COP

COP

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certain degree of pliability, M. Tingry givestlie following receipt. Take of powdered copal2 ounces ; of oil of lavender 6 ounces; of cam-phor one drahm; and of oil of turpentine asmuch as is wanted to give the requifite conflu-ence. The camphor and oil of lavender are tobe feparately liquefied, then the copal diflolvedtherein, and laftly the oil of turpentine addedboiling-hot and incorporated by ftirring. Thisthe author confiders as fit for the ingeniousprocefs of varnilhing wire gauze, in the Chinefemanner, for lanthorns, to be ufed where a lighterand lefs brittle material than glafs is wanted.

In the compofition of the drying-oil varnilhes■with amber or copal, it is well known that agreater heat is required than in the former fpiritvarnilhes, as it mult be fuffieient to liquify therefin before it will unite with the oil. Bothamber and copal have the difadvantage of be-coming brown and coloured by a melting heat,applied in the common way, and hence it is agreat object to find fome method of meltingthefe refins without impairing that tranfparencyfor which they are fo much valued.

M. Tingry finds this obje£t to be confider-ably attained by inclofing the copal in a wire-net hanging in the centre of a fmall furnace ofpeculiar confirmation, and with a very moderateand well regulated fire, whence the copal, asfoon as liquefied, falls down through a conduc-ing tube, and may be thus dropped in a liquidftate into hot drying oil fet below to receive it.They immediately unite, and when afterwardstempered with fuffieient hot oil of turpentine, afine drying oil varnilh is formed, which has butlittle colour and retains its tranlparency.

If the melted copal is received into water afmall quantity of oil is feparated, which is foundfloating at the top, and the copal appears to berendered thereby fomewhat more foluble in dif-ferent menftrua.

As copal is expenfive it is fometimes adulte-rated with gum anime when very tranfparent.The latter is diftinguilhed by being more friable,and for giving a fweet odour when rubbed.Copal will unite with other refins in compoundvarnilhes, and many of the liquors commonlyfold for copal varnilh, contain only a fmall por-tion of copal,, the other refinous bafis beingeompofed of maftich, fandrach, and others ofthe moll colourlefs refins.

COPPER. Cuprum , Lot. Kupfer,. Germ.Cuivre , Fr.

Copper is a malleable and ductile metal of apale-red colour with a tinge of yellow. It is

•Kirwan, Hauy, Brochant. Jatnefon,

foluble with effervefcence in nitrous acid, towhich it gives a Iky-blue colour: on the ad-dition of liquid ammonia a green precipitate isthrown down, which is re-foluble in an excefsof ammonia, forming a very rich purplilh-bluefluid, and from this, if flightly fuperfaturatedwith muriatic acid, the copper is again precipi-table in its metallic form by a bar of clean iron.

The ores of this metal are very numerous, 1and may with moll convenience be arrangedunder the eight following families.

I. Family. Native Copper.

Sp. I. Native Copper. Gediegen Kupfer.Cuivre nat'f.

Its colour is a clear copper-red, often tar-nilhed externally yellowilh, blackilh or greenilh.It occurs in mafs, difleminated, in leaves, inrolled pieces, in grains, capillary, filiform, mofs-like, dendritical and cryllallized.

x. In cubes, either entire or truncated at theedges and angles.

2. In octahedrons, either regular or combinedwith the cube.

3. In pyramidal dodecahedrons formed oftwo fix-fided pyramids, with a fhort fix-fidedprifm interpofed.

The cryftals are fmall or very fmall, feldomfingle and moll commonly implanted in eachother, forming dendritical or cluttered maflfes.Its external luftre is cafual, its internal is glif-tening and metallic. Its fraCture is hackly;when cut or rubbed it has a Ihining metallieluftre. It is not very hard, is malleable andflexible without being elaftic, and difficultlyfrangible. Sp. gr. of the Hungarian 7-72, ofthe Siberian 8,58.

It is fufible before the. blowpipe, and appearsto be pure copper-

It occurs in veins and beds in quartz andgranite, ih Hate, porphyry, ferpentirie, hornftoneand limeftone, accompanied by various otherores of copper, particularly the red oxyd, mala-chite and copper pyrites, with galena, horn-filver, native filver, calcareous fpar, heavy-fparand fluor.

It is very generally, though not often veryabundantly diffufed. The fineft fpecimens comefrom the Tourinlki mines on the eaftern fide ofthe Uralian mountains, from Herrngruiid inHungary, from Saxony , the Hartz, Fahlun inSweden, and Cornwall . It is faid to be remark-ably abundant in Japan and Brazil , and to con-tain a confiderable proportion 01 gold. It isalfo procured in quantity from the Copper-mineriver within the Arctic circle in America .

Emraerling, Bournon in Phil. Tianf.