INFLUENCE OF INITIAL INFLAMMATION. 



109 



3. Velocities (per second). 



Mean velocities 



Hence it is seen that the velocity increases rapidly from the 

 starting point to the fifth cm., from which 

 point the numbers obtained may be re- 

 garded as almost constant, at least within 

 the limit of the errors of the experiments, 

 which have a very considerable relative 

 value at the commencement, for such short 

 intervals. 



The establishment of a regular system 

 can only be effected successfully when the 

 sparks that inflame the compound are 

 strong enough. With feeble sparks, the 

 period of variable condition can be greatly 

 prolonged : over a space of 10 metres, 

 mean velocities of 2126 metres and even 

 661 metres were thus obtained. Analogous 

 phenomena are observed with the other ex- 

 plosive compounds. Electrolytic gas mixed 

 with nitrogen, for example H 2 + + 2N, 

 gave a velocity of 41 -9 metres per second 

 in the two first cms., 1068 metres in the 

 consecutive sections of 5*25 metres, and 

 1163 metres in the consecutive sections 

 of 10 metres. 



The influence of the initial inflammation 

 is in this case still more marked, the velo- 

 city having fallen by accident to 445 and 

 435 metres, without any apparent change 

 in the power of the initial spark ; more- 

 over, the nature of its product, in this case, 

 indicated a different mode of combustion. 



These discrepancies are not, in general, 

 observed 1 with the process of registration 

 based upon the employment of the ful- 

 minate interrupters, which tends to prove 

 that the fulminate, by the sudden pressures 



1 Mention may here be made of an experiment in which the compound 

 H 2 + + N gave an exceptional velocity of 1564-5 metres, instead of the 

 normal result 2121 metres ; probably on account of the exceptional weakness 

 of the priming. 



