A piece of wood, like everything else when placed within the medium of fire, suffers de-electrisation and acquires medium of space: this twofold procedure continuing, the wood becomes split or burst asunder, and its elements gradually forced out by the centrifugal pressure; some of which are precipitated, some contribute to the medium of fire, others are recombined differently and exist for a short space of time as flame, and others, with matter from the air, form soot. Such is the most rational theory of combustion, consistent with the inertia of matter and the absence of heat.

Friction rubs away electric matter, percussion forces it out, combustion and ignition follow, and without being promoted by either heat or fire. The kindling matter of a coal-laid fire requires the de-electrising spark at first, and the de-electrised kindling de-electrises the coal; the wood fire, effected by means of friction, is independent of even the spark of fire for its commencement, from having been otherwise de-electrised at first. Within the fire, one part de-electrises another, and the centrifugal pressure decomposes the whole.

Animal combustion is consequent on the internal organs and flesh being de-electrised, the stomach first, by means of spirituous liquors, which, like fire in so doing, promote the sensation of heat. The stomach and adjacent organs, from being thus de-electrised, are prepared to receive the decomposing medium; and from oxygen, to exclude electric matter, being absent, the flesh is brought to the state of smothered combustion and charred: it may now be considered in the light of a mortuum caput.

The spontaneous combustion of greasy clothes, damp hay and other things, is promoted by the limited quantity of air in which such articles are confined. To the hand the air seems warm before combustion has commenced, which indicates deficiency of electric matter, but which, in time, the air acquires from greasy clothes, and from damp hay, the removal of which is succeeded by the destroying medium, by which the elements of the combustible become separated, set free, and dispersed.

In summer, when the atmosphere is greatly deficient of what may be termed winter electric matter, all woodwork is in a desiccated condition; and the slight friction of limb against limb is sufficient to make space for medium of space to enter in excess, and convert to fire, tree after tree, the whole of a forest.

The combustion of a candle is well worthy the philosopher's attention. The candle while burning, comprises a series of the simplest operations, and far beyond the powers of art to effect or otherwise imitate; yet from indifference to the familiar, and the paucity of skill required in the construction, there is nothing less noticed with philosophic acumen. The mechanism and materials to be wrought are the same; which consist in a slender, compact, portable cylinder of tallow, within which is included an equal length of wick. The various operations of de-electrising, fluidifying, and gas-making, are performed in silent, regular succession, unretarded by friction and unincumbered with containing vessels, Nature furnishes the power. The wick answers the purpose of service-pipes, through which the half-wrought materials are conveyed in a gaseous form to the refining fire, within which they remain as in a gasometer of supply, to be gradually diffused through the surrounding flame, and there receive the finishing lustrous polish. The new formation is now a refinery to the work in progress, and is curiously situated over the materials where only it could serve the numerous requisite purposes. Nor does the gradual consumption of the machinery derange the order of operation, work and wear being carried on simultaneously to the end. The many-coloured tissue wrought, of starlight shine and of expanded base, is tastefully tapered as if to please in appearance, as well as lighten our darkness. Thus by natural means, operating on almost uncostly materials, mankind are supplied with that by which darkness is turned to day—the candle flame.

All combustion is on the same principle, previous de-electrisation the commencement, and, by the same cause continued, the centrifugal pressure, which is on the increase from being derived from the general pressure. Flame, or the electric spark, de-electrises the gases, oxygen and hydrogen, before their conversion to water takes place; compression effects the same. The inflammable air in mines becomes exploded from the de-electrising consequence of flame, when inadvertently exposed; and at times the de-electrisation is effected by the atmosphere, as in spontaneous combustion. The mine explosion, promoted by the atmosphere, is a case of spontaneous detonation, if not combustion, which, from sad experience taught, should be anticipated by the application of a rocket fired by a train. The foul air should be got rid of timely, not left to accumulate, and the weather dictates when. "The Davy" may be said to insulate the flame of the lamp from the electric matter of the air within the mine. The flame, when exposed, de-electrises the foul air, and in fluent medium of space causes the explosion.