1802.] to the Detection of Benzoline Vapour, fyc. 97 



Proportion of 

 benzolised air to air 

 in mixture. 



Behaviour of the mixture 

 with a naked flame. 



Height of the 

 " cap" over the hydrogen 

 safety-lamp flame in the 

 mixture. 



1 : 4 



Violently explosive. 





1:5 r 



Burns rapidly, and would 





1:6 < 



probably be explosive if 





1:7 [ 



fired in large quantity. 





1 : 8 



Burns around a flame only. 





1 : 9 



Non-inflammable. 





1 : 23 



5) 



52 mm. " cap." 





I 



43 „ 



1 : 36 





(4 ,, with benz- 





1 



oline flame.) 



1 :72 





31 mm. " cap." 



1 : 144 





22 „ 



The results of these experiments showed that the 10 mm. hydrogen 

 flame in the Ashworth safety-lamp will detect a quantity of benzoline 

 vapour in air which is only l/36th that of the explosive proportion, 

 and l/20th of that which is inflammable when mixed with air. The 

 benzoline flame shows a very small but distinct " cap " when the 

 amount of benzoline vapour is l/9th that requisite for the production 

 of an explosive mixture, and l/5th that which will yield an inflam- 

 mable mixture. 



Further experiments of a similar kind are being: made with the 

 vapour of alcohol and of ether. 



I have to acknowledge with pleasure the valuable manipulative 

 skill and fertility of resource of W. T. Rigby, who has assisted me 

 in carrying out the experiments with the test-chamber. 



VOL. Ll. 



H 



