3.—A fuze containing 9 grains of fulminate of mercury, strongly confined, exploded in contact with compressed gun-cotton, or dynamite, detonates it with certainty.
4.—An equal quantity of fulminate of mercury, similarly confined, does not detonate uncompressed gun-cotton in which it is imbedded, but merely disperses and inflames it.
5.—150 grains of compressed gun-cotton, detonated in proximity to dynamite, detonates the latter.
6.—3 ounces of dynamite, and very much larger quantities, detonated in contact with compressed gun-cotton, only disperses it.
7.—A wrought-iron rail can be destroyed by detonating 8 ounces of compressed gun-cotton placed unconfined on the rail.
8.—A piece of wet gun-cotton, quite uninflammable, removed from a fire, and detonated upon a block of granite, using a small primer of dry gun-cotton, shatters the block.
9.—A submerged charge of wet gun-cotton, open on all sides to the water, and merely confined around the dry initiative, or primer, by means of a net, can be exploded.
Explosive Agents in Torpedoes.—The explosive agents that at the present time are most generally used in torpedoes are gunpowder, gun-cotton in the wet compressed state, and dynamite, and these may be compared as to their properties and their explosive effects.
Gunpowder.—Gunpowder is a familiar material, in general use for all military purposes. It can be handled and transported with safety and ease, and it can be fired by ordinary methods. But for submarine purposes it has the disadvantage of being very easily injured by water, so that it is absolutely necessary to enclose it in water-tight cases.
Gun-cotton.—Gun-cotton is free from liability to accidents, and in this matter, and the safety of its manufacture, it compares favourably with gunpowder.