Note note 4, p. 273 — BOOK VIII.

[4] Cadmia bituminosa. The description of this substance by Agricola, given below, indicates that it was his term for the complex copper-zinc-arsenic-cobalt minerals found in the well-known, highly bituminous, copper schists at Mannsfeld. The later Mineralogists, Wallerius (Mineralogia, Stockholm, 1747), Valmont De Bomare (Mineralogie, Paris, 1762), and others assume Agricola's cadmia bituminosa to be "black arsenic" or "arsenic noir," but we see no reason for this assumption. Agricola's statement (De Nat. Foss., p. 369) is "... the schistose stone dug up at the foot of the Melibocus Mountains, or as they are now called the Harz (Hercynium), near Eisleben, Mannsfeld, and near Hettstedt, is similar to spinos (a bituminous substance described by Theophrastus), if not identical with it. This is black, bituminous, and cupriferous, and when first extracted from the mine it is thrown out into an open space and heaped up in a mound. Then the lower part of the mound is surrounded by faggots, on to which are likewise thrown stones of the same kind. Then the faggots are kindled and the fire soon spreads to the stones placed upon them; by these the fire is communicated to the next, which thus spreads to the whole heap. This easy reception of fire is a characteristic which bitumen possesses in common with sulphur. Yet the small, pure and black bituminous ore is distinguished from the stones as follows: when they burn they emit the kind of odour which is usually given off by burning bituminous coal, and besides, if while they are burning a small shower of rain should fall, they burn more brightly and soften more quickly. Indeed, when the wind carries the fumes so that they descend into nearby standing waters, there can be seen floating in it something like a bituminous liquid, either black, or brown, or purple, which is sufficient to indicate that those stones were bituminous. And that genus of stones has been recently found in the Harz in layers, having occasionally gold-coloured specks of pyrites adhering to them, representing various flat sea-fish or pike or perch or birds, and poultry cocks, and sometimes salamanders."