Chapter 39

COASTING, usually called tobogganing (q.v.) in Europe, the sport of sliding down snow or ice-covered hills or artificial inclines upon hand-sleds, or sledges, provided with runners shod with iron or steel. It is uncertain whether the first American sleds were copied from the Indian toboggans, but no sled without runners was known in the United States before 1870, except to the woodsmen of the Canadian border. American laws have greatly restricted, and in most places prohibited, the practice, once common, of coasting on the highways; and the sport is mainly confined to open hills and artificial inclines or chutes. Two forms of hand-sled are usual in America, the original "clipper" type, built low with long, pointed sides, originally shod with iron but since 1850 with round steel runners; and the light, short "girls' sled," with high skeleton sides, usually flat shod. There is also the "double-runner," or "bob-sled," formed of two clipper sleds joined by a board and steered by ropes, a wheel or a cross-bar, and seating from four to ten persons.

In Scandinavia several kinds of sled are common, but that of the fishermen, by means of which they transport their catch over the frozen fjords, is the one used in coasting, a sport especially popular in the neighbourhood of Christiania, where there are courses nearly 3 m. in length. This sled is from 4 to 6 ft. long, with skeleton sides about 7 in. high, and generally holds three persons. It is steered by two long sticks trailing behind. On the ice the fisherman propels his sled by means of two short picks. The general Norwegian name for sledge is _skijälker_, the primitive form being a kind of toboggan provided with broad wooden runners resembling the ski (q.v.). In northern Sweden and Finland the commonest form of single sled is the _Sparkstottinger_, built high at the back, the coaster standing up and steering by means of two handles projecting from the sides.

Coasting in its highest development may be seen in Switzerland, at the fashionable winter resorts of the Engadine, where it is called tobogganing. The first regular races there were organized by John Addington Symonds, who instituted an annual contest for a challenge cup, open to all comers, over the steep post-road from Davos to Klosters, the finest natural coast in Switzerland, the sled used being the primitive native _Schlittli_ or _Handschlitten_, a miniature copy of the ancient horse-sledge. Soon afterwards followed the construction of great artificial runs, the most famous being the "Cresta" at St Moritz, begun in 1884, which is about 1350 yds. in length, its dangerous curves banked up like those of a bicycle track. On this the annual "Grand National" championship is contested, the winner's time being the shortest aggregate of three heats. In 1885 and the following year the native _Schlittli_ remained in use, the rider sitting upright facing the goal, and steering either with the heels or with short picks. In 1887 the first American clipper sled was introduced by L. P. Child, who easily won the championship for that year on it. The sled now used by the contestants is a development of the American type, built of steel and skeleton in form. With it a speed of over 70 m. an hour has been attained. The coaster lies flat upon it and steers with his feet, shod with spiked shoes, to render braking easier, and helped with his gloved hands. The "double-runner" has also been introduced into Switzerland under the name of "bob-sleigh."

See _Ice Sports_, in the Isthmian Library, London (1901); _Tobogganing at St Moritz_, by T. A. Cook (London, 1896).

COATBRIDGE, a municipal and police burgh, having the privileges of a royal burgh, of Lanarkshire, Scotland. Pop. (1891) 15,212; (1901) 36,991. It is situated on the Monkland Canal, 8 m. E. of Glasgow, with stations on the Caledonian and North British railways. Until about 1825 it was only a village, but since then its vast stores of coal and iron have been developed, and it is now the centre of the iron trade of Scotland. Its prosperity was largely due to the ironmaster James Baird (q.v.), who erected as many as sixteen blast-furnaces in the immediate neighbourhood between 1830 and 1842. The industries of Coatbridge produce malleable iron, boilers, tubes, wire, tinplates and railway wagons, tiles, fire-bricks and fire-clay goods. There are two public parks in the town, and its public buildings include a theatre, a technical school and mining college, hospitals, and the academy and Baird Institute at Gartsherrie. Janet Hamilton, the poetess (1795-1873), spent most of her life at Langloan--now a part of Coatbridge--and a fountain has been erected to her memory near the cottage in which she lived. For parliamentary purposes the town, which became a municipal burgh in 1885, is included in the north-west division of Lanarkshire. About 4 m. west by south lies the mining town of Baillieston (pop. 3784), with a station on the Caledonian railway. It has numerous collieries, a nursery and market garden.

