ust be treated both as a metal and as a mineral. Under the first head, its history and uses may be described; and under the second, its characters and combinations, as it occurs in nature.

Copper got the name of Venus among the alchymists, on account of the facility with which it unites with other metallic bodies.

Gold, silver, and brass are the metals which are first mentioned in history, being those which occur frequently in a native or pure state; and although the quantity thus produced may bear but a small proportion to the whole yet the advancement of science requisite to separate the metal from its ore sufficiently accounts for the precedence which these have taken over all others.

The metal called brass, in sacred and profane history, and which was employed for the purpose of money, was in fact, the copper of modern times; whilst the brass of the present day is an alloy of copper, mixed according to the purpose for which the alloy may be required. See the article BRASS. The ancients, at a very early period, discovered the benefit derivable from the mixture of copper with other metals, as the alloy constantly produced a harder and more durable substance, and at the same time was no disadvantage to the material in melting or casting. It was employed in many of the illustrious works which the ancients left for the admiration of succeeding times. The enormous statue of the Sun, known by the name of the Colossus of Rhodes, erected by Chares of Lyndus, an eleve of Lysippus, was composed entirely of this metal; and many others are mentioned, which prove that the ancients were at least as well acquainted with the difficult art of working in brass as we are at the present time.

In a pure state, copper is a very brilliant metal, and susceptible of a high polish. It is of a fine red colour, differing from every other metal except titanium. Its specific gravity varies according to its density, from 8.584 to 8.9. According to Brard, the cubic foot of melted copper weighs 6,545 lbs. Of native metal, 6,000 lbs. Of copper medals, 6,200 lbs.

In a native state, it is not an uncommon mineral. It occurs in arborescent groups, very beautifully crystallized, in Siberia, imbedded in limestone, and in very considerable masses. In the cabinet of Ajuda, near Lisbon, a mass of native copper is said to be preserved, of the enormous weight of 2617 pounds (Brard). In Cornwall it occurs in many of the mines, and also in the island of Anglesea; and in the island of Nasso, one of the Faroe group, it occurs very beautifully crystallized, along with zeolite, imbedded in amygdaloidal trap.

Great as the use to which copper was applied by the ancients, it was very limited compared with the uses it has been put to in modern times.

Metallic copper is used for culinary vessels in many parts of Europe; but for this purpose the inner surface of the vessel should be tinned. Large vessels for distilling, brewing, dyeing, and the like processes, are made of copper. The making of these vessels constitutes the ordinary business of the coppersmith.

Copper rolled into sheets is employed for covering the wooden work of the roofs of churches and large edifices in Germany, Sweden, and other countries. It is a costly covering, and does not possess any notable advantage over lead.

A modern, and now a very extensive use of sheet-copper, is for the sheathing of ships. That part of the hull of the ship that is in the water is covered with sheet-copper. This covering preserves the wood from the attacks of the worm, and thereby gives the ship the advantage of passing more rapidly through the water, as the copper bottom remains always smooth; for sea-weed and shells will not take root and attach themselves to copper, as they do to the bare planks, owing to the galvanic effect produced by the action of the sea water. As this action, however, produces a rapid decay of copper, it was proposed by Sir Humphry Davy to neutralize it by applying metallic protectors, an object which he accomplished; but as this also deprived the copper of the effect it was intended to produce, and allowed the molluscous tribes to attach themselves, the protecting process was abandoned.

Its malleability and ductility are very considerable. A wire of 0.078 of an inch diameter will support 302 pounds avoirdupois.

Copper bolts are used for fastening the planks and timbers of ships. This is a modern improvement in ship-building. A copper-fastened ship or boat is preferable to one with iron fastenings, because the copper bolts remain unaltered by rust, and endure longer than the wood which they hold together, particularly when used in the state of alloy, which preserves it from waste by neutralizing the galvanic action.

For the frames of delicate dipping needles and magnetic compasses, copper is employed; as it has been found that the brass generally used in philosophical instruments sometimes contains iron, which of course might affect the magnetic needle.

Copper is drawn into wire, used for the communication with the bells in houses, and for other purposes.

Small pipes for conveying the pit-coal gas from the level of the street to the aperture by which the gas issues, were made of copper or of brass till superseded by tin. These pipes were fitted on an iron cylindrical mandril, and a cylindrical ring is drawn over the outside. By this means copper and brass tubes are drawn out. The brass tubes for telescopes are drawn out in the same manner.

The mixture, consisting of a large proportion of copper and a small proportion of silver, called billon in France, is used for coins of small value in that country, in Germany, and in other parts of Europe. In Britain this alloy is not now used; all coins being made either of standard gold, of standard silver, or of copper. The use of billon is objectionable, as it renders the value of the coins uncertain.

