Dr. Pope tells us of one he faw in the Mines of Friuli, who in half a year's time was fo impregnated with the Metal, that on putting a piece of Brass in his mouth, or even rubbing it in his fingers, it would turn white as Silver. Nor can this be wondered at, fince it has been known to amalgamate the Gold earrings of the falivated wearer; and I have myself feen very minute globules in the rotten proceffes of fome bones, when I diffected under the inftructions of the accurate Dr. Hunter. Non femel in

fepulchris argentum vivum capitibus reperi. Anton. Mufa Brafavolus, in tract. de morb. Gallic.

Lead, Plumbum; alfo Plumbum Nigrum, to distinguish it from the Plumbum Album or White Lead, which was the name given by Pliny to Tin, although it is radically a distinct Metal. It is ftiled Saturn, from the Planet of that name. It is feldom found malleable and purely metallick; for what have been taken for fpecimens of native Lead, have produced, very often, three parts in four of fine Silver; from whence many have fuppofed, that there is no fuch thing as native Lead: Į have however seen two specimens of it, in the poffeffion of Mr. Bennallack in this

county.

This Metal feems to confift in part of an impure leprous earth, of a fulphureous nature; and it abounds also with something very acid and corrofive, though cold, and caufing paralytick complaints in those who are much concerned in the melting of it. It may be diffolved in many forts of weak acid menftrua, much better than in those of the greatest strength; and it will incorporate indifferently well with Quickfilver; but does not admit of ignition, for it melts in a very small degree of heat.

The only Lead Ores which we have feen in Cornwall, are these four forts: firft, the lead coloured bluish gray, of no particular form; fecondly, the Antimoniated ftriated glittering Ore; thirdly, the fteel grained; and laftly, the teffellated or diced Lead: most of which are so extremely rich both for Silver and Lead, as to be well worth the working, if the Cornish Lead Lodes were of a larger fize, and more lafting than they generally are. The small profits arifing from this Metal hitherto wrought with us, have damped the ardour of our adventurers in their purfuit of it; and the Lead which has been discovered in the weft of the county, has for the most part offered itself accidentally, when the Miners have been searching for Copper, with which it is more generally affociated than with Tin. For my

own part, I have never feen it blended with Tin; but with Copper frequently; and always very rich for Silver, but in no quantity. Black Jack and Mundick are very close companions with it; but they, and Copper Ore, are all of them distinct and difcernible from each other, in the Stone or Mineral state. In fearching for Copper Ore in Nanfkuke Downs, in a very promifing Goffan, we difcovered a leader, fix inches wide, of very rich Lead of the Antimoniated kind upon the north wall of the Lode. The Silver in it was plenty, infomuch as to render the Mineral worth £.18 or .20 ton without any dreffing. It produced about a ton and half, and then totally disappeared.

It is a mistake of those who think that Lead becomes brittle by extracting the Silver from it, for it is rather more ductile. The deleterious properties of Lead I have already hinted at, in treating of Quickfilver; and I may obferve in this place, that any faturnine preparation given inwardly, must be very hazardous, unless adminiftered under the direction of a skilful practitioner.

In degree next to our provincial Metal, Tin, this ifland has been famous in the annals of paft ages for its peculiar production of Lead; and the kingdom in general has been more remarkable for the quanity produced, infomuch that Pliny faith, “In "Britain it runneth ebb in the uppermoft coat of the ground, " and that in fuch abundance, that, by an express act among "the islanders themselves, it is not lawful to dig and gather "Ore above fuch a proportion fet down by ftint." And Sir Joshua Child, in his difcourfe of Trade, tells us, "That our "Lead and Tin, which are natives, and by God's bleffing infeperably annexed to this kingdom, carry on much of our "trade to Turkey, Italy, Spain, and Portugal; befides great "quantities that are fold to Holland, to France, and to the "Indies, as is well known to all the merchants that trade to "those parts."

We have had many ancient Mines of Lead in Cornwall, particularly in Perran Zabulo; the Garres in St. Allen; and elfewhere. It is faid that the wars in France were carried on by the Silver of those and the Devonshire Mines. The Ore in the Garres, when last wrought about fixty years fince, was fo rich in Silver, as to yield one hundred ounces to one ton of Lead.

Silver,

Silver, Argentum, C Luna, from its attributed planet. Of all Metals, Gold excepted, this Metal is found moft frequently native; and it is, indeed, found in that ftate, more commonly than in Ore; and if you break the ftony Glebe or Mineral, you will fometimes find folid grains and lumps of malleable Silver contained in them. Silver is ufually mixed with other Metals, particularly in Cornwall with Copper and Lead, though but in a fcattered form and minute quantity, in the former no way adequate to the expence of extracting it.

Real Silver Mines distinct from any mixture with other Minerals, we have none in England. We read of fuch, but they give us no produce to value ourselves upon them; and indeed the two nobler Metals are foreign to our country, at the same time the base and more useful Metals are beftowed upon us in common with the reft of the world. In our kingdom of Danmonii Silver Mines were discovered in Edward the firft's time, when 337 men were brought from the peak in Derbyshire to work them. Edward the third had great profits from them; and queen Elizabeth prefented a cup made of Silver to the earl of Bath, with an infcription upon it, from which inscription we must conclude, that thofe Silver Mines, fo called, were abfolutely Lead Mines rich with Silver.

