Note note 9, p. 233 — BOOK VII.

[9] There are four forms of copper named as re-agents by Agricola:

Copper filingsAeris scobs elimata.

Copper scalesAeris squamae.

Copper flowersAeris flos.

Roasted copperAes ustum.

The first of these was no doubt finely divided copper metal; the second, third, and fourth were probably all cupric oxide. According to Agricola (De Nat. Fos., p. 352), the scales were the result of hammering the metal; the flowers came off the metal when hot bars were quenched in water, and a third kind were obtained from calcining the metal. "Both flowers (flos) and hammer-scales (squama) have the same properties as crematum copper.... The particles of flower copper are finer than scales or crematum copper." If we assume that the verb uro used in De Re Metallica is of the same import as cremo in the De Natura Fossilium, we can accept this material as being merely cupric oxide, but the aes ustum of Pliny—Agricola's usual source of technical nomenclature—is probably an artificial sulphide. Dioscorides (V, 47), who is apparently the source of Pliny's information, says:—"Of chalcos cecaumenos, the best is red, and pulverized resembles the colour of cinnabar; if it turns black, it is over-burnt. It is made from broken ship nails put into a rough earthen pot, with alternate layers of equal parts of sulphur and salt. The opening should be smeared with potter's clay and the pot put in the furnace until it is thoroughly heated," etc. Pliny (XXXIV, 23) states: "Moreover Cyprian copper is roasted in crude earthen pots with an equal amount of sulphur; the apertures of the pots are well luted, and they are kept in the furnace until the pot is thoroughly heated. Some add salt, others use alumen instead of sulphur, others add nothing, but only sprinkle it with vinegar."