COPPER. 



is prepared by fusing equal parts of cop- 

 per and phosphoric gas, with 'th of the 

 whole of charcoal in powder. Copper 

 combines with sulphur by different pro- 

 cesses. If sulphur in powder and filings 

 of copper are mixed together, and form- 

 ed into a paste with a little water, when 

 they are exposed to the air, the mass 

 swells up, becomes hot, and is convert- 

 ed into a brown matter, which efflores- 

 ces slowly in the air, and is converted 

 into sulphate of copper. 



Copper combined with sulphur is one 

 of the most common ores of this metal. 

 According to the experiments of Proust, 

 the natural production, known by the 

 name of copper pyrites, is a sulphuret of 

 copper, combined with an additional por- 

 tion of sulphur. It is distinguished by 

 its brittleness, metallic lustre, and yellow 

 colour. 



The alloys of copper (that is, those in 

 which this metal predominates) are more 

 numerous and more important in the arts 

 than those of any other metal. Many of 

 tli em are perfectly well known, and have 

 been in use from very ancient times; of 

 many, the exact composition, and particu- 

 larly tlie mode of preparing, are kept as 

 secret as possible ; for even when the 

 precise composition of an alloy is found 

 by chemical analysis, it may often be 

 extremely difficult to produce a mixture 

 by common methods, which shall have 

 exactly the same shade of colour, the 

 same malleability, texture, susceptibility 

 of polish, or some other excellence, 

 which, perhaps, a mere accident has dis- 

 covered to the possessor. 



The principal objects of alloying cop- 

 per appeai-s to be, to render it less lia- 

 ble to tarnish, and especially to be act- 

 ed on by common animal or vegetable 

 substances, to make it more fusible, and 

 harder, and able to take a higher polish, 

 and to alter its colour either to a golden 

 yellow or silvery white. All these ob- 

 jects are attainable by different alloys. 

 Copper, alloyed with gold, silver, and 

 platina, is seldom, if ever, used in the 

 proportions in which it would be reck- 

 oned as alloy of copper, being much 

 too costly for any purpose of manufac- 

 ture ; with this exception, however, that 

 a very small portion of silver much im- 

 proves the composition of the alloy of 

 copper and tin, when used as bell- 

 metal or speculum-metal. Copper is 

 used largely as an alloy of gold and 

 silver, and it is often plated with one or 

 the other. 

 Tutenag is a white alloy of copper, 



zinc, and iron, according to Keir, which 

 is very hard, tough, and sufficiently duc- 

 tile to be wrought into various articles of 

 furniture, such as candlesticks, &c. which 

 take a high polish, and when made of the 

 better sort of tutenag are hardly distin- 

 guishable from silver. The inferior kinds 

 are still white, but with a brassy yellow. 

 The Chinese petong is another fine, 

 white, malleable alloy of copper, Ihe 

 composition of which is not exactly- 

 known, but it contains a small portion 

 of silver. Copper unites with lead very 

 intimately by fusion, but when a mass of 

 this alloy is exposed to a heat less than 

 that at which the whole melts, the lead 

 alone sweats out, leaving almost all the 

 copper in a porous or honey-combed 

 state. When the copper holds a small 

 portion of silver, the lead carries the 

 latter out with it, and this is the prin- 

 ciple of the old process of eliquation, 

 formerly much used in the extracting 

 of silver from copper ores. Copper, 

 with about a fourth of its weight of lead, 

 forms pot-metal, used by the ancients for 

 their coins. 



Copper nearly saturated with zinc, 

 forms brass, the most important of all 

 the alloys of this metal. See BRASS. 

 With a much less proportion of zinc, the 

 colour of the alloy approaches very near- 

 ly to that of gold, and the malleability 

 increases. Mixtures chiefly of these 

 two metals are used to form a variety 

 of yellow or gold-coloured alloys, known 

 by the names of tombac, Manheim, or 

 Dutch gold, tinsel, similor, Prince Ru- 

 pert's metal, Pinchbeck, &c. ; but the 

 precise composition varies according to 

 the fancy or the experience of different 

 manufacturers. The Dutch gold may be 

 beaten out into extremely fine leaves, 

 which, when fresh, have nearly the bril- 

 liance of gold-leaf, and are used as a 

 cheap imitation of it ; but they tarnish 

 very soon. The mixture may be made, 

 either by directly melting copper and 

 zinc, or by mixing brass and copper. In 

 either case the copper should be melted 

 first, and the zinc added afterwards, the 

 whole stirred together with wood, cover- 

 ing it with a little charcoal, and poured out 

 immediately, to prevent the loss by the 

 burning off the zinc. A kind of tombac 

 is the material of which a large propor- 

 tion of the Roman coins was composed : 

 Klaproth, on Analyzing several struck dur- 

 ingthe first century of the emperors found 

 them all to consist either of pure copper, 

 or of copper and zinc, in which the lat- 

 ter metal made generally from a fifth to 



