Chapter II: BLEACHING of =Linen=:--Linen may be bleached in a similar way to (20)

_Prop., Purific., &c._ Copaiba, though usually called a 'balsam,' is not correctly so named, as it contains no benzoic or cinnamic acid. It is correctly described in the B. P. as an 'oleo-resin.' Considerable variation exists in the colour, odour, consistence, and transparency, as well as in the proportion of oil and resin yielded by different samples, scarcely any two of which exactly agree. The sp. gr. varies from ·950 to ·996. Brazilian copaiba is thin, clear, and pale; whilst the West Indian variety is thick, golden yellow, less transparent, and has a less agreeable and somewhat terebinthinate smell. Some varieties are opaque, and continue so unless filtered. This is often a most troublesome operation. The opacity generally arises from the presence of water, which it retains with great tenacity. The following is the plan we have found to answer on the large scale:--Place the casks upon their ends in a warm situation, and leave them so for 10 days or a fortnight, or longer, if convenient. They may then be tapped a little above the bottom, when the contents of some of them will generally be found quite transparent, and may be drawn off and vatted, care being taken to avoid shaking up the bottom. The copaiva that remains foul must be filtered through one or more long Canton flannel bags, sunk in the bottom of a tin cistern, placed over a suitable receiver, in a similar way to that adopted for oils; a few pounds of coarsely powdered charcoal being mixed up with the first 5 or 6 gallons thrown in. This will rapidly fill up the pores of the bag, and make the balsam soon flow clear and pale. The "bottoms" of the casks, containing the water and impurities, may be poured into a large can or jar, and allowed to settle for a few days, when the copaiba may be poured off the top and filtered. A sudden change of temperature will frequently turn a transparent sample of this article opaque or milky; it is not, therefore, deemed fit to send out by the wholesale trade, unless it stands this test. To ascertain this point a common practice is to fill a small bottle with the copaiba, and to leave it out of doors all night in an exposed situation.

_Pur., Tests, &c._ This substance is frequently adulterated; indeed, fully one half that sold for copaiba does not contain 10% of the genuine balsam. This is particularly the case with that sold in capsules, at low prices, in the shops. Pure balsam of copaiba may be recognised by the following characters:--

1. (Ph. E.) It is transparent; free of turpentine odour when heated; soluble in 2 parts of alcohol; and dissolves one fourth of its weight of carbonate of magnesia with the aid of a gentle heat, and continues translucent.

2. (Chevallier.) A drop of the balsam, placed on a piece of unsized paper, and heated until all the essential oil is expelled, forms a semi-transparent, well-defined spot; but if the balsam has been adulterated with a fatty oil, it is surrounded by an oily areola.

3. (Planche.) 2-1/2 parts of balsam shaken with 1 part of solution of ammonia, sp. gr. ·965, forms a mixture which becomes clear and transparent in a few moments, and may be heated to 212° Fahr. without becoming opaque.

4. (Vigne.) Boiled with 50 times its weight of water for 1 hour, it should lose at least half its weight.

5. (Adder.) By agitating the suspected sample with a lye of caustic soda, and setting the mixture aside to repose, the balsam after a time rises to the surface, and the fatty oil present (if any) forms a soapy, thick mass below.

6. ('Journ. de Pharm.,' 1842.) Pure copaiba may be adulterated with 50 per cent. of a fat oil (nut, almond, or castor oil), without it ceasing to give a clear solution with 2 parts of alcohol; but it combines badly with magnesia and ammonia. Excess of alcohol, however, separates the oil in all cases. It was formerly considered that the best test for detecting the fat oils was pure alcohol, to which some caustic potash had been added.

7. (Dr Hager.) Copaiba which is adulterated with Gurgun balsam is not quite clear, and frequently exhibits prisms of gurginic acid under the microscope. The author states that the adulteration may be easily detected by mixing the suspected sample with four volumes of petroleum ether; the mixture at once becomes turbid, and gradually deposits a sediment, which, after half an hour's settling, occupies the same volume as the copaiba operated upon. A mixture of pure copaiba with petroleum ether is clear at first, and either remains clear upon standing or it deposits after several hours a very slight sediment, which merely covers the bottom of the test tube like a thin film. Benzol may be used in place of petroleum ether.

8. (Muter.) Three to four grams of the sample are weighed into a clean, dry flask, and saponified on the water bath with 50 c. c. of alcohol, and a lump of caustic soda weighing not less than 5 grams. When all is dissolved water is added, and the whole washed into a half-pint basin, so as to nearly fill it, and evaporated to 100 c. c. over a low gas flame. Dilute sulphuric acid is then added till the whole just becomes permanently turbid, and then solution of caustic soda is dropped in till it just clears again. By this means a solution is obtained with the least possible excess of alkali, and with a good amount of sodium sulphate. The whole is now to be evaporated to _perfect dryness_ on the water bath, stirring towards the end, so that the sulphate may mix with the soaps, and produce an easy pulverulent residue. The residue is moved from the basin into a small, wide-mouthed, stoppered bottle, treated with 70 c. c. of ether-alcohol, and well shaken up. As soon as it is fairly settled the fluid is filtered off through a _quick_ filter, and this is repeated with two successive quantities of 70 c. c., making 210 c. c. in all of the solvent used. The residue in the bottle and in the filter now consists of sodium oleate and sulphate if the balsam be impure, and of the latter only if pure, with a little trace of the insoluble resin soap already referred to. The contents of the bottle and filter are then dissolved in warm water, and after heating until all smell of ether is gone the whole is boiled freely acidulated with hydrochloric acid, and set to cool.

If, when cold, nothing but a few specks of brown resin should rise to the surface, the balsam is pure; but if an oily layer be formed it is adulterated, and the smell of the separated oleic acid will at once determine whether it is actually castor oil or not.

In the case of the presence of oil, 2 grams of pure and dry white wax are added, and the whole heated till the wax melts with the oleic acid. On cooling, a solid cake is formed, which is detached from the side of the beaker, and the fluid below passed through a filter. The cake is once more melted in boiling water, cooled, detached, dried by gentle pressure between blotting paper, dried in a water-oven in a weighed platinum dish, and then weighed, and the weight of the wax used deducted. The beaker, filter, rod, &c., used are, if at all dirty, dried, extracted with ether, and the residue left, after evaporation, weighed and added to the total.

