368 
ME. F. A. ABEL’S CONTEIBTJTIONS TO 
blished and transmitted : while in the other case the diluent, which is liquid, or is at 
any rate first applied in the liquid state, envelopes each particle of the solid explosive 
agent, so that a complete casing (or film) of inert material surrounds each, isolating 
it from its neighbours ; even therefore if the amount of diluent applied is only small, 
it must oppose comparatively great resistance to the transmission of detonation 
throughout the mass, either if it remain in the liquid condition or if it afterwards 
solidifies*. 
If the dilution or impregnation with a liquid be carried to the full extent, the diluent 
will, in the case of gun-cotton, penetrate, at any rate to some extent, to the interior of 
the small particles of hollow fibre composing the compressed mass, and the deadening 
effect will thus be greatly increased. 
Experiments have been made with the view of ascertaining how small a proportion 
of water, distributed through compressed gun-cotton, interferes with its detonation by 
the ordinary means employed in practice ; i. e. by exploding a fuse containing about 
15 grains (1 grm.) of mercuric fulminate, confined in a sheet-tin tube in contact with 
it. Cakes of gun-cotton of known weight were kept upon supports in a small chamber, 
the bottom of which was covered with a layer of tow, thoroughly wetted with water ; 
their increase of weight, due to absorption of moisture, and their susceptibility to deto- 
nation were periodically ascertained. When 3 per cent, over and above the normal 
proportion (2 per cent.) of water had been absorbed, the detonation of the cakes was 
doubtful. Other specimens which were impregnated with oil, or soaked in melted fat 
until the latter had penetrated to the centre of the mass, could not be detonated by the 
explosion of the usual “ detonator ” (containing about 1 grm. of fulminate) firmly 
imbedded in them. The explosion of the freely exposed damp gun-cotton was, however, 
accomplished by greatly increasing the strength of the detonator ( i . e. by employing a 
large amount of confined mercuric fulminate) ; and it occurred to my assistant, Mr. E. 
O. Brown, to apply the detonation of dry gun-cotton itself to the development of the 
explosive force of the compressed material when in a moist or wet state. 
Gun-cotton, immediately on removal from the press, in which the wet pulp has been 
submitted to a pressure of not less than four tons on the square inch, retains about 
15 per cent, of water. In this condition it cannot be burned by the simple application 
of fire to its surface, nor can it be detonated except by the employment of a fulminate 
“ detonator ” of very considerable power ; but if a piece of air-dry compressed gun- 
cotton, weighing about 0-5 ounce (14 grms.), be placed in contact with it and detonated 
by means of two or three grains of confined mercuric fulminate, the moist gun-cotton is 
* In the attempts made by me and by Mr. E. C. Prentice, a few years ago, to moderate the rapidity of ex- 
plosion of gun-cotton sufficiently for its safe application to propulsive purposes, the most successful results were 
obtained by uniformly impregnating the compressed explosive agent with solid substances ( e . g. india-rubber, 
collodion, paraffine, or stearine) applied with the aid of solvents which, on evaporation, deposit the diluent in 
the form of a film, continuous throughout the mass and completely enveloping each particle of gun-cotton. The 
rapidity with which explosion extends through a mass may be regulated to a considerable nicety by varying 
the strength of the solution of diluent employed or the thickness of the layer deposited between the particles. 
