matic crystals are obtained, wnich are deliquescent, and very soluble in water.The combinations of peroxide of copper with phosphoric, carbonic, and other acids, are effected by adding to a solution of nitrate or sulphate of copper a solution of a neutral salt, containing the acid with which the copper is designed to be combined. Copper is slowly oxidated by a number of weaker acids, as by some vegetable juices, when acted on by them with the admission of air. Acetic acid, or vinegar, in particular, forms an important compound with the oxide of copper. To obtain it, copper plates are exposed to the fumes of vinegar. A crust is soon formed of a green color, which is the verdigris of commerce.—All the salts of copper are decomposed by the alkalies and earths. Potash, soda, and the alkaline earths, throw down precipitates, which are of various shades of green or blue, according to the quantity of alkali added, the color being green, if a small quantity is added, and becoming blue from a larger quantity. These precipitates are sub-salts, the alkali attracting the greater portion of the acid, but the oxide precipitated still retaining a portion of the acid combined with it.The action of ammonia upon the salts of copper is more remarkable. It first abstracts a portion of the acid, and throws down a green or blue precipitate, which is a sub-salt; but, when added in larger quantity, it redissolves this precipitate, and forms a transparent solution, of a very deep-blue color, which, when evaporated, affords fine blue crystals. A triple compound, used in medicine under the name of ammoniuret of copper, is prepared by triturating together two parts of sulphate of copper with one part of carbonate of ammonia, the mass becoming soft from the mutual action of the two salts, the carbonic acid being disengaged with effervescence, and the triple compound of sulphuric acid, oxide of copper, and ammonia, being obtained of a deep violet-blue color. Copper is precipitated in its metallic state, from its saline solutions, by zinc and iron; either of these metals attracting the oxygen which serves as the medium of its union with the acid of the solution. Its oxide is precipitated by albumen, and the precipitate is almost inert; hence the whites of eggs have been recommended as an antidote to the poisonous salts of copper.-The best mode of detecting copper, when suspected to be present in mixed fluids, is by sulphureted hydrogen. The sulphuret, after being collected, should be placed on a piece of

porcelain, and digested in a few drops of nitric acid. A sulphate of copper is formed, which, when evaporated to dryness, strikes the characteristic deep blue, on the addition of a drop of ammonia.-Copper and sulphur unite by fusion, the combination being attended with the evolution of heat and light. A bi-sulphuret of copper also exists in copper pyrites.-Copper combines with a great number of the metals by fusion. It communicates hardness to gold and silver, without much impairing their ductility, or debasing their color, when in small proportion; hence it is employed in the standard alloys of these metals, that of gold containing one twelfth, that of silver one sixteenth, of the mass. With platina, it forms an alloy, ductile, and susceptible of a fine polish. With tin, it forms several valuable alloys, which are characterized by their sonorousness.

Bronze is an alloy of copper, with about 8 or 10 per cent. of tin, together with small quantities of other metals, which are not essential to the compound. Cannons are cast with an alloy of a similar kind, and the ancient bronze statues were of nearly the same composition. (See Bronzes.)

Bell-Metal is composed of 80 parts of copper and 20 of tin. The Indian gong, so much celebrated for the richness of its tones, contains copper and tin in this proportion. The proportion of tin in bellmetal varies, however, from one third to one fifth of the weight of the copper, according to the sound required, the size of the bell, and the impulse to be given. M. d'Arcet has discovered that bell-metal, formed in the proportion of 78 parts of copper, united with 22 of tin, is, indeed, nearly as brittle as glass, when cast in a thin plate, or gong; yet, if it be heated to a cherry red, and plunged into cold water, being held between two plates of iron, that the plate may not bend, it becomes malleable. Gongs, cymbals and tamtams have been manufactured with this compound.

