¢ 

408 Mr, Avcuorne’s Experiments, &c. 
low as two ounces and a half of copper, with half anounceof _ 
tin, to twelve ounces of gold, But thefe are not. worth par- . 
ticularizingg for they all bore hammering, and flatting by 
rollers, to the thinnefs of {tiff paper, and afterwards working 
into watch-cafes, cane-heads, &c. with great eafe. They all, 
indeed, grew more hard and harth, in proportion to the quan- 
tity of alloy; but not one of them had the appearance of 
what all workmen well know by the name of brittle gold. 
Whence it fhould feem, that neither tin in fubftance, or the 
fumes of it, tend much to render gold unmanufacturable. 
Whenever, therefore, brittlenefs has followed the adding: 
{mall quantities of tin to fine gold, it muft be fuppofed to have 
arifen from fome unfriendly mixture in the tin, probably from 
Arfenic; for other experiments have fhewn me, that twelve 
grains of regulus of arfenic, injected into as many ounces of 
fine gold, will render it totally unmalleable. | 
From the foregoing experiments, I prefume, we may fairly 
conclude, that though tin, like other inferior metals, will 
contaminate gold, in proportion to the quantity mixed with it, 
yet there does not appear any thing in it {pecifically inimical to 
this precious metal. And this being contrary to the doétrine 
of moft chemical writers, I fubmit to your better judgement, 
whether it may not be ufeful to publifh thefe experiments, by 
laying them before the Royal Society. 
* Bam, es 
Ss. ALCHORNE 
“ey 

