1891.] Prof. E. B. Dixon on the Bate of Explosions in Gases. 443 



WEEKLY EVENING MEETING, 



Friday, June 12, 1891. 



Sm Frederick Bramwell, Bart. D.C.L. F.K.S. Honorary Secretary 

 and Vice-President, in the Chair. 



Harold B. Dixon, Esq. M.A. F.E.S. Professor of Chemistry in tho 

 Owens College, Manchester. 



The Bate of Explosions in Gases. 



The rapid act of chemical change, which follows the kindling of 

 an explosive mixture of gases, has of late years attracted th^ interest 

 both of practical engineers and of theoretical chemists. To utilise 

 for motive power the expansive force of ignited gases ; to minimise 

 the chance of disastrous conflagrations of fire-damp m coal mines ; 

 to follow the progress of chemical changes under the simplest condi- 

 tions are some among the problems presented to us m industry or 

 science, demanding for their solution a knowledge of the phenomena 



of the explosions of gases. „ , . . ... . 



To understand the nature of explosions m gases it is necessary to 

 know certain fundamental properties of the explosive mixture.^ With 

 ihis obiect in view experimenters have sought to determine for 

 various mixture of gases : -the heat of chemical combination ; the 

 temperature of inflammation; the pressure developed ; and lastly, 

 the rate at which the explosion is propagated under different con- 



^'^'iris on the last of these problems-the determination of the 

 velocity with which the flame travels through the gas— that I have 



been asked to speak. , .-, i -i j j? 



Twentv-four years ago Bunsen described a method of measuring 

 the raoiditv of the flame in gas explosions. Passing a mixture of 

 explosive gases through an orifice at the end of a tube and igniting 

 the eases as they issued into the air, he determined the rate at which 

 the gases must be driven through the tube to prevent the flame 

 passing back through the opening, and exploding insi.le the tube. 

 Bv this method he found that the rate of propagation of the ignition 

 of hydrogen and oxygen was 34 metres per second, while the rate 



