The flame of a candle, burning freely in still air, presents in general the form of a pyramid, of which the base is supported on a hemisphere. It consists of four distinct parts: the immediate products of the decomposition of the combustible by the heat which is produced, occupy the centre, _o_, where they exist in the state of an obscure gaseous matter, circumscribed by a brilliant and very luminous envelope, _s_; the latter is nothing but the obscure matter itself, in the circumstances where, on coming into contact with the atmosphere, it combines with the oxygen which exists therein, and forms what is properly called _flame_. The blueish light which characterises the inferior part of the flame, _s_, is produced by a current of cold air, which, passing from below _upwards_, hinders the combustion from taking place at the bottom of the flame, at the _same_ temperature that exists in the parts of the flame not immediately subject to this influence. Finally, on observing attentively, we perceive a fourth part, which is but slightly luminous, and exists as an envelope of all the other parts of the flame. The greatest thickness of this envelope corresponds with the summit of the flame. From this point it gradually becomes thinner, till it arrives at the lowest part of the blueish light, where it altogether disappears. It is in this last-described portion of the flame that the combustion of the gas is finished, and there it is that we find the seat of the most intense heat which the flame of the candle affords. If we compare the temperature of the different parts of the flame, we find that the _maximum_ of heat forms a ring corresponding to the zone of insertion, A A; a point which is the limit of the superior extremity of the blueish light. When the flame is acted upon by the blowpipe, it is subject to two principal modifications:-- 1. If, by means of a blowpipe with a very fine orifice, you direct a current of air through the middle of the flame, you project a portion of the flame in the direction of the blast. The jet thus formed appears like a tongue of fire, blueish, cylindrical, straight, and very long; the current of air occupies its interior. This flame is enveloped on all sides by an almost invisible light, which, extending beyond the blue flame, forms a jet, A´ B, very little luminous, but possessing an extremely high temperature. It is at the point A´, which corresponds with the extremity of the blue flame, that the _maximum_ of heat is found. The extreme point of the jet B possesses a less degree of heat. This flame is adapted for mineralogical assays, for soldering, for working enamels, and in general for all small objects.