BOOK 1. 3 



oven tin and bismuth" arc treated differently from lead. Although the 



evaporation of juices is an art apparently quite distinct frt)m metallurgy, 



yet they ought not to bo considered separately, inasmuch as these juices 



are also often dug out of the ground solidihed, or they are produced from 



e> rtain kinds of earth and stones which the miners dig up, and some of the 



juices are not themselves devoid of metals. Again, their treatment is not 



simple, since there is one method for common salt, another for soda', 



another for alum, another for vitriol 8, another for sulphur, and another 



for bitumen. 



Furthermore, there are many arts and sciences of which a miner should 



not be ignorant. First there is Philosophy, that he may discern the origin, 



cause, and nature of subterranean things ; for then he will be able to dig 



out the veins easily and advantageously, and to obtain more abundant results 



from his mining. Secondly, there is Medicine, that he may be able to look 



after his diggers and other workmen, that they do not meet with those 



'■ Galen calls the metallic earth a compound which is really a mixture, but he who wishes to 

 " instruct others should bestow upon each separate thing a definite name." 



For convenience of reference we may reduce the above to a diagram as follows : 



I. Fluids and gases. 



Mineral 

 bodies 



Homogenous 

 bodies 



(Earths 



(a) Simple I Solidified juices 



minerals] Stones 

 VMetals 



(b) Compound j Being homogenous mixtures 



minerals I of (a) 



B. Mixtures. Being heterogeneous mixtures of (a) 

 ^ . . . . plumbum .... candidum ac cinereum vel nigrimi. " Lead 

 " . . . white, or ash-coloured, or black." Agricola himself coined the term plumbum 

 cinereum for bismuth, no doubt following the Roman term for tin — plumbum candidum. 

 The following passage from Bermannus (p. 439) is of interest, for it appears to be 

 the first description of bismuth, although mention of it occurs in the Niitzlich Bergbuchlin 

 (see Appendix B). " Bermannus : I will show you another kind of mineral which is numbered 

 " amongst metals, but appears to me to have been unknown to the Ancients ; we call it 

 " bisemutum. Naevius : Then in your opinion there are more kinds of metals than the 

 " seven commonly believed ? Bermanjins : More, I consider ; for this which just now I 

 " said we called bisemutum, cannot correctly be called plumbum candidum (tin), nor nigrum 

 " (lead), but is different from both and is a third one. Plumb%tm candidum is whiter and 

 " plumbum nigrum is darker, as you see. Naevius : We see that this is of the colour of 

 " galena. Av.con : How then can bisemutum, as you call it, be distinguished from galena ? 

 " Bermannus : Easily ; when you take it in your hands it stains them with black, unless 

 " it is quite hard. The hard kind is not friable like galena, but can be cut. It is 

 " blacker than the kind of rudis silver which we say is almost the colour of lead, and thus 

 " is different from both. Indeed, it not rarely contains some silver. It generally indicates 

 " that there is silver beneath the place where it is found, and because of this our miners 

 " are accustomed to call it the 'roof of silver.' They are wont to roast this mineral, and 

 " from the better part they make metal ; from the poorer part they make a pigment of a 

 " kind not to be despised." 



''Nitrum. The Ancients comprised many salts under this head, but Agricola in the 

 main uses it for soda, although sometimes he includes potash. He usually, however, refers 

 to potash as lixivium or salt therefrom, and by other distinctive terms. For description 

 of method of manufacture and discussion, see Book XII., p. 558. 



^Airamentum sutorium — " Shoemaker's blacking." See p. 572 for description of method 

 of manufacture and historical footnote. In the main Agricola means green vitriol, but he does 

 describe three main varieties, green, blue, and white (De Naiura Fossilium, p. 219). The blue 

 was of course copper sulphate, and it is fairly certain that the white was zinc vitriol. 



