fo) and would answer every purpose of it, if it was not in general fo united to the principles of Iron and Arfenick. It is the most plentiful Mineral we have next to Mundick, and has of itself diftinct Lodes; but it is most commonly mixed with Mundick in fome of our Copper Lodes, before they are wrought to any great depth. It has been much used for the making of Brass, instead of Calamy: several ladings have been shipped off for that purpose, at the price of forty fhillings down to a moidore ton; which might pay for the drefling of it, as the Burrows, or heaps of refuse in fome Copper Mine Bals, will fupply great quantities of it.

To extract the Zinc, the Calamy must be finely pulverized, and well mixed with one eighth part of charcoal dust, and put into a close retort, to prevent the accefs of air, which would inflame the Zinc as it rifes. The retort is to be placed on a violent fire, fufficient to melt Copper. After fome time, the Zinc rifes, and appears in the form of metallick drops within the neck of the retort, which, when cool, you break to take out the Zinc.

Lapis Calaminaris with Copper, makes Brafs; Zinc with Copper, makes Princes Metal, or Bath Metal; and improves Tin in whitenefs and hardness, in the compofition of fome

Pewter.

Stibium. Antimony. This Semi-metal in its Mineral Ore, is of a dark lead colour, ftaining the hands black; and is generally full of long fhining needle-like ftriæ; though often of an exceeding fmall clofe grained texture, hard, brittle, and very heavy. It is found in different parts of Europe, as Bohemia, Saxony, Tranfilvania, France, and even in England in fome. confiderable quantities, though as far as we yet know, confined to the counties of Cornwall, Devon, and Somerset; from the north-weft quarter of the latter, only a few specimens ; from different parts of Devon some tons; and formerly from Cornwall, in quantities of twenty, and even thirty tons. In the laft three years this county has produced about one hundred and twenty tons from one Mine called Huel Boys, in the parish or Endelian ; viz. in the year 1774, nineteen tons, at £.13

ton; in 1775, forty tons, at £.13 10; and, in 1776, thirty-fix tons, at £.14 14 ton. The expence of getting this Antimony, exclufive of driving an adit to the Mine, has been less than one third of the amount of its produce. The

remainder

remainder of the one hundred and twenty tons above mentioned, is chiefly the product of a Mine near Saltafh, belonging to Mr. Thomas Reed and partners.

The direction of the antimonial veins, is moftly from north to south; but there are now and then fome fmall quantities found in veins which run different courfes, and which, from their fuperior product of other Minerals, are denominated according as the different Metals predominate. Antimony lies in its veins or Lodes extremely unequal, but generally more fo length-wife than in depth. It is not uncommon to have the vein two or three feet wide, and in driving as many, not only the Mineral, but even the vein itself will be fcarce perceptible. We have not known any of this Mineral wrought more than fourteen fathoms deep. The Mine of Huel Boys above mentioned is about twelve fathoms, and in the bottom promises

continuance.

Foreign Antimony does not come to us in the state of its Ore, but what is, however, called Crude Antimony; which is obtained from its earthy and more stubborn mineral particles, by a kind of eliquation, in the following manner. The Mineral is put into earthen pots pierced in their bottoms with fmall holes; thefe pots are placed in a furnace, where they receive the neceffary heat for the fufion of the Antimony; but much less than is fufficient to fufe any other of its mixtures, except Lead, with which it is often combined, and which even this fufion will be fufficient to melt with it into the fame mafs. For this reafon, Crude Antimony ufed medicinally fhould undergo an examination, to discover whether it has Lead in it; as I am informed it have a confiderable quantity without altering its ftriated texture, and for which reafon I am inclined to believe, that English Antimony is the leaft proper for medicinal ufe, as it is more liable than Foreign to a faturnine mixture. This Crude Antimony comes to us in the form of the pots or moulds in which it has been melted. Some of the Antimonial Ores of this

may

county, without any fuch preparatory fufion, have been found to produce at least as large a quantity of Regulus, and equally fine, as the best Foreign Crude; and as they generally lie very rich in the earth, this fufion is moftly rendered unneceffary.

Mr. Reed has erected furnaces in Feock parish, on Restronguet river, for extracting its Metal, commonly called Regulus of Antimony; which is performed by mixing the clippings of

the

the Tin-Plate Workers with the Mineral Ore, firft well cleanfed from its ftony carthy parts, and fmelting this mixture in pots containing from a half hundred, to one hundred weight: in which operation the reguline part of the Antimony, freed from its Sulphur, by the latter's uniting with the Iron in the beforementioned clippings, by its fuperior gravity finks to the bottom of the pot, leaving the other parts in a light mineral-like scoria on the top, which readily feparates when cold. The foreign Ores of Antimony are melted in London, for these purposes, in the fame manner; only Mr. Reed's is done in an air furnace, and in London they ufe the bellows as in other fmall founderics. The ufe of the clippings is for the fake of cheapnefs and convenience, for a somewhat lefs quantity of fmall Iron alone will effect the precipitation. Regulus of Antimony may also be obtained by fubftituting, for the Iron, Copper, Lead, or Tin; but thefe must be added in a much greater quantity, and the operation confequently will be attended with much more expence, and greater difficulty, and are, therefore, fubftituted only on very particular occafions. The greatest confumptions of Antimony, befides the medicinal, are made by mixing its Regulus with Tin to make Pewter hard and fonorous; and with Lead, &c. for Printing Types; though it has feveral other

ufes.

