The firing of gaseous mixtures by compression

During the course of the experiments described in the preceding paper, in which the movements of the flame in the explosion of electrolytic gas were recorded on a rapidly moving photographic film, we observed a new phenomenon. In addition to the ordinary effects accompanying the explosion,* the photograph showed a new luminous wave advancing from one end of the explosion-tube to meet the flame spreading slowly from the point of origin in the middle of the tube. As we had not noticed this before in any one of the hundreds of photographs of the explosion-flame taken in this laboratory, we were led to suspect that this spontaneous ignition was caused by the peculiar shape of explosion-tube used for the first time in the above experiments. The electrolytic gas was enclosed in a glass tube, one end of which had been previously drawn out to a fine capillary in the blow-pipe flame, in order to facilitate the sealing of the tube after the gaseous mixture had been introduced. Following the device of H. B. Baker, the capillary was first closed by allowing a small quantity of molten fusible metal to solidify in it. The end of the narrow tube could then be sealed off with a small flame without fear of the gases being prematurely exploded. One end of the tube was therefore shaped like a funnel (fig. 1,a ).