backwardness of the Copper companies, by erecting more furnaces, and running the fame Regule into fine Copper; a circumftance of great notoriety, which might be followed by many good confequences for them and their neighbourhood.

is

Lead Ore, like that of Copper, as it comes out of the Mine, very little of it merchantable, or fit for fale or fmelting; the foffils and foil mixed with it, muft first be separated by breaking and washing, according to the nature, richness, of poverty

of the Ore.

As for Lead Ore that does not rife very folid, it ought to be bucked and jigged, and very feldom carried to the strêke, or ftamps, except it be very scarce and thin in the ftone; but when it is fo poor as to make bucking and jigging improper and coftly, then it is fcarce worth the trouble of ftamping and dreffing: however, when it is fo treated, the grate of the ftamping-mill fhould be yet coarfer than for Copper Ore; becaufe Lead Ore breaks into Facets or flakes, and is thence liable to float away and be loft, even with a very easy stream of water. The method of jigging has been used a long time in the Lead Mines in Cornwall, though but very lately in the Copper Mines, and they find it to turn to good account both in the one and the other. There can be no doubt, that the Cornish were almost entirely obliged to the Derbyshire and other Lead Miners, for the best method of dreffing Copper Ores in the first place; which I fuggeft from the antiquiry of Lead Mines in the northern counties, and the much later difcovery of Copper Ore in Cornwall to which we must add, that the great fimilarity in the nature and gravity of Copper and Lead Ores, would naturally incline us to ufe one and the fame method for their purification. Nevertheless, it must be allowed, that the great varieties of Copper Ores in Cornwall, fome of which require a very nice management in dreffing, have given her Miners a preeminent judgment in that matter, which is warranted by continual obfervation and experience.

But when Lead Ore rifes rich, in large folid pieces, it is broke with a hammer into cubes, from half an inch to one inch of a fide; and this is called Bing in Derbyshire, but in Cornwall it is stiled Cobbed Ore. Such part of the Ore which is too impure for bing, is further beaten down with a broad headed hammer called a Bucker, according to its degree of mixture with foffils, &c. which this beating is intended to break off,

and

and prepare for feparation in water. This, with what was neceffarily broken to an under-fize in making bing, they term Knock-bark, i. e. Bucked Ore; which being put into a wire fieve, and washed in a kieve or vat filled with water, the Ore preponderates in the fieve according to its fpecifick gravity. Thus the smaller parts of the Ore go through the meshes of the fieve into the vat, the larger parts reft on the bottom of the fieve, and the foffil part forms a ftratum above the Ore, which is taken off with a femi-circular fat board or hand fhovel called a Limp, and is thrown away; and the Ore remaining in the fieve, thus feparated, is called Peafy. Thofe particles which paffed through the meshes of the fieve, in feparating the peafy from the foflils, with all fuch small particles of Ore as have been pulverized in getting or dreffing, together with those in the wafte hillocks, (halvans and henaways) is again washed over in the fieve and vat, once, twice, or three times, in order to separate and cleanse the Ore, which they call Smitham. In this manner are formed the three affortments of Lead Ore, viz. Bing, Peafy, and Smitham. Now in Cornwall these three forts are generally mixed together for fale; before which, we call the Bing, Cobbed Ore; and the Peafy and Smitham, Jigged Ore, the Peafy being first Bucked. So much in general do the methods of dreffing Copper and Lead Ores agree, that in the foregoing account they differ in nothing but terms of art.

There is another method of dreffing very tender Copper and Lead Ores, fpeedier than bucking, viz. in dry stamps, where the Ore has no water to carry it through a grate, but it is stamped dry or a little moiftened. In dry ftamping, it falls out of the mill, partly in grofs lumps; and one attends who with a fhovel throws it on a proper fized hurdle, through which the fmaller pieces fall; and the larger that run down to the foot of the hurdle, being pounded small enough to pafs through the hurdle likewife, the whole is dreffed and cleansed by jigging as before.

When the Ores of Copper or Lead are dreffed and made faleable in Cornwall (for Lead Ore is disposed of in a different manner in Derbyshire, and the northern counties) the piles or heaps are either kept separate for a market, if the quantities are large; or else the different forts are well mixed together in one pile, very rarely exceeding one hundred and eighty or two hundred tons in one parcel, and from thence, down to one hundred, eighty, fixty, fifty, forty, twenty, ten, five, or even

one

one ton, if the feller pleases, which is feldom the cafe, and never for his advantage. If a Mine has four hundred tons of Copper Ore dreffed ready for fampling, the managers may divide one half of the quantity, for inftance, in two parcels of one hundred tons each, and the other two hundred tons thus ; one parcel of eighty, another of fifty, another of forty-two, another of twenty-one, and the last may be a small parcel of poor ftamped Ore computed feven tons, in all, four hundred. But the reader is not to understand, that thefe different parcels were ever mixed with each other: they may belong to separate takers upon tribute each parcel, they may lie at feveral diftances from each other, and be of very unequal value; for the first hundred tons may fell for four pounds ton, the next for five pounds ten fhillings, the eighty for fifteen pounds ton, the fifty for eight pounds five fhillings, and fo on of all the rest. It is very common, however, for tributors to mix their Ores with the owners, or with each other of their fellow tributors, fo that the Ores of four or five different sets of people may be all mixed together to make one fample for conveniency of fale, pursuant to the directions of the managers or captains of the Mine, previous to which, their separate parcels must be nicely weighed and private famples taken: but I have illuftrated this matter in book iii. chap. iv.

