COAL, a solid mineralized vegetable matter that can be used for fuel. In the sense of a piece of glowing fuel, thence a piece of fuel, whether dead or alive, the word is common to all languages of the Gothic stock, and seems allied to the Latin caleo, to be hot, and is allied to glow and kiln. The different sorts of fuel are distinguished by prefixes, as char-Coal, pit-Coal, sea-Coal, but, owing to the eminent importance of mineral or pit-Coal, the word Coal alone has come to be used in this special signification. Coal is one of the most important of all minerals; it consists chiefly of carbon, and is universally regarded as of vege table origin. It occurs generally in strata or beds; it is always of black or blackish-brown color; some of the va rieties have considerable vitreous or resinous luster; some are destitute of luster; some have a shell-like fracture, and some have a sort of salty structure, and are readily broken into cubical or rhomboidal fragments. In a general way we may define Coal as a fossil fuel of a black color and stony consistency, which, when heated in close vessels, is con verted into coke with the escape of vola tile liquids and gases. The variety known in Great Britain as blind Coal, and in the United States as anthracite, no doubt gives off scarcely any volatile matter; but this is because it has under gone a natural distillation through meta morphism or other cause.
Divisions.—We may, therefore, divide Coal into two primary divisions, viz., An thracite, which does not, and Bituminous, or soft Coal, which does, flame when kin dled. Anthracite averages in analysis 85 to 87 per cent. of fixed carbon. The term "anthracite" is applied to all Coals con taining more than 80 per cent. of fixed carbon. Various synonyms, such as stone Coal, glance Coal, culm, and Welsh Coal, also are used to designate this sub.. stance, which in Great Britain is used chiefly for smelting purposes and for raising steam, but in the United States is used also almost entirely for domestic fuel and manufacturing purposes. It is
difficult to kindle, but gives out a high heat in burning, and holds fire for a long time. Bituminous Coal includes an al most endless number of varieties, one of the best marked being cannel or parrot Coal. Cannel Coal is so called from burning with a bright flame like a candle, and the name 'prI.;.Tot Coal" is given to it in Scotland from the crackling or chattering noise which some kinds of it make when burned. That of different localities varies much in appearance, but it is commonly dull and earthy, or with only a slight luster; some kinds are, however, bright and shining. In texture it is nearly always compact, and certain beds of it admit of being polished in slabs of considerable size, which ap proach black marble in appearance. Of this material vases, inkstands, boxes, etc., are made. Cannel Coal, from its comparative scarcity and high price, is not suitable for house fires, and is for the most part consumed in making gas, of which it yields from 8,000 to 15,000 cubic feet per ton. When distilled at a low red-heat it yields paraffine oil. The other varieties of bituminous Coal are so numerous that there are as many as 70 kinds of it imported into London alone. Still, among these there are three leading kinds: (1) Caking Coal, which cakes or fuses into one mass in the fire. It breaks into small uneven fragments, and is found largely at Newcastle and some other localities. (2) Splint, or hard Coal, occurring plentifully in Scot land, which is hard and has a kind of slaty fracture. It is not very easily kin dled, but when lighted makes a clear, lasting fire. (3) Cherry, or soft Coal, which breaks easily into small, irregular cubes, has a beautiful, shining luster, is readily kindled, and gives out a cheerful flame and heat. It is common in Staf fordshire. Brown Coal, or lignite, though inferior to true Coal, is, never theless, an important fuel in some coun tries, in default of a better kind.