A TREATISE ON GAS-LIGHT,

49

THEORY

OF

THE COMBUSTION OF COAL

IN

ELUCIDATION OF THE NATURE AND PRODUCTION

GAS LIGHT.

Pit-coal exists in this island in strata, which,as far as concerns many hundred generationsafter us, may be pronounced inexhaustible;and is so admirably adapted, both for do-mestic purposes and the uses of the arts, thatit is justly regarded as a most essential con-stituent of our national wealth. Like all otherbituminous substances, it is composed of afixed carbonaceous base or bitumen, united tomore or less earthy and saline matter consti-tuting the ashes left behind when this sub-stance is burnt. The proportions of theseparts differ considerably, in different kinds ofcoal; and according to the prevalency of oneor other of them, so the coal is more or lesscombustible, and possesses the characters of

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