The calculation is then performed as follows:--

(1.) To the weight in grams found add ·20 for loss of oleic acid in solvent, and then say as 95 : 100 :: total oleic acid.

(2.) Calculate the per-centage from the quantity taken, and from this deduct 6 per cent. for possible altered resin in the balsam. The error, owing to the correction, of course, increases with the amount of oil present; but it is stated to be always an error in the direction of under-estimation, which is the great point for public analysts. When working on 3 to 4 grains with an admixture of not over 25 per cent. the errors due to loss of oleic acid and insoluble resin soap are said to so nearly balance each other, that any correction is unnecessary, and the actual amount of oleic acid found may be taken as correct within a per cent.

9. (B. P.) According to the British Pharmacop[oe]ia, copaiba should be soluble in an equal bulk of benzol.

10. (The evaporation test.) Mr Siebold says: "This is an excellent and exceedingly simple test, but is clumsily applied by many. Instead of boiling the balsam with water for many hours, a small quantity (about 1 to 1·5 gram) of the sample should be carefully heated in a watch-glass until all the oil is driven off, which is the case as soon as the residue has assumed a rich brown colour. A few minutes suffice for the experiment.

"If the remaining resin is perfectly brittle and pulverisable there is no fatty matter present, for 1 per cent. of oil would diminish the brittleness of the resin, so that it cannot be reduced to a fine powder. One per cent. of oil is thus readily detected, and with larger quantities of the adulterant (3 to 5 per cent.) the resin feels quite sticky.

"On heating the resin castor oil and linseed oil may be distinguished by the odour. By mixing the adulterated balsam with ten, twenty, forty, and fifty volumes of pure maranham balsam respectively, and testing each dilution in this manner, it is easy to find in which the oil has been reduced to below 1 per cent., and thus to ascertain whether the adulterant amounted to more than 10, 20, 30, 40, or 50 per cent., and this, I think, would be sufficiently near the mark for the purpose of public analysts."

_Uses, &c._ Balsam of copaiba is considered detersive vulnerary, diuretic, and astringent; and appears to possess a sort of specific power over diseases of the mucous membranes of the urino-genital organs. It is hence a favourite remedy in gonorrh[oe]a, as soon as the first inflammatory symptoms have subsided, antiphlogistic and soothing measures being previously adopted. _Dose_, 20 to 60 drops on sugar, floating on water, or made into an emulsion with yolk of egg or gum arabic, 3 or 4 times daily, if the stomach will bear it. The addition of a few drops of sweet spirits of nitre and laudanum have been recommended, to allay the nausea. By adding 1 dr. of oil of orange (ol. aurantii) to each oz. of the balsam, its flavour becomes far from disagreeable, and it sits well upon the stomach. Copaiba is also given in capsules and pills. See CAPSULES, EMULSION, OIL, PILLS, &c.

_Obs._ Numerous preparations of this article are sold under such names as 'soluble copaiba,' 'specific solution,' 'salt of copaiba,' &c.; none of these appear to possess equal activity and certainty of operation to the natural balsam. As the whole virtue of copaiba as a medicine depends on the essential oil it contains, the value of any of these preparations may be estimated by the quantity of that article which is found in them. In the case of the first two articles above named the quantity is very small indeed, and in the last it is wholly deficient.

The following forms are current in the trade for the reduction (adulteration) of balsam of capivi:--

1. Balsam of copaiba, 4 lbs.; castor oil, 3 lbs.; mix well.

2. Balsam, 7 lbs.; castor oil, 4 lbs; yellow resin, 2 lbs.

3. Equal parts of balsam of copaiba and Canada balsam.

4. To the last add Venice turpentine, 1 lb.

5. Balsams of Canada and copaiba and nut or castor oil, equal parts.

6. Copaiba, 7 lbs.; nut oil, 3 lbs.; yellow resin, 2 lbs.; Canada balsam, 1 lb. Used to fill the cheap capsules; and to sell in the lower parts of London and in the manufacturing districts. See also COPAIBA, FACTITIOUS (_below_).

=Copaiba, Facti''tious.= _Syn._ COBAI'BA FACTI''TIA, BAL'SAMUM COPAI'BÆ FACTI''TIUM, L. _Prep._ 1. Castor oil (warm), 7 quarts; copaiba bottoms, 1 quart; mix, and filter through flannel.

2. Castor, oil, 1 gal.; yellow resin, 3 lbs.; Canada balsam, 2 lbs.; oil of juniper, 2 oz.; oil of savin, 1 oz.; essences of orange and lemon, of each 1/2 oz.; powdered benzoin, 1 oz.; melt the resin with the castor oil and benzoin, and when nearly cold add the essences.

3. Canada balsam, 9 lbs.; castor oil, 7 lbs.; yellow resin, 1 lb.; Venice turpentine, 2 lbs.; oils of rosemary, juniper, and savin, of each 1 dr.; essential oil of almonds, 20 drops.

4. Canada balsam, 3 lb.; Venice turpentine, 1 lb.; oils of fennel, juniper, and savin, of each q. s.

Used chiefly to fill capsules. It is readily distinguished from balsam of copaiba by the proper tests. (See _above_.) Train oil or nut oil is frequently substituted for the castor oil.

=Copaiba and Ka'li.= _Syn._ COPAIBA CUM POTASSÂ, L. _Prep._ Carbonate of potassa and water, of each, equal parts; dissolve, and add gradually, transparent balsam of copaiba, until the fluid, at first milky, turns quite clear. Resembles miscible copaiba (see _below_).

=Copaiba, Miscible.= _Prep._ From balsam of copaiba (pure and transparent), mixed with half its volume of solution of potassa made of double the strength ordered in the B. P.

_Obs._ As different samples of copaiba often require slightly different quantities of the solution of potassa, it is best to mix the two gradually and cautiously together. Should the mixture be opaque, a little more of one or other of the ingredients, as the case may be, will render it clear. No heat must be used. This article is miscible with water, with which it forms a kind of milk; and from containing all the volatile oil of the copaiba, is a very valuable preparation. Its activity is considered equal to that of the balsam itself, and it is given in similar doses.