COATESVILLE, a borough of Chester county, Pennsylvania, U.S.A., on the west branch of Brandywine Creek, 39 m. W. of Philadelphia. Pop. (1890) 3680; (1900) 5721 (273 foreign-born); (1910) 11,084. It is served by the Pennsylvania and the Philadelphia & Reading railways, and interurban electric lines. For its size the borough ranks high as a manufacturing centre, iron and steel works, boiler works, brass works, and paper, silk and woollen mills being among its leading establishments. Its water-works are owned and operated by the municipality. Named in honour of Jesse Coates, one of its early settlers, it was settled about 1800, and was incorporated in 1867.

COATI, or COATI-MUNDI, the native name of the members of the genus _Nasua_, of the mammalian family _Procyonidae_. They are easily recognized by their long body and tail, and elongated, upturned snout; from which last feature the Germans call them _Rüsselbären_ or "snouted bears." In the white-nosed coati, a native of Mexico and Central America, the general hue is brown, but the snout and upper lip are white, and the tail is often banded. In the red coati, ranging from Surinam to Paraguay, the tail is marked with from seven to nine broad fulvous or rufous rings, alternating with black ones, and tipped with black. Coatis are gregarious and arboreal in habit, and feed on birds, eggs, lizards and insects. They are common pets of the Spaniards in South America. (See CARNIVORA.)

COB, a word of unknown origin with a variety of meanings, which the _New English Dictionary_ considers may be traced to the notions of something stout, big, round, head or top. In "cobble," e.g. in the sense of a round stone used in paving, the same word may be traced. The principal uses of "cob" are for a stocky strongly built horse, from 13 to 14 hands high, a small round loaf, a round lump of coal, in which sense "cobble" is also used, the fruiting spike of the maize plant, and a large nut of the hazel type, more commonly known as the cob-nut.

"Cobbler," a patcher or mender of boots and shoes, is probably from a different root. It has nothing to do with an O. Fr. _coubler_, Mod. _coupler_, to fasten together. In "cobweb," the web of the spider, the "cob" represents the older _cop, coppe_, spider, cf. Dutch _spinnekop_.

COBALT (symbol Co, atomic weight 59), one of the metallic chemical elements. The term "cobalt" is met with in the writings of Paracelsus, Agricola and Basil Valentine, being used to denote substances which, although resembling metallic ores, gave no metal on smelting. At a later date it was the name given to the mineral used for the production of a blue colour in glass. In 1735 G. Brandt prepared an impure cobalt metal, which was magnetic and very infusible. Cobalt is usually found associated with nickel, and frequently with arsenic, the chief ores being speiss-cobalt, (Co, Ni, Fe)As2, cobaltite (q.v.), wad, cobalt bloom, linnaeite, Co3S4, and skutterudite, CoAs3. Its presence has also been detected in the sun and in meteoric iron. For the technical preparation of cobalt, and its separation from nickel, see NICKEL. The metal is chiefly used, as the oxide, for colouring glass and porcelain.

Metallic cobalt may be obtained by reduction of the oxide or chloride in a current of hydrogen at a red heat, or by heating the oxalate, under a layer of powdered glass. As prepared by the reduction of the oxide it is a grey powder. In the massive state it has a colour resembling polished iron, and is malleable and very tough. It has a specific gravity of 8.8, and it melts at 1530° C. (H. Copaux). Its mean specific heat between 9° and 97° C. is 0.10674 (H. Kopp). It is permanent in dry air, but in the finely divided state it rapidly combines with oxygen, the compact metal requiring a strong heating to bring about this combination. It decomposes steam at a red heat, and slowly dissolves in dilute hydrochloric and sulphuric acids, but more readily in nitric acid. Cobalt burns in nitric oxide at 150° C. giving the monoxide. It may be obtained in the pure state, according to C. Winkler (_Zeit. für anorg. Chem._, 1895, 8, p. 1), by electrolysing the pure sulphate in the presence of ammonium sulphate and ammonia, using platinum electrodes, any occluded oxygen in the deposited metal being removed by heating in a current of hydrogen.

