86 Professor William Arthur Bom [Feb. 28, 



must be tired at an initial pressure of about 1| atmosphere in a 

 stout leaden coil of about 1 inch internal diameter. Even then, it 

 is necessary to start the explosion wave in a special firing piece 

 containing electrolytic gas under pressure. I therefore regret that, 

 owing to the special arrangements requisite for success, it is not 

 possible to make the experiment to-night. I will, however, give you 

 the results obtained on detonating the mixture in my laboratory, but 

 before doing so, I will carry out an experiment on the explosion of 

 the gases at an initial pressure of 15 atmospheres. 



The cylindrical steel bomb on the table is part of an apparatus 

 recently installed in the Fuel and Metallurgical Laboratories of the 

 University of Leeds for investigations on gaseous explosions under 

 high pressures. The bomb is about a foot long with an external 

 diameter of 4 inches, and the central cylindrical explosion chamber 

 is 8 inches long by 1 inch in diameter. It has been tested by 

 hydraulic pressure up to 2000 atmospheres, and has been repeatedly 

 used for experiments with mixtures of hydrocarbons and oxygen at 

 initial pressures of as much as 40 atmospheres. The bomb is now 

 connected, through a valve at the top, with a standard Bourdon gauge, 

 and contains an equimolecular mixture of ethane and oxygen at a 

 pressure of 15*8 atmospheres. The valve will now be closed, and the 

 mixture fired by means of an electrical arrangement in the special 

 firing piece. 



All that is audible of the explosion is a sharp click, and on open- 

 ing the valve connecting with the gauge again, the final pressure of 

 the cold products of explosion is recorded. After applying the 

 necessary correction for the '' dead space " in the gauge connections, 

 but the final "corrected" pressure is as nearly as possible 30*8 

 atmospheres, corresponding to a ratio p^lVi = 1'93. I would now 

 direct your attention to the tabulated results of a similar bomb 

 experiment carried out a few weeks ago at Leeds at an initial 

 pressure of 25 atmospheres, and also at the same time to those of 

 another experiment in which the gases were detonated in a lead coil 

 at an initial pressure of 1| atmosphere. 



In both these experiments carbon was deposited, and it is evident 

 also, that steam was formed. The ratio ^a/Pi? ^^s ^^ nearly as pos- 

 sible 2*0 instead of the 2*5 required by the theory of the preferential 

 combustion of carbon. Moreover, a notable feature of the results is the 

 presence of as much as 7 per cent, of methane among the products of 

 the experiment at 25 atmospheres ; the fact that so much methane 

 survived when all other hydrocarbons were battered to pieces during 

 the explosion (no traces of either acetylene or ethylene being found 

 in the products) is a remarkable testimony to its relatively great 

 stability at the highest temperatures of explosion flames. There is no 

 evidence in these experiments, of any real discontinuity between the 

 chemical phenomena of ordinary " infiammatimi " and those of " deto- 

 nationy The higher temperatures, and more violent conditions in 



