[Pg 408][47] This expression is usually used for hearth-lead, but in this case the author is apparently confining himself to lead ore, and apparently refers to lead carbonates. The German Translation gives pleyschweiss. The pyrites mentioned in this paragraph may mean galena, as pyrites was to Agricola a sort of genera.
[48] (Excoquitur) ... "si verò pyrites, primò è fornace, ut Goselariae videre licet, in catinum defluit liquor quidam candidus, argento inimicus et nocivus; id enim comburit: quo circa recrementis, quae supernatant, detractis effunditur: vel induratus conto uncinato extrahitur: eundem liquorem parietes fornacis exudant." In the Glossary the following statement appears: "Liquor candidus primo è fornace defluens cum Goselariae excoquitur pyrites,—kobelt; quem parietes fornacis exudant,—conterfei." In this latter statement Agricola apparently recognised that there were two different substances, i.e., that the substance found in the furnace walls—conterfei—was not the same substance as that which first flowed from the furnace—kobelt. We are at no difficulty in recognizing conterfei as metallic zinc; it was long known by that term, and this accidental occurrence is repeatedly mentioned by other authors after Agricola. The substance which first flowed into the forehearth presents greater difficulties; it certainly was not zinc. In De Natura Fossilium (p. 347), Agricola says that at Goslar the lead has a certain white slag floating upon it, the "colour derived from the pyrites (pyriten argenteum) from which it was produced." Pyriten argenteum was either marcasite or mispickel, neither of which offers much suggestion; nor are we able to hazard an explanation of value.
Historical Note on Zinc. The history of zinc metallurgy falls into two distinct [Pg 409]lines—first, that of the metal, and second, that of zinc ore, for the latter was known and used to make brass by cementation with copper and to yield oxides by sublimation for medicinal purposes, nearly 2,000 years before the metal became generally known and used in Europe.
There is some reason to believe that metallic zinc was known to the Ancients, for bracelets made of it, found in the ruins of Cameros (prior to 500 B.C.), may have been of that age (Raoul Jagnaux, Traité de Chimie Générale, 1887, II, 385); and further, a passage in Strabo (63 B.C.-24 A.D.) is of much interest. He states: (XIII, 1, 56) "There is found at Andeira a stone which when burnt becomes iron. It is then put into a furnace, together with some kind of earth, when it distils a mock silver (pseudargyrum), or with the addition of copper it becomes the compound called orichalcum. There is found a mock silver near Tismolu also." (Hamilton's Trans., II, p. 381). About the Christian era the terms orichalcum or aurichalcum undoubtedly refer to brass, but whether these terms as used by earlier Greek writers do not refer to bronze only, is a matter of considerable doubt. Beyond these slight references we are without information until the 16th Century. If the metal was known to the Ancients it must have been locally, for by its greater adaptability to brass-making it would probably have supplanted the crude melting of copper with zinc minerals.
It appears that the metal may have been known in the Far East prior to such knowledge in Europe; metallic zinc was imported in considerable quantities from the East as early as the 16th and 17th centuries under such terms as tuteneque, tuttanego, calaëm, and spiauter—the latter, of course, being the progenitor of our term spelter. The localities of Eastern production have never been adequately investigated. W. Hommel (Engineering and Mining Journal, June 15, 1912) gives a very satisfactory review of the Eastern literature upon the subject, and considers that the origin of manufacture was in India, although the most of the 16th and 17th Century product came from China. The earliest certain description seems to be some recipes for manufacture quoted by Praphulla Chandra Ray (A History of Hindu Chemistry, London, 1902, p. 39) dating from the 11th to the 14th Centuries. There does not appear to be any satisfactory description of the Chinese method until that of Sir George Staunton (Journal Asiatique Paris, 1835, p. 141.) We may add that spelter was produced in India by crude distillation of calamine in clay pots in the early part of the 19th Century (Brooke, Jour. Asiatic Soc. of Bengal, vol. XIX, 1850, p. 212), and the remains of such smelting in Rajputana are supposed to be very ancient.
