L 84 ] 



VII. An Analysis of the Radiation emitted in Gaseous 

 Explosions. By Major W. T. David, M.A.* 



1. TN this paper the results of some experiments are given 

 JL on an analysis of the radiation emitted during 

 explosion and subsequent cooling of mixtures of coal-gas 

 and air and of hydrogen and air. These experiments are ? 

 it is thought, of considerable interest in that some fairly 

 definite conclusions may be drawn from them as to the 

 origin of the radiation emitted. 



2. The radiation from the exploded mixtures was mea- 

 sured f after passing through clear plates of fluorite, quartz,, 

 and plate glass. The fluorite plate transmits almost exactly 

 95 per cent, of the radiation emitted by the exploded 

 mixtures. The quartz plate transmits about 70 per cent, 

 of the radiation of wave-length between about 2 fi and 

 3*5 fju ; it is opaque to radiation of longer wave-length, 

 but it is more transparent to radiation of shorter wave- 

 length. The plate glass transmits some 60 to 70 per cent, 

 of the radiation transmitted by the plate of quartz. 



3. It is probable that the emission spectrum of an 

 exploded mixture of coal-gas and air is similar in form 

 to that of a Bunsen flame, the important part J of which 

 consists of two clearly defined bands whose maxima are 

 at approximately 2*8 /jl and 4*4 /u- § . The fluorite plate 

 transmits both the 2'8 fi and the 4*4 fi bands. The quartz 

 and plate glass transmit very little of the 4'4/^ band, and 

 the radiation measured through them is mainly that of the 

 2-8 fM band. 



4. The emission spectrum of a hydrogen flame consists 

 mainly of the 2*8 //, band. The experiments on the hydrogen 

 and air mixtures indicate, however, that some radiation of 



* Communicated by the Author. 



t For full details of the experimental methods employed see Phil. 

 Trans. A. vol. ccxi. p. 375. The measurements recorded in the present 

 paper were all made when the bolometer was placed in position A. 



% That is, the part containing- the bulk of the energy. 



§ The4 # 4/u band is due entirely to C0 2 and the 2*8^ band is due 

 partly to C0 2 and partly to water vapour. There is also an emission 

 band at about 15 \i due to C0 2 , but the energy in the radiation in this 

 band is small in comparison with that in the 2 - 8/a and 4'4/u bands at the 

 high temperatures developed in these explosions. 



