half of tin to 
the two pounds of melted copper, about one ounce of 
the tin were to be referved and added to it in the fucceed- 
ing melting, before it is caft off into the moulds, the 
compofttion would be the more beautiful, and the grain 
of it much finer: this I know by experience to be the 
cafe. 
The beft method for giving the melted metal a good 
furface is this : the moment before it is poured off, throw 
into the crucible a fpoonful of charcoal-duft ; imme- 
2 diately 
