The next application of the word was to ruby copper (?), a suboxide whose beautiful crystals are formed in the natural state. Pollux and Hesychius the grammarian (D.D. 380) define it as copper (χαλκός) resembling gold; and Cicero puts the question whether, if a person should offer a piece of gold for sale, thinking he was disposing of only a piece of orichalcum, an honest man ought to inform him that it was really gold, or might fairly buy for a penny what is _worth a thousand times as much_.[296] Buffon compares it with tombac, or Chinese copper containing gold.[297] Beckmann (_s. v._ ‘Tin’) notes _aurichalcum_ or Corinthian brass in Plautus, ‘Auro contra carum.’ Festus speaks of ‘orichalcum (copper), stannum (zinc or pewter?), cassiterum (tin), and aurichalcum (brass).’ The same signification occurs in Ambrose, Bishop of Milan (fourth century); in Primasius, Bishop of African Adrumetum (sixth century), and in Isidore, Bishop of Seville (seventh century). Albertus Magnus (thirteenth century), the Dominican monk, in treating ‘De Natura et Commixtione Æris,’ describes how _cuprum_ became _aurichalcum_.
Strabo is mysterious. In one place he tells us that the Cyprian copper alone produces the Cadmian stone, copperas-water, and oxide of copper. In another (lib. xiii.) he says, ‘There is a stone near Andeira which, being burnt, becomes iron. It is then put into a furnace, together with some kind of earth,[298] when it (the stone? the earth? or both?) drops or distils a ψευδάργυρος (mock silver, zinc?), which, with the addition of copper, produces what is called _the mixture_, and which some term _oreichalcum_.’ Pseudargyros, also found in the neighbourhood of Tmolus, would here seem to mean zinc or _Cadmia fossilis_ (natural calamine or carbonate of zinc). Pliny (xxxiv. 22) confuses with cadmia, furnace calamine, and a particular ore of copper opposed to calchitis. When Dioscorides (v. cap. 84) seems to allude to artificial or furnace-calamine, an impure oxide of zinc, he may mean the more modern _tutiya_ (Avicenna), _toutia_, _thouthia_,[299] _cadmie des fourneaux_, or tutty. Reduced to powder, and mixed with an equal quantity of wetted charcoal by way of fondant or flux, it is melted with copper to form brass. The Avocat de Launey (1780) and Bishop Watson both agree that Strabo’s orichalcum is brass.