[ 306 ] 
Extract. 
“ Mr. Henry Rofewarne, of Truro, fays, that 
<{ when he Tent the nrfl fpecimen (prefented to the 
“ Royal Society by me William Borlafe, and now 
“ lodged in their Mufeum) he mentioned as a proof 
“ of its being native tin, that between the ore and the 
“ tin there was a mixture of quartz : but, upon a 
tc nearer examination and fome trials with aqua fortis, 
“ he and another perfon found it was not quartz. At 
“ laft, on melting a piece, he perceived no fmall 
<c quantity of arfenic to be mixed with it, and there- 
“ fore fulpefted that the white parts which had 
“ pafled for quartz were nothing but arfenic. Accord- 
“ ingly he fcraped off a little of it and put it on a red 
hot iron, where it immediately caught fire, and 
£< evaporated into fmoke, leaving behind it the mofl 
**' poifonous ftench they ever fmelt. This confirmed 
£t fome, who had hitherto doubted, in the mofl 
“ firm belief that it really was native tin and genuine, 
£ ‘ it being impofilble for tin to be melted and the 
t( arfenic left untouched.” 
XLi A Sup- 
