The substances called pompholyx[1644] and spodos[1645] 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. CHAP. 34.—SPODOS: FIVE REMEDIES. The Cyprian spodos[1646] is the best. It is formed by fusing cadmia with copper ore. This substance, which is the lightest part of the metal disengaged by fusion, escapes from the furnace, and adheres to the roof, being distinguished from the soot by the whiteness of its colour. Such parts of it as are less white are indicative of incomplete combustion, and it is this which some persons call “pompholyx.” Such portions of it as are of a more reddish colour are possessed of a more energetic power, and are found to be so corrosive, that if it touches the eyes, while being washed, it will cause blindness. There is also a spodos of a honey colour, an indication that it contains a large proportion of copper. All the different kinds, however, are improved by washing; it being first skimmed with a feather,[1647] and afterwards submitted to a more substantial washing, the harder grains being removed with the finger. That, too, which has been washed with wine is more modified in its effects; there being also some difference according to the kind of wine that is used. When it has been washed with weak wine the spodos is considered not so beneficial as an ingredient in medicaments for the eyes; but the same kind of preparation is more efficacious for running sores, and for ulcers of the mouth attended with a discharge of matter, as well as in all those remedies which are used for gangrene. There is also a kind of spodos, called “lauriotis,”[1648] which is made in the furnaces where silver is smelted. The kind, however, that is best for the eyes, it is said, is that produced in the furnaces for smelting gold. Indeed there is no department of art in which the ingenuity of man is more to be admired; for it has discovered among the very commonest objects, a substance that is in every way possessed of similar properties. CHAP. 35.—FIFTEEN VARIETIES OF ANTISPODOS.