Cobalt, is a denfe compact and ponderous Mineral; very bright and fhining, and much refembling fome of the Antimonial Ores. It is fometimes found of a deep, dufky, bluish black; very heavy and hard, and of a granulated structure, looking like a piece of pure Iron where fresh broken: at other times it is found more compact and heavy, and of a very even texture, not granulated or compofed of any feparate Moleculæ, but resembling a dusky mass of melted Lead on the surface, and will bear to be cut with the knife. The inner part, where it is always very bright when fresh broken or cut, is alfo found, in fome places, in a much more beautiful appearance than either of thefe, being of a fine bright filver gray, and of a beautiful ftriated texture, the ftriæ running all great lengths, but very flender and variously bent, undulated, and in fome parts broken. It is alfo fometimes foft, and covered with a blufh coloured efflorefcence, which is generally rich in Regulus.

We have given our thoughts upon the fubject of Arfenick, and suggested that it may be cheaply rendered by our Mundick fublimations, after the manner in which it is procured from

Cobalt ;

Cobalt; and the more we look into, and confider the operations whereby Arfenick, Zaffre, and Smalt, are obtained from this Mineral, the more we are convinced, that a skilful hand may improve upon the hint in relation to the different forts of our repudiated Mundick.

We have had but one Cobalt Mine that ever was diftinguished by that name in this vicinity, which was difcovered accidentally by Mr. Beauchamp, in an adit that he drove through fome part of his eftate at Pengreep in Gwenap. He difcovered a Lode of three feet breadth, which contained a branch of real Cobalt ; and it happening about the time when the Society of Arts, &c. offered a premium of thirty guineas for the beft Cobalt to be difcovered in England, he was honoured with the reward for his fpecimen, purfuant to the advertisement. It did not hold in

depth, but foon deferted the purfuers; who were likewise very foon after obliged to fufpend their fearch, by a prodigious influx of water to their workings.

ton.

At Huel Trugo alfo, a Copper Mine near St. Columb, fome of the pureft Cobalt has been worked. It was in a small vein, four to fix inches big, in which there were no other mixtures. It croffed the Copper Lode, which was pretty large, though not rich; and the Cobalt lay in the vein juft where it joined the other, but did not hold to any length, fo as to make it worth purfuing. It was very fine, and fuppofed by fome who think they know the value of it, to be worth more than fixty pounds It was of a pale red, or rather bloffom colour; and, on being expofed to the air for any confiderable time, the furface was covered with a farinaceous fubftance resembling the fublimate of Arfenick, which it probably was; but left the fine colour should evaporate, the proprietor, Mr. Champion, ordered it to be put into cafks filled up with water. The common air was, or feemed to be, the menftruum, which diffolved the furface of this Mineral, which it is probable in process of time, as it became longer exposed to it, would have totally crumbled into that floury substance. Cobalt is alfo fuppofed to be in no fmall quantity in Dol-Côth Copper Mine, for the affayers generally find their pots tinged with blue; yet it feems to be fo blended with Copper and Iron that it does not discover itseif in a mineral state, being probably but in the general term of Mundick. Very good Cobalt has also been difcovered in Dudnan's Mine in Illogan parifh; and in a Mine wrought for Tin and Gal near Pons-Nooth in Perran-Arwothall.

In the last place, we come to define Metals only, which we fhall prefume to be fuch on the respective principles of their ductility and gravity. Their malleability may arise from the figure of their parts, perhaps oblong or fquare, which may occafion their cohering fo strongly, as not eafily to be separated; and it is probable, the pores of their conftituent particles, or of the whole mass, are few and fmall; which may account for their being fo much heavier than any other bodies. The radical characters of Metals ftand thus: the weight of Gold to that of Glass, is as 9 to 1; and the weight of Tin, the lightest of all Metals, is to that of Gold, as 7 to 19: which confiderably furpaffes the weight of all Stones, and other the most folid bodies. The fpecifick weight of the feveral Metals, and of Granate, Water, and Air, ftands thus:

Formerly there were but fix Metals fo denominated, to which by fome was added Quickfilver, which has every property of Metal except fixidity. To these we shall add another original Metal lately discovered in the Spanish Weft-Indies, and by the Spaniards called Platina, from its refemblance in colour to Silver, from which it would not be fo well distinguished, but by its fuperiour gravity, and inferiour ductility; which particularities are extremely remarkable.

Gold, by the ancients, was characterized the fun, which they imagined did influence and produce it. Gold is very rarely feen in a state of Ore; being of all Metals moft frequently found native. It is a general opinion, that it never was found in a mineral state, but always pure and metallick: I have, however, feen, in the poffeffion of that curious investigator of natural productions, Dr. Hunter, a large fpecimen of mineralized Gold, which the doctor had from Germany: one point of it was pure Metal and Quartz; and the other, I confefs, had all the appearance of a mineralized Gold Ore.

Gold is free from Sulphur and Arfenick; has no certain figure; and is found pure in Flint, white Quartz, or debased

Crystal.