II. On the application of a hydrogen flame in an ordinary safety-lamp to the detection and measurement of firedamp

In a former paper (‘Roy. Soc. Proc.,’ vol. 50, p. 122) an apparatus was described in which the appearance of the “cap” over the flame of a safety-lamp could be observed and measured when the lamp was exposed to definite mixtures of air with methane or firedamp. The relative sensitiveness of different forms of lamp, and of different flames, when they are applied to the detection and measurement of “gas,” was thus readily ascertained. It was stated that the flames of colza oil, rape oil, mixed oils, benzoline, methylated spirit, and hydrogen had been experimented upon : and that the non-luminous flames producible by benzoline, alcohol, and hydrogen far excelled the more or less luminous oil flames in their power of indicating low percentages of inflammable gas or vapour in the air.