OF CORNWALL. 209 
under examination, feveral gentlemen having concurred to fet up 
furnaces for melting and refining copper-ore in Cornwall, and to 
the fuccefs of the experiment, without entering into the difpute, 
I refer it. 
CHAP. XVIII. 
Of Silver, Lead , and ^uickftlver found in Cornwall. 
I T is reported that Edward I. and Edward III. reaped confider- sect.i. 
able benefit from the filver found in thefe parts, fince which ° f fllver - 
feveral gentlemen have fearched for the fame metal at feveral times, 
but without fuccefs ' ; and in the fixteenth century, one Mr. Bur- 
chard Craneigh, a German, feems to have had the direction of fome 
mines carried on to raife this valuable metal ; he fet up a refining- 
houfe alfo in the hundred of Weft fome little time before Mr. 
Carew’s writing, though with fmall advantage “. Silver found in 
Cornwall by itfelf, unmixed, (I mean, free from tin, copper or lead,) 
I have never feen but once, and that was found native, about the 
bignefs of a walnut, (of which I have part,) in Huel-cock, a cop- 
per-work in the Parifh of St. Juft. It is indeed feldom that filver 
is found any where native w ; ’tis generally fo intermixed with 
ftone, that it is not to be known but by men of experience x : ’tis 
ufually mixed alfo with other metals, tho’ ofteneft in a kind of black 
ftony glebe, full of fhining ftreaks : it has a corrofive fulphur or 
bitumen always attending it y . What may be mixed with the ore 
of copper has been hinted already in the foregoing page ; and if any 
unknown ore fufes and runs before it ignites, it is moft probably 
filver, and merits farther enquiry \ 
Lead and tin were anciently * reckoned only two different ftates sect. n. 
of one and the fame metal. Tin was called the Plumbum album, lead - 
and efteemed the pureft ; and what we call Lead, was the Plum- 
bum nigrum : but if thefe were really but two forts of one metal, 
as not only the ancients but fome moderns b have thought, then 
there would be different and intermediate ftates of purity and 
weight, whereas we find lead always of the fame determinate weight, 
lead being to water as 11345 to 1000, and tin always as 7321 to 
1 Carew, page 7. and forty-five, and a fourth three hundred and 
“ Ibid, page 130. forty pounds weight. Pontop. parti. Englilh, 
w Some furprizing inftances however there are page 188. 
of this kind in the Norway filver-mines. In the * Alonfo Barba, page 77, 78. 
Royal Mufeum at Copenhagen, there is preferved r Boyle’s Hydroft. balance, 
a piece of native filver five hundred and fixty z Boyle ut fupr. 
pounds weight, another piece two hundred and * Plin. lib. xxxiv. chap. xvi. 
feventy-nine pounds weight, another two hundred b Clerk’s Phyf. page 136. 
H h h 
1000, 