=Copaiba, Sol'uble.= _Syn._ COPAI'BA SOLUBIL'IS, L. _Prep._ 1. Heat miscible copaiba in an earthen, glass, or bright-tinned copper vessel, to nearly the boiling-point, pour it while still hot in a separator, cover it up, and allow it to cool very slowly. After a few days, draw off the clear portion from a cock or hole placed at or near the bottom of the vessel, observing to reject the first few drops which pass through, and to stop the stream before any of the floating oil (_oleum copaibæ_) reaches the orifice. A very little concentrated liquor of potassa, added before applying the heat, renders it more soluble. Thick, transparent, soluble in pure water, and resembles the natural balsam in appearance.

2. Balsam of copaiba and solution of potassa (B. P.), equal parts, by volume; mix, boil for a few minutes, and then proceed as before. Thinner than the last.

_Prop._ Less powerful than miscible copaiba, but it sits better on the stomach, and is about four times as strong as specific solution of copaiba. See SOLUTION.

=Copaiba, Res'in of.= _Syn._ COPAI'BÆ RESI'NA, L. The residuum of the process of distilling the oil of copaiba from the balsam. It consists principally of copaibic acid. It has been recommended for gonorrh[oe]a, but is nearly inert, even in 1/2 oz. or 3/4 oz. doses. See OIL.

=Copaiba, Salt of.= _Syn._ SAL COPAI'BÆ, L. There are two preparations sold under this name; the one, crude copaibic acid; the other, copaibate of an alkali. Neither of them possesses the valuable properties of copaiba, which reside almost entirely in its essential oil, "We have taken the 'sal copaibæ,' and have watched its action on others, but have not been able to perceive any good effects to result from its administration." (Cooley.)

=COPAI'BIC ACID.= _Syn._ CAPIV'IC ACID. YELLOW RESIN OF COPAIBA. An amber-coloured, brittle, semi-crystalline, resinous substance, obtained from resin of copaiba, soluble in alcohol, rectified spirit, ether, and oils, reddens litmus paper, and forms salts with the bases, called copaibates.

=CO'PAL.= _Syn._ COPAL', GUM COPAL. A resinous substance, which exudes spontaneously from various trees belonging to the genera _Hymenæa_, _Guibourtia_, and _Trachylobium_. The varieties commonly met with in commerce are East Indian copal, or anine, which is the produce of _Hymenæa Courbaril_, and West Indian copal, obtained from numerous species.

_Prop._ When of good quality it is too hard to be scratched by the nail, has a conchoidal fracture, and a sp. gr. ranging from 1·059 to 1·072. Unlike other resins, it is dissolved with difficulty by alcohol and essential oils; and this property, combined with its extreme hardness, renders it very valuable for making varnishes. See VARNISH.

=COP'PER.= Cu. _Syn._ CU''PRUM, L.; CUIVRE, Fr.; KUPFER, Ger.

_Sources._ Metallic copper (native copper) is found in many parts of the globe, diffused in isolated particles in the form of thin laminæ, in loose grains intermixed with quartz (copper sand, copper barilla), in dendritic pieces, and in solid blocks, occasionally of many tons weight. The richest deposits of native copper are those of Lake Superior, in North America. More frequently and more abundantly it occurs as an ore, _e.g._ red oxide, black oxide, green carbonate of copper or mal'achite, blue carbonate of copper, vitreous sulphide of copper, purple copper, copper pyrites, or yellow copper ore, with sulphur, antimony, or arsenic, and other metals (true grey copper ore or fah'lerz), as an impure hydrated silicate (chrys'ocolla), and as an impure hydrated oxychloride (atac'amite). The most abundant and important ore is copper pyrites. It is principally obtained from the mines of Cornwall, Devonshire, and Cuba. The carbonates of copper are now largely imported from Australia; the metal produced by smelting them is generally of the best quality.

_Prep._ We will not attempt to give a minute description of the various complex processes by which the reduction of copper from its ores is effected, but will merely give an outline of the common or Welsh process. This process includes six distinct operations, as follows:--1. The ore (copper and iron pyrites), containing from 8 to 10% of copper, is roasted in a reverberatory furnace, called a 'calciner,' by which much of the sulphide of iron is converted into oxide. 2. The calcined ore is melted with 'metal slag' (a product of a subsequent operation--No. 3), in a melting furnace called the 'ore furnace.' The products are a regulus, termed 'coarse metal,' containing about 35% of copper, and 'ore-furnace slag,' which is thrown away. Much of the iron, and the whole of the so-called earthy matter of the ore, are thus separated as slag. 3. The coarse metal, having been granulated by causing it to flow from the furnace into water, is calcined with free access of air in a calciner, and a considerable amount of sulphur is expelled. 4. The calcined granulated, coarse metal is melted with the addition of matters rich in oxides of copper, namely, 'roaster' and 'refinery slags' (from the two remaining operations, Nos. 5 and 6, respectively), and native carbonates of copper, or ores containing oxide of copper. The products are a regulus, termed 'metal,' which contains about 75% of copper, and metal slag (see No. 2). The metal should be in the state of 'white metal,' compact and brittle, with a feeble metallic lustre and a dark, bluish-grey colour. It is tapped off into sand moulds. 5. The pigs of regulus obtained by the last operation are roasted in a furnace through which air passes. The temperature is so regulated that the regulus may be melted in from 6 to 8 hours. The slag is skimmed off, and after a time the heat is lowered, to allow the regulus to solidify. It is again melted and tapped into sand moulds, the product being called 'blister copper.' 6. This, the last operation, is termed 'refining.' From 6 to 8 tons of blister copper, in pigs, are melted in a furnace, and kept exposed for about 15 hours to the oxidising influence of the air. The slag is skimmed off through the end opening. When the oxidation has been sufficiently prolonged, anthracite or free-burning coal, as pure as possible, is thrown upon the surface of the metal, and after a short time the thick end of a long birch or oak pole is plunged into the molten mass. This part of the operation is termed 'poling.' The wood in contact with the copper is rapidly decomposed; much gas is evolved, which causes the metal to be splashed about, and every part of it to be exposed to the reducing action of the coal. When the refiner finds the metal to be at the state of 'tough pitch,' the pole is taken out, and the coal pushed back from the end opening, through which the copper is then ladled out as quickly as possible, and cast into suitable moulds. For full details of this and other processes, the reader is referred to Dr Percy's work on 'Metallurgy,' and Ure's 'Dictionary of Arts, Manufactures, and Mines.'

