1915] 



on Gaseous Explosions 



301 



apparatus indicated. The explosion and cooling line is clearly 

 shown, and the temperature of the gaseous contents is marked on a 

 scale at the side. The lower rising line indicates the bolometer 

 temperature, and the scale for that line shows the heat passed by 

 radiation into the bolometer at each point. The lower dotted line 

 shows the change of rate of the passage of heat through the fluorite 

 window : and it is interesting to observe that the maximum rate of 

 heat flow by radiation occurs before the maximum temperature of 

 the burning gases is attained. Chemists and physicists have long 

 held that radiation from combining gases proceeds more rapidly at 

 the moment of combination than at other times of equal temperature. 



Fig. 28. 



This is clearly shown by the diagram. It is evident that, given 

 equal conditions of temperature, radiation is greatest when chemical 

 combination is proceeding. The diagram shows, too, that the rate of 

 radiation rapidly falls with the fall of temperature, but radiation at 

 the end of half a second is still quite considerable. 



Fig. 28 shows in section the explosion chamber fitted with David's 

 bolometer and also with a platinum resistance thermometer, to 

 determine the mean temperature from the centre to the ends by 

 Hopkiuson's method already described. 



Fig. 20 shows an explosion diagram and a bolometer temperature 

 diagram taken with the apparatus. 



Vol. XXL (No. 109) x 



