A Dictionary of Arts, Manufactures and Mines / containing a clear exposition of their principles and practice

by Andrew Ure

Of the assays by the humid way.—The assays by the humid way, not reducible to very simple processes, are true chemical analyses, which may in fact be applied with much advantage, either to ores, or to the products of the furnace; but which cannot be expected to be practised in smelting-houses, on account of the complication of apparatus and reagents they require. Moreover, an expert chemist is necessary to obtain results that can be depended on. The directors of smelting-houses, however, should never neglect any opportunities that may occur of submitting the materials operated upon, as well as their products, to a more thorough examination than the dry way alone can effect. One of the great advantages of similar researches is, to discover and appreciate the minute quantities of injurious substances which impair the malleability of the metals, which give them several bad qualities, about whose nature and cause, more or less error and uncertainty prevail. Chemical analysis, rightly applied to metallurgy, cannot fail to introduce remarkable improvements into the processes.—See the different metals, in their alphabetical places.

For assays in the dry way, both of stony and metallic minerals, the process of Dr. Abich deserves recommendation. In consists in mixing the pulverized mineral with 4 or 6 times its weight of carbonate of baryta in powder, fusing the mixture at a white heat, and then dissolving it after it cools, in dilute muriatic acid. The most refractory minerals, even corundum, cyanite, staurolite, zircon, and felspar, yield readily to this treatment. This process may be employed with advantage upon poor refractory ores. The platinum crucible, into which the mixed materials are put for fusion, should be placed in a Hessian crucible, and surrounded with good coak.

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The following tabular view of the metallic produce of the British mines, is given by two very skilful observers, in a work published in 1827, entitled Voyage Metallurgique en Angleterre, par MM. Dufrénoy et Elie de Beaumont:—

				Tons.			Tons.
Tin			Cornwall alone				3,160
Copper	-		Cornwall	9,331		-	11,469
			Devonshire	537
			Staffordshire	38
			Anglesey	738
			Wales	55
			Cumberland	21
			Ireland	738
			Scotland	11
Lead	-		Wales	7,500		-	31,900
			Scotland	2,800
			Cornwall and Devonshire	800
			Shropshire	800
			Derbyshire	1,000
			Cumberland	19,000
Cast Iron			about				600,000	[32]

[32] I have converted the weights of lead and cast iron, given in kilogrammes, into tons, at the rate of 1000 kilogrammes per ton; which is sufficiently near.

The manganese raised in England exceeds 2000 tons.

M. Heron de Villefosse inserted in the last number of the Annales des Mines for 1827, the following statistical view of the metallic products of France:—

	Tons.
Lead in pigs (saumons)	103
Litharge	513
Sulphuret of lead, ground galena (alquifoux)	112
Black copper	164
Antimony	91
Manganese	765
Crude cast iron	25,606
Bar iron	127,643
Steel	3,500
Silver in ingots	1	1⁄6