Now, as to the use of these various things. First of all, let us examine the flame, as produced by a candle, which is typical of flames obtained by other means described, except the Bunsen lamp. A candle flame (see fig. 7) consists of the following parts:-- 1. A dark core (_a_), which contains the gaseous products of decomposition given off by the melted tallow drawn up by the wick. 2. A highly luminous zone (_b_), in which only partial burning of the combustible gases takes place. In this, oxygen from the air combines chiefly with the combustible hydrogen, whilst the carbon is separated in a highly heated state, which causes the luminosity. 3. An outer mantle of blue tint (_c_), where the oxygen of the air is always present in excess, so that the separated carbon is here burnt. The highest temperature is found in this part of the flame. [Illustration: Fig. 7.--Candle and Gas Flames.] Technically, the outermost zone (_c_) is known as the _oxidising_ flame, and the inner luminous zone (_b_) the _reducing_ flame. The two portions of the candle flame act in different manners on specific mineral substances, and the blowpipe operator may use either of them at will. The method of doing this is illustrated in the same figure. To obtain the reducing flame, the blowpipe jet is brought to the edge of the flame a little distance above the burner, or wick. The operator then produces a gentle blast, which deflects the latter (upper figure) without altogether passing into it, so that the flame is still charged with glowing carbon. A yellowish luminous flame is the result, the most active part of which lies at a short distance from the end. On the other hand, the oxidising flame is utilised by passing the blowpipe jet a little farther into the flame (lower figure) and blowing more strongly. A pointed non-luminous flame is the result. This will be seen to possess an inner blue cone, before the point of which the hottest part is situated. Substances to be fused are placed in this part of the flame, whilst those to be oxidised are placed a little farther away, in order that they may be exposed to the air at the time they are being highly heated.