292 Proceedings of Societies, 
the nature and effects of the products into which it was resolved on ex- 
plosion. As to the chemical nature of the material itself, the gun-cotton 
differed from the gun-cotton generally made, in its complete conversion 
into a uniform chemical compact. General Leuk secured the production 
of his gun-cotton by several precautions. Of these the most important 
were, the cleansing and perfect dessication of the cotton as a preliminary 
to its immersion in the acid; the employment of the strongest acids 
obtainable in commerce ; the steeping of the cotton in a fresh strong 
mixture of acids, after its first immersion and consequent imperfect con- 
version into gun-cotton ; the continuance of this steeping for forty-eight 
hours. Equally necessary is the thorough purification of the gun-cotton 
so produced from every trace of free acid. There is one part of the pro- 
cess of the manufacture, the value of which is not open to doubt—viz., 
the treatment of the gun-cotton with a solution of silicate of potash, com- 
monly called water-glass. The chief advantages of the material were 
set forth in the mechanical report, but it was “here stated that the fact 
that gun-cotton is not injured by damp like gunpowder, is one of its re- 
commendations, while a still greater chemical advantage which it pos- 
sesses arises from its being perfectly resolved into gases on explosion, so 
that there is no smoke to obscure the sight of the soldier who is firing, 
or to point out his position to the enemy, and no residue left in the gun 
to be get rid of before another charge can be introduced. 
Mr Scott Russert, F.R.S., submitted the mechanical report. After 
a long and careful examination, the committee were able to understand 
and reconcile themselves to the tact that greater mechanical effects are 
produced from gases generated by gun-cotton than by those generated 
by gunpowder. The same quantity of gases and the same number of 
atmospheres seemed to be produced from both materials, and it did not 
appear to mechanical men that there was a greater advantage i in gun- 
cotton in that respect. ‘The next inquiry was into the distinctive nature 
between the action of these gases in gunpowder and the action of those 
gases in gun-cotton. The great waste of force in gunpowder constituted 
an important difference between it and the gun-cotton, in which there 
wasno waste. Gunpowder consisted of about 68 per cent. of solid matter, 
only 32 of which was useful gases. It might be seen, therefore, that one- 
third of gunpowder is not directly useful in producing gases. There was 
another peculiar feature of gun-cotton—it could be exploded in any 
quantity instantaneously. General Leuk had discovered the means of 
giving gun-cotton any velocity of explosion that is required by merely 
the mechanical arrangement under which it is used. Gunpowder in his 
hands had any speed of explosion, from one foot per second, to one in 
1000th of a second, or to instantaneity. The spontaneous explosion of a 
large quantity of gun-cotton is made use of when it is required to produce 
destructive effects, and it is found that the condition necessary to pro- 
duce instantaneous combustion is the absolute perfection of the closeness 
of the chamber containing the gun-cotton. On the other hand, if they 
desired gun-cotton to produce a different effect, they must provide for its 
slower combustion. It must be opened out mechanically, so as to occupy 
a large space, and in this state it can be made to act even more slowly 
than gunpowder, and the limits for the purposes of artillery. In general 
it is found that the proportion of 1llbs. of gun-cotton occupying one 
cubic foot of space, produce a greater force than gunpowder, and a force 
of the nature required for ordinary artillery. But each gun and each 
kind of projectile requires a certain density of cartridge. Practically, 
gun-cotton is most effective in guns, when used as a quarter to one-third 
