76 
CHEMICAL HISTORY AND APPLIANCES OF GUN-COTTON. 
established. It has already been ascertained by very recent experiments of the lecturer, 
that gun-cotton prepared and purified with the most scrupulous care, speedily under¬ 
goes some amount of decomposition when exposed to temperatures ranging from 82° to 
06° C.; it remains to be seen whether such decomposition, if once established by ex¬ 
posure of gun-cotton to some temperature within the above limits, will cease perma¬ 
nently, when the material is removed from the influence of heat, or whether precau¬ 
tions or efficient supplementary processes can be adopted in the manufacture, to coun¬ 
teract the tendency to change exhibited by gun-cotton under the above circumstances. 
These are only some of the points which need patient investigation before it is posi¬ 
tively known whether the requisite confidence can be placed in the material as an agent 
susceptible of substitution for gunpow r der. 
It has been ingeniously argued that a slight indication of spontaneous change in gun¬ 
cotton need give rise to no alarm, because gunpowder is also liable to slight spontaneous 
change, reference being made to the fact that a very minute proportion of the sulphur 
in that material has been noticed to undergo oxidation. It need hardly be stated that 
such a minute change cannot have the slightest effect upon the stability of the mecha¬ 
nical mixture, gunpowder, in which variations, as regards purity and proportions of 
ingredients, occur, to an extent which render this change of absolute insignificance;, 
whereas in the case of gun-cotton as now manufactured, the development of acid, how¬ 
ever minute the proportion, may very possibly give rise to an important disturbance of 
chemical equilibrium, in a compound, the stability of which is based upon the perfect 
uniformity of its composition ; and it may also be at once productive of further change, 
by the tendency which the acid itself has to exert chemical action upon certain ele¬ 
ments of the gun-cotton. 
The general properties of gun-cotton as an explosive agent have long been popularly 
known to be as follows :—When inflamed or raised to a temperature ranging between 
137° and 150° C. it burns with a bright flash and large body of flame, unaccompanied by 
smoke, and leaves no appreciable residue. It is far more readily inflamed by percussion 
than gunpowder; the compression of any particular portion of a mass of loose gun¬ 
cotton between rigid surfaces will prevent that part from burning when heat is applied. 
The products of combustion of gun-cotton, in air, redden litmus paper powerfully ; they 
contain a considerable proportion of nitric oxide, and act rapidly and corrosively upon 
iron and gun-metal. The explosion of gun-cotton, when in the loose, carded condition— 
the form in which it was always prepared in the early days of its discovery,—resembles 
that of the fulminates in its violence and instantaneous character ; in the open air it may 
be inflamed, when in actual contact with gunpowder, without igniting the latter; in a 
confined space, as in a shell or the barrel of a gun, the almost instantaneous rapidity of 
its explosion, when in this form, produces effects which are highly destructive as com¬ 
pared with those of gunpowder, while the projectile force exerted by it is comparatively 
small. 
Many attempts have been made, from time to time, to diminish the rapidity of ex¬ 
plosion of gun-cotton; but’ the only one attended by any success is that which, in 
General von Lenk’s hand, has led to the development of a system of mechanical arrange¬ 
ment of gun-cotton, as ingenious and simple as it is effective. By manufacturing the 
cotton into yarn, of different thicknesses and degress of compactness or fineness of twist, 
before its conversion into gun-cotton, this material is at once obtained in forms which 
not only burn Avith great regularity and much less rapidity, when used in the original 
condition, than the loose gun-cotton wool, but which also, when employed in the form 
of reels, wound more or less compactly, or when converted into plaits or hollow ropes, 
may be made to burn gradually, in a manner similar to gunpowder, or to flash into 
flame instantaneously, exerting an explosive action very far exceeding that of the latter. 
The modifications in the nature and degree of explosive force exerted by gnn-cotton, 
which are essential for its application to military and industrial purposes, as a substitute 
for powder, are therefore arrived at by means of very simple variations of the mecha¬ 
nical condition of the material. Thus, to obtain the gradual action essential for the 
employment of gun-cotton in cannon, cartridges are made up of coarse yarn, which is 
wound firmly round a hollow cylinder of wood, of dimensions regulated by the size of 
the gun-chamber and the weight of the charge used, the best result being obtained 
by so arranging the latter that the cartridge entirely fills the space allotted to the 
charge in the gun. Similarly, small-arm cartridges are made of cylindrical plaits of 
