even tin and bismuth[1] are treated differently from lead. Although the evaporation of juices is an art apparently quite distinct from metallurgy, yet they ought not to be considered separately, inasmuch as these juices are also often dug out of the ground solidified, or they are produced from certain 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[2], another for alum, another for vitriol[3], 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
- ↑ … plumbum … candidum ac cinereum vel nigrum. "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 Nützlich 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? Bermannus: 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. Plumbum candidum is whiter and plumbum nigrum is darker, as you see. Naevius: We see that this is of the colour of galena. Ancon: 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.
- ↑ Atramentum 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 Natura Fossilium, p. 219). The blue was of course copper sulphate, and it is fairly certain that the white was zinc vitriol.
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:1. Fluids and gases. Earths
| 2. Mineral bodies | A. Homogenous bodies B. Mixtures. |
(a) (b) | |||
| Being heterogeneous mixtures of (a) | |||||
| Compound minerals. Being homogenous mixtures of (a) | |||||
| Simple minerals | Earths Solidified juices Stones Metals | ||||
