EXPERIMENTAL ARRANGEMENTS. 



91 



The transmission of the energy, under these conditions of 

 extreme rapidity of action, is perhaps effected with greater 

 facility between gaseous molecules of the same nature, in virtue 

 of a kind of unison causing similar movements, than between 

 the molecules of gas and the enclosing vessel. 



The action is not the same, as will be shown, in cases where 

 the system in ignition has time to lose a portion of its heat, 

 which is communicated to foreign gases or to bodies in the 

 vicinity not capable of undergoing the same chemical trans- 

 formation. 



2. EXPEEIMENTAL AERANGEMENTS. 



1. The mode of procedure adopted in this study is very 

 simple. It consists, 



(1) In filling with a detonating mixture under a given pressure, 

 a tube of great length (about 40 metres, Figs. 9 and 10). 



(2) In effecting the ignition at one of the extremities, by means 

 of an electric spark (Fig. 11). 



(3) In interrupting, by means of the flame itself, two electric 



Fig. 9. Tube with its interrupters. 



currents, placed at certain points in the tube, the interval 

 between which is exactly defined by two couplings which 

 connect the consecutive portions of the tube (Figs. 13 and 14). 

 The currents are transmitted along very narrow strips of tin 

 (Fig. 12), gummed upon paper, and held by the couplings 

 between the two insulating discs of leather, which have a hole 

 in the centre, so as to establish the complete continuity of the 

 bore. These strips are arranged normally to the direction of 

 the flame. 



A grain (about '010 of a gramme) of mercury fulminate 

 exploding on contact with the flame, destroys the strip and 

 interrupts the current. 



Potassium picrate has also been used to produce the same 

 effect. 



The gaseous compound is ignited by means of an electric spark, 

 either at the beginning of the tube or at some given point. 



