1874.] History of Explosive Agents. 169 



wires. The trains of dynamite were arranged like those of gun-cotton, 

 compressed charges of this material, 3 inches (-0759 metre) long and 1 

 inch (-0253 metre) in diameter, being placed end to end or with definite 

 spaces intervening between them. The nitroglycerine was placed in V-- 

 shaped troughs of thin sheet metal, through which the insulated wires were 

 passed transversely at the requisite intervals, so as to be immersed in the 

 liquid. 



A number of experiments with dry gun-cotton compressed, demon- 

 strated that the rate at which detonation is transmitted from mass to 

 mass, when these are in actual contact with each other, is between 17,500 

 and 20,000 feet (5320 metres and 6080 metres) per second, and that the 

 rate of transmission is affected by the compactness of the material, but not 

 by a difference in the form and arrangement of the individual masses, nor by 

 very considerable variations in their weight. By the experiments with 

 spaced gun-cotton disks, it was demonstrated that the separation of the 

 masses may retard the rate at which detonation is transmitted, the extent 

 of such retardation being, of course, determined by the relation between 

 the size of the individual masses and the extent of space intervening be- 

 tween them. With compressed gun-cotton, containing fifteen per cent, 

 of water, detonation was transmitted at a slightly higher velocity than 

 with the dry substance of the same compactness ; but when gun-cotton 

 saturated with water was employed, the increase in the rate of trans- 

 mission was very marked, being equal to about 20,000 feet per second, 

 with disks which, when dry, detonated at a rate of about 17,500 feet per 

 second. With " nitrated " gun-cotton the rate of transmission was, as 

 might have been anticipated, decidedly slower than with the pure dry 

 material ; it ranged between 15,500 and 16,000 feet (4712 metres and 

 4864 metres) per second. 



The results obtained with dynamite and nitroglycerine presented some 

 very interesting points of difference from those furnished by compressed 

 gun-cotton, which are ascribable to the liquid nature of the explosive 

 material. The dynamite used was in the form of compressed rolls or 

 cylinders, similar in firmness or solidity to stiff but not very plastic clay. 

 Rows or trains of these charges, pressed together end to end, so as to 

 form perfectly continuous masses 28 feet (8'533 metres) and 42 feet 

 (12*8 metres) in length, were detonated by means of a fulminate detonator 

 of the kind used with gun-cotton, which was inserted into a small 

 cylinder of gun-cotton, or into a small cartridge of dynamite, and placed 

 upon one extremity of the train. The rate at which detonation 

 was transmitted ranged between 19,500 and 21,600 feet (5928 and 

 6566 metres) per second ; it was therefore decidedly higher than with 

 compressed gun-cotton. The separation of the individual cartridges 

 or cylinders by spaces of 0'5 inch ('013 metre) produced, however, a 

 very much greater retarding effect than was the case with a sepa- 

 ration to the same extent of masses of compressed gun-cotton; the 



VOL. XXIT. 



