Radiation emitted in Gaseous Explosions. 89 



The results of these are shown in Table V. It will be 

 noted that these results are similar to those obtained from 

 the coal-gas and air experiments. The ratio of the emission 



Table V. 



Hate at which Radiation is received from 25*4 per cent, mixtures 

 of Hydrogen and Air per sq. cm. per sec. through plates of 

 Fluorite and Quartz. 



rime from 

 ignition, 

 (sees.) 

 0-017 



0-045 



Mean gas 

 temp. 



(° C. abs.) 



2400 



(max. temp.) 



2200 



Fluorite. 

 4-7 

 35 



Quartz. 

 3-65 

 26 



Quartz 



Fluorite' 



0-79 

 0-74 



0-07 



2000 



2-45 



1-65 



0-67 



0-12 



1800 



T7 



1-0 



0-59 



0-175 



1600 



1-1 



06 



0-55 



0-25 



1400 



0-7 



0-3 



0-43 



0-38 



1200 



035 



o-i 



0-29 



0-60 



1000 



0-15 



nearly zero 



nearly zero 



through quartz to that through fluorite decreases as the 

 temperature decreases, and the 2'8 fju band disappears at 

 the same temperature as was found for the C0 2 . H 2 

 mixtures. Above this temperature the ratio is higher 

 than was found in the case of the latter mixtures. This 

 is accounted for by the fact that the hvdrogen mixture 

 has no strong 4'4 //, band. There must, however, be some 

 radiation from this mixture of greater wave-length than 

 '2'8 fi, for except in the neighbourhood of the maximum 

 temperature developed (2400° to 2000° 0. abs.) the radiation 

 transmitted through the fluorite is greater than that through 

 the quartz even after making an allowance of 30 per cent, 

 for the absorption of the quartz plate *. 



9. In the neighbourhood of the maximum temperature 

 (2400° to 2000° 0. abs.) the ratio of the emission through 

 quartz to that through fluorite is a little greater than 0*7. 



* See footnote, p. 85. The absorption spectrum of water vapour 

 indicates that this long- wave-length radiation is probably due to 

 water vapour. It is conceivable, however, that it may be due to the 

 nitrogen or the excess oxygen. The absorption spectrum of the latter 

 gas shows shallow bands whose maxima are at 3-2 ft and 4*7 /i. 



