500 
ME. F. A. ABEL’S CONTEIBUTIONS TO 
resulting from the ignition of the charge of fulminate destined to furnish the initiative 
detonation. 
Some small pellets (T5 inch in diameter) of compressed gun-cotton saturated with 
nitroglycerine were placed in a cylindrical wooden case open at one end and fixed at 
the bottom of a trough of water; the air-spaces between the separate pellets were 
thus occupied by water, the height of which above the charge was about one foot. 
An electric fuse, primed with 2 - 6 grms. (40 grains) of mercuric fulminate and rendered 
thoroughly waterproof by being coated with a cement composed of gutta percha and 
pitch, was weighted and placed at the bottom of the trough, on one side of the cylinder 
and at a distance of 2 inches from it. The detonation of the fulminate did not explode 
the charge ; the experiment was then repeated, the water-space which intervened be- 
tween the fuse and the wooden cylinder being reduced to 1 inch. In this instance the 
firing of the fuse exploded the immersed pellets, the water was projected to a great 
height, the trough was broken into small fragments, and a crater was formed in the 
ground upon which it rested. This experiment was repeated with the same results. 
A small cylinder about 1 inch in diameter and 2 inches long of compressed gun-cotton, 
saturated with nitroglycerine, was enclosed in a paper case, which was thickly coated 
with the gutta-percha cement. A screen of thin sheet copper, 4 inches square, was 
placed at the bottom of a trough and the waterproofed charge of explosive material was 
weighted and placed upon one side of the screen at 025 inch distance from it. A water- 
proofed electric fuse primed with 2'6 grms. (40 grains) of mercuric fulminate was 
placed on the other side of the screen at a distance of 1 inch from the latter ; the trough 
was then filled with water, so that the screen, charge, and fuse were each surrounded 
and separated by the liquid. In the first experiment, the explosion of the fuse did not 
affect the charge, but upon repeating the experiment with a fuse placed at a distance of 
0*75 inch from the screen, the charge was violently exploded as in the former experiment. 
A precisely similar experiment was tried with cylinders consisting of compressed gun- 
cotton only, and enveloped in coatings of some thickness of the gutta-percha cement ; 
but even when the charge and the fuse were placed close to the sides of the screen 
which separated them under water, the gun-cotton was not exploded by the detonation 
of the fulminate ; the same negative result was obtained when a fuse (enveloped in 
the waterproof coating) was placed immediately upon a gun-cotton charge enclosed in 
the paper case and waterproof cement, and exploded under water or in open air. These 
negative results were instructive, as indicating that the thick yielding envelope which 
enclosed the gun-cotton charge (possibly assisted by the thin air-cushion by which the 
enclosed charge was also surrounded) served to protect the comparatively less sensitive 
explosive material, gun-cotton, by reducing or absorbing the power of the blow or con- 
cussion (or whatever the disturbing impulse maybe). The same description of envelope 
did not protect the more readily explosive substance, nitroglycerine, as the preceding 
experiment showed. 
A cylinder of gun-cotton, enclosed in a water-tight case of thin sheet metal, and 