In the laboratory copper is commonly employed under the following forms:--

1. BEAN-SHOT COPPER. Produced by simply lading the melted copper from the refining furnace into hot water. In small lumps like peas and beans; hence its name. Used to make alloys, solutions, &c.

2. ELECTROTYPE COPPER. A very pure form, obtained by decomposing sulphate of copper in an electrotype apparatus. It does not contain lead, whereas most varieties of commercial copper do contain that metal.

3. FEATHER-SHOT COPPER, GRANULATED C. Produced by lading the refined copper from the furnace into cold water. In small pieces, with a feathered edge. Used to make calamine, brass, solution of copper, &c.

4. COPPER IN PLATES OR FOIL. Those of commerce (best, annealed) are generally employed.

5. COPPER IN POWDER.--_a._ A solution of sulphate of copper is heated to the boiling-point, and precipitated with distilled zinc; the precipitated copper is then separated from the adherent zinc by dilute sulphuric acid, washed with water, and dried by exposure to a moderate temperature.

6. COPPER PREPARED BY THE HYDROMETALLURGICAL METHOD.--One of the oldest processes of this kind, is that known as the 'cementation' method, and consists in precipitating copper from a solution of the sulphate of the metal, by means of metallic iron. In some mines solutions of the sulphate are met with occurring naturally, in others they are prepared artificially by treating poor ores containing oxide of copper, with sulphurous acid or diluted sulphuric acid, and sometimes by roasting copper pyrites and afterwards washing them with water to extract the resulting sulphate. The copper obtained by any of the above processes is called 'cementation copper.' In the Isle of Anglesea the cementation liquid containing the dissolved sulphate of copper, is first run into large vessels where the suspended matters are allowed to subside; from these it is conveyed to tanks containing old scrap-iron, which serves as the precipitating agent. The scrap-iron is occasionally stirred up so as to renew the metallic surface presented to the solution. The muddy liquor which contains metallic copper as a spongy mass, besides impurities, is run into vessels where it deposits the copper, which after the removal of the supernatant fluid, is removed and dried in a furnace.

7. WET PROCESS. (Henderson's process.) The ores (Spanish and Portuguese pyrites) treated by this method vary very slightly in composition, rarely containing much more than 3 per cent. of copper, nearly 50 per cent. of sulphur, from 43 to 44 per cent. of iron, with small quantities of lead, arsenic, zinc, lime, &c. The ores are first employed by the vitriol manufacturers, as a source of sulphuric acid. In the process of burning they lose about 30 per cent. of their sulphur. The copper is extracted from the residue by subjecting this latter to the following processes, which are thus described in the 'Encyclopædia Brittanica.'

I. _Grinding._ The burnt ore, as received from the acid burners, is first mixed with about 15 per cent. of common salt, and ground to a fine powder by passing it between a pair of heavy cast-iron rolls. As the amount of sulphur left in the burnt ore is apt to vary, it is necessary to ascertain its proportion in each parcel of burnt pyrites. When the sulphur falls short of the proportion necessary for effecting the decomposition which follows, a sufficient quantity of 'green' or unburned pyrites is added to produce a proper balance. If, on the other hand, the sulphur has been sufficiently extracted, dead roasted ore is added.

II. _Calcination._ This operation is accomplished in several kinds of furnaces, that used by the Tharsis Sulphur and Copper Company, being a large muffle or close furnace. By others a patent furnace with a revolving hearth and mechanical stirring arrangement has been adopted with good results; and some use open reverbatory furnaces heated by gas from Siemens's generators. During the roasting the mixture is frequently stirred, and in the case of hard-worked furnaces, turned with long rabbles, and the completion of the operation is ascertained by test assays. When the copper has been brought into a soluble condition, the charge is raked out of the furnace and permitted to cool under a screen at its mouth. By the calcination the sulphur in the compound is first oxidised, sulphate of sodium is formed, and at the same time the chlorine from the sodium chloride unites with the copper to form cupric chloride. A small proportion of cuprous chloride is also formed, and special precautions have to be taken to prevent the extensive formation of this compound which is dissolved only with difficulty. The hydrochloric acid and other gaseous products evolved during the calcination are condensed as 'tower liquor' in ordinary condensing towers, and the product is used in the subsequent process of lixiviation.

III. _Lixiviation._ The calcined ore is conveyed to tightly caulked wooden tanks, in which it receives repeated washings with hot water, tower liquor, and dilute hydrochloric acid till all the soluble copper is thereby extracted. The product of the latter washings is pumped or drawn up by a modification of Gilford's injector, to serve as a first liquor for subsequent charges of the lixiviating tanks, and no solution under a definite strength is permitted to pass on to the next stage in the process. The insoluble residue in the tanks consist of "purple ore," an almost pure ferric oxide, largely used in "settling" blast furnaces, and for smelting purposes; besides which it is available as jewellers' rouge.

IV. _Precipitation._ The precipitation of metallic copper from the solution of its chloride is accomplished in large tanks by means of metallic iron in the same way that cementation copper is obtained from solutions of the sulphate. The solution is run into the tanks in which there are miscellaneous heaps of old malleable iron; the chlorine combined with the copper unites with the iron, and metallic copper in the state or fine division is thrown down. The completion of the precipitation is ascertained by dipping a bright steel knife into the solution in the tank, and when no deposit of copper covers the steel, the liquor is run off and a new charge conveyed into the tank. The tanks are drained periodically for removing the precipitate, which is first roughly separated from the small pieces of iron, after which it is more thoroughly freed from iron, &c., by washing in water in a rocking sieve apparatus. The precipitate so obtained should contain 80 per cent. of metallic copper, which is either smelted directly for blister copper, or may be fused with the white metal of the ordinary smelting process, and subsequently roasted. It has been found possible to extract in this process with profit the small proportions of lead, silver and gold, which Spanish pyrites is known to contain. Two processes are in operation for this purpose--one devised by Mr P. Claudet, and the other by Mr W. Henderson, the original patentee of the wet process. The liquors from the first three washings contain practically, all these metals, and they alone are treated. Mr Claudet precipitates them from the solution by means of iodide of potassium. Mr Henderson dilutes his solution from 20° to 25° Twaddell, and adds a very weak solution of lead salt, such as the acetate by which he obtains a cream-coloured precipitate containing 5 or 6 per cent. of silver, and 3 oz. of gold to each ton of the precipitate. The importance of the wet process may be estimated from the fact, that although it originated only in 1860, already 14,000 tons of copper, are annually produced by it in Great Britain alone, out of an annual production for the whole world estimated at from 126,000 to 130,000 tons.

