Edin. Dub. Copper.

Syn. Cuivre (F.), Kupfer (G.), Koper (Belg.), Kobber (Dan.), Koppar (S.), Rame (I.), Cobre (Swed.), Miedss (Polish), Mjed (Russian), Shemboo ( Tarn.), Tambaga (Malay), Nehass(Arab.), Tamba (Duk. & H.), Tamra (San.), Ka-noo-yak (Esquimaux). •

Copper is a metal of a yellowish or brownish red colour, found very abundantly in many countries in both hemispheres of the globe.1 It is procured

1 The richest copper mines are those of Cornwall in England, the Pyrenees, and of Fahlan in Sweden. 2 Vide Aikins Chymical Dictionary, art. Copper.

The sulphurets are the most abundant ores, and those from which copper is usually extracted. In Britain these are pro-cured chiefly in Cornwall.1 The ore is first roasted to volatilize the sulphur, which escapes partly as sulphurous acid, partly as simple sulphur, which is collected in chambers connected by flues with the kilns. The metal is thus oxidized; it is reduced by smelting it, in contact with the fuel, in a large reverberatory furnace, with the addition of sand to separate the iron; which, being less fusible than the copper, remains in the scoria as an oxide, while the melted copper is drawn off through a plug-hole into earthen moulds. The copper, however, in this state, is still very impure; and therefore it is remelted and granulated; and lastly, refined by being again melted with the addition of a little charcoal, which brings it to a state fit to bear the hammer, and to answer the various purposes of art.

Pure copper has a yellowish red colour; is sonorous, ductile, malleable, tenacious; has a styptic, disagreeable taste, and emits an unpleasant odour when rubbed: its point of fusion is 1996 Fahr. The specific gravity, when it is pure, and has been only fused is 8.667. It has a granulated texture, and breaks with a hackly fracture; melts at a temperature equal to 27° of Wedgwood; is volatilized by a greater heat; and is oxidized, when heated in contact with atmospherical air, even at a temperature below that of ignition. It is capable of receiving a brilliant lustre by polishing. It remains unchanged in dry air; but when exposed to humidity and to air at the same time, it is tarnished, and a green crust is formed on its surface, which is a carbonate of the black oxide of copper.

The Parys mine in the Isle of Anglesea is now nearly exhausted. The Uarz mines yield annually fifty tons of copper.

Although copper in its metallic state was used as a remedy by the ancients, yet it is completely discarded from modern practice: and notwithstanding so much has been said of its deleterious effects, there is every reason for believing that clean copper, when taken into the stomach, exerts no action whatever on the system. Two cases of halfpence being swallowed by children have come under my observation, in one of which the copper coin remained six months in the intestines, and in the other two months. Both were evacuated without having in the smallest degree injured the health, although the impressions on the coins were nearly effaced, and the metal was much corroded. But poisoning from the use of copper utensils in cookery arises either from the formation of the green carbonate, mentioned above, owing to the vessels not being well cleaned, and the food being allowed to stand for some time in the pan exposed to the air, after it is taken from the fire; or from the formation of verdigris, when vinegar, used in making pickles, and other acid liquors intended for internal use, are boiled in brass or copper vessels.

The salts of copper thus formed are poisons, exciting inflammation of the stomach; and many fatal accidents have arisen from the carelessness which produces them in cooking utensils, and from the equally dangerous mode of giving a fine green colour to vegetables by boiling halfpence with them; on which account copper utensils should be altogether banished from the kitchen and also from the laboratory, where they are sometimes employed in making decoctions. The salts of copper may be detected in any suspected liquor, by boiling first with dilute acetic acid and filtering: which separates the copper from all vegetable or animal matter. This solution is then to be treated by passing through it a stream of sulphureted hydrogen gas, collecting the precipitate, drying it, incinerating it in a glass tube, and converting the sulphuret into the sulphate by the addition of a few drops of nitric acid. The copper may be now rendered obvious, by diluting the solution of the sulphate, and placing it in a piece of clean polished iron wire, on which the copper is precipitated in a metallic state; or by dropping into the solution an excess of ammonia, which produces a beautiful blue colour, if any salt of copper be present : or by adding a drop or two of a solution of the ferro-cyanate of potassa, which throws down a brown precipitate, and is one of the most delicate of the tests for the salts of copper.

In cases of poisoning by any of the salts of copper, albumen is the best antidote.

The oxides of copper unite with acids, and form salts which act very powerfully on the animal system; but of these the acetate and the sulphate only are admitted into the list of Materia Medica.

1. Acetate of copper.

Officinal. Diacetas Cupri, Lond. Aerugo, Dub. Subacetas Cupri, Edin. Dub. Verdigrise, or Subacetate of Copper. Syn. Vert de gris (F.), Grunspan crystalle (G.), Verdegrise (I.), Cardenillo

(S.), Vungala patchei ( Tarn.), Zungar (Pers. & Duk.), Sennang (Malay), Zunjar (Arab.), Pitrai (H.), Pitalata (San.).

This salt, which is an acetate, is principally manufactured in the south of France, at Montpellier, and Grenoble.1 In the former place, the marc of the grape, that is, the cake which remains in the wine-press after the juice is expressed, composed of the husks and stalks, is moistened with water, or with wine if poor, and disposed. so as to excite in it the acetous fermentation. When this takes place it is spread in jars between well hammered plates of copper, about l-24th of an inch in thickness, five inches long, and three broad: these are strongly heated over a pan of burning charcoal, and a layer of fermented marc placed between each plate of copper. The jars, each of which contains about 40lbs. of copper 1, besides marc, are then loosely stopped with straw, and left at rest for ten, fifteen, or twenty days; at the end of which time the marc begins to whiten and the copper is found to be covered with a green crust, interspersed with distinct silky green crystals. This is termed cottoning the copper.