Three characteristic oxides of cobalt are known, the monoxide, CoO, the sesquioxide, Co2O3, and tricobalt tetroxide, Co3O4; besides these there are probably oxides of composition CoO2, Co8O9, Co6O7 and Co4O5. Cobalt monoxide, CoO, is prepared by heating the hydroxide or carbonate in a current of air, or by heating the oxide Co3O4 in a current of carbon dioxide. It is a brown coloured powder which is stable in air, but gives a higher oxide when heated. On heating in hydrogen, ammonia or carbon monoxide, or with carbon or sodium, it is reduced to the metallic state. It is readily soluble in warm dilute mineral acids forming cobaltous salts. Cobaltous hydroxide, Co(OH)2, is formed when a cobaltous salt is precipitated by caustic potash in the absence of air. A blue basic salt is precipitated first, which, on boiling, rapidly changes to the rose-coloured hydroxide. It dissolves in acids forming cobaltous salts, and on exposure to air it rapidly absorbs oxygen, turning brown in colour. A. de Schulten (_Comptes Rendus_, 1889, 109, p. 266) has obtained it in a crystalline form; the crystals have a specific gravity of 3.597, and are easily soluble in warm ammonium chloride solution. Cobalt sesquioxide, Co2O3, remains as a dark-brown powder when cobalt nitrate is gently heated. Heated at 190-300° in a current of hydrogen it gives the oxide Co3O4, while at higher temperatures the monoxide is formed, and ultimately cobalt is obtained. Cobaltic hydroxide, Co(OH)3, is formed when a cobalt salt is precipitated by an alkaline hypochlorite, or on passing chlorine through water containing suspended cobaltous hydroxide or carbonate. It is a brown-black powder soluble in hydrochloric acid, chlorine being simultaneously liberated. This hydroxide is soluble in well cooled acids, forming solutions which contain cobaltic salts, one of the most stable of which is the acetate. Cobalt dioxide, CoO2, has not yet been isolated in the pure state; it is probably formed when iodine and caustic soda are added to a solution of a cobaltous salt. By suspending cobaltous hydroxide in water and adding hydrogen peroxide, a strongly acid liquid is obtained (after filtering) which probably contains _cobaltous acid_, H2CoO3. The barium and magnesium salts of this acid are formed when baryta and magnesia are fused with cobalt sesquioxide. Tricobalt tetroxide, Co3O4, is produced when the other oxides, or the nitrate, are heated in air. By heating a mixture of cobalt oxalate and sal-ammoniac in air, it is obtained in the form of minute hard octahedra, which are not magnetic, and are only soluble in concentrated sulphuric acid.

The cobaltous salts are formed when the metal, cobaltous oxide, hydroxide or carbonate, are dissolved in acids, or, in the case of the insoluble salts, by precipitation. The insoluble salts are rose-red or violet in colour. The soluble salts are, when in the hydrated condition, also red, but in the anhydrous condition are blue. They are precipitated from their alkaline solutions as cobalt sulphide by sulphuretted hydrogen, but this precipitation is prevented by the presence of citric and tartaric acids; similarly the presence of ammonium salts hinders their precipitation by caustic alkalis. Alkaline carbonates give precipitates of basic carbonates, the formation of which is also retarded by the presence of ammonium salts. For the action of ammonia on the cobaltous salts in the presence of air see _Cobaltammines_ (below). On the addition of potassium cyanide they give a brown precipitate of cobalt cyanide, Co(CN)2, which dissolves in excess of potassium cyanide to a green solution.

Cobalt chloride, CoCl2, in the anhydrous state, is formed by burning the metal in chlorine or by heating the sulphide in a current of the same gas. It is blue in colour and sublimes readily. It dissolves easily in water, forming the hydrated chloride, CoCl2·6H2O, which may also be prepared by dissolving the hydroxide or carbonate in hydrochloric acid. The hydrated salt forms rose-red prisms, readily soluble in water to a red solution, and in alcohol to a blue solution. Other hydrated forms of the chloride, of composition CoCl2·2H2O and CoCl2 · 4H2O have been described (P. Sabatier, _Bull. Soc. Chim._ 51, p. 88; Bersch, _Jahresb. d. Chemie_, 1867, p. 291). Double chlorides of composition CoCl2·NH4Cl·6H2O; CoCl2·SnCl4·6H2O and CoCl2·2CdCl2·12H2O are also known. By the addition of excess of ammonia to a cobalt chloride solution in absence of air, a greenish-blue precipitate is obtained which, on heating, dissolves in the solution, giving a rose-red liquid. This solution, on standing, deposits octahedra of the composition CoCl2·6NH3. These crystals when heated to 120° C. lose ammonia and are converted into the compound CoCl2·2NH3 (E. Frémy). The bromide, CoBr2, resembles the chloride, and may be prepared by similar methods. The hydrated salt readily loses water on heating, forming at 100° C. the hydrate CoBr2·2H2O, and at 130° C. passing into the anhydrous form. The iodide, CoI2, is produced by heating cobalt and iodine together, and forms a greyish-green mass which dissolves readily in water forming a red solution. On evaporating this solution the hydrated salt CoI2·6H2O is obtained in hexagonal prisms. It behaves in an analogous manner to CoBr2·6H2O on heating.

