Crested Butte have been changed locally to anthracite by the metamorphic action of igneous intrusions. Excellent coking coals are found near Trinidad. The New Mexican coals are in part an extension of the Colorado veins, and bear a good reputation, as do also many of the Wyoming coals. California has little fuel of good quality, and has for many years drawn on Australia for its coal-supply, but in recent years the coals of Oregon, Washington, and British Columbia have become a source of supply. The rocks of the small Rhode Island area have been so highly metamorphosed that the coal has been altered to graphitic anthracite. It is sold on the market as amorphous graphite, and has little value as a fuel.

CANADA. The Acadian field includes deposits in Nova Scotia and New Brunswick, the former being quite important. The coals are bituminous and of good quality. In the mountain ranges of British Columbia extensive coal-seams have been discovered, and they are now under development. A good quality of coke is made from the coal of Crow's Nest Pass, which finds a market at the British Columbian smelters. The most productive mines of the Pacific Coast are located on Vancouver Island, whence large shipments of bituminous coal are made to San Francisco and other ports in the Western United States. SOUTH AMERICA. Coal, probably of Carboniferous age, is found in the Brazilian States of São Pedro, Rio Grande do Sul, Santa Catharina, also in the neighboring Republic of Uruguay. Very little development work has been done in the fields, and the output is inconsiderable. In Argentina and Chile, where Cretaceous coal occurs, there is more activity; but these countries still depend largely upon Great Britain for their supplies. In Peru both Cretaceous and Carboniferous deposits are found at various points in the interior, the former occupying a position on the first rise of the Andes, while the latter occurs in higher ground and at a greater distance from the coast.

UNITED KINGDOM. Next to the coal-fields of the United States, those of the United Kingdom are of the greatest economic importance. With in the limits of England, Scotland, and Wales there are more than twenty areas underlain by seams of anthracite, bituminous, and cannel coal. The largest of these areas is that of South Wales, in Monmouthshire and Pembrokeshire, which has a length of about 50 miles and a width of nearly 20 miles. The coal-measures form an elliptical basin, and are several thousand feet in thickness. Coal is found in three horizons, of which the upper has no less than 82 seams, measuring 180 feet in all. The lowest horizon yields valuable steam and blast-furnace coal. In the north of England the coal-fields of Lancashire, Derbyshire, and Yorkshire are the largest. The Lancashire field is of irregular quadrilateral form, with a width of about 18 miles from north to south, and a length from east to west of more than 50 miles. It includes about 100 feet of coal in workable seams, which dip at a high angle and are much broken by faulting. The Yorkshire and Derbyshire measures occupy a single area that extends for a distance of about 60 miles from Bradford on the north to near Derby on the south, and has a breadth of from 3 to 32 miles. They yield bituminous coal, excellent for steaming and iron-making purposes.

North of the Yorkshire field is the large basin of Northumberland and Durham, from which steam. ing, coking, and house coals are produced. In Scotland the coal-measures are extensively developed in Ayrshire, Lanarkshire, Stirlingshire. and Fifeshire. The productive coal-fields of the United Kingdom belong to the Carboniferous period; brown coal of Jurassic or Tertiary age is known to occur, but the seams are too small to be profitably exploited. The exports of coal from this country are of great importance. Much of the coal goes to Italy, Russia, Holland, and to the European countries that possess small resources of the mineral, while the remainder is exported to the more remote parts of the world. Further details regarding the distribution of coal will be found under the titles of countries. OUTPUT. The world's annual production at the present time is about 1,000,000,000 short tons; the output in 1900, or the latest year for which statistics are available, according to The Mineral Resources, was distributed as follows:

It is interesting to follow the progress of the United States as a coal-producer. In 1868 Great Britain produced 3.6 times as much coal as the United States, while Germany's product that year was 15 per cent. greater than that of the United States. In 1871 the United States exceeded Germany's output by about 10 per cent., but afterwards fell back to third place until in 1877 she once more sprang forward, and gained on both Germany and Great Britain. In 1899 the United States led the world, and in 1904 supplied 36 per cent. of its production.

