The substances called pompholyx[1] and spodos[2] are also found in the furnaces of copper-smelting works; the difference between them being, that pompholyx is disengaged by washing, while spodos is not washed. Some persons have called the part which is white and very light "pompholyx," and say that it is the ashes of copper and cadmia; whereas spodos is darker and heavier, being a substance scraped from the walls of the furnace, mixed with extinguished sparks from the metal, and sometimes with the residue of coals. When vinegar is combined with it, pompholyx emits a coppery smell, and if it is touched with the tongue, the taste is most abominable. It is useful as an ingredient in ophthalmic preparations for all diseases of the eyes, as also for all the purposes for which spodos is used; this last only differing from it in its action being less powerful. It is also used for plasters, when required to be gently cooling and desiccative. For all these purposes it is more efficacious when it has been moistened with wine