Brass. Copper and zinc unite in several proportions, forming alloys of great importance in the arts. The best brass consists of four parts of copper to one of zinc; and, when the latter is in greater proportion, compounds are formed called tombac, Dutch gold and pinchbeck. An al loy called Bath metal is made by adding 9 pounds of zinc to 32 of brass; and an extremely pale, nearly white metal, used by the button-makers of Birmingham, under the name of platina, by adding 5 pounds of zinc to 8 of brass. The brothers Keller, who were very celebrated statue

founders, used an alloy, 10,000 parts of which contained 9140 of copper, 553 of zinc, 170 of tin, and 137 of lead. Their castings are famous, and some are of very large size, as the equestrian statue of Louis XIV, cast at a single jet, by Balthazar Keller, in 1699, which is 21 feet high, and weighs 53,263 French pounds. These statues are usually called bronze statues, although made of brass. Brass was well known to the Romans, under the name of orichalcum, who took advantage of its resemblance to gold, in robbing the temples, and other public places, of that precious metal.. Thus Julius Cæsar robbed the capitol of 3000 pounds weight of gold, and Vitellius despoiled the temples of their gifts and ornaments, and replaced them with this inferior compound.

The art of tinning copper consists in covering that metal with a thin layer of tin, in order to protect its surface from rusting. For this purpose, pieces of tin are placed upon a well-polished sheet of copper, which, if the process is skilfully conducted, adhere uniformly to its surface. The oxidation of the tin-a circumstance which would entirely prevent the success of the operation-is avoided by employing fragments of resin, or muriate of ammonia, and regulating the temperature with great

care.

ORES OF COPPER.-1. Native Copper, like the metal, is of a red color, but frequently tarnished. Its lustre is metallic: it is flexible, ductile and malleable: its fracture is hackly. It occurs in branched pieces, dendritic, in thin plates, and rarely in regular crystals, under the form of the cube or octoedron. It is found in the veins of primitive rocks, and of the older secondary. It is occasionally accompanied by several of the ores of copper, and sometimes those of other metals. One of the largest masses of this substance ever noticed was discovered by Schoolcraft, in the North West Territory, about 30 miles from lake Superior, on the west bank of the river Ontonagon. It weighs, by estimation, 2200 pounds. It lies near the water's edge, at the foot of an elevated bank of alluvion. Native copper is frequently found in connexion with the secondary greenstone and red sandstone formation in the U. States. Its greatest known depositories, however, are the mines of Cornwall in England.

2. Sulphuret of Copper. Under this name may be described a series of ores containing copper, sulphur, and variable proportions of other metals, which, by some mineralogists, are conceived to pass

into each other, and, of course, are improperly arranged as distinct species. Its principal varieties are the vitreous copper ore, the purple copper, gray copper, and yellow copper pyrites.

a. Vitreous Copper is of a lead or irongray color. It occurs crystallized in regular six-sided prisms, mostly modified on the terminal edges, and in acute, double, six-sided pyramids, with triangular planes. It also occurs massive. The cross-fracture of the crystallized is often conchoidal, with a vitreous lustre: the massive varies greatly in respect of hardness and color. It is sometimes sectile and soft. The fracture is even, or flat conchoidal. Specific gravity, 4.8 to 5.4. It consists, according to Chenevix, of 81 copper and 19 sulphur. It occurs in veins and beds, in primitive and early secondary rocks, and is found with other ores of copper. In the U. States, it has been met with very often in the old red sandstone, but is nowhere wrought, as yet, to advantage. It abounds in Cornwall, and many European countries.

b. Purple Copper occurs both massive and crystallized. Its color is between copper-red and tombac-brown. It is often possessed of an iridescent tarnish, in which blue is apt to prevail. The general form of the crystal is that of a cube, of which the solid angles are replaced. It is soft, easily frangible, and sectile in a slight degree. Specific gravity, 5.033. That of Norway consists of copper 69.50, sulphur 19, iron 7.50, and oxygen 4. It is fusible into a globule, which acts powerfully upon the magnetic needle. The purple copper is found in Norway, Saxony and England, and occurs under similar circumstances with the other ores of copper.

c. The Gray Copper, or Fahlerz, is of a steel-gray or iron-black color. It occurs crystallized in the form of the tetraedron, in which no regular structure is visible: it also occurs massive and disseminated. Its fracture is uneven or imperfectly conchoidal, with a shining or glistening metallic lustre. It is brittle. Specific gravity, 4.5. It consists of 52 copper, 23 iron, and 14 sulphur; but it also contains, mixed with these constituents, various other metals, in very variable proportions, as lead, antimony and silver. It occurs in Russia, France, Spain, England, Chile and Mexico.