The larger part of the increase during recent years has been due to the great expansion in the mining of bituminous coal. The output of anthracite in 1904 amounted to 73,156,709 short tons, showing a gain since 1880 of 44,506,897, tons, or 155 per cent. In the same year the production of bituminous coal was 279,153,718 short tons, an increase of 236,321,960 tons or 552 per cent. This feature will, doubtless, be more accentuated in the future than in the past owing to the wide distribution and industrial use of the bituminous variety. The production in 1904 represented about 4.24 tons per capita of population and was almost entirely consumed within the United States.

There has been recently considerable discussion in regard to the possible exhaustion of the anthracite coal beds in the United States. The opinion is that, in spite of the large consumption

and the small area containing anthracite coal, there is no immediate danger of exhaustion.

MINING OF COAL. The presence of coal in paying quantities having been determined by prospecting and geological surveys, the next consideration is to extract this coal from seams. No definite rules can be given for the selection of a method of mining that will cover all conditions; each mine furnishes a distinct and separate problem. Every system of mining, however, aims to extract the maximum amount of the deposit in the best marketable shape and at a minimum cost and danger. Speaking broadly, all methods of mining come under the head of either open working or closed working. Open working is employed when the deposits have no overburden of barren rock or earth, or where this overburden is of such small depth that it can be easily and cheaply removed, leaving the coal deposit exposed. The mining of such exposed seams of coal is really a process of excavation or quarrying, and the machines used in making open-pit excavations and in quarrying are applicable to the work. Closed working is adopted when the depth of the overburden is so great that the mining must be conducted underground. The first task in opening up underground coal-seams is to secure access to the seam by means of shafts, slopes, or tunnels. Shafts are vertical openings from the ground surface to the coal-seams. In the United States shafts are usually made square or rectangular in form. This practice is largely due to the fact that timber is used for lining shafts. In Europe round or oval shafts are frequently employed with linings of brick, iron, or masonry.

Generally the shafts are divided into two or more compartments, in each of which is installed an elevator for hoisting the coal-cars to the surface. The number of compartments in a shaft and their arrangements depend upon the particular use to which the shaft is to be put, the number of shafts employed, and their depths. Where the seams are comparatively near the surface, it is usually cheaper to sink a number of two or three compartment shafts than it is to haul all the ore to one large shaft; while, when the shafts are very deep, it is preferable to sink a smaller number of four or six compartment shafts and extend the underground haulage to a single shaft over a great area of the workings. Where timber lining is employed, a stronger construction is obtained by placing the compartments side by side in a long, narrow shaft than by grouping them in a square shaft. In shallow mines separate shafts are often employed for hoisting and for pumping, ventilation and ladder-ways. One of the largest coal-mine shafts in America is situated at Wilkesbarre, Pa.; it is 1039 feet deep, 12 × 52 feet in size, and has five compartments. The methods of sinking mine shafts are essentially the same as those used in sinking shafts for tunnels. (See TUNNEL.) Slopes are openings begun at the outcrop of an inclined seam, which they follow down into the earth. Slopes are usually made with three compartments side by side, two of which are used as hoistways and the third for the traveling-way, piping, etc. When the dip of the slope is under 40 degrees the slope is made about seven feet high, but when the dip exceeds 40 degrees cages have to be used and a great height is necessary. Slopes are usually

lined with timber. Tunnels are nearly horizontai passageways beginning on the side of a hill or mountain and extending into the earth until they meet the coal-seam; they are built for both haulage and drainage purposes, and are constructed like railway tunnels, except that the cross-section is usually much smaller, and that it is lined with timber instead of with per manent masonry. The forms of timbering used in coal-mining are various, and are of interest chiefly to the practical miner; special treatises should be consulted by those interested in the details. In a general way, it may be said that timber used for underground support in mines should be of a light and elastic variety of wood. Oak, beech, and similar woods are heavy and have great strength, but when they do break it is suddenly and without warning, thus bringing disaster to the miners who might escape if a tough wood were employed which gives warning of rupture by bending and cracking. It is a very common practice to employ preserved timber in mining work. See FORESTRY.