Cobalt fluoride, CoF2·2H2O, is formed when cobalt carbonate is evaporated with an excess of aqueous hydrofluoric acid, separating in rose-red crystalline crusts. Electrolysis of a solution in hydrofluoric acid gives cobaltic fluoride, CoF3.

Sulphides of cobalt of composition Co4S3, CoS, Co3S4, Co2S3 and CoS2 are known. The most common of these sulphides is cobaltous sulphide, CoS, which occurs naturally as syepoorite, and can be artificially prepared by heating cobaltous oxide with sulphur, or by fusing anhydrous cobalt sulphate with barium sulphide and common salt. By either of these methods, it is obtained in the form of bronze-coloured crystals. It may be prepared in the amorphous form by heating cobalt with sulphur dioxide, in a sealed tube, at 200° C. In the hydrated condition it is formed by the action of alkaline sulphides on cobaltous salts, or by precipitating cobalt acetate with sulphuretted hydrogen (in the absence of free acetic acid). It is a black amorphous powder soluble in concentrated sulphuric and hydrochloric acids, and when in the moist state readily oxidizes on exposure.

Cobaltous sulphate, CoSO4·7H2O, is found naturally as the mineral bieberite, and is formed when cobalt, cobaltous oxide or carbonate are dissolved in dilute sulphuric acid. It forms dark red crystals isomorphous with ferrous sulphate, and readily soluble in water. By dissolving it in concentrated sulphuric acid and warming the solution, the anhydrous salt is obtained. Hydrated sulphates of composition CoSO4·6H2O, CoSO4·4H2O and CoSO4·H2O are also known. The heptahydrated salt combines with the alkaline sulphates to form double sulphates of composition CoSO4·M2SO4·6H2O (M = K, NH4, &c.).

The cobaltic salts corresponding to the oxide Co2O3 are generally unstable compounds which exist only in solution. H. Marshall (_Proc. Roy. Soc. Edin._ 59, p. 760) has prepared cobaltic sulphate Co2(SO4)3·18H2O, in the form of small needles, by the electrolysis of cobalt sulphate. In a similar way potassium and ammonium cobalt alums have been obtained. A cobaltisulphurous acid, probably H6[(SO3)6·Co2] has been obtained by E. Berglund (_Berichte_, 1874, 7, p. 469), in aqueous solution, by dissolving ammonium cobalto-cobaltisulphite (NH4)2Co2[(SO3)6·Co2]·14H2O in dilute hydrochloric or nitric acids, or by decomposition of its silver salt with hydrochloric acid. The ammonium cobalto-cobaltisulphite is prepared by saturating an air-oxidized ammoniacal solution of cobaltous chloride with sulphur dioxide. The double salts containing the metal in the cobaltic form are more stable than the corresponding single salts, and of these potassium cobaltinitrite, Co2(NO2)6·6KNO2·3H2O, is best known. It may be prepared by the addition of potassium nitrite to an acetic acid solution of cobalt chloride. The yellow precipitate obtained is washed with a solution of potassium acetate and finally with dilute alcohol. The reaction proceeds according to the following equation: 2CoCl2 + 10KNO2 + 4HNO2 = Co2(NO2)6·6KNO2 + 4KCl + 2NO + 2H2O (A. Stromeyer, _Annalen_, 1855, 96, p. 220). This salt may be used for the separation of cobalt and nickel, since the latter metal does not form a similar double nitrite, but it is necessary that the alkaline earth metals should be absent, for in their presence nickel forms complex nitrites containing the alkaline earth metal and the alkali metal. A sodium cobaltinitrite is also known.

Cobalt nitrate, Co(NO3)2·6H2O, is obtained in dark-red monoclinic tables by the slow evaporation of a solution of the metal, its hydroxide or carbonate, in nitric acid. It deliquesces in the air and melts readily on heating. By the addition of excess of ammonia to its aqueous solution, in the complete absence of air, a blue precipitate of a basic nitrate of the composition 6CoO·N2O5·5H2O is obtained.

By boiling a solution of cobalt carbonate in phosphoric acid, the acid phosphate CoHPO4.3H2O is obtained, which when heated with water to 250° C. is converted into the neutral phosphate Co3(PO4)2·2H2O (H. Debray, _Ann. de chimie_, 1861, [3] 61, p. 438). Cobalt ammonium phosphate, CoNH4PO4·12H2O, is formed when a soluble cobalt salt is digested for some time with excess of a warm solution of ammonium phosphate. It separates in the form of small rose-red crystals, which decompose on boiling with water.

