116 
GUN-COTTON. 
is secured by its being washed in a stream of water for several weeks. Subsequently a 
weak solution of potash may be used, but this is not essential. The prolonged continu¬ 
ance of these processes, which would appear superfluous at first sight, is really essential, 
when we consider that each cotton fibre is a long, narrow tube, often twisted and even 
doubled up, and the acid has first to penetrate into the very farthest depths of these 
tubes, and has afterwards to be soaked out of them. Hence the necessity of time. 
It appears that gun-cotton, prepared in this manner, is a true chemical compound, and 
is not liable to the objections which have been urged against that mixture of compounds 
which has been usually employed in experiments. The advantages which it possesses 
may be classed as follows :— 
1. It is of uniform composition, and thus the force of the gases generated on explosion 
may be accurately estimated. 
2. It will not ignite till raised to a temperature of 300° F. (as a rule, the temperature 
must be raised much higher). This is considerably lower than the igniting point of 
gunpowder, but, being much above the heat of boiling water, it can only occur when 
artificially produced by means which would render gunpowder itself liable to ignition. 
3. It is almost absolutely free from ash when exploded under pressure in a confined 
space. 
4. It has a very marked superiority in stability over other forms of gun-cotton, having 
been kept unaltered for fifteen years. 
One great advantage which gun-cotton possesses over gunpowder, and which ought 
to have considerable weight in any discussion of their comparative uses for national pur¬ 
poses, is, that gun-cotton is unaffected by water. Gunpowder in a damp atmosphere 
will soon be completely spoiled, and it cannot afterwards be restored to a serviceable 
condition without being again submitted to the processes of manufacture, starting al¬ 
most from the commencement. Gun-cotton, on the contrary, although it gets damp in 
a moist atmosphere, rapidly returns to its ordinary state when exposed to air of average 
dryness. Complete immersion in water for an indefinite period has no injurious action 
on it, for when afterwards dried by exposure to the air, it is as good as ever. The ab¬ 
solute safety which this property would confer upon the magazines of forts and ships 
cannot be too highly urged ; the explosive material could be kept permanently in tanks 
full of water, in which case a lighted candle or even a red-hot shot would be a harmless 
visitant. When required for action, a centrifugal drying-machine and a hot-water closet 
would supply the combatants with any quantity at a few hours’ notice. 
When gun-cotton is ignited in a close vessel, such as a shell or the chamber of a gun, 
it is at once converted into certain gases, the principal being carbonic oxide, carbonic 
acid, nitrogen, light carburetted hydrogen, hydrogen, and steam. The introduction of 
the hyponitric acid, a compound containing a large excess of oxygen, gives to the cotton 
a sufficient amount of this gas to reduce it completely to the state of vapour ; but al¬ 
though only gases are produced, there is not enough oxygen for their complete com¬ 
bustion. About 40 per cent, are inflammable, and produce a bright flash when they 
emerge into the air from the mouth of the gun. 
II.— The Mechanics oe Gun-Cotton. 
The mechanical application of gun-cotton may be considered to be due exclusively to 
Major-General Lenk, of the Austrian service. Pure gun-cotton becomes either a power¬ 
ful explosive agent, or a docile performer of mechanical duty, not according to any 
change in its composition, or variation in its elements or their proportions, but according 
to the mechanical structure which is given to it, or the mechanical arrangements 
of which it is made a part. It was General Lenk who discovered that structure was 
quality, and mechanical arrangement the measure of power, in gun-cotton; and 
in his hands, a given quantity of the same cotton becomes a mild, harmless, ineffec¬ 
tual firework, a terrible, irresistible, explosive agent, or a pliable, powerful, obedient 
workman. 
The first form which General Lenk bestowed on gun-cotton was that of a continuous 
yarn or spun thread. Gunpowder is carefully made into round grains of a specific size. 
Gun-cotton is simply a long thread cf cotton fibre, systematically spun into a yarn of 
given weight per yard, of given tension, of given specific weight. A hank of a given 
length is reeled, just like a hank of cotton-yarn to be made into cloth, and in this state 
gun-cotton yarn is bought and sold like any other article of commerc?. 
