The Romance of Modern Chemistry

FLAME: WHAT IS IT? Fra. ß.—The flame of burn in g hydrogen. one serves as an air passage. The top of the lamp glass is covered with an asbestos disc, in the middle of which there is a hole. When the gas is turned on, the air in the lamp glass is driven out, and the latter then contains an atmosphere of coal gas, the excess of which escapes through the disc at the top. This escaping gas may be lighted, and gives the ordinary flame of coal gas burning in air. If, now, the long tube which passes through the cork at the bottom is pushed up until it reaches the burning jet at the top, something at the end of this tube is seen to catch fire, and to remain alight, giving a visible flame even when the tube is drawn down again. The explanation of this interesting phenomenon is that air is being drawn up the long tube and is burning in the atmosphere of coal gas which surrounds the end of the tube. This apparatus, then, in which we can see both coal gas burning in air, and air burning in coal gas, shows that the terms “ combustible,” and “ supporter of combustion11 are inter- changeable. There is no real distinction; the chemical process which goes on is the same in both the flames observed. When we come to look more closely at a flame we find that it has a structure. It may seem odd to speak of a mobile, elusive thing like a flame as having a structure, and certainly with a mixture such as coal gas being con- sumed at some ingenious modern burner, it is not easy to detect this structure. But if we take a simple gas such as hydrogen burning at the end of a plain round tube, we find the character of the flame to be exceedingly simple. The actual flame, as will be seen from the accompanying 156