16 Mr Bevan Lean and Mr. H. B. Dixon on 



Experiments on the Transmission of Explosions across 

 Air gaps. By Bevan Lean, B.Sc, Dalton Chemical 

 Scholar, and Harold B. Dixon, F.R.S., Professor 

 of Chemistry in the Owens College. 



{Received October 20th, 1891.) 



How far the shock produced by the explosion of a 

 gaseous mixture can be transmitted through a column 

 of air so as to ignite a gaseous mixture beyond — is a 

 question often asked in the discussions raised as to the 

 nature of colliery explosions. Some practical men have 

 expressed the opinion that the shock can be transmitted 

 through air along great lengths of straight gallery, so as 

 to cause the explosion of accumulations of fire damp at 

 the further end ; others hold that a few score yards of 

 gallery free from firedamp and dust, will effectually 

 prevent the propagation of an explosion in a mine. To 

 obtain some data by which to decide the question, the 

 following experiments were tried on the small scale. 



Apparatus. — The apparatus consisted of two lead tubes, 

 880 mm. in length, and 17^ mm. internal diam., which 

 could be connected together by glass tubes of varying 

 dimensions by means of brass junctions. 



Explosive Mixture. The explosive mixture employed 

 was one of two vols, of hydrogen mixed with slightly more 

 than 1 vol of oxygen. The mixture was kept over water 

 in a stale gas-holder. The hydrogen was made from zinc 

 and sulphuric acid, without special purification, and the 

 oxygen was prepared from potassium chlorate. 