_Prop., &c._ Copper has a brilliant yellowish-red colour, a nauseous, styptic taste, and emits a disagreeable odour when rubbed; is very malleable and ductile; unchanged in dry air; in damp air it soon becomes covered with a greenish rust (carbonate of copper); slightly soluble in dilute sulphuric and hydrochloric acid; freely soluble in boiling oil of vitriol (sulphurous anhydride being evolved); dilute nitric acid dissolves it readily with copious evolution of nitric oxide; heated to redness in the air, it rapidly becomes covered with a black scale (oxide); it fuses at a full red heat; its crystals are either octahedra or dodecahedra; sp. gr. 8·8 to 8·96; it forms numerous compounds (alloys and salts) with other bodies, all of which are more or less poisonous; its salts are either blue or green, and most of them (when neutral) are soluble in water.

_Tests._ Metallic copper may be recognised by the above properties; its oxides, salts, &c., by the following characters and reactions:--The solutions of copper possess a blue or green colour, which they retain even when considerably diluted with water:--With caustic potassa they give a light-blue, bulky precipitate, turning blackish-brown or black on boiling the liquid:--Ammonia and carbonate of ammonium produce a bluish-white precipitate, soluble in excess, yielding a rich deep-blue solution:--The carbonates of potassium give a light precipitate, insoluble in excess:--Ferrocyanide of potassium gives a reddish-brown precipitate:--Sulphuretted hydrogen and sulphydrate of ammonium give blackish-brown or black ones:--A polished rod of iron, on immersion in an acidulated solution, quickly becomes coated with metallic copper.

_Estim., &c._ Copper is generally WEIGHED under the form of black oxide, but sometimes as pure metal:--By throwing it down from its solution by pure potassa, after which it must be carefully collected, washed, dried, ignited in a platinum crucible, and weighed therein as soon as it is cold. Every 5 parts of the ignited precipitate (oxide) represents 4 parts of copper (nearly); or, more accurately, every 39·7 parts are equal to 31·7 of pure metallic copper:--By immersing a piece of polished steel in the solution, and weighing the resulting precipitate of the copper (see _above_). Less delicate than the preceding.

Copper can be separated from the other metals by means of the following processes:--

From lead. By adding sulphuric acid to the nitric solution, and evaporating to dryness, when water digested on the residuum will dissolve out the sulphate of copper, but leave the sulphate of lead behind. From this solution the oxide of the copper may be thrown down as before.

From tin. By digestion with hot nitric acid, which dissolves out the tin.

From zinc. By sulphuretted hydrogen, which throws down the sulphide of copper from an acid solution.

From silver. By digesting it in the state of filings or powder in a solution of chloride of zinc, which dissolves the first, but leaves the last unchanged.

Copper may be separated, in a state of great purity, from ANTIMONY, ARSENIC, BISMUTH, LEAD, IRON, TIN, ZINC, &c., as it exists in bell-metal, brass, bronze, gun-metal, mosaic gold, and other commercial alloys, by fusing it in a crucible for about half an hour, along with copper scales (black oxide) and ground bottle-glass, or other like flux. The pure metal is found at the bottom of the crucible, whilst the impurities are either volatilised or dissolved in the flux. The proportions for refining commercial copper are, metal, 10 parts; copper scales and bottle-glass, of each 1 part. The Society of Arts conceived this process to be so valuable, that they presented one of their gold medals to its inventor, Mr Lewis Thompson.

_Uses, &c._ The ordinary uses of copper are well known. In _medicine_, 3 or 4 gr. of the filings or powder were formerly given in rheumatism, and to prevent hydrophobia. Some of its salts are still used as astringents, emetics, and caustics. Its alloys are of great value. With zinc it forms BRASS; with tin, BRONZE, BELL-METAL, GUN-METAL, and SPECULUM-METAL. WHITE COPPER is formed by the addition of metallic arsenic, and GERMAN SILVER is a mixture of nickel, zinc, and copper.

_Ant._ Copper in the metallic state is almost inert, but all its compounds are poisonous. The antidotes are--the white of egg, milk, or flour, mixed with water. The hydrated sulphides of iron, iron filings, and ferro-cyanide of potassium have also been strongly recommended, and are exhibited in the same way. Sugar is likewise highly spoken of as an antidote. In all cases a strong emetic should be first given.

_Obs._ Culinary and pharmaceutical vessels are very commonly made of copper, but too much caution cannot be exercised in their employment. Acid syrups, vegetable juices, aqueous extracts, soups, stews, &c., prepared in copper saucepans, or boilers, receive a metallic contamination proportional to the length of time they are exposed to the action of the metal. Such vessels are frequently tinned, for the purpose of protecting the copper from contact with their contents, but this film of tin is necessarily very thin, and soon becomes imperfect by constant use. When copper vessels are allowed to remain wet or dirty, or, more especially, greasy, a poisonous green rust forms upon the surface, somewhat similar to verdigris. If articles are prepared in them in this state, serious consequences may ensue. Cases of poisoning from this cause are frequently met with, and instances of vomiting following the use of such articles are almost of daily occurrence, without the reason being suspected. We have occasionally seen confections and extracts, prepared in copper pans, deposit a coating of that metal upon the knives used to stir them. The ashes of the inspissated juices of fresh vegetables, and especially the pulps of fruit, prepared in vessels of this metal, have exhibited the presence of copper on the application of chemical tests. Ketchup is frequently rendered poisonous in this way. The most wholesome material for culinary utensils is thin sheet iron, or tinned iron plate (TIN), which is very durable if kept clean and dry when not in use. Copper vessels of every kind should be cleaned out, immediately before use, even though they may not appear to require it, and on no account should they be employed for any fluids that are the least acidulous, or that may have to remain long in them.

