210 
NATURAL HISTORY 
1000, or as y-'-Xt 0 lC: Befides, lead will diHolve in acids, 
but tin, like gold, in aqua regia only. Lead therefore and tin are 
two metals radically diftindt, each conftant to its own peculiar fpe- 
cific weight, and requiring a different menfiruum from the other. 
Lead is of great ufe, not only in fheets, pipes, or more folid fub- 
ftances, but for refining other metals, for making paints, varnifhing 
pottery-ware, for yielding oils, tinctures, and fome other affiffances 
in phyfic ; lead will alio yield filver, and fome lead a quantity very 
profitable to the owner. 
sect. hi. of this metal many mines have been anciently and lately worked 
Mines o^f Cornwall d , and in many places it is difcovered among other 
wall. metals but in too fmall quantities to yield much profit. The mines at 
Penrofe, near Helfton, have been wrought above two hundred years, 
and have yielded tolerable profit within thefc thirty years ; the ore 
is moftly of that fort called Potter’s ore, but fometimes yellow e . 
Dr. Woodward (vol. II. page 29) gives a very advantageous cha- 
racter of the ore found at Guarnek, in the parifh of St. Allen, 
near Truro. “ It was a blue lead ore, very rich in filver, perhaps 
beyond any in England befides : this ore, when only drefied, fells 
for eight pounds a ton, which is about the value of lead itfelf ; one 
of the proprietors, and fome of the workmen, averred, that a ton 
of this lead yields one hundred and forty ounces of filver : the vein 
of ore was about a foot over, but in fome parts near three feet, 
and about fifteen fathom deep.” 
sect. iv. Lead is for the moft part of a greyifh blue colour in the mine, 
featfores 110 muc ^ unlike what it is in the metallic ftate. Of this kind 
there are feveral forts ; as, firft, potter’s or teflellated ore, confift- 
ing of a fhining, rectangled, tabulated ftrudlure, and always break- 
ing into granules of like parallelopiped fhape ; and, when lead is 
cheap, this ore, well cleanled, is worth about fix pounds a ton. 
This is found in Sithney, Cambom, and many other parts of Corn- 
wall. Secondly, that which is of a flaky, fmooth, and glofiy tex- 
ture, not breaking into cubical dies, but more ponderous, and there- 
fore containing more lead. Thirdly, a very clofe-grained ore, break- 
ing into an uneven fparkling furface like a grey tiflue, very rich in 
filver. This is fcarce in Cornwall f . 
c Boerh. by Shaw, page 59. 
d 1 ° the parifhes of St. Meran, Boconek, Piran- 
Sands, St. Agnes, Crowan, Sithney, Gwinear, 
St. Ifly, St. Columb, Ulogan, and Camborn. The 
works moft noted formerly, are thofe of Penrofe, 
Penwortey, Trevafcus, Reliftian, and Guarnek. 
See Woodward’s Cat. vol. I. page 217, 218, and 
vol. II. page 30. 
" Woodward’s Cat. vol. II. page 28, line 7,2. 
f Some of it was fent me from the works at 
Beerferris in Devonfhire, and I have it alfo from 
Cardiganfhire in Wales. There is a mock-lead 
very fhining, and like the true of this colour ; 
the irregular fhape and texture of its granules, 
and its want of weight, will difcover it. By fire, 
it will divide into a powder, which may be ftrewed 
upon writing. 
Lead 