Copper may be plated; that is, its surface may be covered with a layer of silver, by rubbing the surface with a mixture of nitrate of silver, muriate of soda, and acidulous tartrate of potash (cream of tartar). But the method practised at Birmingham is the most permanent and effectual. A plate of copper, with a plate of silver applied to it, and borax placed in the interstice, is heated to a particular degree, which it requires the skill of the workman to know; a degree of heat, in short, near that at which copper and silver melt. The two metals thus heated, and in contact, are then taken out of the furnace and passed through rollers. There is a fusion and combination of the adjacent surfaces; and their adhesion is perfected by the pressure of the rollers. Copper thus plated is manufactured at Birmingham into candlesticks, teapots, buttons, buckles, and a variety of other articles.

Standard silver coins contain a small proportion of copper, for the purpose of giving them hardness. This proportion is regulated by each government in Europe, and varies a little in different countries. The combination of gold and copper in various proportions is used for making rings and other trinkets.

Copper is gilded by applying on its surface an amalgam of gold with mercury. Bronze ornaments are gilded in the same way.

Copper united with tin forms bronze. This combination is hard and brittle if the proportion of tin be great; but when the proportion of tin is small, the bronze is soft, and possesses tenacity so as not to be easily broken. The ancients employed hard bronze, containing much tin, in making sword blades, spear heads, hatchets, and cutting instruments. Bronze cramps are found in ancient buildings in Egypt. Statues and bas-reliefs, various culinary vessels, and different kinds of instruments of soft bronze, are seen in the collections of antiquities. In modern times soft bronze is used for casting cannon and statues.

Copper melted with a large proportion of tin constitutes bell metal, which is hard and brittle. The metal of which the Chinese gongs are made is composed of the same ingredients; and it has the property of being in some degree malleable at a certain stage of its cooling, for the gongs are covered with marks of the hammer.

To obtain copper from the yellow sulphuret or copper pyrites, which is the most common copper ore, it is necessary to smelt the ore several times before the metallic copper is obtained free from sulphur. The slag or scorie produced in these smeltings is formed into large bricks, used in building and coping walls in Wales and some other parts of Britain, in the vicinity of which the smelting of copper is carried on.

The chief use made of the native combinations of copper found in the earth is to extract the metallic copper from them. Sulphur is sometimes manufactured in treating the copper pyrites.

Oxide of copper obtained from the annealing that copper and brass wire undergoes, is used in dyeing.

In enamel colouring, oxide of copper, at a low degree of oxidation, produces an opaque-red or brownish-red enamel, called porporino. When the copper is more oxidated, it gives a green colour in enamelling upon earthenware and porcelain, and in stained glass.

Sulphate of copper, when concentrated or crystallized, is transparent and blue. It is manufactured for the use of the dyer and calico-printer.

Nitrate of copper is also blue. If fragments of soft wood, such as poplar or fir, be impregnated with a solution of this salt, these sticks, when dried, burn gradually to the end, and may serve as quick-match for firing cannon.

Muriate of copper is green; that which is formed by direct solution of copper in muriatic acid is transparent, and soluble in water; but the native muriate of copper, with excess of oxide, is insoluble. This is found in Peru in the form of green sand, and has got the name of attacmite, from the district of country in which it occurs. Being opaque, it is used in painting.

Verdigris (Verdit-gris) is an acetate of copper with excess of oxide. It is prepared in the wine districts of the south of France, by laying copper plates in strata alternately with the grape stalks and husks from which the juice has been pressed. The fermentation of the husks produces vinegar, which acts upon the copper. Verdigris is used in painting, because it possesses, on account of its excess of oxide, the opacity necessary for making a coloured paste with oil; it is also used in dyeing. Crystallized acetate of copper is the acetate without excess of oxide; it is in green crystals, and is also used in dyeing.

Scheele's green is an opaque precipitate, of a grass-green colour, composed of copper and arsenic. It is used in oil-painting.

Prussiate of copper is an opaque-brown precipitate, formed by adding prussiate of potash to a solution of sulphate of copper, and may be used in painting. The colour, however, wants durability.

Average Quantity of Fine Copper raised in Cornwall.

| Years | Tons Ore. | Tons Metal. | Sold for | |-------------|-----------|-------------|----------| | 1799 to 1808, ten years | 5,820 per annum | | | | 1809 to 1818 | | | | | 1819 to 1828 | | | | | 1829 to 1832, four years | | | |

Produce of the Copper Mines of Cornwall.

| Years | Tons Ore. | Tons Metal. | Sold for | |-------|-----------|-------------|----------| | 1820 | 91,473 | 7,508 | 602,441 12 0 | | 1825 | 107,454 | 8,226 | 726,353 12 0 | | 1830 | 133,904 | 10,748 | 773,846 4 0 | | 1831 | 144,402 | 12,043 | 806,090 15 6 | | 1832 | 137,357 | 11,947 | 825,612 6 0 |

Copper, considered as a mineral. See Mineralogy, Index.