THE ROYAL ARTILLERY INSTITUTION. 
fouling, and the diminished weight of the charge; the last being indeed of 
no importance with light pieces, but of sensible effect with very heavy 
artillery. Lastly, the shells would have a greater destructive power, on 
account of the increased violence of their bursting charge and the increased 
number of splinters produced. 
In small arms the advantages arising from the absence of fouling will be 
equally great, the accuracy of the aim being at present more impeded by 
that fault of the powder than by any defect in the barrel or the bullet. The 
loading will become easier, the piece will not be injured by any neglect in 
cleaning it, which is so liable to happen when a soldier is tired by a long 
day's skirmishing and marching, and any difference in weight of the gun or 
ammunition, or in simplicity of parts, will be on the favourable side. 
There remains one important feature of gun-cotton which has not yet 
been noticed. It has been hitherto spoken of as an explosive compound, 
and explosive it is, but when it is not subject to any pressure the explosion 
is harmless. 
If an ounce of loose gun-cotton be ignited in a common pair of scales the 
scale in which it rests will not be disturbed; whereas, with gunpowder the 
scale would be depressed. Similarly, a bag of gun-cotton will have no effect 
against a door or gate, although a bag of gunpowder will blow it open. If, 
however, the gun-cotton be put into a box, whose sides offer some resistance 
to the gases, it will do more harm than the gunpowder. The reason of this 
is that the force exerted depends on the quickness and completeness of the 
ignition. When the gases produced at the point of ignition are at all 
confined they rapidly penetrate the rest of the cotton, but when they have 
a free escape the ignition is communicated by degrees, and little or no force 
is exerted. 
The practical use of this gradual ignition is that gun-cotton may be 
used instead of quick match or trains of powder to carry fire to mines or 
other exploding charges. Loose gun-cotton laid as a train burns about 
1 ft. per second; gun-cotton woven into a hollow line and coated with india 
rubber burns about 30 ft. per second, because there is some pressure on the 
gases. The flame does not however have much destructive effect, for a line 
of this sort may be folded crossways without interrupting the regular 
progress of the flame from one end to the other. It does not leap from one 
point to another where the folds touch. If the gun-cotton is made into the 
form of a close twisted rope it explodes with some violence. 
The more perfectly the gases are kept inclosed, without means of escape 
or expansion, until the whole mass of cotton is ignited, the more powerful is 
the explosive effect. At the same time some little free space must be left for 
them as a channel of passage from the point of starting to every other part. 
If their passage is stopped and the penetration prevented the ignition is 
incomplete. For instance, if a piece of gun-cotton be held tightly between 
the fingers and one end of it be lighted the ignition will not extend to the 
part where the pressure keeps the cotton close. It goes out on reaching 
the fingers, and there is so little heat or force that the fingers are not hurt. 
Large charges of gun-cotton require more management in this respect than 
similar quantities of gunpowder. The perfect ignition can however be easily 
ensured by making up the cotton in the form of a hollow twisted rope, how¬ 
ever close the chamber where it is exploded may be. 