A dreffed parcel of Ore, before the day of fampling, is very well mixed by feveral men, who turn it over again and again, a person standing on the top of the pile or parcel, who spreads every fhovelful circularly, and as equally as he poffibly can, fo that in fact, it is mixed with great exactness. This parcel, if less than ten tons, is divided into three Doles or piles; if above ten, into four Doles; and if ever fo many more than nineteen tons, it is divided into fix Doles; and then it is ultimately ready to be fampled.

Now when the famplers meet upon the fpot according to appointment, either of them, indifferently, fixes upon the one-fixth, one-fourth, or one-third Dole of a parcel according as it is great or small, to take their famples from. The Miners then cut or part that Dole athwart and across down to the ground, fo that is divided nearly into quarters, by these transverfe channels which are cut through it. Then a fampler with a fhovel pares down a little of the Ore from all parts of the channels, to take as equal and regular a fample throughout the whole, as he can, to the amount of two or three hundred

weight, which is carried to a clean floor or laid on boards, and there well and regularly mixed in a fmall heap by itself. Next, a fampler cuts this alfo into quarters, ordering any two of the oppofite or adverfe quarters, to be returned to the great Dole from whence they were brought. The remaining half he still mixes and quarters, until it is brought to a small compass or quantity, when it is fifted through a small coarse wire fieve; and the larger ftones which cannot pass through the fieve are broken with a fledge or flat polled hammer till all will pafs through the meshes. After this, he mixes it very curiously three or four times over; and fo quarters and remixes it as before, until it is reduced to a fmall quantity. Laftly, he puts about a pound or two of it in a small bag, which is a fample of the whole parcel. Each of his brother famplers fills his bag likewife, in order to affay or prove its value by fire, as fhall be hereafter shewn.

СНАР. III.

A Summary of the Dreffing of Gold, Silver, Quickfilver, and Semi-Metals.

T

HE inhabitants of Africa, and of Brazil, dress their Gold-duft in fmall bowls, after the manner that Goldfmiths wash their fweeps; and I fufpect, that the Spaniards in Mexico, and on the continent, drefs their Ore in the fame way: but the inhabitants of Brazil will fometimes find a kind of Goldduft, so very weak and minute, that they cannot fave it well in bowls. This has obliged them to have recourse to another method of making the most of this very fmall Gold-duft, by laying an ox-hide on the ground, with the grain of the hair against the water, which paffes gently over it. On this they ftir and mix the fand and Gold-duft; by which means, the small particles fink, and are intercepted in the hair of the hide; while the fand washes off. This method feems very rational and well contrived; and Sir John Pettus, in his Fleta Minor, fays, "The Gold-washers ufe ftrong black and ruffet woollen "cloth for the fame purpose, in like manner.'

From the feveral methods prefcribed for cleanfing Ores by water, it is easy for one who has a tolerable notion of dreffing

:

Tin and Copper Ore, thence to conceive, what may be the best way of drefling Gold, or Silver Ore, conformable to the wafte or mixture which abounds in either. Yet there can be no certain rules prescribed without feeing the matter to be dreffed, because its plenty or scarcity of Metal, the different fizes, the various quantities of its brood or waste, may probably cause great variety in the methods of dreffing it; but as rich Ores, on account of their great ponderofity, are eafier cleanfed than any others; fo alfo, in refpect to their intrinfick value, they require a more curious and artificial management and operation. I have seen some forts of pure Silver Ore, which contained near one half pure filver, the wafte being a light Quartz, fomewhat tranfparent now to drefs a quantity of this, I fhould advise its being bucked fmall, and then I fhould prefer jigging before any other way of washing it. I should chufe this method of dreffing a quantity of Gold and Silver Ores, provided they were rich in quality, or contained much Gold and Silver in proportion to the wafte in them; but if there were little Metal in the Ore, so that it would not well anfwer the charge of jigging, in that cafe I fhould rather wash it in a ftrêke, on which I would try an experiment of fixing an ox-hide as above, or rather of covering the ftrêke with a flannel cloth, or the like, to intercept and retain the fine particles of Metal: but this is not to be underftood of fuch Gold or Silver as is intermixed with base Metals or Minerals; for then the methods of cleanfing Tin, Lead, and Copper Ore must be pursued, and afterwards the Gold or Silver may be extracted by fire, S. A.

As for the Ore of Quickfilver, it is generally ponderous, and therefore may be dreffed like other Ores. Iron Ore, I doubt, will scarce defray the charge of cleanfing, and perhaps it needs washing but feldom, because it often rifes rich with very little

mixture.

Thus, according to one or other of the foregoing methods for dreffing of Ores, may the Semi-metals of Bifmuth, Cobalt, and Antimony, be cleansed by water, and by comminuting them more or lefs in proportion to their richness and ponderofity. As for thofe Minerals which are foluble in water, as Alum, Copperas, and all Mineral Salts, they must be extracted from their impure mixtures by means of water only, in which they must be further purified.

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