Bismuth: Sweated Out of Native Ore in Inclined Iron Tubes, the Schneeberg Way (Thorpe, 1912)

The old way of getting bismuth from ore that holds it as the metal: heat the lumps just enough in sloping iron tubes and the bismuth, which melts easily, runs out of the rock into pots under charcoal. It takes 30-60 minutes a charge but gets only about two-thirds of the metal. Not given: the furnace temperature. Source: E. Thorpe, Dictionary of Applied Chemistry vol. I (1912), Bismuth, p. 458. Picture: Thorpe's Fig. 1, the furnace in plan.