Nine Books on the Nature of Things

Silver and copper are separated by ordinary aqua fortis in this way. Reduce copper containing silver, or silver containing copper, into very thin plates or grains by the method already given. Put it into a glass vessel and add enough ordinary aqua fortis. In this way the silver will be calcined and sink to the bottom like a white calx, while the copper will dissolve and be converted into a clear water. If this water, together with the dissolved copper, is drawn away from the silver calx through a glass funnel into a separate glass, the copper dissolved in the water can then be struck down with ordinary rainwater, river water or warm seawater, so that it covers the bottom of the glass like sand.