BOOK VII.

233

galena ; also copper, the same either roasted or in leaves or filings 9 ; also theslags of gold, silver, copper, and lead ; also soda 10 , its slags, saltpetre, burnedalum, vitriol, sal iosius, and melted salt 11 ; stones which easily meltin hot furnaces, the sand which is made from them 12 ; soft tophus 13 ,

litharge, but there is no valid reason for assigning to it any special one of their terms, so faras we can see.

•There are four forms of copper named as re-agents by Agricola :

Copper filings — Aeris scobs elimata.

Copper scales — Aeris squamae.

Copper flowers — Aeris flos.

Roasted copper — Aes ustum.

The first of these was no doubt finely divided copper metal; the second, third, andfourth were probably all cupric oxide. According to Agricola (De Nat. Fos., p. 352), thescales were the result of hammering the metal; the flowers came off the metal when hot barswere quenched in water, and a third kind were obtained from calcining the metal. “ Bothflowers (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 DeNatura Fossilium, we can accept this material as being merely cupric oxide, but the aesustum of Pliny—Agricola’s usual source of technical nomenclature—is probably an artificialsulphide. 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.”

10 The reader is referred to note 6, p. 558, for more ample discussion of the alkalis.Agricola gives in this chapter four substances of that character :

Soda (nitrum). Lye. “ Ashes which wool-dyers use.”

“ Salt made from the ashes of musk ivy.”

The last three are certainly potash, probably impure. While the first might be eitherpotash or soda, the fact that the last three are mentioned separately, together with otherevidence, convinces us that by the first is intended the nitrum so generally imported intoEurope from Egypt during the Middle Ages. This imported salt was certainly the naturalbicarbonate, and we have, therefore, used the term “soda.”

u In this chapter are mentioned seven kinds of common salt:

Salt —

Rock salt —

“ Made ” salt —

Refined salt —

Melted salt —

And in addition sal tostus and sal torrefactus.

salt. The melted salt would apparently be salt-glass. What form the sal tostus and saltorrefactus could have we cannot say, however, but they were possibly some form of heatedsalt ; they may have been combinations after the order of sal artiflciosus (see p. 236).

Sal.

Sal fossilis.

Sal factictius.

Sal purgatius.

Sal liquefactus.

Sal facticius is used in distinction from rock-

12 “Stones which easily melt in hot furnaces and sand which is made from them”(lapides qui in ardentibus fornacibus facile liquescunt arenae ab eis resolutae). These wereprobably quartz in this instance, although fluorspar is also included in this same genus, Forfuller discussion see note on p. 380.

lz Tophus. (Interpretatio ; Toff stein oder topstein). According to Dana (Syst. ofMin., p. 678), the German topfstein was English potstone or soapstone, a magnesian silicate.It is scarcely possible, however, that this is what Agricola meant by this term, for such asubstance would be highly infusible. Agricola has a good deal to say about this mineral inDe Natura Fossilium (p. 189 and 313), and from these descriptions it would seem to be atufaceous limestone of various sorts, embracing some marls, stalagmites, calcareous sinter,etc. He states : “ Generally fire does not melt it, but makes it harder and breaks it intopowder. Tophus is said to be a stone found in caverns, made from the dripping of stonejuice solidified by cold .... sometimes it is found containing many shells, and“ likewise the impressions of alder leaves; our people make lime by burning it.” Pliny,upon whom Agricola depends largely for his nomenclature, mentions such a substance(xxxvi, 48): " Among the multitude of stones there is tophus. It is unsuitable for