“One day we took the children to see a goldsmith refine gold after the ancient manner of the East. He was sitting beside his little charcoal fire. ("He shall sit as a refiner"; the gold- or silversmith never leaves his crucible once it is on the fire.) In the red glow lay a common curved roof tile; another tile covered it like a lid. This was the crucible. In it was the medicine made of salt, tamarind fruit and burnt brick dust, and imbedded in it was the gold. The medicine does its appointed work on the gold, "then the fire eats it," and the goldsmith lifts the gold out with a pair of tongs, lets it cool, rubs it between his fingers, and if not satisfied puts it back again in fresh medicine. This time he blows the fire hotter than it was before, and each time he puts the gold into the crucible, the heat of the fire is increased; "it could not bear it so hot at first, but it can bear it now; what would have destroyed it then helps it now." "How do you know when the gold is purified?" we asked him, and he answered, "When I can see my face in it [the liquid gold in the crucible] then it is pure.”