BOOK VIII. 



UESTIONS of assaying were explained in the last 

 Book, and I have now come to a greater task, that 

 is, to the description of how we extract the metals. 

 First of all I will explain the method of preparing 

 the ore* ; for since Nature usually creates metals 

 in an impure state, mixed with earth, stones, and 

 solidified juices, it is necessary to separate most of 

 these impurities from the ores as far as can be, 

 before they are smelted, and therefore I will now 

 describe the methods by which the ores are sorted, broken with hammers, 

 burnt, crushed with stamps, ground into powder, sifted, washed, roasted, 

 and calcined*. 



^As would be expected, practically all the technical terms used by Agricola in this 

 chapter are adaptations. The Latin terms, canalis, area, lacus, vasa, cribrum, and fossa, 

 have had to be pressed into service for many different devices, largely by extemporised 

 combinations. Where the devices described have become obsolete, we have adopted the 

 nomenclature of the old works on Cornish methods. The following examples may be of 

 interest : — 



Simple huddle = Canalis simplex Short strake ■= Area curta 



Divided buddle = Canalis tabellis distinctus Canvas strake = Area linteis exlensis contecta 



Ordinary strake = Canalis devexus Limp = Radius. 



The strake (or streke) when applied to alluvial tin, would have been termed a " tye " 

 in some parts of Cornwall, and the " short strake " a " gounce." In the case of the stamp 

 mill, inasmuch as almost every mechanical part has its counterpart in a modern mill, we 

 have considered the reader will have less difficulty if the modern designations are used 

 instead of the old Cornish. The following are the essential terms in modern, old Cornish, 



and Latin : — 



Stamp . . Stamper 



Stamp-stem . . Lifter 



Shoes . . Stamp-heads . 



Mortar-box . .Box 



Cam-shaft . . Barrell 



Denies 



Pili denies 



Laminae foraminum plenae 



Lacus 



. Pilum Cams . . Caps 



.Pilum Tappets ..Tongues 



. Capita Screens . . Crate 



. Capsa Settling pit . . Catchers 



.Axis Jigging sieve . .Dilleugher . .Cribrum anguslum 



"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 metal- 

 lurgical 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 Probierbiichlein 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 



