550 APPENDIX. 



diameter of 5 mm., the external diameter being 12 mm. and 

 the length 39'8 m. The velocity was found to be 1616 m. per 

 second. The tube after the explosion was rent in long plates in 

 the direction of the length of the tube. 



2. Glass tubes. Numerous experiments were made, but the 

 results were not very concordant. The following are extreme 

 numbers : 



Internal diam. Thickness. Velocity per second. 



3 mm. 4'5 mm. 2482 m. 



3 2-0 2191 



3 1-0 1890 



The thinnest glass tube resisted longer than the canvas-covered 

 caoutchouc, but the glass tubes were pulverised in every case by 

 the explosion. 



3. Britannia metal tubes, Experiments made with tubes 3 mm. 

 internal and 6 mm. external diameter, and about 50 m. long, all in 

 one piece, showed an average velocity of 1217 m. This metal 

 offers less resistance and breaks more quickly than the thinnest 

 glass and canvas-covered caoutchouc. 



4. Steel tubes. Specially drawn steel tubes, in uniform lengths 

 of 5 m., were obtained which had been very carefully annealed 

 by heating in a closed vessel for 42 hours, in order to prevent all 

 crystalline structure. The internal diameter was 3 mm, and the 

 external 15 mm. 



Experiments were made in tubes about 20 m. long, formed of 

 four lengths carefully joined together in a special manner. 



Average velocities of 2155 m, and 2094 m. were observed. All 

 the steel tubes operated with, opened during the explosion, and 

 were split into long plates as in the caoutchouc tubes. 



The fracture of such thick steel tubes shows that there is no 

 hope of being able to detonate a liquid explosive in a metallic 

 tube in its own volume without breaking it, whatever be the 

 thickness of the tube. This is explained by the fact established 

 by the theory of elasticity, that the resistance of a metallic tube 

 does not increase indefinitely with its thickness. The resistance 

 tends towards a certain limit beyond which the walls of the vessel 

 tear whatever be the thickness. Now explosive liquids, like 

 methyl nitrate, offer this remarkable property that the volume 

 defined by their density is less than the volume limit below which the 

 gases or liquids produced by the explosion are susceptible of being 

 reduced by the pressure developed in the limits of the experiments. 



It is known that gases cannot be indefinitely reduced in volume 

 by compression, their compressibility diminishing beyond certain 

 limits. This is still more the case with solids and liquids, the 

 volumes of which cannot be materially altered by pressure. 

 Suppose, for instance, that the gases produced by the explosion 

 of methyl nitrate carbonic acid, carbonic oxide, nitrogen, gaseous 

 water at about 3000, the temperature developed by the explosion, 

 tend towards a density near unity; then the possible volume of 

 the gas will be about one-fifth greater than that of the methyl 

 nitrate (density 1*182). Consequently the vessel will necessarily 

 be ruptured before the whole of the matter has detonated, and 



