TJie Length of Flame in Explosions. 175 



To confirm the conclusions arrived at, a few experiments 

 were made with a longer column of the explosive mixture. 

 A brass tube, 4 feet in length, was substituted for the former 

 one, which was 2 feet in length. In this case the length of 

 the explosive column became I35'5 cm. 



Experiments were made employing a mixture of i vol. 

 of coal-gas and 7 vols, of air. 



Mean 



It will be observed that great differences exist between 

 individual experiments : vibrations are set up of large 

 amplitude, which in the case of the tube c may almost 

 totally prevent the appearance of any flash beyond the tube- 

 If, however, we select those experiments in which the 

 extension of the flame is greatest, we find that it exceeds 

 by very little the length of the explosive mixture. 



The following are the chief deditctions which may be 

 drawn from these experiments : — 



(i) The mixture containing i volume of coal-gas with 7 of air 

 gives the most violent explosion, and with it the pro- 

 jection of the flame along a tube is the greatest. 



(2) With mixtures containing i volume of coal-gas with not 

 more than 8 volumes of air, the extension of the flame 

 increases with the length of the tube up to a certain limit; 



