338 
ME. E. A. ABEL’S CONTEIBUTIONS TO 
symptom of detonation was developed *. Two ounces of nitroglycerine, in the form of 
dynamite (i.e. converted into a plastic mass by admixture with one fourth its weight of 
Kieselguhr), were also exploded in close contact with a cylinder of compressed gun- 
cotton ; but the same negative result furnished by the preceding experiments was 
obtained. While, therefore, gun-cotton might be detonated by 0 '32 grm. (5 grains) of 
mercuric fulminate, or by 3‘25 grms. (50 grains) of chloride of nitrogen (of which sub- 
stances only 0‘07 grm., = l grain, and 0T grm.,=T5 grain, are respectively required to 
detonate nitroglycerine), it was found not to be detonated even by the explosion in 
contact with it of 124‘8 grms. (4 ounces) of nitroglycerine. 
The obvious incompatibility of such results as these with the general conclusion 
(founded upon extensive and varied experiments with different explosive substances), 
that the facility with which an explosion accomplishes the detonation of such substances 
is proportionate to the mechanical force and heat developed by that explosion, led me 
to suggest that a similarity in character, or synchronism, of the vibrations developed by 
the explosion of particular substances might operate in favouring the detonation of one 
of such substances by the initial detonation of a small quantity of another, while, in the 
absence of such synchronism, a much more powerful initiative detonation, or the appli- 
cation of much greater force, would be needed to effect the detonation of the material 
operated upon. This view has been favourably regarded by many, as affording a rea- 
sonable explanation of the apparently anomalous results above referred to, and appears 
to have received some support from the results of certain interesting experiments recently 
instituted by MM. Champion and Pellet^ with iodide of nitrogen and one or two other 
explosive substances. They observed, in the first instance, that the detonation of about 
0-03 grm. of iodide of nitrogen at one extremity of a tube 13 mm. diameter and 
2 ‘4 metres (and even 7 metres) in length immediately determined the explosion of a 
similar quantity of the iodide placed at the other extremity. By inserting a pith-ball 
pendulum into the tube they demonstrated that the concussion transmitted through it 
was very slight. They also found that the detonation of small quantities of nitro- 
glycerine, mercuric fulminate, or nitroerythrite at one end of the tube exploded the 
iodide placed at the other extremity ; and that if the tube were divided, so as to intro- 
duce an interval of 5 or 6 mm. between the two parts, a much more powerful ex- 
plosion was required to determine the detonation of iodide at the furthest extremity. 
Some experiments which they made, by attaching small quantities of iodide of nitrogen 
to the strings of a double-bass and causing these to vibrate, appeared to indicate that 
only a particular pitch or rapidity of vibration determined the explosion of the iodide, 
similar results being also obtained with vibrating plates of metal. These, and some 
other results obtained with the aid of parabolic mirrors, led them to conclude that the 
* In one instance, among a large number of experiments, the detonation of two ounces of nitroglycerine in 
contact with, a disk of compressed gun-cotton (supported by a wrought-iron plate) furnished a result which 
appeared to indicate that the gun-cotton had detonated. 
j- Comptes Bendus, tome lxxv. p. 210. 
