FLAME

, the subtlest and brightest part of the fuel, ascending above it in a pyramidal or conical figure, and heated red-hot. Sir Isaac Newton defines Flame as only red-hot smoke, or the vapour of any substance raised from it by fire, and heated to such a degree as to emit light copiously. Is not Flame, says he, a vapour, fume, or exhalation, heated red-hot; that is, so hot as to shine? For bodies do not Flame without emitting a copious fume; and this fume burns in the Flame. The ignis fatuus is a vapour shining without heat; and is there not the same difference between this vapour and Flame, as between rotten wood shining without heat, and burning coals of fire? In distilling hot spirits, if the head of the still be taken off, the vapour which ascends will take fire at the Flame of a candle, and turn into Flame. Some bodies, heated by motion or fermentation, if the heat grow intense, fume copiously; and if the heat be great enough, the fumes will shine, and become Flame. Metals in fusion do not Flame, for want of a copious fume. All flaming bodies, as oil, tallow, wax, wood, fossil coal, pitch, sul- phur, &c, by burning, waste in smoke, which at first is lucid; but at a little distance from the body ceases to be so, and only continues hot. When the Flame is put out, the smoke is thick, and frequently smells strongly: but in the Flame it loses its smell; and, according to the nature of the fuel, the Flame is of divers colours. That of sulphur and spirit of wine is blue; that of copper opened with sublimate, green; that of tallow, yellow; of camphire, white; &c. Newton's Optics, p. 318.