68 
MINUTES OE PROCEEDINGS OF 
We may then try what explosive power the cotton has when it is sub-* 
stituted for powder as the bursting charge of a shell. For this purpose the 
cotton must be made up in a form rather different from that in which it was 
applied as a firing charge, but if rightly prepared, and duly apportioned to 
the capacity of the shell, it will produce about twice as many fragments as 
w'ould be obtained from a corresponding shell burst by a charge of powder. 
We may test the same kind of power in other ways less connected with the 
artillery service, such as blasting rocks or removing any kind of obstacle* 
and the observations will corroborate the first result in showing that gun¬ 
cotton can exert a greater explosive power than gunpowder. 
So far the comparison is easily made, and the results are self-evident, but 
a more difficult inquiry remains. It is important, in order to become 
thoroughly acquainted with gun-cotton, to determine the rate of its ex¬ 
plosion, the temperature generated at the moment of explosion, and the 
compounds produced by the explosion. It is also desirable to measure the 
dynamic force exerted by charges of gun-cotton under various conditions, 
and information on these points can only be gained by delicate observations 
and experiments conducted with great care. None of them have yet been 
sufficiently determined. It has indeed been learned that the rate of explosion 
depends very much on the amount of space which the cotton occupies, and 
that the rate may be varied from one foot per second up to one thousand feet 
in the same unit of time,* but the means of regulating it by previous calcu¬ 
lation, so as to give the required result in every case, are not yet established. 
It is on this power of regulating the rate of explosion that the practical 
value of gun-cotton for artillery purposes mainly depends, and its too rapid 
explosion in the early trials was enough to justify its rejection at that time. 
The difference between an instantaneous and a progressive ignition of the 
charge is all-important. The former has such an immediate effect on 
the surrounding material that the breech of a weak piece would be blown 
out before the movement of the shot could give the gases a free exit at the 
muzzle; it is, in consequence, far more dangerous to the gun, and even if 
the construction is strong enough to bear the strain there is less velocity 
communicated to the shot. 
But if the rate of explosion can indeed be regulated under all circum¬ 
stances with such exact nicety as to combine the maximum of effect on the 
range and velocity of the shot with the minimum of strain upon the gun, the 
superiority of gun-cotton over gunpowder for the charges of fire-arms will 
be quite indisputable. With gun-cotton charges the absence of fouling 
would enable the windage to be reduced, or in other words allow of a better 
fit between the shot and the bore, in muzzle-loading pieces, and the accuracy 
of the firing could not fail to be increased thereby. The velocity and range, 
if not improved, would remain at least equal to what are at present obtained. 
Firing might be carried on in closed batteries at a continuous rate which is 
now unattainable because of the heating of the guns and the volumes of 
smoke. The service of the guns would be facilitated in all cases by the 
saving of labour which results from the smallness of recoil, the absence of 
* Mr Abel has lately shown some experiments, in his lectures on gun-cotton, in which he 
controlled the ignition of gun-cotton thread to an extent far beyond what is here mentioned. 
