BOOK VII. 233 



galena ; also copper, the same either roasted or in leaves or filings' ; also the 

 slags of gold, silver, copper, and lead ; also soda^", its slags, saltpetre, burned 

 alum, vitriol, sal tostus, and melted salt^^ ; stones which easily melt 

 in hot furnaces, the sand which is made from them^^ ; soft tophus^^, 



litharge, but there is no valid reason for assigning to it any special one of their terms, so far 

 as 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, 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 iflos) and hammer-scales (squama) have the same properties as cremaium copper. 

 " . . . The particles of flower copper are finer than scales or cremaium 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 untilit 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." 



'"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 either 

 potash or soda, the fact that the last three are mentioned separately, together with other 

 evidence, convinces us that by the first is intended the nitrum so generally imported into 

 Europe from Egypt during the Middle Ages. This imported salt was certainly the natural 

 bicarbonate, and we have, therefore, used the term "soda." 



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



Salt — Sal. 



Rock salt — Sal fossilis. 



" Made " salt — Sal factictius. 



Refined salt — Sal purgatius. 



Melted salt — Sal liquef actus. 

 And in addition sal tostus and sal torrcfactus. Sal facticius is used in distinction from rock- 

 salt. The melted salt would apparently be salt-glass. What form the sal tostus and sal 

 torrefactus could have we cannot say, however, but they were possibly some form of heated 

 salt ; they may have been combinations after the order of sal artificiosus (see p. 236). 



'^ "Stones which easily melt in hot furnaces and sand which is made from them" 

 (lapides qui in ardentibus fornacihus facile liquescunt arenae ab eis resolutae). These were 

 probably quartz in this instance, although fluorspar is also included in this same genus. For 

 fuller discussion see note on p. 380. 



^^Tophus. (Interpretatio ; Toffstein oder topstein). According to Dana (Syst. of 

 Min., p. 678), the German topf stein was English potstone or soapstone, a magnesian silicate. 

 It is scarcely possible, however, that this is what Agricola meant by this term, for such a 

 substance would be highly infusible. Agricola has a good deal to say about this mineral in 

 De Natura Fossilium (p. 189 and 313), and from these descriptions it would seem to be a 

 tufaceous 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 into 

 " powder. Tophus is said to be a stone found in caverns, made from the dripping of stone 

 " juice 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 



