Great

Britain alone, out of an annual production for the whole world estimated at from 126,000 to 130,000 tons. Prop., . 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 di olves it readily with copious evolution of nitric oxide; heated to redne 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 le 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, ., by the following characters and reactions:—The solutions of copper po e a blue or green colour, which they retain even when considerably diluted with water:—With caustic pota a 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 exce , yielding a rich deep-blue solution:—The carbonates of pota ium give a light precipitate, insoluble in exce :—Ferrocyanide of pota ium 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., . Copper is generally WEIGHED under the form of black oxide, but sometimes as pure metal:—By throwing it down from its solution by pure pota a, 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 ). Le delicate than the preceding. Copper can be separated from the other metals by means of the following proce es:— From lead. By adding sulphuric acid to the nitric solution, and evaporating to dryne , when water digested on the residuum will di olve 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 di olves 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 di olves 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 , ., as it exists in bell-metal, bra , 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-gla , or other like flux. The pure metal is found at the bottom of the crucible, whilst the impurities are either volatilised or di olved in the flux. The proportions for refining commercial copper are, metal, 10 parts; copper scales and bottle-gla , of each 1 part. The Society of Arts conceived this proce to be so valuable, that they presented one of their gold medals to its inventor, Mr Lewis Thompson. Uses, . 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 pota ium 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 ve els are very commonly made of copper, but too much caution cannot be exercised in their employment. Acid syrups, vegetable juices, aqueous extracts, soups, stews, ., 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 ve els are frequently tinned, for the purpose of protecting the copper from contact with their contents, but this film of tin is nece arily very thin, and soon becomes imperfect by constant use. When copper ve els 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 inspi ated juices of fresh vegetables, and especially the pulps of fruit, prepared in ve els 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 ve els 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 ve els, 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 ma is then poured out, and after cooling, is rubbed up to a paste. The copper ve el is then coated inside with this preparation, which is applied by means of a brush, and the ve el 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 ve el 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.