134 Mk- Harold B. Dixon on 



useful to repeat and extend these experiments. My objects 

 were chiefly : (i) to determine as accurately as possible the 

 rate of the explosion-wave for some well-known mix- 

 tures ; (2) to measure the rate of the explosion wave in 

 carbonic oxide and oxygen with different quantities of 

 steam; and (3) to determine the influence of inert gases on 

 the propagation of the wave. 



§3. For a description of the apparatus employed, the 

 mode of preparation of the gases and the chronograph 

 arrangements, I must refer to my Memoir in the Philoso- 

 phical Transactions for 1893. 



Briefly, my apparatus differed from that of Berthelot's 

 in the following particulars : — 



a. The explosion tube was longer and wider. 



b. The interrupters or ' bridges ' were of silver foil, and 



no fulminate was used. 



c. A longer space was allowed between the firing spark 



and the first ' bridge,' where the record of the rate 

 was begun. This was found essential in several 

 cases, especially when the mixture was fired under 

 reduced pressure, or in presence of inert gases, in 

 which cases the explosion does not reach its 

 maximum rate for some feet. 



d. The errors of the chronograph were largely eliminated 



by making blank experiments, and by repeating 

 each experiment with the connexions of the chrono- 

 graph reversed. 



The results obtained with hydrogen and oxygen, with 

 hydrogen and nitrous oxide, and with marsh gas and 

 oxygen in exact proportions for complete combustion, were 

 in close accordance with the mean results of Berthelot ; 

 for ethylene, acetylene, and cyanogen my numbers differed 

 appreciably, but in no case differed by more than 7 per 

 cent, from the rates observed by Berthelot : — 