The following enamel is recommended in Dingler's Polytechnic Journal for coating the inside of the copper vessels, used for cooking fruit or vegetables:--12 parts of white fluor-spar, 12 parts of unburnt gypsum, and 1 part of borax, are finely powdered, intimately mixed, and fused in a crucible. The fused mass is then poured out, and after cooling, is rubbed up to a paste. The copper vessel is then coated inside with this preparation, which is applied by means of a brush, and the vessel is placed in a moderately warm place, so that the coating may dry uniformly, when it is subjected to a gradually increasing heat, till at length the preparation fuses. On cooling, the vessel is found to be protected internally by a white opaque enamel, adhering very firmly to the copper, not chipping off by ordinary knocking and rubbing, and impervious to vegetable acids.

Copper may be cleaned by applying a small portion of the following paste, and rubbing it dry by a flannel or leather:--1 oz. oxalic acid, 6 oz. rotten stone, 1/2 oz. gum arabic, all in powder, 1 oz. of sweet oil, and sufficient water to make a paste.

=Copper, Neu'tral Acetate of.= Cu(C_{2}H_{3}O_{2})_{2}. _Syn._ NOR'MAL CUPRIC ACETATE, ACETATE OF COPPER, CRYS'TALLISED VER'DIGRIS. _Prep._ Dissolve common verdigris or cupric hydrate in hot acetic acid, so as to form a highly concentrated solution; filter and place in a cool situation to crystallise.

_Prop._ Beautiful dark, bluish-green prisms, which dissolve in 14 parts of cold and 5 parts of boiling water.

=Copper, Ba'sic Acetates of.= _Syn._ BA'SIC CU'PRIC ACETATES, SUB-AC'ETATES OF COPPER. Common verdigris is a mixture of several basic acetates which have a green or blue colour. One of these (SESQUIBASIC ACETATE) is obtained by digesting powdered verdigris in tepid water, filtering, and leaving the soluble part to spontaneous evaporation. It may also be obtained in a state of purity by adding liquor of ammonia in small portions to a boiling concentrated solution of the neutral acetate till the precipitate is just redissolved, and leaving the solution to cool. It forms a blue, crystalline mass, but little soluble in cold water. The green, insoluble residue of the verdigris, after treatment with tepid water, contains another acetate (TRIBASIC ACETATE); this may be formed by digesting neutral acetate of copper with the hydrated oxide. A third salt (DIBASIC ACETATE, BLUE VERDIGRIS) is prepared on a large scale in France by exposing copper to the air in contact with fermenting wine-lees.

=Copper, Ammo''nio-sul'phate of.= _Syn._ SULPHATE OF CUPRAMMONIUM. CU'PRO-SULPHATE OF AMMO''NIA; CU'PRI AMMO''NIO-SULPHAS, L.; CUIVRE AMMONIACAL, Fr.; KUPFER SALMIAK, Ger. _Prep._ Sulphate of copper, 1 oz.; sesquicarbonate of ammonium, 1-1/2 oz.; rub together until carbonic acid ceases to be evolved, then wrap it in bibulous paper, and dry it in the air.

_Pur._ Pulverulent; dark blue; at an intense heat it is changed into oxide of copper, at first sesquicarbonate of ammonia, and, afterwards, sulphate of ammonia, being thrown off. It is soluble in water to a splendid purple-blue solution, from which the salt is precipitated by alcohol in blue crystals. This solution has the peculiar property of dissolving CELLULOSE (cotton, paper, &c.). The cellulose may be precipitated from the solution in colourless flakes by the addition of acids.

_Uses., &c._ It is occasionally employed in _pyrotechny_. In _medicine_, it has been given in chorea, epilepsy, hysteria, &c., but is now principally used as an injection, as a wash for foul ulcers, used as a collyrium, in opacity of the cornea.--_Dose_, 1/4 gr., gradually increased to 5 gr., twice a day. Great care must be taken in drying, as it is apt not only to lose a large portion of its weight, but to become of an inferior colour. Both the ingredients should be separately reduced to powder before mixing them.

=Copper, Ar'senite of.= Cu(AsO_{2})_{2}. See GREEN PIGMENTS (Scheele's Green).

=Copper, Carbonate of.= CuCO_{3}. _Syn._ DIBA'SIC CARBONATE OF COPPER, DICARBONATE OF C.; CUPRI CARBONAS, L. _Prep._ Add carbonate of soda in excess to a solution of sulphate of copper, and warm the mixture till the pale-blue, flocculent precipitate becomes sandy and assumes a green tint. Used as a pigment. See GREEN PIGMENTS and VERDITER.

_Obs._ As prepared above, the carbonate contains 2 equivalents of water. The beautiful green mineral, MAL'ACHITE, has a similar composition, but contains only 1 equiv. of water. Another carbonate (TRIBASIC C., BLUE C.), occurs as a natural ore in large, transparent crystals, of the most intense blue; it has not yet been artificially imitated.

=Cuprous Chloride.= CuCl. _Syn._ DICHLORIDE OF COPPER, SUBCHLORIDE OF COPPER. _Prep._ By exposing the neutral chloride of copper to the action of heat.

_Prop._ White; fusible; slightly soluble in water; and decomposed by exposure to the air.

=Copper, Chloride of.= CuCl_{2}. _Syn._ NEUTRAL CHLORIDE OF COPPER. _Prep._ From copper scales or black oxide of copper dissolved in hydrochloric acid, and the solution evaporated and crystallised.

_Prop., &c._ Green, acicular crystals; deliquescent; soluble in alcohol, the flame of which it colours green. When gently heated it loses water, and assumes the form of a yellowish-brown powder (ANHYDROUS CUPRIC CHLORIDE, or CHLORIDE OF COPPER); at a high temperature it loses half its chlorine, and becomes converted into cuprous chloride.

=Cupric Iodide.= CuI_{2}. _Syn._ IODIDE OF COPPER, DINI'ODIDE OF COPPER; CU'PRI IODI'DUM. L. _Prep._ By adding iodide of potassium to a solution of sulphate of copper, and washing out with alcohol the free iodine from the precipitate formed. A greenish-white precipitate.

(Commercial.) To a solution of sulphate of copper, 1 part, and protosulphate of iron, 3 parts, add a solution of iodide of potassium, and wash and dry the precipitate. This is the preparation commonly known in trade by the name of 'iodide of copper.'