Cobaltous cyanide, Co(CN)2·3H2O, is obtained when the carbonate is dissolved in hydrocyanic acid or when the acetate is precipitated by potassium cyanide. It is insoluble in dilute acids, but is readily soluble in excess of potassium cyanide. The double cyanides of cobalt are analogous to those of iron. Hydrocobaltocyanic acid is not known, but its potassium salt, K4Co(CN)6, is formed when freshly precipitated cobalt cyanide is dissolved in an ice-cold solution of potassium cyanide. The liquid is precipitated by alcohol, and the washed and dried precipitate is then dissolved in water and allowed to stand, when the salt separates in dark-coloured crystals. In alkaline solution it readily takes up oxygen and is converted into potassium cobalticyanide, K3Co(CN)6, which may also be obtained by evaporating a solution of cobalt cyanide, in excess of potassium cyanide, in the presence of air, 8KCN + 2Co(CN)2 + H2O + O = 2K3Co(CN)6 + 2KHO. It forms monoclinic crystals which are very soluble in water. From its aqueous solution, concentrated hydrochloric acid precipitates hydrocobalticyanic acid, H3Co(CN)6, as a colourless solid which is very deliquescent, and is not attacked by concentrated hydrochloric and nitric acids. For a description of the various salts of this acid, see P. Wesselsky, _Berichte_, 1869, 2, p. 588.

_Cobaltammines._ A large number of cobalt compounds are known, of which the empirical composition represents them as salts of cobalt to which one or more molecules of ammonia have been added. These salts have been divided into the following series:--

Diammine Series, [Co(NH3)2]X4M. In these salts X = NO2 and M = one atomic proportion of a monovalent metal, or the equivalent quantity of a divalent metal.

Triammine Series, [Co(NH3)3]X3. Here X = Cl, NO3, NO2, ½SO4, &c.

Tetrammine Series. This group may be divided into the

Praseo-salts [R2Co(NH3)4]X, where X = Cl.

Croceo-salts [(NO2)2Co(NH3)4]X, which may be considered as a subdivision of the praseo-salts.

Tetrammine purpureo-salts [RCo(NH3)4·H2O]X2.

Tetrammine roseo-salts [Co(NH3)4·(H2O)2]X3.

Fuseo-salts [Co(NH3)4]OH·X2.

Pentammine Series.

Pentammine purpureo-salts [R·Co(NH3)5]X2 where X = Cl, Br, NO3, N02, ½SO4, &c.

Pentammine roseo-salts [Co(NH3)5·H2O]X2.

Hexammine or Luteo Series [Co(NH3)6]X3.

The hexammine salts are formed by the oxidizing action of air on dilute ammoniacal solutions of cobaltous salts, especially in presence of a large excess of ammonium chloride. They form yellow or bronze-coloured crystals, which decompose on boiling their aqueous solution. On boiling their solution in caustic alkalis, ammonia is liberated. The pentammine purpureo-salts are formed from the luteo-salts by loss of ammonia, or from an air slowly oxidized ammoniacal cobalt salt solution, the precipitated luteo-salt being filtered off and the filtrate boiled with concentrated acids. They are violet-red in colour, and on boiling or long standing with dilute acids they pass into the corresponding roseo-salts.

The pentammine nitrito salts are known as the xanthocobalt salts and have the general formula [NO2·Co·(NH3)5]X2. They are formed by the action of nitrous fumes on ammoniacal solutions of cobaltous salts, or purpureo-salts, or by the mutual reaction of chlorpurpureo-salts and alkaline nitrites. They are soluble in water and give characteristic precipitates with platinic and auric chlorides, and with potassium ferrocyanide. The pentammine roseo-salts can be obtained from the action of concentrated acids, in the cold, on air-oxidized solutions of cobaltous salts. They are of a reddish colour and usually crystallize well; on heating with concentrated acids are usually transformed into the purpureo-salts. Their alkaline solutions liberate ammonia on boiling. They give a characteristic pale red precipitate with sodium pyrophosphate, soluble in an excess of the precipitant; they also form precipitates on the addition of platinic chloride and potassium ferrocyanide. For methods of preparation of the tetrammine and triammine salts, see O. Dammer's _Handbuch der anorganischen Chemie_, vol. 3 (containing a complete account of the preparation of the cobaltammine salts). The diammine salts are prepared by the action of alkaline nitrites on cobaltous salts in the presence of much ammonium chloride or nitrate; they are yellow or brown crystalline solids, not very soluble in cold water.