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BOOK IX.

charcoal is not abundant, no copper is made from them. From the silver-lead poured into iron moulds they likewise make cakes ; when these cakeshave been melted in the cupellation furnace, the silver is parted from thelead, because part of the lead is transformed into litharge and part intohearth-lead, from which in the blast furnace on re-melting they make

recognise his conterfei from the furnaces as the same substance as the zincum from Silesia.The first correlation of these substances was apparently by Lohneys, in 1617, who says(Vom Bergwerk, p. 83-4) : “ When the people in the smelting works are smelting, there is" made under the furnace and in the cracks in the walls among the badly plastered stones, a“ metal which is called zinc or counterfeht, and when the wall is scraped it falls into a vessel“ placed to receive it. This metal greatly resembles tin, but it is harder and less malleable.“ . The Alchemists have a great desire for this zinc or bismuth.” That this metal

originated from blende or calamine was not recognised until long after, and Libavis(Alchymia, Frankfort, 1606), in describing specimens which came from the East,did not so identify it, this office being performed by Glauber, who says ( De ProsperitateGermanias, Amsterdam, 1656) : “ Zink is a volatile mineral or half-ripe metal when it is“ extracted from its ore. It is more brilliant than tin and not so fusible or malleable . . .

“ it turns (copper) into brass, as does lapis calaminaris, for indeed this stone is nothing but“ infusible zinc, and this zinc might be called a fusible lapis calaminaris, inasmuch as both“ of them partake of the same nature. ... It sublimates itself up into the cracks of the“ furnace, whereupon the smelters frequently break it out.” The systematic distillationof zinc from calamine was not discovered in Europe until the 18th Century. Henkel isgenerally accredited with the first statement to that effect. In a contribution published asan Appendix to his other works, of which we have had access only to a French translation(Pyrilologie , Paris, 1760, p. 494), he concludes that zinc is a half-metal of which the best oreis calamine, but believes it is always associated with lead, and mentions that an Englishmanlately arrived from Bristol had seen it being obtained from calamine in his own country. Hefurther mentions that it can be obtained by heating calamine and lead ore mixed with coalin a thick earthen vessel. The Bristol works were apparently those of John Champion,established about 1740. The art of distillation was probably learned in the East.

Definite information as to the zinc minerals goes back to but a little before theChristian Era, unless we accept nebular references to aurichalcum by the poets, or what ispossibly zinc ore in the “ earth ” mentioned by Aristotle {De Mirabilibus, 62): " Men say“ that the copper of the Mossynoeci is very brilliant and white, no tin being mixed with it;“ but there is a kind of earth there which is melted with it.” This might quite well be anarsenical mineral. But whether we can accept the poets or Aristotle or the remark ofStrabo given above, as sufficient evidence or not, there is no difficulty with the descrip-tion of cadmia and pompholyx and spodos of Dioscorides (1st Century), parts of whichwe reproduce in note 26, p. 394. His cadmia is described as rising from the copper furnacesand clinging to the iron bars, but he continues : “ Cadmia is also prepared by burning the“ stone called pyrites, which is found near Mt. Soloi in Cyprus. . . . Some say that“ cadmia may also be found in stone quarries, but they are deceived by stones having a“ resemblance to cadmia.’’ Pompholyx and spodos are evidently furnace calamine. Fromreading the quotation given on p. 394, there can be no doubt that these materials, natural orartificial, were used to make brass, for he states (v, 46): “ White pompholyx is made every" time that the artificer in the working and perfecting of the copper sprinkles powdered“ cadmia upon it to make it more perfect, the soot arising from this .... is pompholyx.”Pliny is confused between the mineral cadmia and furnace calamine, and none of his statementsare very direct on the subject of brass making. His most pointed statement is (xxxiv, 2):“ . - . . Next to Livian (copper) this kind best absorbs cadmia, and is almost as good

as aurichalcum for making sesterces and double asses.” As stated above, there can be littledoubt that the aurichalcum of the Christian Era was brass, and further, we do know of brasssesterces of this period. Other Roman writers of this and later periods refer to earth usedwith copper for making brass. Apart from these evidences, however, there is the evidence ofanalyses of coins and objects, the earliest of which appears to be a large brass of the Cassiafamily of 20 b.c., analyzed by Phillips, who found 17.3% zinc (Records of Mining andMetallurgy, London, 1857, p. 13). Numerous analyses of coins and other objects datingduring the following century corroborate the general use of brass. Professor Gowland(Presidential Address, Inst, of Metals, 1912) rightly considers the Romans were the first tomake brass, and at about the above period, for there appears to be no certainty of any earlierproduction. The first adequate technical description of brass making is in about 1200 a.d.,being that of Theophilus, who describes (Hendrie’s Trans., p. 307) calcining calamina andmixing it with finely divided copper in glowing crucibles. The process -was repeated byadding more calamine and copper until the pots were full of molten metal. T his methodis repeatedly described with minor variations by Biringuccio, Agricola {De Nat. Fos.), andothers, down to the 18th Century. For discussion of the zinc minerals see note on p. n 2 -