=Cupric Nitrate.= Cu(NO_{3})_{2}. _Syn._ NITRATE OF COPPER; CU'PRI NI'TRAS, L. _Prep._ By dissolving the copper in dilute nitric acid to saturation; evaporating to dryness; redissolving in distilled water; filtering, evaporating, and allowing to crystallise; or from black oxide of copper and nitric acid in the same manner.

_Prop., Uses, &c._ Deep-blue prismatic crystals, very soluble in water and deliquescent, soluble in alcohol. Generally used in medicine externally, in injections, or as a caustic, but sometimes given internally, dissolved in mucilaginous liquids.--_Dose_, 1/8 to 1/4 gr.

=Cuprous Oxide.= Cu_{2}O. _Syn._ RED OXIDE OF COPPER, DINOX'IDE, SUBOXIDE; CUPRI SUBOX'YDUM, L. _Prep._ Add grape sugar to a solution of sulphate or acetate of copper, then further add caustic potassa in excess; the blue solution heated to ebullition deposits the suboxide, which must then be collected, washed, and dried.

A solution of cane sugar, 27 parts, in water, 60 parts, is poured over hydrated oxide of copper (weighed in the compressed and still moist state), 9 parts; a solution of caustic potassa, 18 parts, in water, 60 parts, is then added, and the whole mass well agitated together at the ordinary temperature, and strained through linen. If the dark-blue filtrate is next heated (continually stirring), over a water bath, anhydrous cuprous oxide is disengaged, and the liquor becomes nearly colourless.

_Prop., Uses, &c._ A superb red powder, with a metallic lustre. It often occurs in beautiful transparent, ruby-red crystals, associated with other ores of copper, and can be obtained in this state by artificial means. It is used as a pigment and a bronze, and as a stain for glass and enamels, to which it gives a rich red colour. By heat it is converted into the black oxide. With ammonia it forms a colourless solution, which rapidly becomes blue from the action of the air.

=Cupric Oxide.= CuO. _Syn._ OX'IDE OF COPPER, BLACK OXIDE, PROTOXIDE; CU'PRI PROTOX'YDUM. _Prep._ By heating the nitrate or carbonate of copper to redness. When it ceases to lose weight the conversion is completed, and the oxide appears as a heavy, black powder.

By heating in the air the hydrated oxide thrown down from solutions of copper by pure potassa.

By adding caustic potassa, in excess, to a solution of a cupric salt, and heating the whole to a boiling-point; the precipitate is then collected, washed, and dried. A heavy, dark-brown powder.

_Uses, &c._ Protoxide of copper is unchanged by heat unless combustible matter is present, when it readily parts with its oxygen; hence its general use in ORGANIC ANALYSIS as a source of that element. It communicates a beautiful green colour to glass and enamels. With the acids it produces the ordinary salts of copper.

=Cupric Sulphate.= CuSO_{4}.5Aq. _Syn._ SULPHATE OF COPPER, BLUE COP'PERAS, B. VIT'RIOL; CU'PRI SUL'PHAS, L.; SULFATE DE CUIVRE, Fr.; KUPFER VITRIOL, Ger.; NEELA TOOTIA, Hind. _Prep._ (Commercial.) The sulphate of copper of commerce is obtained by the oxidation of native sulphide of copper (COPPER PYRITES); by the joint action of air, heat, and moisture, the copper is converted into an oxide, and the sulphur into sulphuric acid. The resulting salt is washed out, and the solution evaporated and crystallised. The water found in and issuing from copper mines often furnishes such a solution ready to the hands of the manufacturers. A large quantity of sulphate of copper is also obtained as a secondary product in the refining of silver, and is occasionally prepared by dissolving in sulphuric acid an oxychloride of copper, made for the purpose by exposing sheets of copper to the joint action of air and hydrochloric acid.

(Pure.) By the direct solution of the metal, or preferably, of its oxide or carbonate in sulphuric acid, or by purifying the commercial salt by recrystallisation, &c.

_Prop., Uses, &c._ Fine blue crystals, slightly efflorescent, having an intensely styptic and metallic taste. By heat the blue salt loses its water of crystallisation, and becomes a white, anhydrous powder. It dissolves in 4 parts of water at 60° Fahr., and in 2 parts at 212°; is insoluble in alcohol and ether; and is decomposed at an intense heat into protoxide of copper, sulphurous acid, and oxygen. It has been used to prevent the dry rot in timber and in dyeing. It is largely employed as a source of metallic copper in the ELECTROTYPE. Grain is steeped in a weak solution of it by the farmer, to prevent the 'smut,' As a medicine, it is employed chiefly as a styptic (in solution) and caustic (in substance) to destroy 'proud flesh,' and, less frequently, as an astringent or tonic (from 1/4 gr. to 2 gr.), and an emetic (3 or 4 gr. to 10 or 12 gr). It is exceedingly poisonous.

=COP'PERAS.= This is a generic name for the CRUDE METALLIC SULPHATES. When used without a qualifying adjective, it generally means sulphate of iron.

=Copperas, Blue.= Crude sulphate of copper. See COPPER (_above_).

=Copperas, Calcined'.= From green copperas, heated in an unglazed earthen pot until it becomes white and dry. Used as an astringent and 'drier,' and in making ink and dyeing.

=Copperas, Green.= _Syn._ COPPERAS. Crude sulphate of iron. See IRON.

=Copperas, White.= Crude sulphate of zinc. See ZINC.

=COP'PERING.= Iron may be covered with a thin film of copper by merely immersing it (previously scoured clean) in an acidulated solution of sulphate of copper, after which it must be rinsed in clean water. This film soon rubs off, but still it lasts long enough to deceive the travelling tinker's customers, who imagine that their copper kettles are properly repaired. Metals may be conveniently coated with compact copper to any desired thickness by means of voltaic electricity. See ELECTROTYPE.

=COP'ROLITE.= _Syn._ DUNG'STONE, FOSSIL MANURE. This mineral is the petrified dung of carnivorous reptiles. (Buckland.) Coprolites are found in all the secondary and tertiary strata. They contain a considerable proportion of phosphate of lime, for which reason they are largely employed in the manufacture of artificial manures. They form the bases of Lawes' SUPERPHOSPHATE OF COPROLITE MANURE. The nodules, after being washed, are ground to powder in a mill, and mixed with an equal weight of oil of vitriol.

