Instantaneous Pressures in the Explosion- Wave, 177 



With equal volumes of cyanogen and oxygen, a very 

 high pressure is produced in the explosion-wave. Soda-lime 

 glass tubing of 18 mm. external diameter, and 2-5 mm. 

 thickness, was fractured by the explosion. Green glass 

 tubing of 28 mm. in thickness held. Experiments with 

 the hydraulic press showed a very considerable difference 

 in the strength of these tubes. Three pieces of the first 

 glass broke when submitted to the following pressures : — 



1. 890 lbs. on the square inch. 



2. 95° » 



3. 1220 „ 



mean 1020 „ „ = 70 atmospheres. 



We think it safer to take the mean breaking strain of 

 the three pieces as representing the strength of the tubes 

 broken by the explosion, than to take the highest figure as 

 the minimum force exerted by the explosion. We thus 

 come to the conclusion that the pressure exerted in the 

 explosion-wave exceeded 70 atmospheres. Pieces of the 

 green glass tubing which withstood the explosion gave very 

 unequal results on the press : — 



1. 2050 lbs. on square inch. 



2. 145° » 



mean 1750 „ „ =120 atmospheres. 



Unfortunately we had no other specimens of the same 

 kind to test. Our result, therefore, is that in the explosion 

 of equal volumes of cyanogen and oxygen, the pressure 

 produced falls between the limits of 60 to 140 atmospheres, 

 and more probably between 70 and 120 atmospheres. 



In the next experiments, the mixture of equal volumes 

 of cyanogen and oxygen was diluted with its own volume 

 of nitrogen. The reaction occurring may be written : — 

 C 2 N 2 + 2 + 2N 2 = 2 CO + 3N 2 . 



The " effective pressure " produced on firing this mixture 



