COP
•( 333
COP
rifes in diftillation, The muriatic acid howeveris not fufficient in this ore to faturate the oxydof copper, and lienee by Ample boiling in wateronly a fmall portion is diiTolved, which givesluna cornea with nitrat of filver.
This ore was analyzed by Klaproth in thefollowing Ample manner, its general contentshaving been afeertained by the above-mentionedexperiments. One hundred grains of the orewere diffolved in nitric acid without heat, duringwhich about i-(- of iron ochre was depofited.
It was then diluted and nitrat of filver added toafeertain the quantity of lunea cornea. Of thislaft, 64-t grains were obtained, of which 10grains w r ere muriatic acid, according to feparateexperiments by which it appears that 100 grainsof filver form 133 of luna cornea, and of the33 grains additional weight, 12.-5- are oxygen,and 20-5 muriatic acid. The copper was thenprecipitated as ufual by iron, and weighed 57-5grains in the metallic ftate, equal to 73 of thebrown oxyd. Klaproth does not confider theiron however as effential to the ore, and there-fore excludes it from the eftimate.
This rare mineral was analyzed by Klaproth in the following way. It was firft diflolved innitric acid, which made a clear blue folution,leaving untouched 16 parts out of 100, whichwere quartz. The folution was then juft fatu-rated with potafh to engage any excefs of nitricacid, and acetited lead was then added, whichgave a copious white precipitate, and a fmallexcefs of the acetite was ufed to enfure thecompleat precipitation, This white infolublefait from appearance might be either fulpliat,or arfeniat, or muriat, or phofphat of lead, butit was proved to be the latter by the two fol-lowing tells: ill. when fufed by the blowpipe,in the moment of cooling it affumed a garnet-like form with Ihining furfaces, which fuddencryftallization is peculiar to phofphat of lead •,and 2dly, when digelted with dilute fulphu-ric acid, fulphat of lead was formed, andnaked phofphoric acid remained in the liquor,which being neutralized, partly by foda andpartly by ammonia, gave the well-known micro-cofmic fait. The native phofphoric acid wastherefore feparated from the copper in this ana-lyfis, and from 100 grains (exclufive of thequartz) 138 grains of phofphat of lead wereformed, the phofphoric acid of which was efti-mated from other experiments to amount to30.95 grains. The cupreous folution was thentreated with a little fulphat of foda, to feparate
11 Hatchett. Phil.Tranf. vol. 93,
)
the lead from the excefs of the acetite remain-ing; fome naked fulphuric acid was then added,and the copper was feparated by iron in themetallic Hate, which (increafed in the proportionof 125 to 100), was found equal to 68.13 ofoxyd of copper.
The above analyfes include almoft all theimportant ores of copper, except thofe in whichit is combined with tin, which will be treatedof under that metal. It may be mentionedhowever that the moll accurate way of fepa-rating copper from tin appears to be to immerfein a folution of both metals a flick of tin, whichwill precipitate all the copper, whiift the lofs ofweight of the immerfed tin fubtrafled from theentire quantity of tin afterwards obtained fromthe folution, will indicate the quantity of tinbelonging to the ore.
To proceed to the properties of pure copper.
Copper is a metal of a brownifh red colour,very dubtile, malleable, and tenacious, fo asreadily to be flattened into thin plates, and to bedrawn out into wire of great ftrength compa-ratively to its thicknefs, more fo (according toCount Sickingen ) even than gold. It breaks witha hackly fracture. When rubbed, it emits a dif-agreeable fmell, and it gives a flyptic and nau-feous tafte. The fpecific gravity of the pureftSwedifh copper is 8.895 k , that of the betterkinds met with in commerce but of lefs puritythan the former, varies from this weight toabout 8.6. The Japanefe copper is found byBergman to be 9.0.
Copper requires for fufion what is commonlycalled a white heat, which is apparently notmore, however, than is required to melt gold orfilver. Before it melts, it {hews on its furfacechangeable prifmatic colours. When in fufion,or even at a heat fomewliat below, if with accefsof air, it begins to oxidate on the furface form-ing thin brown feales. Thefe may readily beknocked off when cold, and are then very brittle.This is an imperfect oxyd of copper, formerlycalled copper q/hes , as te/htm, or cinis arts , and byrepeatedly heating and cooling a bar of thismetal, the whole may be thus changed. Thefefeales are found by Prouft 1 to confift of about62 of the black or compleat oxyd, and 38 ofcopper nearly metallic. Dilute fulphuric acidafeevtajns this by diffolving (when without heat)only the former part. By feparate calcinationthe whole is reducible into the black oxyd,which weighs one-fourth more than the copperfrom which it is procured. When intenfelyheated the oxyd runs into a bright red-brown*- An. Chim. tom. 32.