Infra-red Emission from Gaseous Explosions

Abstract

THE catalytic effect of water and other substances on the speed of explosions of mixtures of carbon monoxide and oxygen has been studied from the point of view of infra-red emission. This has been rendered possible by the use of a Downing galvanometer kindly loaned to us by Prof. A. V. Hill. With this galvanometer and a Hilger infra-red spectrometer, it is a comparatively easy matter to survey the infra-red spectra of gaseous explosions. The explosion spectrum of carbon monoxide and oxygen is qualitatively the same as that of the flame, but the ratios of the intensities of the 2.8μ and the 4.4μ bands are widely different in the two cases. For the explosion of the gases dried over P₂O₅ this ratio is nearly 1: 1 for a 35 cm. tube, and for the flame 1: 11. When the gases are saturated with water vapour the ratios are 2: 1 and 1: 10 respectively. The intensity of infra-red emission is markedly greater for the dry than for the wet gases, although the speed of explosion in the former is slower. The ratios of the deflexions obtained for the dry and wet gases were about 3: 2 for the 2.8μ band, and 3: 1 for the 4.4μ band. The absorption of infra-red radiation by the water vapour in front of the explosion wave is negligible (cf. Hettner, Ann. Phys., 1918, 55, 496). This we have checked by absorption measurements on the wet and dry explosive mixtures. Thus the decrease in the infra-red emission which occurs when water is added to the explosion of carbon monoxide must be ascribed to some cause operating on the hot gases themselves.