Ore into the fieve, which the jigger dips into the water and shakes twice or thrice until the smaller part falls through to the bottom of the kieve. What remains in the fieve, he reserves by itself, till there is a quantity. This coarfer fize made by the fieve, is jigged pure and clean, if it be well given for Ore; or elfe it is picked, and the refuse bucked over again, pursuant to its richness or poverty, and the dreffers direction and judgment. When the kieve is almoft full, they pour off the water, and take out the small Ore, which perhaps they fort again after the fame manner in fieves with leffer holes. Being thus divided, they dress each fort apart, in kieves half full of water with proper fieves, whofe holes are small enough to keep the Ore from running through.

The jigging fieve made of brafs wire four or five holes to each square inch, and sometimes for fmall Ores seven or eight holes, is held by the jigger in the kieve, while a girl throws two or three fhovels full of the Ore into it. The jigger dips and shakes it a few times in the water, by a peculiar indefcriptive motion and turning of the hand, which makes the light waste, such as Quartz and Killas-gravel, &c. rife uppermoft in the fieve, the Ore lying under it, and the Mundick (if in any quantity) under the Ore, each according to its fpecifick gravity. Now to separate thefe, the jigger takes a fmall femi-circular piece of wood called a Limp, being the shape and fize of half the head of a quarter hundred powder barrel, with which he fcums or rakes off the light refufe or gravelly part, and throws it by, perhaps to be jigged over again. In like manner he fcums off the good Ore, and lays it afide for fale. Lastly he referves the remaining Mundick, until it comes to fome quantity, in order to jigg it over again; because the firft operation may not be fufficient entirely to take out all the Ore, either from that or the light waste that lay uppermoft.

This refufe part of the Ore is commonly fo light, being as I have just said, a Quartz and Killas-gravel, that it may fometimes be very properly put to the ftrêke, and washed in a pretty quick ftream of water, which will carry the wafte to the tail or hinder part of the ftrêke, fo as to be divided from the good Ore, which lies at the head. But the flimy fine Ore, which falls through the fine fieves to the bottom of the kieve, is often cleansed by the tye, which is the fame as the ftrêke, but with an exceeding flow and fmall ftream of water, or, which is much

like it, by buddling or framing, the fame as Tin Ore; alfo by jigging it in a very fine clofe fieve like a dilluer.

All this is varied and modified according to the discernment of the dreffer: and though Ore cannot be perfectly dreffed by water so as to be entirely clean, yet all Ore, except Tin-stuff, is best cleansed by jigging, though it is the flowest way, and of confequence the most coftly; alfo the flimy earthy part is apt to lie among the last or smallest Ore, more than in the other methods of dreffing, and thereby depreciate its value: therefore I suppose the fine flimy part of it may be packed in kieves like black Tin; but the dresser's guide in this case, should be the tenderness and value of the Ore. Here is not, however, that waste of Ore, that is made by the strakes, which is the reason why the method of jigging ought to have the preference.

As the foregoing is the moft general rule for dreffing of Copper Ore that I can form, it would render my differtation upon the fubject too prolix, minutely to defcribe the various methods of cleansing different forts of Ore: I fhall, therefore, content myself with just hinting the feveral diftinct operations each fort separately requires, and leave the regulation of them to those who are employed in the bufinefs.

Common yellow Ore fhould be separated at the Shaft fide, the rough from the fmall, either by griddle or ftrêke. The folid Ore fhould be further difunited from the ftony part, by spaling with fledges, or cobbing with hammers to a proper fize.

Dredge Ore, which may be left from the above, or which may rife fo and diffeminate in the ftone from the Mine, as poor to deferve that name, in the firft place, fhould be fpaled, cobbed, and then bucked to a proper fize to run through a fieve two holes to the inch, preparatory to its being jigged in a four or five hole fieve. The remainder fhould be washed, and then put on a table of loofe deal boards, that the pickers may chufe the good from the bad, that the good may be handled as the first. The small, which runs through the four or five hole jigger, fhould be tyed in a fine small stream of water; and thus by repetition be made fit for fale.

If Copper and Tin Ore are mixed together, which is often the cafe, the latter being moftly the heaviest body, may be wholly faved in the fore part of the tye, by repeated effays.

But

But if each Ore is of equal gravity, (and I apprehend some poor Tin Ore, which they call dry for Metal, may be lefs ponderous than Copper Ore) if the tye will not separate them, they should be first cleanfed from every other impurity, and then moderately, calcined in a burning-house. The Copper Ore being thus rendered light, will eafily feparate from the Tin, and both will be made faleable by buddle, kieve, dilluer, &c. I am not certain whether all this may be too expenfive or not, especially when I recollect that fome buyers of Copper Ore may prefer it with some Tin for smelting to pot and bell-metal.

Copper Ore that is charged with Mundick, may be disunited, at the ftrêke or by jigging, provided the Mundick is hard and solid; but if it is small and fine like sand, it must be separated by the tye, buddle, kieve, &c.

If the infection is Black-Jack, care must be taken in cobbing and picking to divide them, as they are nearly of one weight., Some have advised calcination; but they are alike ponderous after calcination; and, therefore, water will equally float them away. Mock-Lead is not the worst brood in Copper Ore, especially for the use of the brass founders, it being a Zinc Ore.

