Proposed Substitutes for Gunpowder. 91 
retain their original appearance and explosive characters. 
Several large ammunition-cases, closely packed with gun- 
cotton, have been preserved for six months in a chamber, 
the temperature of which was maintained for three months 
at 492 C. (1202 F.), and afterwards at 542—55° C. (1308 F.), 
arrangements having been made for periodically 
registering the temperature within the boxes, which were 
kept closed. In no instance has the latter temperature 
risen to an extent to indicate serious chemical change, z. ¢., 
it has always been below the temperature of the air in the 
chamber. These few examples of results already obtained 
are given to show that the behaviour of gun-cotton manu- 
factured in England by Von Lenk’s process, does not, as 
yet, at all justify the condemnation which the material has 
recently received in France. 
One most important point in connection with the preser- 
vation of gun-cotton, appears to have been lost sight of by 
the French experimenters. The material may be most 
perfectly preserved, apparently for any period, either by 
immersion in water, or, still more simply, by being impreg- 
nated with just sufficient moisture to render it perfectly 
uninflammable. In this condition, gun-cotton is much 
safer than gunpowder can be rendered, even by mixture 
with very large proportions of incombustible materials. It 
may be transported with quite as much safety as the un- 
converted cotton; indeed, it appears to be very much less 
prone to gradual decay, if preserved for very long periods 
ina damp condition, than cotton or other vegetable sub- 
stances. Many specimens of gun-cotton, preserved for 
several months in a very damp chamber, together with 
paper, cotton fabrics, and wood, retained their strength of 
fibre and all their original properties, and no signs even of 
mildew upon them, while the paper fabrics in immediate 
contact with them had completely rotted away, and the 
wood was covered with fungi. 
Considerable progress has been made in the manipula- 
tion of gun-cotton, with the object of modifying its 
explosive action. The rapidity with which gun-cotton 
burns 77 open air admits of ready and very considerable 
variation by applying the simple expedients of winding, 
twisting, or plaiting, gun-cotton yarn of different sizes, 
But, although a mass of gun-cotton may be made to burn 
in a comparatively gradual manner by being very tightly 
wound, a charge of the material in that form acts quite as 
destructively when exploded in the bore of a gunas an 
