34 Professor Abel [March 21, 



important change ; the surface of the mass thus immersed becomes 

 white and opaque, apparently in consequence of some small absorption 

 of water, but no nitro-glycerine is separated, and on re-exposure to 

 the air the material gradually assumes once more its original aspect. 

 It has consequently been proposed to render the storage of blasting 

 gelatine comparatively safe by keeping it immersed in water till 

 required for use, but the test of time is still needed to establish the 

 unalterableness of the material under this condition. 



There can be little question that this interesting nitro-glycerine 

 preparation, either in its most simple form, or modified in various 

 ways, by the addition of other ingredients, promises, by virtue of its 

 great peculiarities as a detonating agent, to present means for im- 

 portantly extending the application of nitro-glycerine to industrial 

 purposes ; and it is not improbable that, through its agency, this most 

 violent of all explosive agents at present producible upon a large scale 

 may also come to acquire special value for important war- purposes. 



It has been pointed out that the complete solidification, by 

 freezing, of plastic preparations containing nitro-glycerine, such as 

 dynamite and the blasting gelatine, has the effect of facilitating the 

 transmission of detonation throughout the mass, and of thus developing 

 or increasing the violence of their action, under certain conditions of 

 their applications, i. e. when they are either freely exposed to air or 

 not very closely or rigidly confined. But while, under circumstances 

 favourable to the detonation of these substances, when in the frozen 

 state, their full explosive force is thus much more readily applied 

 than when they are in their normal (thawed) condition, the frozen 

 substances are less sensitive to detonation by a blow or an initiative 

 detonation. On the other hand, if subjected to the rapid application 

 of great heat (as for example by the burning of portions of a mass of 

 the explosive substance itself), a detonation is much more readily 

 brought about with the frozen material than if it be in its normal 

 condition. Thus a package containing 50 lb. of cartridges of plastic 

 dynamite, when surrounded by fire, burned away without any indica- 

 tion of explosive action ; on submitting 10 lb. of frozen dynamite to 

 the same treatment, that quantity also burned without explosion, 

 though at one time the combustion was so fierce as to indicate an 

 approach to explosive action ; but when the experiment was rej)eated 

 on the same occasion with 15 lb. of frozen dynamite a very violent 

 detonation took place after the material had been burning for a short 

 time, a deep crater being produced in the ground beneath. 



The following is offered as the most probable explanation of this 

 result. When a mass of dynamite, as in these cartridges, is exposed 

 to sufiicient cold to cause the nitro-glycerine to freeze, it does not 

 become uniformly hardened throughout, partly because of slight 

 variations in the proportion of nitro-glycerine in different portions of 

 the mixture composing the cartridge, and partly because unless the 

 exposure to cold be very prolonged the external portions of the 



