As seen from the following quotations from Agricola, on cadmia and cobalt, there was infinite
confusion as to the zinc, cobalt, and arsenic minerals ; nor do we think any good purpose is
served by adding to the already lengthy discussion of these passages, the obscurity of which
is natural to the state of knowledge ; but we reproduce them as giving a fairly clear idea of
the amount of confusion then existing. It is, however, desirable to bear in mind that the
mines familiar to Agricola abounded in complex mixtures of cobalt, nickel, arsenic, bismuth,
zinc, and antimony. Agricola frequently mentions the garlic odour from cadmia metallica,
which, together with the corrosive qualities mentioned below, would obviously be due to
arsenic. Bermannus (p. 459). " This kind of pyrites miners call cobaltum, if it be allowed
' to me to use our German name. The Greeks call it cadmia. The juices, however, out
' of which pyrites and silver are formed, appear to solidify into one body, and thus is produced
' what they call cobaltum. There are some who consider this the same as pyrites, because
' it is almost the same. There are some who distinguish it as a species, which pleases me,
' for it has the distinctive property of being extremely corrosive, so that it consumes the
' hands and feet of the workmen, unless they are well protected, which I do not believe that
' pyrites can do. Three kinds are found, and distinguished more by the colour than by other
' properties ; they are black (abolite ?), grey (smallite ?), and iron colour (cobalt glance ?).
' Moreover, it contains more silver than does pyrites. . ." Bermannus (p. 431). " It (a
' sort of pyrites) is so like the colour of galena that not without cause might anybody have
' doubt in deciding whether it be pyrites or galena.....Perhaps this kind is neither
' pyrites nor galena, but has a genus of its own. For it has not the colour of pyrites, nor the
' hardness. It is almost the colour of galena, but of entirely different components. From
' it there is made gold and silver, and a great quantity is dug out from Reichenstein which
' is in Silesia, as was lately reported to me. Much more is found at Raurici, which they call
' zincum ; which species differs from pyrites, for the latter contains more silver than gold,
' the former only gold, or hardly any silver."
(De Natura Fossilium, p. 170). " Cadmia fossilis has an odour like garlic " . . (p. 367).
' We now proceed with cadmia, not the cadmia fornacis (furnace accretions) of
' which I spoke in the last book, nor the cadmia fossilis (calamine) devoid of metal, which
' is used to colour copper, whose nature I explained in Book V, but the metallic mineral
' (fossilis metallica), which Pliny states to be an ore from which copper is made. The
' Ancients have left no record that another metal could be smelted from it. Yet it is a fact
Three librae of silver per centumpondium would be equal to 875 ounces per short ton.