The systems of working the coal-seams after access is attained to them by the means described are two, known as the room-and-pillar and the long-wall systems. The room-and-pillar method-also known as the pillar-and-chamber or board-and-pillar method, which may include the pillar and stall system-is the oldest of the systems, and the one very generally used in the United States. By this system, coal is first mined from a number of comparatively small places, called rooms, chambers, stalls, boards, etc., which are driven either square from or at an angle to the haulageway. Pillars are left to support the roof. In the long-wall method the whole face of the coal-seam is taken out, leaving no coal behind, and the roof is allowed to settle behind as the excavation progresses, care being taken to preserve haulageways through the falling material. Both the room-and-pillar and the long-wall methods are employed in various modifications, for the details of which spe-cial treatises on coal-mines should be consulted. The coal is cut from the seam by hand or by some form of coal-cutting machine. In America machine cutting is used extensively. There are four general types of machines in general use: Pick machines, chain-cutter machines, cutter-bar machines, and long-wall machines; the machinesmost used in America are pick machines and chain-cutter machines. Both compressed air and electricity are used for operating coal-cuttingmachines. Pick machines are very similar to a rock-drill; chain - cutter machines consist of a low metal bed frame upon which is mounted a motor that rotates a chain to which suitable cutting teeth are attached. The ventilation of the workings, owing to the presence of gases, is a very important feature of coal-mining, and great care is taken to lay out the workings soas to facilitate ventilation. Mechanical ventilation by means of fans and blowers (see BLOWING MACHINES) is usually employed. Hoisting in mines is accomplished by means of cages running up and down the shafts, and operated by large hoisting engines on the surface. There are two general systems of hoisting in usehoisting without attempt to balance the load, in which the cage and its load are hoisted by the engine and lowered by gravity, and hoisting in balance, in which the descending cage or a spe

cial counter-balance assists the engine to hoist the loaded ascending cage. Haulage in mines is accomplished by animal power or by steam hoisting engines operating a system of rope haulage or by mine locomotives operated by steam, electricity, compressed air, or gasoline.

The preparation of mined coal for the market consists in screening the coal over bars and through revolving or over shaking screens, together with breaking it with rolls to produce the required market size. The large lumps of slate or other impurities are separated by hand, while the smaller portions are picked out by automatic pickers or by hand by boys or old men seated along the chutes leading to the shipping pockets or bins. When coal contains much sulphur, this is frequently removed by washing it with water in special washing plants.

BIBLIOGRAPHY. Lesley, Manual of Coal and Its Topography (Philadelphia, 1856)— a good work, but difficult to find; Chance, "Coal-Mining," in Second Geological Survey of Pennsylvania, Report AC (Harrisburg, 1883); Hughes, A Textbook of Coal-Mining (London, 1899); Peel, Elementary Textbook of Coal-Mining (London, 1901); Macfarlane, The Coal Regions of America, Their Topography, Geology, and Development (New York, 1875); Nicolls, The Story of American Coals (Philadelphia, 1897); Lesley and others, "Reports on the Coal-Fields of Pennsylvania," in various publications of the Second Geological Survey of Pennsylvania (Harrisburg); Cockin, Practical Coal Mining (New York, 1905). See also the following annuals and periodicals: Transactions of the American Institute of Mining Engineers (New York); The Mineral Industry (New York); The Engineering and Mining Journal (New York); Mines and Minerals (Scranton, Pa.); "Mineral Resources of the United States," United States Geological Survey (Washington). For foreign coal deposits, consult: Memoirs of the Geological Survey of Great Britain (London); Reports of Progress of the Geological Survey of the United Kingdom (London); Annales de la société géologique de Belgique (Liége, 1874 et seq.); Bulletin de la société belge de géologie, de paléontologie et d'hydrologie (Brussels, 1877 et seq.); Annales des mines (Paris, 1816 et seq.); Bulletin de la société géologique de France (Paris, 1896 et seq.); Lozé, Les charbons britanniques et leur épuisement (Paris, 1900); Zeitschrift für prak tische Geologie (Berlin, 1893 et seq.). See ANTHRACITE; BITUMINOUS COAL; CARBONIFEROUS SYSTEM; COKE; CULM; CRETACEOUS SYSTEM; PEAT; TERTIARY SYSTEM; GRAPHITE; CARBON; FIRE-CLAY; and the articles on the different States and countries in which coal has been found.

COAL APPLES. The name given to some curious specimens of spheroidal anthracite coal found in the Mammoth seam of Pennsylvania. They vary from one-fourth inch to ten inches in diameter, but are usually about the size of a hen's egg. They are thought to be due to jointing.

