The ores of copper furnish a number of resources[1] that are employed in medicine; indeed, all kinds of ulcers are healed thereby with great rapidity. Of these, however, the most useful is cadmia.[2] This substance is formed artificially, beyond a doubt, in the furnaces, also, where they smelt silver, but it is whiter and not so heavy, and by no means to be compared with that from copper. There are several kinds of it. For, as the mineral itself, from which it is prepared artificially, so necessary in fusing copper ore, and so useful in medicine, has the name of "cadmia,"[3] so also is it found in the smelting-furnaces, where it receives other names, according to the way in which it is formed. By the action of the flame and the blast, the more attenuated parts of the metal are separated, and become attached, in proportion to their lightness, to the arched top and sides of the furnace. These flakes are the thinnest near the exterior opening of the furnace, where the flame finds a vent, the substance being called "capnitis;"[4] from its burnt appearance and its extreme lightness it resembles white ashes. The best is that which is found in the interior, hanging from the arches of the chimney, and from its form and position named "botryitis."[5] It is heavier than the first-mentioned kind, but lighter than those which follow. It is of two different colours: the least valuable is ash-coloured, the better kind being red, friable, and extremely useful as a remedy for affections of the eyes.

A third kind of cadmia is that found on the sides of the furnace, and which, in consequence of its weight, could not reach the arched vaults of the chimney. This species is called "placitis,"[6] in reference to its solid appearance, it presenting a plane surface more like a solid crust than pumice, and mottled within. Its great use is, for the cure of itch-scab, and for making wounds cicatrize. Of this last there are two varieties, the "onychitis," which is almost entirely blue on the exterior, and spotted like an onyx within; and the "ostracitis,"[7] which is quite black and more dirty than the others, but particularly useful for healing wounds. All the species of cadmia are of the best quality from the furnaces of Cyprus. When used in medicine it is heated a second time upon a fire of pure charcoal, and when duly incinerated, is quenched in Aminean[8] wine, if required for making plasters, but in vinegar, if wanted for the cure of itch-scab. Some persons first pound it, and then burn it in earthen pots; which done, they wash it in mortars and then dry it.

Nymphodorus[9] recommends that the most heavy and dense pieces of mineral cadmia that can be procured, should be burnt upon hot coals and quenched in Chian wine; after which, it must be pounded and then sifted through a linen cloth. It is then pulverized in a mortar and macerated in rain water, the sediment being again pounded until it is reduced to the consistency of ceruse, and presents no grittiness to the teeth. Iollas[10] recommends the same process; except that he selects the purest specimens of native cadmia.