443 



COPPER COPT. 



a. Blue Carbonate, or Azure Coffer Ore, is fouiul 

 in sinning, trunslucent crystals, whose figure is that 

 it rhombic prisms, variously acuuiiiuited, and modifi- 

 ed by secondary planes. The colour is azure-blue, fre- 

 iiuenily of great inU-usity. It sometimes occurs in 

 an earthy form, as an incrustation, and is occasion- 

 ally massive, without lustre. As analyzed by Mr 

 Philips it consists of 69 peroxide of copper, 25-4 

 carbonic acid, and 5-4 water. It occurs in the cop- 

 per mines of England, and of European countries 

 generally, also in South America. 



b. Green Carbonate of Copper, or Malachite, occurs 

 massive, disseminated, and crystallized in capillary 

 and acicular crystals. Its colour is green, and the 

 lustre of the fibrous varieties silky and pearly. It is 

 soft and brittle, but admits of a beautiful polish, and 

 is highly esteemed in inlayed work. It contains 

 more oxygen and more water than the blue carbon- 

 ate. It occurs along with the other ores of copper. 

 The finest specimens are brought from Siberia. 



5. Phosphate of Copper is a rare ore, which was 

 formerly regarded as malachite, but is now known to 

 be a bi-phosphate of the peroxide of copper. It oc- 

 curs massive, and disseminated in minute prismatic 

 or octoedral crystals, of a green colour. It is found 

 in Hungary. 



C. Muriate of Copper is another rare species, which 

 occurs in angular grains, of a bright green colour, 

 among the sands of the river Lipas, in the desert of 

 Atacama, separating Chile from Peru ; also in mi- 

 nute prismatic crystals, of an emerald-green colour, on 

 brown iron stone, at Remolinos, in Chile. It is soft 

 and brittle. Specific gravity, 4-4. It tinges the 

 flame of the blowpipe of a bright green and blue, 

 muriatic acid fumes are evolved, and a bead of copper 

 remains on the charcoal. 



7. Arseniate of Copper. Copper, combined with 

 arsenic acid, forms several species, differing in the re- 

 lative proportions, and in the quantity of water in 

 them. Five are usually enumerated, which were dis- 

 tinguished by Chenevix. One variety the octoedral 

 arseniate of copper occurs crystallized in the form 

 of an obtuse octoedron. Its usual colour is sky-blue ; 

 sometimes apple or grass-green. It is translucent, 

 shining, and brittle. Specific gravity, 2-881. It 

 consists of peroxide of copper 49, arsenic acid 14, 

 and not less than 35 of water. A second, copper 

 mica, or the rhomboidal arseniate of copper of 

 Phillips, is crystallized in hexaedral tables, bevelled 

 on the terminal planes. Its colour is deep emerald- 

 green, with considerable lustre and transparency. 

 It is less hard and less heavy than the foregoing 

 species, and consists of 58 of oxide of copper, 21 of 

 arsenic acid, and 21 of water. A third, the right 

 prismatic arseniate of copper, as it is termed by Phil- 

 lips, is crystallized in the form of an acute octoedron, 

 the crystals being sometimes capillary, in some speci- 

 mens appearing as delicate fibres, and sometimes in 

 layers, flat or mammillated, and of a fibrous texture. 

 The colour 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 prisms, generally extremely 

 small : they are of a beautiful bluish-green colour, 

 but, from decomposition, often black; when unal- 

 tered, 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 English 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 re- 

 maining ore is then smelted in contact with the fuel. 

 The iron present in the ore, not being so easily re- 

 duced or fused as the copper, remains in the scoria, 

 while the copper is run out. It often requires re- 

 peated 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 com- 

 merce is never altogether pure, but generally con. 

 tains a little lead, and a smaller portion of antimony. 

 The carbonates of copper reduced by fusion, in con- 

 tact with the fuel, afford a purer copper, as does al-o 

 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 ap- 

 plied to many useful purposes. It is formed into 

 thin sheets by being heated in a furnace, and sub 

 jected 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 con- 

 structing 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 of 

 preserving articles of food, is by no means free from 

 danger, on account of the oxidizement to which cop- 

 per 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 coat- 

 ing 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 hi 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 colour 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 evapora- 

 tion. 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, port- 

 able ink. 



COPPERPLATES. See Engraving. 



COPT, a name given to the natives of Egypt be- 

 longing to the Jacobite or Monophysite sect, is a 

 term of Arabic formation, manifestly a corruption of 

 the Greek word Alywrnat, 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 elaas, the Arabian commander, 

 who granted to them immunities which they had not 



