EXPLOSIONS OF COAL-GAS AND AIR, 



.'593 



PART H.--Tm: DIATMI -;i;\i V.VCY AND EMI->I\I. POWER OF THE HOT GASEOUS 



MIXTURE AFTER EXPLOSION. 



After the experiments just described had been made some of them were repeated 

 with an explosion vessel of the same shape and size whose interior surface was silver- 

 plated and therefore reflecting. It at once appeared that the gaseous mixture when 

 exploded in this vessel emitted radiation much more strongly than a mixture of the 

 same strength exploded in the vessel with black walls. Curve A P , fig. 13, shows the 

 radiation absorted by the bolometer per square centimetre when it was protected by 

 the plate of quart/* during the explosion and subsequent cooling of a 15-per-cent. 

 mixture of coal-gas and air at atmospheric density in the vessel with reflecting walls. 

 Curve A B in the same figure shows the same thing when the walls were black. The 

 corresponding gas temperature curves (T P and T B ) are also shown. The maximum 

 gas temperature reached after explosion is about 3 per cent, greater and the 

 subsequent rate of cooling much slower when the mixture is enclosed in the vessel 

 with reflecting walls than it is when the mixture is enclosed in the vessel with 

 black walls. This is in agreement with Prof. HOPKINSON'S recent experiments, t 

 In the following table the second and third columns give the rate at which that part 



TABLE X. 15-per-cent. Mixtures of Coal-gas and Air. Quartz Window. 

 Bolometer close up to Quartz Window. 



of the radiation from the gaseous mixture which is transmitted through the plate of 

 quartz is absorbed by the bolometer per square centimetre when the walls of the 

 vessel are reflecting and blackened respectively. These figures are taken from the 



* No measurements were made of the radiation transmitted through the fluorite window when the walls 

 of the vessel were reflecting. The platinum bolometer, having only a thermal capacity equivalent to 

 008 gr. of water per square centimetre, would have been heated up to a temperature of over 300* C. 

 with a 15-per-cent. mixture, and the correction to be applied for the loss of heat by the bolometer would 

 have baen so great as to make the results unreliable. 



t 'Roy. Soc. Proc.,' A, vol. 84, p. 155. 



VOL. coxi. A. 3 E; 



