And Calaminaris Stone.

It is a metallic mineral, of a whitish or yellowish colour, and, in a state of purity, transparent, variously mixed; it is heavy and hard; of a middle nature betwixt stone and earth, occurring in copper mines, and those of lead and iron; it is found in England, Germany, and other countries, either in distinct mines, or intermixed with the ores of lead or other metals. It is a calx of zinc, and sometimes contains a small portion of iron; its specific gravity 3.5236, electrical by heat, volatile, rising in whitish flowers, with a bluish flame. Dissolved in the nitrous acid, it becomes gelatinous. Haiiy thinks the calamine a pure ore of zinc without any carbonic acid; but Mr. Smithson, in the Philosophical Transactions for 1803, analysed the calamine from Bley-berg, from Mendip hills in Somersetshire, and from Derbyshire. In each he found carbonic acid; viz. in the first 0.135; in the second 0.352; in the third 0.348. The calx of zinc was respectively 0.714, 0.648, and 0.652. The electric calamine from Hungary contained quartz and calx of zinc only. It is generally exposed to heat before it is brought into the shops, in order to separate some sulphureous and arsenical particles, which it is supposed to contain, and also to render it more easily reducible into powder.

If this ore is not already calcined, it must be heated to a strong red heat, then quenched in water; and this process must be repeated three times. Before calcination it is frequently of a grey or red colour; but when calcined it is yellow.

It is an error of some writers to say that the calamy is a recrement of melted copper, and that tutty is a recrement of melted brass; though it is true that the best calamine is what sticks to the iron rods used in stirring the matter in the furnaces while brass is making.

Though the calamine stone is an ore of zinc, it is not the only one; for zinc is found in the ore of lead, and of other metals. The principal use of this mineral is for changing copper into brass, which it does by its metallic part mixing with the copper while it is in a state of fusion. See AEs.

For medicinal uses, the calamine, after being calcined, should be levigated to an impalpable powder; it is then called lapis calaminaris, ppt.; for the mode, see Comminutio. When thus prepared, it is useful in col-lyria, as an astringent and corroborant, in defluxions of thin acrid humours on the eyes, in obfuscations of the cornea, and in ointments for cutaneous exulcerations. If it is exquisitely fine, it acts as an absorbent or desic-cative; but if not, it is an escharotic. In the Medical Commentaries it is recommended, by Dr. Adair, in doses of from five grains to a scruple, in the diarrhoeas of cachectic patients as a corroborant.

Ceratum epuloticum. Cicatrising cerate of the London college, now called ceratum lapidis ca-i.aminaris. Calamine cerate is made-with olive oil, a pint; yellow wax, calamine prepared, of each half a pound: the wax is melted with the oil, and, as soon as the mixture begins to thicken, the calamine gradually added and stirred till it is quite cold. This hath been called ceratum Turneri. Dr. James says that he remembers to have met with a like cerate in a publication by an old English surgeon who preceded Dr. Turner. The Edinburgh college calls it ung. lapidis calaminaris.

The magistery of calamine consists of the muriated calamine, precipitated by the volatile alkali, and carefully washed. In doses from three to seven grains it is emetic and cathartic. See Neuman's Chemical Works. Lewis's Materia Medica, and the Dictionary of Chemistry, 4to.