COAL-BREAKER. A structure containing machinery for the purpose of crushing, sorting, and cleaning anthracite coal. The breaker is often as much as 150 feet high, and rarely less than 80 feet. The coal, as it is hoisted out of the mine, is carried up to the top of the breaker and discharged into a hopper, whence it passes

downward over bars, through screens and crushers, and is finally discharged into bins at the bottom. The admixed slate is separated partly by special screens, and the slaty coal (bone coal) is picked out by boys as it slides down the chutes. In the more modern breakers water-jigs are used very successfully to separate the slate and coal. The sizes produced are described in the article on ANTHRACITE. The capacity of a coal-breaker is commonly about 1000 tons per day, but some exceed 2000 tons in output. Consult Chance, "Report on Coal-Mining," Report AC of the Second Geological Survey of Pennsylvania (Harrisburg, 1883).

COALFISH (so named from its color). (1) esting chirid fish (Anoploma fimbriata) of the The pollack (q.v.). (2) A singular and interNorth Pacific, which is usually slaty-black above and white below, but variable with age and place. It is about 18 inches long, allied to candlefish, and skilfish. the rock-trout, and called in California beshow,

COAL-GAS. See GAS, ILLUMINATING.

COALING SHIP. In modern naval vessels coaling ship has become an operation of importance. Special machinery is provided for handling it, and the men are drilled at coaling expeditiously. Notwithstanding all that can be done in the way of drill and the improvement of appliances, the operation of coaling must take many hours, and in time of war may necessitate a trip to the nearest coaling-station. This loss of time may prove most serious and defeat the plans of a campaign. Means of coaling at sea without leaving station, or while en route to a place, are therefore sought. Several plans have been devised, in the most successful of which a steel hawser runs between the collier and the vessel to be coaled, starting from a high point on the collier's mast. This serves as a stay on which bags, carried by a trolley, pass to and fro, very much after the fashion of a cableway (q.v.). COAL-MEASURES. See COAL; CARBONIFEROUS SYSTEM.

COAL-OIL. See PETROLEUM.

COAL-TAR, or GAS-TAR. The thick, black, opaque liquid that comes over and condenses in the pipes when gas is distilled from coal. It is slightly heavier than water, and has a strong, disagreeable odor. Coal tar is a mixture of many distinct liquid and solid substances, and the separation of the more useful of these constitutes an important branch of manufacturing chemistry. By distilling from wrought-iron stills, the tar is first broken up into five fractions, which are then further subjected to fractional distillation separately:

(1) Crude Naphtha or Light Oil is the fraction distilling over before the temperature of the tar has risen to 170° C. This portion contains a number of valuable hydrocarbons, including benzene, toluene, xylene, etc. Another important product obtained from this fraction is the so-called solvent or burning naphtha of commerce, which is largely used for burning in lamps, as a solvent for india-rubber and guttapercha, and for a variety of other purposes. The benzene obtained from this fraction is also used as a solvent, though most of it is converted into aniline, all of the vast amount of aniline manufactured at present being derived from nitro

benzene, which is, in its turn, made from benzene. To separate its constituents, the crude naphtha is first divided into three fractions by distillation; each of these fractions is washed successively with sulphuric acid and caustic soda, as well as with water, and subjected to further fractional distillation.

(2) Middle Oil or Carbolic Oil is the crude fraction distilling over from tar between the temperatures of 170° and 230° C. This fraction contains large quantities of naphthalene and carbolic acid, the former separating out in the form of a crystalline mass, while the latter remains liquid. The naphthalene thus obtained is purified by washing with caustic soda and sulphuric acid, and distilling. On the other hand, the crude liquid is treated with caustic-soda solution, which takes up all of the carbolic acid and from which the latter is separated by adding sulphuric acid; the impure carbolic acid thus obtained is further purified by distillation. Naphthalene is extensively used in the manufacture of colors. Carbolic acid is extensively used as a disinfectant and for the manufacture of picric acid.

(3) Creosote Oil is the crude fraction distilling over from coal-tar between the temperatures of 230° and 270° C. This somewhat heavy oil is largely used for the preservation of timber. See CREOSOTE.

