Some writers have imagined coal to be the remains of antediluvian timber, which floated upon the waters of the deluge until several strata of mineral substances had been formed: others conceive it to have been antediluvian peat bog. It is called pit coal, from the circumstance only of its being obtained from mines or pits; and, in London, for no better reason than its having been conveyed thither by sea, it has the name of sea coal.
Its uses as fuel are too extensively known to need here any observations. By the distillation of coal an inflammable gas is produced, which has of late been introduced for the lighting of manufactories, and lighting several of the streets and shops of the metropolis. This gas is conveyed by pipes, from the reservoir in which it is collected, to great distances; and the light which it yields is peculiarly brilliant and beautiful. It was at the foundery belonging to Messrs. Boulton and Watts, at Birmingham, that the first public display of gas lights was made, in the year 1802, on the occasion of the rejoicings for peace. In 1805 the cotton mills of Messrs. Phillips and Lee, at Manchester, were lighted with gas, to the exclusion of lamps, candles, and every other source of artificial light. In the beginning of 1816 it was estimated that, at the three gas-light stations, in Peter-street, Westminster, Worship-street, and Norton Falgate, London, twenty-five chaldrons of coals were used daily; and that these were sufficient to supply with gas 125,000 large lamps. At the works in Dorset-street, Fleet-street, the daily consumption of coal was about three chaldrons, which afforded gas for 1,500 lamps.
The production of the gas light is easily effected in miniature, by putting common coal, pounded small, into the bowl of a tobacco-pipe, and closely covering this with clay made into a stiff lute with water. When the clay is dry, the bowl of the pipe must be put into the fire, and there heated gradually. In a few minutes a stream of gas will issue from the end of the pipe. This may be set on fire with a piece of paper, and will burn with a bright flame. When the gas is no longer disengaged, there will be found in the bowl of the pipe the remains of the coals, in the form of coke.
It is estimated that one chaldron of good coals will afford from 17,000, to 20,000 cubical feet of gas; and that one of the large burners in the shops of London, consumes about four cubical feet per hour.
Soot is produced from the smoke of burned coal, and is used as a manure for cold, moist, and clayey meadows and pastures: and pounded coal has been applied to the same purpose in some parts of the Continent. By a process called charring, coal is divested of its humid, acid, and bituminous particles, and is converted into a kind of cinder called coke. This is employed in cases where intense heat is requisite, as for the smelting of iron ore; and likewise where acid and bituminous particles of coal would be detrimental, as in the drying of malt.
What is usually termed culm is the refuse or dusty coal, produced in working the common coals. It contains much earthy matter, will not kindle in an ordinary fire-place, but produces considerable heat and flame in a furnace, where a strong current of air is introduced. In England it is exempted from the high duty imposed on other coals, and is sold at a very low price. It is used for burning lime, making salt, and in steam engines.
219. CANNEL COAL is of black colour, with little lustre, is not laminar, but breaks in any direction, like pitch, and does not stain the fingers.
This highly inflammable kind of coal is found abundantly in the neighbourhood of Wigan, in Lancashire, where there is an entire stratum of it about four feet in thickness. It is also found near Whitehaven, in some of the pits at Newcastle, and in some parts of Scotland. Doubts have been entertained respecting the name of this coal; but when it is recollected that in Lancashire, whence it is chiefly brought, the word candle is usually pronounced with the omission of the letter d, and that, in many instances, the coal is used by the poor as a substitute for candles, these will be immediately removed. In Scotland it has the name of parrot coal.
No kind of coal takes fire so readily, nor burns with so cheerful and brilliant a flame as this: and its not soiling the fingers, like pit coal, renders the use of it peculiarly pleasant; but it does not cake, and soon burns away. When first kindled, it crackles and splinters very much; and, on this account, would be dangerous, were it not easily prevented from so doing by being previously immersed for a little while in water. Cannel coal has much the appearance of jet. It admits of being turned in a lathe, and takes a good polish; and snuff-boxes and trinkets made of it have in many instances been sold as jet ([222]). Of all the kinds of coal that are used for gas-lights, none are said to be so useful as this.
220. STONE COAL, KILKENNY COAL, WELSH COAL, or GLANCE COAL, is of a dark iron-black colour, with a metallic lustre and foliated texture; and consists almost entirely of charcoal.