Gaseous combustion at high pressures.—Part VII. A spectrographic investigation of the ultra-violet radiation from carbonic oxide-oxygen (or - air) explosions

Abstract

The radiation emitted by flames in various circumstances was not much studied until the year 1890 when R. von Helmholtz and (independently) W. H. Julius made the first systematic analyses of the quantity and quality of that emitted by the flames of hydrogen, carbonic oxide, methane and ethylene burning in air at ordinary pressures. Their work, however, does not seem to have been much noticed until, in 1907, H. L. Callendar directed attention to it in connection with the work of the British Association Com­mittee on Gaseous Explosions, which was chiefly concerned with how far radiation is responsible for what is sometimes termed “the missing pressureˮ in closed vessel explosions. In 1910 B. Hopkinson (who was assisted by W. T. David) published his measurements of the total radiation emitted during a coal-gas-air explosion at an initial pressure of one atmosphere in a closed cylindrical vessel (30 cm. × 30 cm.) and the subsequent cooling period. The explosive mixture employed was one of 15 parts coal-gas with 85 of air, such being very nearly the mixture of maximum strength consistent with complete combustion. Two comparative sets of experiments were made, namely:—(i) with the walls of the vessel highly polished, and (ii) in which they were painted with a 0·02 mm. layer of a dead-black lamp-black mixed with a little shellac. The explosion chamber was fitted with a fluorite window, outside of which was fixed a resistance-bolometer, made of a blackened platinum strip, for measuring the radiation emitted.