480 REPORTS ON THE STATE OF SCIENCK. 



An inspection of the figures under columns A and B will at once make 

 it clear why, whereas dilution with hydrogen is invariably found to 

 increase the rate of explosion of a given mixture, an equal dilution with 

 nitrogen or oxygen invariably diminishes it, and also why the retarding 

 influence of oxygen must always be greater than that of an equal pro- 

 portion of nitrogen. The following examples, taken from Dixon's 

 memoir, may be cited in support of the above argument: — 



Effects of Dilution upon the Rate of Explosion of Electrolytic Qas. 



Rate 

 Mixture Exploded Metres per Sec. 



2H 2 +0 2 2,817 



2H„+0 2 +2H, .... 3,268 

 2H 2 +0 2 +4H. 2 .... 3,527 

 2H. 2 +0. 2 +6H. 2 .... 3,532 

 2H,+ 2 +0 2 .... 2,328 

 2H 2 +0,+ 30 2 .... 1,927 

 2H. 2 +0 2 +N 2 .... 2,426 

 2H. 2 +0 2 +3N 2 .... 2,055 



Effects of Dilution with Hydrogen upon the Rate of Explosion of Hydrogen and Chlorine. 



Mixture . . . ttj+CL, . . 2H. 2 +C1. 2 . . 3H 2 +C1. 2 



Rate . . . 1,729 . . 1,849 . . 1,855 metres per sec. 



The Burning of Gaseous Carbon. — Of the many important facts 

 brought to light during the course of Dixon's investigation none are of 

 greater interest than those relating to the burning of gaseous carbon in 

 the explosion wave, as illustrated by the case of cyanogen. In view of 

 the fact that the molecular heat of combustion of cyanogen, when burnt 

 completely to carbon dioxide, is 259*6 kilogram C. units, whereas, if burnt 

 to the monoxide, it would only be 1 23 units, it might be expected that the 

 rate of explosion for a mixture C,N 2 + 20 2 would be much higher than 

 for 2 N 2 + 0„, if gaseous carbon is primarily burnt to carbon dioxide in 

 the wave. The exact opposite is the case, however, as the following 

 results show : — 



Mixture Products Rate 



C. 2 N 2+ 2 . . 200 + N 2 . . 2,7281 

 C 2 N. 2 +20 2 . . 2C0. 2 + N 2 . . 2,321 J metres per seC - 



Still more cogent is the evidence in favour of the initial formation of 

 carbon monoxide in the wave, when the following figures are con- 

 sidered: — 



C 2 N 2 +0 2 C 2 N 2 +0 2 +N 2 C 2 N 2 +0 2 +0 2 



j Rate . . . 2,728 2,398 2,321 



The conclusion to be drawn from the preceding figures is that cyanogen 

 is initially burnt to carbon monoxide and nitrogen in the wave itself, any 

 excess of oxygen afterwards burning up the carbon monoxide as the 

 gases cool down in the rear of the wave. 



This conclusion was driven home by Dixon, in conjunction with 

 Strange and Graham, by photographing on a sensitive film, rotated at 



