Note note 37, p. 476 — BOOK X.

[37] Agricola uses throughout De Re Metallica the term molybdaena for this substance. [Pg 476]It is obvious from the context that he means saturated furnace bottoms—the herdpley of the old German metallurgists—and, in fact, he himself gives this equivalent in the Interpretatio, and describes it in great detail in De Natura Fossilium (p. 353). The derivatives coined one time and another from the Greek molybdos for lead, and their applications, have resulted in a stream of wasted ink, to which we also must contribute. Agricola chose the word molybdaena in the sense here used from his interpretation of Pliny. The statements in Pliny are a hopeless confusion of molybdaena and galena. He says (XXXIII, 35): "There are three varieties of it (litharge)—the best-known is chrysitis; the second best is called argyritis; and a third kind is called molybditis.... Molybditis is the result of the smelting of lead.... Some people make two kinds of litharge, which they call scirerytis and peumene; and a third variety being molybdaena, will be mentioned with lead." (XXXIV, 53): "Molybdaena, which in another place I have called galena, is an ore of mixed silver [Pg 477]and lead. It is considered better in quality the nearer it approaches to a golden colour and the less lead there is in it; it is also friable and moderately heavy. When it is boiled with oil it becomes liver-coloured, adheres to the gold and silver furnaces, and in this state it is called metallica." From these two passages it would seem that molybdaena, a variety of litharge, might quite well be hearth-lead. Further (in XXXIV, 47), he says: "The metal which flows liquid at the first melting in the furnace is called stannum, at the second melting is silver, that which remains in the furnace is galena." If we still maintain that molybdaena is hearth-lead, and galena is its equivalent, then this passage becomes clear enough, the second melting being cupellation. The difficulty with Pliny, however, arises from the passage (XXXIII, 31), where, speaking of silver ore, he says: "It is impossible to melt it except with lead ore, called galena, which is generally found next to silver veins." Agricola (Bermannus, p. 427, &c.), devotes a great deal of inconclusive discussion to an attempt to reconcile this conflict of Pliny, and also that of Dioscorides. The probable explanation of this conflict arises in the resemblance of cupellation furnace bottoms to lead carbonates, and the native molybdaena of Dioscorides; and some of those referred to by Pliny may be this sort of lead ores. In fact, in one or two places in Book IX, Agricola appears to use the term in this sense himself. After Agricola's time the term molybdaenum was applied to substances resembling lead, such as graphite, and what we now know as molybdenite (MoS2). Some time in the latter part of the 18th century, an element being separated from the latter, it was dubbed molybdenum, and confusion was five times confounded.