

J874.] History of Explosive Agents. 161 



and constant in composition than the iodide of nitrogen, might usefully 

 contribute to our knowledge of the behaviour and relation to each other 

 of explosive substances. 



Experiments were first carried on with tubes of cast and wrought iron 

 of different diameters and lengths. The explosive agents used were gun- 

 cotton, in different mechanical conditions, dynamite, mercuric fulminate, 

 and preparations containing the latter as an ingredient. Interesting 

 results were obtained, among others, in the course of these experiments, 

 demonstrating a want of reciprocity in behaviour between gun-cotton and 

 mercuric fulminate, as regards the transmission of detonation from one 

 to the other, similar to that previously observed in the case of nitro- 

 glycerine, chloride of nitrogen and gun-cotton, and showing also how 

 greatly the results, as regards transmission of detonation, may be altered 

 when certain limits in respect to the quantity of material employed as 

 the initiative detonator, are exceeded. Thus 7 grammes of strongly con- 

 fined mercuric fulminate, inserted into one extremity of an iron tube only 

 152 metre (6 inches) long and '025 metre (1 inch) in diameter, was the 

 minimum amount required to determine the detonation of gun-cotton 

 placed in the other extremity of the tube, being at least fifty times the 

 amount requisite to ensure detonation of compressed gun-cotton when 

 exploded in close contact with the latter ; but the detonation of 7 grammes 

 of compressed gun-cotton in one extremity of a channel 2' 128 metres 

 (7 feet) long and '031 metre (1'25 inch) in diameter, consisting of two 

 iron tubes placed end to end, accomplished the detonation of fulminate 

 inserted in the other extremity. When 14 grammes of confined fulminate 

 were employed, detonation of gun-cotton was accomplished through a 

 channel 2-129 metres (7 feet) long and '031 metre (1'25 inch) in diameter, 

 while 7 grammes only just sufficed to develop detonation through a tube 

 of smaller diameter and only *152 metre (6 inches) long, and 10 grammes, 

 through a similar tube only -228 metre (9 inches) long. The foregoing 

 are quoted as illustrations of the instructive results obtained in these 

 experiments. 



A few"experiments werejmade on a comparatively large scale with the 

 above-named explosives, with the view of ascertaining the influence of 

 the material composing the tube, upon the effect produced ; and some strik- 

 ing results were also obtained by interposing very slight obstacles (e. g. 

 loose tufts of cotton wool) in the path of the gas-wave, and thus checking 

 the transmission of detonation, which was certain when the path was 

 unobstructed. But these points were more closely investigated by a 

 series of accurate experiments upon a small scale with silver fulminate, 

 the tubes used being alike in diameter and thickness, but varying in 

 length, and consisting of different materials, viz. glass, pewter, brass, 

 paper, and vulcanized india-rubber. The principal results obtained by 

 the larger operations with other explosives were confirmed by these small 

 experiments, and several additional interesting observations were made. 



