498 
ME. E. A. ABEL’S CONTRIBUTIONS TO 
a compact, hard and homogeneous mass (as obtained by submitting finely, divided gun- 
cotton to powerful pressure). The light and loose gun-cotton is simply scattered with 
violence ; portions of it are sometimes ignited by the flame of the exploding fulmi- 
nate, the latter result being obtained with greater certainty, the less violent the detona- 
tion produced by the fulminate-charge. 
2. The detonation of a small mass of compressed gun-cotton, freely exposed to air, by 
means of a mercuric fulminate-charge, does not accomplish the explosion of light gun- 
cotton-wool or yarn placed in immediate contact with it ; the latter is scattered and par- 
tially inflamed, as in the preceding case*. 
3. If the detonation of the fulminate-charge which is placed in contact with a mass 
of compressed gun-cotton is not sufficiently violent or sharp to effect the explosion, the 
solid mass is shattered and violently dispersed ; if the detonation is upon the verge ot 
that required for determining the violent explosion of the gun-cotton, no inflammation 
of the latter takes place ; but if the explosion of the fulminate-charge is comparatively 
feeble, portions of the gun-cotton are inflamed at the moment of dispersion of the mass. 
4. Explosive substances which are inferior to mercuric fulminate in the suddenness 
and consequent momentary violence of their detonation, cannot be relied upon to effect 
the violent explosion of freely exposed gun-cotton, even if employed in comparatively 
considerable quantities. Thus, even ordinary percussion-cap composition, which consists 
of a mixture of mercuric fulminate and potassic chlorate, cannot be used for the detona- 
tion of freely exposed gun-cotton unless a much more considerable amount be used than 
is necessary of pure mercuric fulminate for that purpose. Many other detonating mix- 
tures, exploding less rapidly and violently than the above ( e . g. very carefully prepared 
mixtures of sulphide of antimony, potassic ferro- and ferricyanides, plumbic ferrocyanide, 
and potassic picrate, with the chlorates), have been tried without success in very con- 
siderable quantities, as agents for developing the detonation of gun-cotton in open air. 
5. The quantity of confined mercuric fulminate required to effect the detonation of 
freely exposed gun-cotton, is regulated by the degree to which the sharpness of its explo- 
sion is increased by the extent of accumulation of force, consequent upon the strength of 
envelope in which the fulminate is confined. Erom 1‘3 to 2-0 grms. (20 to 30 grains) 
are required to detonate the gun-cotton, if the fulminate be confined in a thin case of 
wood, or in several wrapping of paper, while the same result can be produced with 
0-32 grm. (5 grains) if that amount be confined in a cap of thin sheet metal. 
If the fulminate be placed in a wide paper cylinder open at the top, which is rested 
upon the gun-cotton-surface, or if it be placed in a heap directly upon the surface of 
gun-cotton, and if in either instance the violent explosion of the fulminate be effected 
through the agency of a platinum-wire placed at the base of the heap, about 2 grms. 
(25 to 30 grains) of fulminate will also accomplish the detonation of the gun-cotton, the 
* If two disks of compressed gun-cotton, be firmly attached to opposite sides of the metal case which 
contains the minimum charge of fulminate required to produce detonation, when confined, the desired result 
will be produced ; but if the disk be simply rested loosely against the sides of the metal case, they will only be 
violently thrown aside. 