(4) Anthracene Oil passes over above 270° C. This fraction yields all the anthracene of commerce; the anthracene crystallizes out from the cil, and is somewhat purified by washing with the solvent naphtha obtained from the first fraction. Anthracene is extensively employed in the manufacture of the beautiful alizarin dyes, which were formerly made from madder-root. See ALIZARIN.

(5) The Pitch remaining in the stills after the above fractions have passed over is used for making asphalt and varnishes, for protecting wood and metal work, etc.

Coal-tar is produced in large quantities in the manufacture of illuminating gas, and while scarcely half a century ago it was looked upon as nothing but an offensive waste product, at present it constitutes the source of innumerable substances of the greatest value to both science and the industries. See bibliographical references under COAL-TAR COLORS; GAS, ILLUMINATING; and see the articles on the various products

mentioned above.

COAL-TAR COLORS. Coloring matters artificially prepared from coal-tar, chiefly from the hydrocarbons extracted from it. (See COAL TAR.) The first observation of a colored compound of this class was made by Runge in 1834; but the real beginning of the great modern color industry dates from 1856, when W. H. Perkins obtained a violet dyestuff by oxidizing impure aniline with chromic acid, took out a patent for it, and commenced manufacturing it in England. Many other dyes were subsequently obtained from aniline and the substances related to it, by A. W. Hofmann, Gries, Girard, Lauth, and many others. But the most sensational step was the preparation by Graebe and Liebermann (1868) of a natural dyestuff-viz. the coloring principle of madder-root, from the anthracene of coal-tar. In 1880 indigo was first prepared, not from coal-tar products, but by a purely synthetic method, and other natural colors have

since been prepared in a similar manner; that natural dyestuffs reproduced by artificial means need not necessarily originate from coaltar. The artificial indigo and alizarin are not mere substitutes for the natural indigo and madder; they are chemically identical with them, and surpass them in purity, and their adaptability to special methods in dyeing and printing often makes them even more desirable. But as the cost of manufacture is high, they compete with the natural products on about equal terms. The color industry was first developed in England and France, but the more thorough technical instruction at the German universities produced a body of skilled manufacturers and investigators who soon took the lead. At present, in addition to the great factories near Berlin, Frankfurt, Elberfeld, and Mannheim, and a host of smaller ones in various parts of Germany, German capital controls many of the establishments in France, Russia, and other countries. The United States possess few independent factories, and the list of their products is rather limited; indeed, American dyers appear to call for a smaller range of dyestuffs than those of other countries. A peculiar development of the last fifteen years is the extension of the methods of the dye industry to the production of artificial drugs, such as antipyrin, antifebrin, etc., many of which are manufactured in the same establishments which control the dye patents.

CLASSIFICATION. Artificial colors were formerly classified merely according to the sources from which they were obtained. Thus, many of them, including magenta, 'aniline blue,' ‘aniline green,' 'aniline yellow,' etc., were grouped together as aniline colors. At present somewhat different systems of classification are used by different authors, but all systems are based exclusively on the chemical constitution of the dyes.

Many attempts have been made to find a general answer to the question, What must be the chemical nature of a carbon compound in order that it may be a dye? An all-embracing answer to this question has not yet been found. But experience has shown that the true dyestuffs exhibit peculiar groupings of the constituent atoms. Such 'chromophore' groupings produce, however, only a tendency toward color, but not necessarily colors; indeed, many compounds containing them are perfectly colorless, and the majority of true dyes become colorless if deprived of the small amount of oxygen they contain, although their chromophore groups may not be in the least affected. If, however, a chromophore group is combined with certain other atomic groups, the result is a dye. For example, the so-called azo-group (—N=N-) is chromophoric; the compound called azobenzene, CH-N-N-CH,, although colored red and evidently containing the azo-group, is not a dye; but it becomes one when the so-called amidogroup (NH) also is introduced into its molecule, the compound C,H-N-N-C,H,NH2, called amido - azobenzene, being a true dye. If, instead of the amido-group, a hydroxyl group (OH) is introduced, the result is again a dye (an orange one). Further, the tints of dyes are produced by variation in the 'substituting groups which replace hydrogen in the primitive molecule. Thus, the introduction of the