The Abnormality of Flame Gases

Abstract

Hot gases formed as a result of combustion behave differently from normal hot gases of similar composition, and it is believed that a full appreciation of this fact would lead to the opening up of a wide field of profitable research. Experiments are described in the paper which show that flame gases hold within them a long-lived latent energy. It has been found that the latent energy may amount to as much as, or even more than, 15 per cent of the heat of combustion; but it varies greatly with the conditions under which combustion takes place. These conditions have been investigated by means of explosion pressure and heat loss measurements, flame gas temperature measurements, and flame photography. Experiments are also described which show that in virtue of the latent energy an abnormally large amount of dissociation may obtain in flame gases. On account of this, a platinum wire immersed in flame gases may attain a far higher temperature (some hundreds of degrees Centigrade higher) than a similar wire coated with quartz, and this cannot be accounted for in terms of the different emissivities of the surfaces. There seems little doubt that this phenomenon may have an important bearing upon such problems as the transmission of heat from flame gases and the selection of gas fire radiants. Flame gases resulting from the combustion of weak hydrogen-air mixtures behave in a quite exceptional manner and a short account of some experiments with these gases is given in Appendix I, p. 243.