Jupiters Wolf and the Wolfs Foam

Tin ores were mined in the German mountains in the 16 century. The ideal metallurgical reaction for tin manufacture was 

The molten tin was covered with slag, formed from rock minerals and added slag former. For an economical result it was important that the tin content in the slag was low. Now and then disturbances occurred. Foam would appear on the surface of the melt and much valuable tin could stay in this foam as droplets. A ivolfin the ore ate the tin. What the workmen believed was that the foam was the foam of a wolf, Wolf Rohm in German). We now know that foam formation occurred when the tin ore also contained the mineral wolframite (Fe,Mn)WO. This mineral was unknown to the miners. 

From antiquity, the metal tin has been connected with the planet Jupiter and had the same symbol. Early in the 16 century, Georgius Agricola in Bohemia was aware of the phenomenon of foam formation. He used the Latin expression Spuma Lupi (= the wolf s foam) to describe the effect of the strange mineral on the tin manufacturing process. 

In 1761 the mineral that disturbed the tin production was subjected to chemical examination. J. G. Lehmann, known from the history of the chromium discovery, investigated a wolframite from Zinnwald (Cinovec in today s Czech Repubhc). When he melted the mineral sample in sodium nitrate, leached it in water and added hydrochloric acid he observed a white precipitate that gradually became yellow. He had in fact seen tungstic acid, but did not reahze that there was a new element in it. 

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