SUBSTITUTES FOR GUNPOWDEB. 
7S 
great stress upon the explosion of a specimen directly it was introduced into a vessel 
heated to 47° C. (il6°'6 F.). But, at Woolwich, a specimen of ordinary product which 
has been exposed now for twelve months to 65° C. (150° F.), has evolved only a small 
quantity of gas, and retains its original appearance perfectly. Several specimens, after 
having been exposed for some hours to a temperature of 90° C. (194° F.), during which 
period some nitrous vapours were in all instances evolved, have since been exposed to 
light in closed vessels for about twenty months, and still 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 Avhich was 
maintained for three months at 49° C. (120° F.), and afterwards at 54°-55° C. (130° 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, i. e. it has always been below the temperature 
of the air in the chamber. These few examples of results already obtained are given ta 
show that the behaviour of gun-cotton manufactured 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 preservation of gun-cotton appears 
to have been lost sight of by the French experimenters. The material may be most per¬ 
fectly preserved, apparently for any period, either by immersion in water, or, still more 
simply, by being impregnated with just sufficient moisture to render it perfectly unin¬ 
flammable. 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 unconverted cotton; indeed, it 
appears to be very much less prone to gradual decay, if preserved for very long periods 
in a damp condition, than cotton or other vegetable substances. 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 had no signs even of mildew upon them, while the paper fabrics in immediate con¬ 
tact with them had completely rotted away, and the wood was covered with fungi. 
Considerable progress has been made in the manipulation of gun-cotton, with the 
object of modifying its explosive action. The rapidity with which gun-cotton burns in 
opm air admits of ready and very considerable variation by applying the simple expe¬ 
dients 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 Avound, a charge of the material in that form acts quite as destructively 
when exploded in the bore of a gun as an equal charge consisting of the yarn wound 
very loosely, because the pressure of gas established by the first ignition of the charge 
renders the compact packing of the gun-cotton powerless to resist the instantaneous 
penetration of flame between the separate layers of the material. The assertion that a 
power had been acquired of controlling the explosive action of gun-cotton in a firearm 
by simply varying the compactness with which the material was twisted or Avound, has, 
therefore, proved quite erroneous. There are, however, two methods of reducing the 
rapidity of explosion of gun-cotton, which are much more likely to furnish successful 
results. The one consists in diluting the material by its admixture either with a less 
explosive A’ariety of gun-cotton or Avith some inexplosive substance, such, for instance, as 
the cotton in its original form. The latter mode of dilution has recently been applied 
by Messrs. Prentice to the construction of cartridges for sporting purposes, and they 
describe the results already arrived at as very promising. The second method of con¬ 
trolling the explosion of gun-cotton consists in consolidating the material by pressure 
into compact homogeneous masses, and in confining the first ignition of such compressed 
gun-cotton in the bore of the gun, to certain surfaces. The gun-cotton fibre in the form 
of yarn or plait may be compressed into very compact masses by being rammed into 
strong cylinders of pasteboard or other suitable material; but much more perfectly 
homogeneous and'solid masses are produced, independently of cylinders or other cases, by 
a method which Mr. Abel has recently elaborated, and which consists in reducing the 
gun-cotton fibre to a fine state of division or pulp, as in the process of paper-making, 
and in converting this pulp by pressure into solid masses of any suitable form or density. 
This method of operating affords also special facilities for combining both methods, 
dilution and compression, of reducing the explosive violence of gun-cotton. The 
