Note 2 — BOOK VIII.

Agricola uses four Latin verbs in connection with heat operations at temperatures under the melting point: Calefacio, uro, torreo, and cremo. The first he always uses in the sense of "to warm" or "to heat," but the last three he uses indiscriminately in much the same way as the English verbs burn, roast, and calcine are used; but in general he uses the Latin verbs in the order given to indicate degrees of heat. We have used the English verbs in their technical sense as indicated by the context.

It is very difficult to say when roasting began as a distinct and separate metallurgical step in sulphide ore treatment. The Greeks and Romans worked both lead and copper sulphides (see note on p. 391, and note on p. 403), but neither in the remains of old works nor in their literature is there anything from which satisfactory details of such a step can be obtained. The Ancients, of course, understood lime-burning, and calcined several salts to purify them or to render them more caustic. Practically the only specific mention is by Pliny regarding lead ores (see p. 391). Even the statement of Theophilus (1050-1100, A.D.), may refer simply to rendering ore more fragile, for he says (p. 305) in regard to copper ore: "This stone dug up in abundance is placed upon a pile and burned (comburitur) after the manner of lime. Nor does it change colour, but loses its hardness and can be broken up, and afterward it is smelted." The Probierbüchlein casually mentions roasting prior to assaying, and Biringuccio (III, 2) mentions incidentally that "dry and ill-disposed ores before everything must be roasted in an open oven so that the air can get in." He gives no further information; and therefore this account of Agricola's becomes practically the first. Apparently roasting, as a preliminary to the treatment of copper sulphides, did not come into use in England until some time later than Agricola, for in Col. Grant Francis' "Smelting of Copper in the Swansea District" (London, 1881, p. 29), a report is set of the "Doeinges of Jochim Ganse"—an imported German—at the "Mynes by Keswicke in Cumberland, A.D., 1581," wherein the delinquencies of the then current practice are described: "Thei never coulde, nether yet can make (copper) under XXII. tymes passinge thro the fire, and XXII. weekes doeing thereof ane sometyme more. But now the nature of these IX. hurtfull humors abovesaid being discovered and opened by Jochim's way of doeing, we can, by his order of workeinge, so correct theim, that parte of theim beinge by nature hurtfull to the [Pg 268]copper in wasteinge of it, ar by arte maide freindes, and be not onely an encrease to the copper, but further it in smeltinge; and the rest of the other evill humors shalbe so corrected, and their humors so taken from them, that by once rosteinge and once smeltinge the ure (which shalbe done in the space of three dayes), the same copper ure shall yeeld us black copper." Jochim proposed by 'rostynge' to be rid of "sulphur, arsineque, and antimony."