Prof. Dixon and Mr. Smith on 



Incompleteness of Combustion in Gaseous Explosions. 

 By Prof. Harold B. Dixon, F.R.S., and H. W. 

 Smith, B.Sc, Dalton Chemical Scholar, Owens 

 College. 



(Received October 26th, 1888.) 



In the course of an investigation, in which we were 

 engaged, on the rate of propagation of gaseous explosions, 

 it was noticed that when a mixture of hydrogen and 

 oxygen, in the proportions in which they combine to form 

 water, was exploded, there remained an explosive residue in 

 addition to the unavoidable slight excess of one or the 

 other gas due to inaccuracy in mixing. The mixture was 

 exploded in a leaden tube 100 metres long and 9 mm. in 

 diameter ; after the explosion the tap at one end was 

 opened, and air allowed to rush in. Air was then pumped 

 in by a bellows, and the other tap was then opened. On 

 applying a light to the out-rushing gases, for the purpose 

 of determining whether the hydrogen or the oxygen was 

 in excess in the original mixture, the gas at first driven out 

 proved to be rich in oxygen — supporting combustion 

 vividly — and then the succeeding gas burnt with a series of 

 sharp cracklings, and finally there was a flash down the tube. 

 From this, it appeared that even in a mixture of hy- 

 drogen and oxygen, containing a slight excess of oxygen, 

 the hydrogen was not completely burnt. If the mixture 

 had contained an excess of hydrogen it might have been 

 reasonably supposed that the explosive residue was made 

 up of the excess of hydrogen and the air admitted after 

 the explosion. This explanation could not be admitted in 

 tiie present instance, as the mixture contained an excess of 

 oxygen. A similar phenomenon was observed when a 

 slight excess of hydrogen was employed, and the residue 

 was swept out of the tube by a stream of carbonic acid gas. 



