Jeremiah 6:29

The figure from refining metals is continued from Jeremiah 6:27. "In refining, the alloy containing the gold or silver is mixed with lead, and fused in a furnace on a vessel of earth or bone-ash: a current of air is turned upon the molten mass (not upon the fire); the lead then oxidizes, and acting as a flux, carries away the alloy, leaving the gold or silver pure (I. Napier, The Ancient Workers in Metal, 1856, pp. 20, 23). In the case here imagined by the prophet, so inextricably is the alloy mixed with the silver, that, though the bellows blow, and the lead is oxidised by the heat, no purification is effected; only impure silver remains." Dr. p. 39.