=COPTIS TEETA.= (Ind. Ph.) _Syn._ COPTIS, or MISHMI TITA. _Hab._ Mishmel mountains, east of Assam. _Officinal part._ The dried root (_Coptidis Radix_), imported into Bengal from Assam in small rattan baskets, each containing from 1 to 2 ounces of the drug. This consists of pieces of a woody rhizome, of the thickness of a small goose-quill and from 1 to 2 inches in length, often contracted at one extremity into a short woody stem; the surface is usually rough, irregular, more or less annulated, and marked with the remains of rootlets in the shape of short spiny point. Externally, yellowish-brown; internally, much brighter, frequently of a golden-yellow colour, exhibiting on fracture a radiated structure. Taste, persistently bitter, and when chewed tinges the saliva yellow. Contains neither tannic nor gallic acid, but abounds with a yellow, bitter principle, soluble in water and alcohol.--_Prop._ Pure bitter tonic.--_Therapeutic uses._ In debility, convalescence after fevers, and other debilitating diseases, atonic dyspepsia, and in mild forms of intermittent fevers.--_Dose_, 10 to 15 gr. of the powdered root, thrice daily.

=Tincture of Coptis= (_Tinctura Coptidis_). Take of coptis root, in coarse powder, 2-1/2 oz.; proof spirits, 2 pints. Macerate for 7 days in a closed vessel, with occasional agitation; strain, press, filter, and add sufficient proof spirit to make 1 pint.--_Dose_. 1/2 to 2 fl. oz.

=Infusion of Coptis= (_Infusum Coptidis_). Take of coptis root, in coarse powder, 5 dr.; boiling water, 1 pint. Infuse in a covered vessel for 2 hours, and strain.--_Dose_, 1 to 2 fl. oz., thrice daily.

=COR'AL.= _Syn._ CORAL'LIUM, L. The comprehensive term for all calcareous or stony structures secreted by the marine asteroid polypes, or zoophytes. The RED CORAL of commerce, which is so largely employed for beads, earrings, and other ornaments, may be described as the internal skeleton of _Corallium rubrum_.

=Coral, Red= (=Facti''tious=). _Syn._ CORAL'LIUM RU'BRUM FACTI''TIUM, L. Prepared chalk, coloured with a little sesquioxide of iron or rose pink, and passed through a sieve. Sold by the druggists for powdered coral.

=Coral, Prepared' Red.= _Syn._ CORAL'LIUM RU'BRUM PREPARA'TUM. Levigated coral was formerly used in medicine as an antacid or absorbent, and is still occasionally employed as a dentifrice. It consists almost entirely of carbonate of lime, coloured with red oxide of iron, and possesses no advantage over good chalk. It is prepared in a similar manner as chalk.

=CORAL, to Bleach.= Immerse the coral in a mixture composed of one part of hydrochloric acid, and thirty parts of water; and keep it in this liquid until it becomes quite white. It should then be taken out, washed well in cold water, and allowed to dry.

=COPPER, CYANIDE= (CuCy_{2}). This salt is much used in electro-coppering. It may be obtained by adding to a solution of a copper salt, a solution of ferrocyanide of potassium; when a precipitate is obtained, which dried, is of a brown colour, and is cyanide of copper.

=CORALLINE.= See TAR COLOURS.

=CORD'IALS.= _Syn._ CARDI'ACA, L. Warm, stimulating, restorative medicines, that tend to raise the spirits and promote the circulation. The principal cordial medicines are noticed under the heads TINCTURE and SYRUP. See also PATENT MEDICINES.

=Cordials.= Aromatised and sweetened spirits used as beverages. See LIQUEUR.

=CORIAN'DER.= _Syn._ (CORIANDER FRUIT, CORIANDRI FRUCTUS, (B. P.); CORIANDERS, C. SEED; CORIANDRUM (Ph. L. E. & D.), L. "The ripe fruit of the _Coriandrum sativum_, dried." (B. P.) Coriander is chiefly used by confectioners and distillers as a flavouring ingredient. In the East it is much employed as a condiment, being an ingredient in CURRY POWDER. It is aromatic, carminative, and stimulant; and more effectually covers the taste of senna than any other substance.--_Dose_, 20 to 60 gr.; chiefly used as a corrective or adjuvant in compound medicines.

=CORK.= The outer bark of the _Quercus Suber_ or _cork oak_, a tree common in southern France, Italy, and Spain. The bark obtained from the younger branches of the same tree is employed for tanning. See ALCORNOCO.

=Cork.= A stopple or plug for a bottle or jar cut from the above substance. The common practice of employing inferior corks for the purpose of stopping the mouths of bottles is often productive of considerable loss, from the air being only partially excluded, and the contents suffering in consequence. Many a large bin of valuable wine has become, from this cause, in less than a year, little better than sour 'Cape.' Chemical preparations often suffer from a similar cause. The best corks are those called 'velvet corks,' and of these the finest qualities are imported from France. No pains should be spared to obtain sound and soft cork for connecting the combustion- and drying-tubes used in organic analysis.

Ruschhaupt gives the following process for preparing corks for corking bottles containing alcoholic or caustic liquids:--Paraffin is fused in a suitable vessel, the dry corks are added, and immersed in the paraffin by means of a perforated coon or disk. The air is now easily expelled from the pores of the corks, which after about five minutes, are removed and cooled; they may now be cut and bored like wax, are easily driven into the necks of bottles, and readily removed, retain their smoothness and are gas-tight throughout.

Several attempts have been made to introduce cork-cutting by machinery, but they have hitherto failed to supersede hand labour.

=Cork-bo''rer.= A thin brass tube, filed to a cutting edge, used for piercing holes through corks. Several tubes of different sizes, which fit into each other, are generally sold together. This simple and convenient instrument was introduced into the laboratory by Dr Mohr.

=CORN.= _Syn._ CLA'VUS, L. A horny induration of the skin, with a central nucleus, very sensitive at the base. The common cause of corns is continued pressure over the projection of the bones, from tight or stiff boots or shoes. They are of two kinds, hard and soft. The first grow on the exposed portions of the joints; the last, between the toes.

_Preven._ This consists in keeping the feet clean, by frequent ablution with warm water, and in the use of easy, soft boots and shoes. Without the latter precaution, corns will generally return, even after they appear to have been perfectly removed.