204 ELEMENTARY PRINCIPLES OF GUNNERY. 



and the whole is blown away. This trifling advantage is, 

 however, entirely done away with by adopting explosive 

 paper for making up the powder into cartridges, as is prac- 

 tised by Mr. Prince with his breech-loader. But even this 

 is now rendered unnecessary by the increased strength of the 

 Government caps, which readily pierce paper of any thick- 

 ness which can be required for the purpose. 



An explosive cartridge paper may be made by preparing it 

 in the same way as described for guncottoo. The paper 

 should be porous ; and ordinary blotting paper answers very 

 well if made sufficiently stout. But this paper, like gun- 

 cotton, explodes at a temperature very little higher than 300 

 Fahr., and it is therefore dangerous to keep together any 

 number of cartridges enveloped in it. The plan is exceed- 

 ingly ingenious in theory, and for sporting purposes it is 

 practically well adapted, as it is easy to avoid the above heat 

 in this country, but for military cartridges the danger of 

 spontaneous combustion is too great when large masses of all 

 sorts of substances are brought together in the hold of a 

 ship; and even the magazine may possibly have its tempera- 

 ture raised to that degree. 



The various detonating powders used in the manufacture 

 of caps, disks, or tubes for firing the gunpowder of the 

 charges in our fowling-pieces and rifles are so rapid in their 

 combustion as to be useless as a substitute for the two mate- 

 rials which have been already described. Their explosive 

 force is so enormous arid sudden that they will burst the 

 barrel, however strong, instead of moving the projectile in 

 front of them, if employed in sufficient quantity to propel it 

 as far as gunpowder will do. So rapid is the combustion of 

 fulminating mercury, that if a train of gunpowder is crossed 

 by a train of it, and the latter is fired in the usual way, with 

 a poker or wire, the mercury, in its explosion, being more 

 rapid than that of the gunpowder, cuts off the connexion 

 between the two portions of the train, and the second half 

 is not fired at all. 



Fulminate of silver, which is even more rapid in its ex- 

 plosion, is prepared by dissolving 40 or 50 grains of silver (a 

 sixpence will be the most convenient) in J oz. by measure 

 of nitric acid of specific gravity 1*37 or thereabout?, with the 