The discovery of zinc in Europe seems to have been quite independent of the East, but precisely where and when is clouded with much uncertainty. The marchasita aurea of Albertus Magnus has been called upon to serve as metallic zinc, but such belief requires a hypothesis based upon a great deal of assumption. Further, the statement is frequently made that zinc is mentioned in Basil Valentine's Triumphant Chariot of Antimony (the only one of the works attributed to this author which may date prior to the 17th Century), but we have been unable to find any such reference. The first certain mention of metallic zinc is generally accredited to Paracelsus (1493-1541), who states (Liber Mineralium II.): "Moreover there is another metal generally unknown called zinken. It is of peculiar nature and origin; many other metals adulterate it. It can be melted, for it is generated from three fluid principles; it is not malleable. Its colour is different from other metals and does not resemble others in its growth. Its ultimate matter (ultima materia) is not to me yet fully known. It admits of no mixture and does not permit of the fabricationes of other metals. It stands alone entirely to itself." We do not believe that this book was published until after Agricola's works. Agricola introduced the following statements into his revised edition of Bermannus (p. 431), published in 1558: "It (a variety of pyrites) is almost the colour of galena, but of entirely different components. From it there is made gold and silver, and a great quantity is dug in Reichenstein, which is in Silesia, as was recently reported to me. Much more is found at Raurici, which they call zincum, which species differs from pyrites, for the latter contains more silver than gold, the former only gold or hardly any silver." In De Natura Fossilium (p. 368): "For this cadmia is put, in the same way as quicksilver, in a suitable vessel so that the heat of the fire will cause it to sublime, and from it is made a black or brown or grey body which the Alchemists call cadmia sublimata. This possesses corrosive properties to the highest degree. Cognate with this cadmia and pyrites is a compound which the Noricans and Rhetians call zincum." We leave it to readers to decide how near this comes to metallic zinc; in any event, he apparently did not [Pg 410]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 Prosperitate Germanias, 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 distillation of zinc from calamine was not discovered in Europe until the 18th Century. Henkel is generally accredited with the first statement to that effect. In a contribution published as an Appendix to his other works, of which we have had access only to a French translation (Pyritologie, Paris, 1760, p. 494), he concludes that zinc is a half-metal of which the best ore is calamine, but believes it is always associated with lead, and mentions that an Englishman lately arrived from Bristol had seen it being obtained from calamine in his own country. He further mentions that it can be obtained by heating calamine and lead ore mixed with coal in 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 the Christian Era, unless we accept nebular references to aurichalcum by the poets, or what is possibly 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 an arsenical mineral. But whether we can accept the poets or Aristotle or the remark of Strabo given above, as sufficient evidence or not, there is no difficulty with the description of cadmia and pompholyx and spodos of Dioscorides (1st Century), parts of which we reproduce in [note 26, p. 394]. His cadmia is described as rising from the copper furnaces and 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. From reading the quotation given on p. [394], there can be no doubt that these materials, natural or artificial, 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 statements are 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 little doubt that the aurichalcum of the Christian Era was brass, and further, we do know of brass sesterces of this period. Other Roman writers of this and later periods refer to earth used with copper for making brass. Apart from these evidences, however, there is the evidence of analyses of coins and objects, the earliest of which appears to be a large brass of the Cassia family of 20 B.C., analyzed by Phillips, who found 17.3% zinc (Records of Mining and Metallurgy, London, 1857, p. 13). Numerous analyses of coins and other objects dating during the following century corroborate the general use of brass. Professor Gowland (Presidential Address, Inst. of Metals, 1912) rightly considers the Romans were the first to make brass, and at about the above period, for there appears to be no certainty of any earlier production. 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 and mixing it with finely divided copper in glowing crucibles. The process was repeated by adding more calamine and copper until the pots were full of molten metal. This method is repeatedly described with minor variations by Biringuccio, Agricola (De Nat. Fos.), and others, down to the 18th Century. For discussion of the zinc minerals see note on p. [112].
[49] "... non raro, ut nonnulli pyritae sunt, candida...." This is apparently the unknown substance mentioned above.
[Pg 411][50] One drachma is about 3 ounces Troy per short ton. Three unciae are about 72 ounces 6 dwts. Troy per short ton.
[51] In this section, which treats of the metallurgy of plumbum candidum, "tin," the word candidum is very often omitted in the Latin, leaving only plumbum, which is confusing at times with lead. The black tin-stone, lapilli nigri has been treated in a similar manner, lapilli (small stones) constantly occurring alone in the Latin. This has been rendered as "tin-stone" throughout, and the material prior to extraction of the lapilli nigri has been rendered "tin-stuff," after the Cornish.