446 



Professor Harold B. Dixon 



[June 12, 



Table I. shows tlie explosion rates found by Bertbelot, compared 

 with the theoretical velocity of the products of combustion : — 



TABLE I. 



Berthelot's Expebimetns. 



Gaseous Mixture. 



Velocity in Metres per Second. 



Theoretical. 



Found. 



H, + O 



Hydrogen and oxygen. 



2830 



2810 



N^O 



Hs + 



Hydrogen and nitrous oxide. 



CO + o 



Carbonic oxide and oxygen. 



2250 



2284 



1940 



1090 



CO + 



Carbonic oxide and nitrous oxide. 



N^O 



1897 



1106 



CH, + O, 



Marsh gas and oxygen. 



CjH, + Oe 



Ethylene and oxygen. 



2427 



2287 



2517 



2210 



C2N2 + O, 

 Cyanogen and oxygen. 



C2H2 4- O5 



Acetylene and oxygen. 



2490 



2195 



2660 



2482 



CO + H, + O. 



Carbonic oxide, hydrogen, and oxygen 



.} 



2236 



2008 



Two points in Table I. favoured the view that Bertbelot might 

 have here given the true theory of explosions : first, the close coinci- 

 dence between the rates of explosion of hydrogen both with oxygen 

 and nitrous oxide with the calculated mean velocities of the products 

 of combustion ; and secondly, the great discordance between the 

 found and calculated rates for carbonic oxide with both oxygen and 

 nitrous oxide. I had previously discovered that pure carbonic oxide 

 cannot be exploded either with pure oxygen or pure nitrous oxide. 

 The discordance found by Bertbelot was what I should have expected 

 from my own experiments. 



A consideration of Berthelot's results, published in full in the 

 ' Annales de Chimie,' led me to think it would be useful to repeat 

 and extend these experiments. My objects were chiefly: (1) to deter- 

 mine as accurately as possible the rate of the explosion-wave for 



