352 IGNITION.••INFLAMMATION...FLAME OF CANDLES.

IGNITION

Takes place when the combustible body is not in an aeriformstate.

Charcoal, pyrophorus, &c. furnish instances of this kind.

It seems as if the phenomenon of glowing was peculiar to thosebodies which require a considerable quantity of oxigen to becomeconverted into the gazeous state.

The disengagement of caloric and light is rendered more evi-dent to the senses in the act of

INFLAMMATION,

Or accension. Here the combustible substances are moreeasily converted into an elastic or aeriform state. Flame there-fore consists of the inflammable matter in the act of combustionin the gazeous state. When all circumstances are favorable tothe complete combustion of the products, the flame is perfect;if this is not the case, part of the combustible body, capable ofbeing converted into the gazeous state, passes through the lumi-nous flame unburnt, and exhibits the appearance of smoke. Soottherefore always indicates an imperfect combustion. Hence acommon lamp smokes, an Argand’s lamp yields no smoke.

This degree of combustion is very accurately exemplified in the

FLAME OF CANDLES.

When a candle is first lighted, which must be done by the ap-plication of actual flame, a degree of heat is given to the wicksufficient to destroy the affinity of its constituent parts; part ofthe tallow is instantly melted, volatilized, and decomposed; itshidrogen takes fire and the candle burns. As this is destroyedby combustion another portion melts, rises and supplies its place,and undergoes a like decomposition In this way combustion is