COP ( 345 ) COP
cipitate, which is a hydro-fulphuret of cop-per.
Phofphorus unites with copper by fufion, andforms a hard fteei-grey brittle alloy. This com-bination was obferved by Pelletier, in the prepa-ration of phofphorus in the great way. Thephofphoric acid from bones being commonlyevaporated in a copper veflel diffolved a fmallportion of the metal, and in the fubfequent dis-tillation of this vitreous phofphoric acid withcharcoal, feveral metallic globules were oftenfound in the refidue, arifing from the reducedcopper uniting with and keeping down a portionof the phofphorus.
Phofphuret of copper may be made accord-ing to Pelletier c in two ways : in one (imitatingthe accidental difcovery) 8 parts of copperfilings and 8 of vitreous phofphoric acid areintimately mixed with x of charcoal powder, andthen being put into a crucible and covered witha little more charcoal powder, are heated in-tenfely. In this procefs, part of the reduced phof-phorus burns off, but the reft combines with thecopper forming a hard grey brittle alloy, capableof a high polifli. In the other method which isfimpler, copper filings are made red-hot in a cru-cible, and pieces of phofphorus are carefully andrepeatedly projected on the metal which imme-diately melts down into the fame grey phofphu-ret. A hundred parts of copper may be increafedby this means to about 120, and in this ftatethe fpecific gravity, according to Sage, d is 7.122.This phofphuret, if kept in fufion expofed tothe air, Iofes gradually moft of its phofphorus,which burns with the bright flame and fmellpeculiar to this fubftance.
Phofphuret of copper is more fufible thancopper. If kept in fufion covered with charcoalpowder, or under melted glafs of any kind foas not to be expofed to the action of air, it Iofesall the excefs of phofphorus which it may con-tain, above that quantity which is equivalent toan increafe of one twelfth of the weight of thecopper, e after which it remains unaltered inany continuance of clofe fire. This thereforefeems to be a point of mutual faturation, andthis phofphuret is therefore compofed of about7-7 °f phofphorus and 92.3 of copper. Thisphofphuret has the grain and colour of fteel,takes a very high polifh, and remains very longuntarnilhed. in the air, but is brittle. With alefs proportion of phofphorus it again becomesmalleable and of a yellowifh-white colour, fothat it is poflible that this may be found ufeful(with other additions) in producing a white
alloy, which would be ferviceable in manufac-
tures.
The fixed oils when kept fome time in con-tact with copper oxydate and diffolve a portion,and thereby become green.
The alloys of copper are fo numerous andimportant that they will be l'eparately defcribedin the following article.
The ufes of copper, in all its various ftates,are almoft endlefs, and only, if at all, inferior innumber to thofe of iron. Befides the variety ofufes for which copper and its alloys are em-ployed in the metallic ftate, various pigmentsand dyeing materials are obtained from its falts,and the oxyd is ufed to give an emerald greento coloured glades and enamels.
All the falts of copper are more or lefs poi-fonous, producing violent naufea, and thefevereft pain and inflammation of the alimen-tary canal. Yet from the fudden vomitingwhich they excite, a large dofe may be givenwith fafety, and this is fometimes ufed when itis neceflary immediately to empty the ftomach.Copper is however very little ufed medicinallyin any form.
The affinities of the oxyd of copper are givenby chemical writers in the following order/The gallic, oxalic, tartareous, muriatic, fulphu-ric, nitric, arfenic, phofphoric, fuccinic, fluoric,citric, acetic, boracic, pruffic, and carbonicacids; ammonia, and fixed oil.
COPPER, Alloys of.
The alloys of copper (that is, thofe in whichthis metal predominates) are more numerous andmore important in the arts than thofe of anyother metal. Many of them are perfectly wellknown, and have been in ufe from very antienttimes; of many the exact compofition, andparticularly the mode of preparing, are kept asfecret as poflible; for even when the precifecompofition of an alloy is found by chemical
analyfis, it may often be extremely difficult toproduce a mixture by common methods, which{hall have exactly the fame {hade of colour, thefame malleability, texture, fufceptibiiity of po-liffi, or fome other excellence, which, perhaps,a mere accident has difcovered to the poilbfibr.Another circumftance of infinite coniequenceto the manufacturer is the ordinary ftate ofpurity of the materials he employs, and. thisalone will account lor the great fuperiority ofone manufacture over another; thus the bwe-diffi copper is commonly purer than the Britilh,and makes more malleable alloys, the Engliihtin better than moft of the foreign, and the like.
* Jour, de Phyf. tom. 38, • G. B. Sage, Jour. Phys.
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