d. Yellow Copper Ore, or Copper Pyrites, occurs of various shades of yellow, crystallized in the form of the tetraedron, having the solid angles replaced, and massive. It is also stalactitic and botryoidal. It is

arsenic acid, and 21 of water. A third, the right prismatic arseniate of copper, as it is termed by Phillips, is crystallized in the form of an acute octoedron, the crystals being sometimes capillary, in some specimens appearing as delicate fibres, and sometimes in layers, flat or mammillated, and of a fibrous texture. The color in these is dark olive-green, passing into brown or yellow, or greenish-white. It is often transparent; it is harder than the preceding species, and is much heavier. It consists of 50 parts of oxide of copper, from 30 to 40 of arsenic acid, with, in some varieties, 20 of water. Another species occurs crystallized in triedral prisins, generally extremely small: they are of a beautiful bluish-green color, but, from decomposition, often black; when unaltered, they are transparent. It consists of 54 oxide of copper, 30 arsenic acid, and 16 water. All the foregoing species are found along with other copper ores in the Engglish mines.

The sulphurets are the ores from which copper is usually extracted. The ore is roasted by a low heat, in a furnace with which flues are connected, in which the sulphur that is volatilized is collected. The remaining ore is then smelted in contact with the fuel. The iron present in the ore, not being so easily reduced or fused as the copper, remains in the scoria, while the copper is run out. It often requires repeated fusions, and, even after these, it may be still alloyed with portions of metals which are not volatile, and are of easy fusion. Hence the copper of commerce is never altogether pure, but generally contains a little lead, and a smaller portion of antimony. The carbonates of copper reduced by fusion, in contact with the fuel, afford a purer copper, as does also the solution of sulphate of copper which is met with in some mines, the copper being precipitated in its metallic state, by immersing iron in the solution. The precipitate which is thus formed is afterwards fused.--Copper, being ductile and easily wrought, is applied to many useful purposes. It is formed into thin sheets by being heated in a furnace, and subjected to pressure between iron rollers. These sheets being both ductile and durable, are applied to a variety of uses, such as the sheathing of the bottoms of ships, the covering of roofs and domes, the constructing of boilers and stills of a large size, &c. Copper is also fabricated into a variety of household utensils, the use of which, however, for preparing or preserving articles of food, is by no means

free from danger, on account of the oxidizement to which copper is liable. It has been attempted to obviate this danger by tinning the copper, as above described. This method answers the purpose as long as the coating of tin remains entire. Copper may be forged into any shape, but will not bear more than a red heat, and, of course, requires to be heated often. The bottoms of large boilers are frequently forged with a large hammer worked by machinery. The bolts of copper used for ships, and other purposes, are either made by the hammer, or cast into shapes, and rolled. The copper cylinders used in calico printing are either cast solid upon an iron axis, or are cast hollow, and fitted upon the axis. The whole is afterwards turned, to render the surface true.

COPPERAS, or GREEN VITRIOL, is a mineral substance, formed by the decomposition of pyrites by the moisture of the atmosphere. Its color is bright green, and its taste very astringent. A solution of it in water, dropped on oak bark, instantly produces a black spot. Copperas is occasionally found in grottoes, caverns, the galleries of mines, and other places. It is in much request with dyers, tanners, and the manufacturers of ink, and, for their use, is artificially prepared from pyrites. This mineral being moistened and exposed to the air, a crust is formed upon it, which is afterwards dissolved in water: from this the crystals of vitriol are obtained by evaporation. The principal use of vitriol is in dyeing woollen articles, hats, &c. black. It is the basis of ink, and is used in the manufacture of Prussian blue. If it be reduced to powder by the action of fire in a crucible, and mixed with powder of galls, it forms a dry, portable ink.

COPPERPLATES. (See Engraving.)

