BOOK V. 



Ill 



schist, marble, and also in stone which easily melts in fire of the second 

 degree, and which is sometimes so porous that it seems completely decom- 

 posed. Lastly, gold is found in pyrites, though rarely in large quantities. 

 When considering silver ores other than native silver, those ores are 



Arsenical Minerals. Metallic arsenic was unknown, although it has been main- 

 tained that a substance mentioned by Albertus Magnus (De Rebus Metallicis) was the 

 metallic form. Agricola, who was familiar with all Albertus's writings, makes no mention 

 of it, and it appears to us that the statement of Albertus referred only to the oxide from 

 sublimation. Our word " arsenic " obviously takes root in the Greek for orpiment, which 

 was also used by Pliny (xxxiv, 56) as arrhenicum, and later was modified to arsenicum 

 by the Alchemists, who applied it to the oxide. Agricola gives the following in Bermannus (p. 

 448), who has been previously discussing realgar and orpiment : — " Ancon : Avicenna 

 " also has a white variety. Bermannus : I cannot at all believe in a mineral of a white 

 " colour ; perhaps he was thinking of an artificial product ; there are two which the Alchemists 

 " make, one yellow and the other white, and they are accounted the most jxiwerful poisons 

 " to-day, and are called only by the name arsenicum." In De Nalura Fossilium (p. 219) is 

 described the making of " the white variety" by sublimating orpiment, and also it is noted 

 that realgar can be made from orpiment by heating the latter for five hours in a sealed 

 crucible. In De Re Metallica (Book X.), he refers to auripigmentum faciicum, and no doubt 

 means the realgar made from orpiment. The four minerals of arsenic base mentioned by 

 Agricola were : — 



Operment Orpiment (AS2S3) Orpiment 



Rosgeel . . Realgar (As S) . . Realgar 



Arsenik .. Artificial arsenical oxide White arsenic 



A uripigmentum 

 Sandaraca 

 Arsenicum 



Lapis subrutilus alque 

 spiendens 



*Mispickel 



Mistpuckel . . Arsenopyrite (Fe As S) 

 We are somewhat uncertain as to the identification of the last. The yellow and red sul- 

 phides, however, were well known to the Ancients, and are described by Aristotle, Theophrastus 

 (71 and 89), Dioscorides (V, 81), Phny (xxxili, 22, etc.) ; and Strabo (Xll, 3, 40) mentions 

 a mine of them near Pompeiopolis, where, because of its jwisonous character none but slaves 

 were employed. The Ancients believed that the yellow sulphide contained gold — hence 

 the name auripigmentum, and Pliny describes the attempt of the Emperor Caligula to extract 

 the gold from it, and states that he did obtain a small amount, but unprofitably. So late 

 a mineralogist as Hill (1750) held this view, which seemed to be general. Both realgar and 

 orpiment were important for pigments, medicinal purposes, and poisons among the Ancients. 

 In addition to the above, some arsenic-cobalt minerals are included under cadmia. 



