1900.] on Some Modern Explosives. 339 1 



and I have on the tahle the internal crusher gauge which was used, 

 aud which was also totally destroyed. 



The condition of this gauge is very remarkable, and the action 

 on the copper cylinder employed to measure the pressure was one 

 to which I have no parallel in the many thousand experiments I 

 have made with these gauges. The gauge itself is fractured in the 

 most extraordinary way, even in some places to which the gas had 

 no access ; and the copper cylinder, which when confessed usually 

 assumes a barrel-like form — that is, with the central diameter larger 

 than that at the ends as shown in the diagram, Fig. V. — in this ex- 

 periment, and in this only, was bulged close to the piston as you 

 see. It would appear as if the blow was so suddenly given that the 

 laminae of the metal next the piston endeavoured to escape in the 

 direction of least resistance, that being easier than to overcome the 

 inertia of the laminae below. 



The erosive effect of the new explosives is another point of first 

 rate importance in an artillery point of view. The cordite of the 

 service is not, if the effect be estimated in relation to the energy 

 impressed on the projectiles, more erosive than, for example, brown 

 prismatic, which was itself a very erosive powder ; but as we are 

 able to obtain, as you have seen, very much higher energies with 

 cordite than with brown prismatic, the erosion of the former is, for 

 a given number of rounds, materially higher. 



There is, however, one striking difference. By the kindness of 

 Colonel Bainbridge, the Chief Superintendent of Ordnance Factories, 

 I am enabled to show you a section of the barrel of a large gun 

 eroded by 137 rounds of gunpowder. Beside it is a barrel of a 

 4 • 7-inch quick-firing gun eroded by 1087 rounds of gunpowder and 

 another eroded by 1292 rounds of cordite. You will observe the 

 difference. In the former case the erosion much resembles a ploughed 

 field. In the latter the appearance is more as if the surface were 

 washed away by the flow of the highly heated gases. 



But take it in what way you please, the heavy erosion of the 

 guns of the service, if fired with the maximum charges, is a very 

 serious matter, as with the large guns, accuracy, and in a smaller 

 degree energy, are rapidly lost after a comparatively small number 

 of rounds have been fired. 



Cordite was first produced for use in small arms only, where, 

 owing to the small charges employed, the question of erosion is not 

 of the same importance as with large guns, but its employment, from 

 the great results obtained with it, was rapidly extended to artillery ; 

 and the attention of my friends, Sir F. Abel and Professor Dewar, 

 has for some time been devoted, in conjunction with myself, to inves- 

 tigating whether it is not possible materially to reduce this most 

 objectionable erosion. 



With this object I made the following series of experiments. 



I had cordite of the same dimensions prepared with varying pro- 

 portions of nitro- glycerine and gun-cottoa. The nitro-glycerine 