COPT, a name given to the natives of Egypt belonging to the Jacobite or Monophysite sect, is a term of Arabic formation, manifestly a corruption of the Greek word Alyórios, converted, by the Arabs, into Kubti, or Kibti, pronounced Gubti, or Gybti, by the Egyptians. The Jacobites, who were exclusively of pure Egyptian blood, and far more numerous than their adversaries, the Melkites (Greeks in faith as well as origin), having been persecuted as heretics by the Greek emperor, were willing to submit to the arms of Amru-Ibn elàás, the Arabian commander, who granted to them immunities which they had not previously possessed, and protected their church from the encroachments of the Constantinopolitan see. But the Copts soon found that their privileges would be

of little avail under oppressive or fanatical princes. Their wealth, numbers and respectability rapidly declined; and, though rarely intermarrying with their conquerors, and preserving their features, manners and religion unaltered, they soon lost their language, which had resisted the influence of a Grecian court for so many ages. Their alphabetical characters, which, with a very few exceptions, were borrowed from the Greek, and probably first introduced towards the latter end of the 3d century, had contributed to preserve their language in its original form, while a desire of instructing the people had led the monks to compose many religious works in their vernacular tongue; but the poverty and ignorance, which soon sprung up from the oppression under which they labored, could not fail to cut them off from the use of such instructers, and accustom them to neglect a language which served only as an invidious distinction. In the lower, or northern provinces, it appears to have been little, if at all, spoken, as early as the 10th century, though used and studied, as a learned language, as late as the 15th century. In the Said, or Upper Egypt, which was less exposed to foreign influence, it prevailed much longer, and the peculiar dialect of that country was generally spoken by the people in the beginning of the 16th century. Vansleb, who was there in the latter part of the 17th century, saw the last of the Copts to whom this language could be said to be vernacular. It is an original tongue, having no distinct affinity with any other, though many Greek words have been introduced, unaltered, by Christian writers, and several terms appear to have been anciently borrowed from the Hebrew. The Coptic version of the New Testament is valuable on account of its antiquity, dating, according to several critics, as early as the 2d century, and not later than the 5th, at the lowest computation. As a relic of the ancient Egyptian, also, the Coptic language is deserving of attention; and the light which a study of the fragments written in it will throw on the history and antiquities of ancient Egypt has been clearly shown in the works of M. Quatremère and M. Champollion. In person and features, the Copts differ much from the other natives of Egypt, and are evidently a distinct race— an intermediate link in the chain which connects the Negro with the fairer tribes to the north and south of the tropics, strongly resembling the Abyssinians, who, though extremely dark, are much paler

than the genuine Negroes. Dark eyes, aquiline noses and curled hair are the usual characteristics of both nations; and the mummies which have been examined show the resemblance of the modern Copts to their ancestors. (Blumenbach, in Comment. Reg. Soc. Göttingen, xiv, 38.) Reduced, by a long series of oppression and misrule, to a state of degradation, their number and national character have rapidly declined; so that, at the highest calculation, they do not now amount to more than between 400,000 and 500,000 souls: according to another account, their number does not exceed 80,000. They are chiefly employed as agricultural laborers. Many, in the larger cities, are engaged in manufactures and commerce, and most of the various kinds of business requiring much skill. In their hands, moreover, is the whole business of imposing and collecting the taxes. This they have managed ever since the Arabs made the conquest of Egypt. The Turks are generally ignorant, and little disposed to business. The beys and mamelukes, being taken from the class of slaves, cannot even read; and thus the care of the finances falls, almost necessarily, into the hands of the Copts, who make a mysterious science of their administration, which none can understand but themselves. They are quiet, industrious and saturnine, but are often represented, by travellers, as crafty, fraudulent and revengeful. All, however, allow that they show a capacity and disposition, which, under more favorable circumstances, would raise them to a respectable rank in the scale of civilized nations. The Coptic, of which the English Orientalist Woide has published a grammar and dictionary, has become a dead language. In modern times, however, it has been made pretty evident that the dialect of the modern Copts has much resemblance to that of their ancestors; and it has served as a key to the latter, as well as to the long hidden meaning of the hieroglyphics. The celebrated Champollion (q. v.) is said to be publishing a new grammar of the Coptic, which, within a short time, has become a highly important language. It is said that he expects to prove that Coptic is the language used in the ancient hieroglyphics. This indefatigable savant has also composed a Coptico-Egyptian dictionary, in three quarto volumes, comprising the three distinct dialects, viz.: the Thebaic, Memphitic and Heptanomic.

Copy comes from the Latin copia, abundance, because copying a thing is multiplying it. A copyist ought always to un