DETONATION OF HIOH EXPLOSIVES OR BY THE IMPACT OF BULLETS. 451 



developed must be that which would l,e reached if the cotton were fired in a closed 

 chamber of a volume not greatly exceeding that of the slab. The pressure is then 

 d,8sipated with great rapidity by the expansion of the gas, which is resisted only !,y 

 its own inertia and that of the surrounding air. 



Experiments on the detonation of gun-cotton have been made by the method 

 described m this paper. It has only been possible hitherto to use quite small charge 

 and the results are a very rough approximation, but as they thmw light .,., a matter 



Fig. 12. 



of which little is known I have thought it worth while to give them. Briefly, 

 the conclusion is that the pressure at a point distant of an inch from the surface of 

 one ounce of dry gun-cotton (a cylindrical " dry primer " about 1^ inch diameter and 

 l inches long), when detonated with fulminate, has fallen to less than J of the 

 maximum value within 2 x 10~ 8 seconds. At least, 80 per cent, of the blow has been 

 delivered within that time. Over an interval of 10~ 6 seconds round about the time 

 of maximum pressure the average pressure is alxmt .'30 tons per square inch, and tlu- 



3 M 2 