Gray Ores are generally the heaviest of all, and are commonly infected with Iron. They must be dreffed like the common Ores, by forting and fizing them, &c.

In the drefling of light pryany black Copper Ore, very little water is neceffary; for the fmall fhould be fifted, and put to pile from the Shaft fide; and the remainder must be cobbed, bucked, and jigged: but if it is committed to a small stream of water, the major and best part of it will be carried away and loft by its fuperior levity and fineness.

The prime Ore being separated and dreffed by itself, the refufe goes by the names of Halvans and Hennaways; and is generally dreffed over again and again by ftrêke, ftamps, &c. The halvans of halvans are mostly dressed by an undertaker for fo much in the pound fterling of the money they produce, according to the richness or poverty of the Ore, and the price ton it will bring when ultimately dreffed. No exact estimation can be made of the value of a pile of Ore halvans: the method of calculating, is by gueffing how many tons of Ore it will. make for every hundred facks of the pile. As for those halvans,

whose contents are less than half a ton hundred facks, it is fcarce worth the trouble of returning and dreffing it, except the Ore is rich in quality, and will bring a good price: much also depends in this cafe upon conveniencies, care, and expence more or less in carriage and water to dress it.

Halvans ftamped small, and then washed in a strêke with an eafy ftream of water, is termed Stampt Ore. But a finer fort is still to be had from the flime pit, which proceeds from the minute particles that glide away with the mud and water; this fort will not bear a brisk stream, therefore it ftill retains much dirt and mud, whence it is called Slime Ore. The rough part of ftampt Ore should be tyed in a stream of water, and the hinder part of the tye jigged through a fix or seven hole sieve. If it is much adulterated with Tin, Lead, or Mundick, it must be cleansed by frequently tying or buddling of it. In order to clear the earthy fordes from the flime or loobs, it may be trunked, and after purified by the buddle, kieve, dilluer, &c. the fame as flime Tin, if it is worth the expence. It must also be noted, that Copper Ore requires a coarser plate or grate in ftamping, than Tin does, because it is of a lighter nature and more fleaky.

I have heard of a poor fandy Copper Ore fomewhere in Wales, of the appearance of verdigreafe, which is fo light, that the cupreous part of it will not bear even the least stream of water: they drefs it by grinding, dry ftamping, or bucking; then put it into tubs or kieves, and tofs and pack it the fame as I have observed of Tin: now the real Ore in it being without any fulphur, or much Metal, is fpecifically lighter than the waste or fand; therefore the Ore fwims uppermoft, and is fkimmed off in the manner of Tin fkimpings. But I fuppofe those extreme light Ores are fo very poor, that none would be concerned with them, only in hopes of their improvement.

It is worth notice, that Copper Ore may be too curiously or too remiffly dreffed, fo that either way the adventurers may incur a lofs; the ground of which is fometimes not fo well confidered as it deferves. If too much time and coft are expended in dressing the Ore, every one will grant it infers a lofs; but on the other hand, if too much foul Ore is left in it, that will alfo be to the prejudice of the concerned. Every ton of waste Ore cofts as much to be smelted as a ton of clean; at least, the buyer substracts as much for a ton of the one, as the other.

Suppofe

Suppose the buyer allows three pounds sterling for his charges of fmelting and working a ton of Ore, and confequently the fame fum for each ton of wafte in the Ore, which in reality the smelting costs the buyer or refiner; and therefore he must deduct fo much from the produce of the Ore ton. This is the cafe in Cornwall; but in other places, more diftant from the furnaces, in Ireland for inftance, the deduction must amount to more money, in proportion to the duty there on Ore, and also an overplus of freight, and if there be any other furplusage of coft, more than in Cornwall, as a longer carriage by land, and the like, all will operate to leffen the value of the Ore: but where fuch incidents are lefs than common, as a very short freight, or little charge in land carriage, then instead of a deduction, there is room to make a further advance of the price.

To illuftrate this cafe, fuppofe one hundred tons of Copper Ore, to be worth ten pounds ton, the amount of which will be one thousand pounds; suppose also it has so much earth or wafte in it, that it may be reduced to fifty tons, with a moderate charge in dreffing, and with an inconfiderable loss of the Ore; then each ton will contain nearly the Copper which two tons did before: and whereas the buyer would have taken out fix pounds for the charges of carriage, freight, and smelting of two tons, he will now deduct but three pounds for those charges upon the fame Ore in one ton: fo that inftead of deducting three hundred pounds on the one hundred tons of Ore, he will now deduct but one hundred and fifty pounds on fifty tons, whereby the adventurers will fave fo much of the other one hundred and fifty pounds, by how much the parcel of Ore will coft lefs for dreffing and taking out the wafte; for the fifty tons of Ore will now be worth twenty-three pounds ton, which will amount to eleven hundred and fifty pounds inftead of one thousand. Yet if the Ore be light or rich, there may be more of it loft, than the useless wafte carried off may compensate.

Again, if one hundred tons of wafte were mixed with the one hundred tons of Ore worth ten pounds ton, then the buyer would make an additional abatement of three hundred pounds more for his charges upon the one hundred tons of waste; fo that the whole amount of the Ore, would be but feven hundred pounds, instead of one thoufand pounds; for the Ore would be only worth three pounds ten fhillings ton; according to which, it is plain, that Ore may be too curiously or too careleffly dreffed. For Ore rich in nature, may be brought to

a great