43 Aeta

The chemical character for copper is ♀ .

Its gravity is to silver as eight to ten; to gold, as eight to nineteen; and to water, as eight to one: more strictly, it is from 7.780 to 8.584. A wire 1/10 of an inch will support about 300 weight.

It is considerably, but not entirely, fixed in the fire; changing first to a blue, then to a yellow, and then to a violet colour.

It is malleable, and ductile into a fine wire.

It is elastic and sonorous.

It melts not before ignition, or a strong white heat, hut calcines by a weaker red heat into a red powder; and when in contact with the coals gives a greenish blue colour to the flame.

By heat, if the air has free access, it forms an imperfect blackish red oxide; with greater heat, a brown glass. When cooled slowly, it is said to crystallise in quadrilateral pyramids.

The sulphuret of copper is a very fusible mass: the phosphoret a grey and brilliant substance. It unites with the sulphuric acid when concentrated only with the assistance of heat, forming oblong rhomboidal crystals, which contain 0.32 of the metal, and 0.33 of acid.

Lime and magnesia precipitate the copper of a bluish white. Ammonia has a similar effect; but if in the slightest excess the precipitate is re-dissolved, forming the cuprum ammoniacum, the re-dissolved copper forms the aqua coelestis of the pharmaceutists.

Copper is dissolved in diluted nitric acid, and forms crystals in long parallelograms or rhomboids. The muriatic acid only dissolves it when boiling and concentrated. The crystals are acid, of a green colour, and the precipitate is not very readily dissolved by ammonia. The green colour indicates, according to Guyton, a greater degree of oxygenation than the blue. The blue colour, we are told by Gren, when dissolved in ammoniac, does not take place unless air be admitted. Some authors have informed us, that fixed alkalis and neutral salts act on copper best also when exposed to the air and in the cold. Rancid fats and oils equally dissolve it.

Dissolved by fixed alkalis, it is green; by the volatile, it is blue. Dr. Lewis observes, that if the 1/100 part of a grain of copper be dissolved in a pint of water, a blue colour will be produced by adding a volatile alkali to it.

So great is its divisibility, that one grain dissolved in aqua ammoniae will tincture 385,200 times its weight of water. |

A small quantity of arsenic gives to copper a great degree of hardness and whiteness: thus pins may be made white and brittle by it. The hydrargyrus muriatus also whitens it; but pins are usually whitened with a solution of tin. If a piece of bright iron be immersed in the acid solution of copper, the acid quits the copper to attack the iron; and the copper, in its separation from the menstruum, adheres to the iron, which soon appears covered with a metallic cuprous coat. On these principles very minute quantities of copper dissolved in liquors may be readily discovered. The affinities of copper to other metals form no part of our subject at this time: we shall only add, that copper and tin make a good bell-metal, useful in microscopes and reflecting telescopes; copper and zinc, princes metal; copper with bronze and zinc, the white tonbac; with zinc, by fusion, the similor or Manheim gold; or by .cementation with lapis calaminaris, brass.

For an account of the different ores of copper, see Mineralogie de Hauy, vol. iii. 520, etc.

If copper is swallowed in its pure state, it is inoffensive. Some practitioners observe that copper, when-dissolved, is strongly styptic; so far from causing exul-ceration of the intestines, that it heals them: it vomits by its nauseous stimulus, which will continue for several days.