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81 17 8-37 28 7.94 8 7-70 8 7-58 7 3-66 to 4-19 5 3 43 to 3 66 6 2-41 to 3-92 51 6-42 to 8-16 <D .. f S. Wales Average of 37 kinds, 9 05 tt> f|N. of England, K * < Lancasliire, ~& I Scotland, ft ^ Derbyshire, Wood, Peat, Lignite, Coal (Prussian),
The literature relating to coal and coal mining, is very extensive, but the following list includes the titles of the more important works upon these subjects.
England and America.—The Report of the Royal Coal Com mission (3 vols., fol., with Atlas, London, 1870). This is the most comprehensive work upon the subject. Hull, Coal Fields of Great Britain (3d ed. London, 1873). Reports and Maps of the Geological Surveys of the United Kingdom. Descriptive memoirs of each coal field published as completed. Percy, Metallurgy, vol. i., on Fuel (2d ed. London, 1875), containing full details of the chemistry of coal. Greenwell, Practical Treatise on Mine Engineering (2d ed. London, 1869). Andre, Practical Treatise on Coal Mining (London, 1876). Smyth, Coal and Coal Mining (2d ed. London 1872). Jevons, The Coal Question (2d ed. Lon don, 18C6). Rogers, Geology of Pennsylvania (2 vols., Edinburgh, 1850). Proceedings of the South Wales Institute of Engineering (8 vols., Merthyr, 1858-73). Transactions of the North of England Institute of Alining Engineers (1% vols., Newcastle, 1852-74). Various Geological Reports of the State an.d General Governments of the United States ; including Newberry s OhioReports, Cox s Indiana lie- ports, and Hayden s Reports of Geological Survey of the Territories.
France and Belgium.—Burat, Geologic de, la France (8vo. Paris, 1864). Cours d Exploitation de Mines (1871). Matiricl des Houilliercs en France, <L-c. (1861-68). Bulletin de la Societi de Vlndustrie Mineralc, S. Etienne (20 vols. since 1855). Ponson, Traiti de T Exploitation dcs Mines de Houillc (2d ed. Liege, 1868-71). Supplement to the above (1867-72). De Kuyper, Revue Universelk des Mines, <L~c. (Liege, since 1854).
Germany.—Geinitz, Die SteinJcohlcn Leutschlands, <L-c. (3 vols. 4to, Munich, 1865). This is the most complete book on the sub ject. Zinckcn, Die Bramikoldc (2 vols., Hanover, 1865-71). Zeitschrift fur Berg Hiittcn und Salinemvesen, <c. (4to. Berlin, 22 vols. since 1854).
(h. b.)
COANZA, or Quanza, an important river of Western Africa, in the country of Angola. It takes its rise in the Mossamba Mountains, not far from the source of the Cunene, probably in 14 S. lat., and its total length is about 600 miles It receives a large number of tributaries, the most important of which are the Loando and the Cutato in the upper part of its course, the Gango and the Quige in the middle portion, and the Lucalla in the lower. Its progress is broken by several falls, and in the last 200 miles of its journey it descends no less than 4800 feet This diminishes its value as a means of transit ; but it is navigable for large boats about 140 miles from its mouth, which is situated 50 miles south of Loando, in 9 15 S. lat. It there forms a number of islands, and pours into the sea a turbid current, which is visible for some distance outwards by its contrast of colour.
COATBRIDGE, a town of Scotland, in the county of Lanark, and parish of Old Monkland, ten miles east of Glasgow by rail, and about two miles west of Airdrie. It owes it rise to the importance of the surrounding district as a mining field. The town itself is of a straggling descrip tion, and is intersected by a branch of the North Cahler Water, the Monkland Canal, and the Caledonian Railway. It contains eight places of worship, a literary association, and five branch banks. In the immediate neighbourhood are the Gartsherrie iron works, and there are engineering establishments in the town itself. The population of town in 1871, including Gartsherrie, High Sunnyside, and Lang- loan, numbered 15 ; 802 ; of whom 8599 were males and 7203 females.
COBALT, a metal of the iron group. The name is derived from the German Kolold, a miner s term for gnome, or evil spirit, akin to the English gollin, which was applied to a mineral found associated with silver ores, and often replacing them in the mines of Schneeberg in Saxony. The use of the oxide of cobalt in colouring glass was only dis covered in 1540 by Scheurer, and till then the metal had been supposed to be worthless. It was first produced, but in an imperfectly purified condition, in 1733, by Brandt.
Cobalt is found alloyed in small quantity together with nickel in many meteoric irons. The principal mode of occurrence, however, is in various complex minerals con taining arsenic and sulphur and the allied metal nickel. The following are the most important:—
1. Smaltine or speiss cobalt, an arsenide of the isomorphous bases, cobalt, nickel, and iron, of the formula (CoNiFe)As 2 , is a mineral of the cubical system, forming steel or lead-grey crystals of a metallic lustre, tarnishing in damp air to a pink or green tint according to the pre ponderance of cobalt or nickel that is present In the purest condition it may contain 28 2 per cent, of cobalt to 71 8 per cent, of arsenic, but nickel and iron are almost invariably present to some extent. The principal locality is at Schneeberg in Saxony, where it is associated with silver, bismuth, and nickel ores.
2. Cobalt glance, or cobaltine, is a compound of sulphide and arsenide of cobalt, CoS 2 + CoAs 2 , the typical composition being cobalt 35 5, arsenic 45 2, and sulphur 19 - 3 per cent. It occurs in very brilliant complex crystals belonging to the cubical system, the principal locality baing at Tunaberg in Sweden. A part of the metal is sometimes replaced by iron, but as a rule it is free from nickel.
3, Linnaeite, or cobalt pyrites, is analogous in composi tion to copper pyrites, being represented by the formula Co<,S + Co 2 S 3 , with 58 per cent, of cobalt and 42 of sulphur. As a general rule a portion of the base is replaced by copper, nickel, or iron. It is a rare mineral, being found only in the Siegen district in Prussia and in Sweden. Cobalt bloom is a hydrated arseniate produced by the action of air and water upon the above minerals ; the composition ia Co 2 As 2 O 8 4- 8H 2 O, i.e., 37/ per cent, of oxide of cobalt. Earthy cobalt ore is a variety of bog manganese, or wad, a mineral of indefinite composition, but containing at times as much as 8 or 10 per cent, of oxide of cobalt with oxides of manganese, iron, and copper. Cobaltic bismuth ore ia a mixture of finely crystalline speiss cobalt with native bismuth, found occasionally in the Schneeberg mines.
The materials from which cobalt is produced by the smelter consist generally of iron or arsenical pyrites, con taining a minute quantity of the two metals cobalt and nickel, or various products derived from the smelting of the ores of silver and copper in which these metals are concen trated as sulphur or arsenic compounds.
with a slightly reddish tint, taking a very high lustre when polished, and breaking with a finely granular fracture. The specific gravity is variously stated at from 8 52 to 8 70. It is slightly malleable, and. when quite pure of a higher degree of tenacity than iron, according to Deville. The brittle character attributed to it by former observers is clue to impurities, such as arsenic and manganese. It melts at about the same temperature as iron, or a little lower, requiring the strongest heat of a wind furnace. The specific heat is 0-10696 (Regnault). It is susceptible of being magnetized by touch, and retains its magnetism at temperatures below a strong red heat when free from arsenic. Chemically it belongs to the same group as iron, zinc, nickel, manganese, and chromium, which cannot be
separated as sulphides by H.,S from an acid solution. It is