In Sweden they have a Silver Mine 150 fathoms deep, of which they have no records so ancient as the first discovery of it; yet we do not apprehend it is a very profitable concern: neither are there any very rich Silver Mines in Denmark, although there is preserved, in the Royal Museum at Copenhagen, a piece of native Silver five hundred and fixty pounds weight, with three other specimens, above three and two hundred weight in each. There are likewise fome confiderable Silver Mines in Hungary; but none in Europe, it is likely, of a produce equal to the Hanoverian Mines, fome of which are worked at the charge of our most gracious fovereign, and others let out to farm to his private and great emolument. I prefume the fingle Mine of Potofi in Peru, has exceeded every other quarter of the globe, in the richness and quantity of this valuable Metal. From this great vein, which is about fix feet wide, do iffue out fome fmall fprigs of little account, and yet here they refine thirty-eight millions five hundred thousand pounds weight of Silver yearly; one pound of their Ore yielding one ounce of fine Silver, at which rate, they must raise yearly two hundred fifty-fix thousand, two hundred and fifty tons of Ore, before they can answer that

account

account in Silver: but by Gerard Molino's account, they muft raise a great deal more. The vein runs directly north and fouth, floping, hadeing, or underlying, in the hill towards the east. They have an adit or level, which they were twenty-two years driving; but they do not difcharge their Ore through it as formerly, because it is become very long and crooked; therefore they carry up their Ore on their backs, each flave about fifty pounds weight in wallets, on ladders made of ox-hides, three and three in a row, one of them having a candle tied to his right thumb, to light the rest. This work employs above twenty thousand Miners, and is wrought day and night above a thousand yards deep (see Acofta in his Natural History of the Indies) and feveral merchants that have travelled into those parts relate, that this mountain, by reason of the numerous smelting houses upon it, looks at a distance as if it were all on fire. (Waller on the Mines of Sir Carbery Price).

Cramer allows but four forts of Silver Ores, fundamentally fuch; others being only impregnations of that Metal with foreign Minerals. The firft is a vitrean Ore of an irregular figure, fulphureous, and of a lead colour: the second is a horny Silver Ore, femi tranfparent, like rofin in colour, of no external figure, but closely examined it confifts of very thin plates: the third is a red or fcarlet Ore: and the fourth is of a light gray colour: and even this contains more Copper than Silver, even fo as fcarcely to deserve the name of Silver Ore. Oftentimes Silver is found, like Wire, woven one within the other, between the rocks; and fometimes it will refemble Lace, by the Spaniards called Metal Machacada, which, from its description, I apprehend to be like our native Filagree Copper.

Silver readily amalgamates with Mercury, and is easily diffolved in genuine Aqua Fortis; but will not yield to Aqua Regalis, nor any other water impregnated with Sal Gem, Marine Salt, or Sal Ammoniack: these kinds of Salts, or their diftilled waters, may serve to precipitate a diffolution of Silver from Aqua Fortis, only for this ill-consequence, that Silver thus precipitated becomes very harsh and ftubborn for fufion, and is allo rendered partly volatile, fo that it evaporates confiderably in the fire: this is that precipitation of Silver,, which the modern Chymists call Cornua Lunæ. This Metal per fe, is fo foft, that it is expedient to allay it with Copper or Brass to fit

it for use.

Copper,

Copper, Venus, or Meretrix Publica; a common prostitute from its reception of all menftrua, other Metals having their peculiar diffolvents. The acid particles of air will readily diffolve Copper, and fhew itself by an ærugo or ruft upon the Metal. Oils themselves diffolve Copper by means of a Salt contained in them; for even the ends of tallow candles which the Miners leave under-ground, if touched by any cupreous water, will presently be tinged green. This folubility is fo extreme, that a fingle grain diffolved in spirit of Sal Ammoniack, will give a blue colour to 256,806 times its own bulk of clean water; and a faint, yet difcernible one, to above 530,620 times its bulk. Copper in fufion, will not bear the leaft drop of water; for if the moulds be wet, it flies into numerous particles, like fhot from a gun; and may destroy the perfons near it, of which I once met with a dismal instance in one of the workmen at Hayle Copper-house.

Native Copper is frequently found in our Mines, near the day or furface, or commonly but a few fathoms deep; though there are some few inftances of its being found very deep, particularly in the Mine of Cooks Kitchen, from whence feveral tons have been fold to the Cornish Copper Company, for immediate fufion, as it came out of the earth.

On the fide of a rivulet, ten leagues to the fouth of Lake Superior in North America, there is a fingle lump of native Copper, about four tons weight, free from any mixture but a few fmall black Stones of an Iron nature, and fome very fine grains of Crystal. Lake Superior, north from this lump of native Metal, is very wide. No vein of Copper was discovered on the fouth fide of the Lake, near this lump; but fome few very small ones on the north fide, not worth the purfuit. This I had from two credible Miners of Redruth, who were fent over to make discoveries in confequence of this fingular appearance.

We have before observed, that Copper is the most easily diffolved of any Metal, even by common water; but certainly the diffolution must be quicker, if that water is charged with acid or alkaline principles. Wherever Copper is found, there is always green or blue Vitriol, which are foluble and easily mix with every moisture. The action of these principles, will, pursuant to their relative ftrength, diffolve and defecate the Copper particles they meet with, from their impure and heterogene admixtures; and keep them fufpended, till they are