386 
MR. F. A. ABEL’S CONTRIBUTIONS TO 
small perforations in the sides of the trough, sufficiently near to the bottom to ensure 
their being covered by the nitroglycerine. In the first experiment the trough was 
filled to about one third its depth with the liquid, and the initiative detonation was 
developed at one extremity by means of a dynamite cartridge (and detonator) partly 
immersed in the nitroglycerine. Although pains were taken to fix the trough uniformly 
level upon the ground, there was a slight unavoidable elevation at one part — about 
9 feet distant from the point of first detonation ; the layer of nitroglycerine was at this 
point about half the depth of the remainder, and this sufficed to arrest detonation, 
which had been transmitted up to that part of the train at a rate of from 5200 to 6000 
feet per second, the mean velocity being 5573 feet (1794 m.) per second. The layer 
'or train of nitroglycerine used weighed 20 ounces (624 grms.), being at the rate of 
1-4 ounce (43*68 grms.) per foot of the layer or train. In the next experiment a layer 
of fully double the depth was used (weighing about 3 ounces =93*6 grms.) per foot; 
the detonation proceeded along the entire length of the trough with undiminished 
velocity, which was, however, not higher than when the smaller quantity of nitro- 
glycerine was employed, the mean rate of its progression being 5305 feet (1612 m.) 
per second, and the maximum rate, at any part, 5994 feet (1822 m.). The quantity 
of nitroglycerine employed, in a given length of the train, in this last experiment 
corresponded to that used in the two gun-cotton experiments, in which the smallest 
cylinders ( = 3 ounces per foot) were used, arranged in a continuous row, the rate of 
travel of the detonation ranging between 18,500 and 20,600 feet (5624 and 6262 m.) 
per second. 
The very low results furnished by nitroglycerine, when detonated in open air, are 
obviously due to the physical peculiarity (i. e. to the liquid nature) of this explosive 
agent, the transmission of detonation being greatly retarded by the tendency of the 
liquid particles to escape from the blow of the detonation. In the first experiment it 
was demonstrated that when the mass of liquid subjected to the detonation was suffi- 
ciently reduced in quantity, it was actually dispersed, or made to yield so completely 
to the blow, that detonation was arrested while being transmitted at a rate of 5500 feet 
(1672 m.) per second. The very high velocity with which detonation may he trans- 
mitted by nitroglycerine, when that substance is in a condition or position enabling it 
to resist mechanical dispersion, was demonstrated by the results obtained with dyna- 
mite employed in the form of compressed cartridges. On the other hand, the remark- 
able manner in which the velocity of detonation of the latter was reduced by introducing 
such spaces between the cartridges as had no retarding effect upon the detonation of 
corresponding masses of the rigid gun-cotton, demonstrated that the somewhat plastic 
nature of the explosive material, and its consequent tendency to yield to force, affected 
the transmission of detonation very decisively when the conditions were not such as 
to ensure its transmission continuously from particle to particle. 
These results confirm in an interesting manner the conclusions arrived at from ex- 
