118 ANNUAL OF SCIENTIFIC DISCOVERY. 



tamping, a great saving of time and risk of life, impossible with 

 either of the others ; and it can be stored in damp cellars, or un- 

 der water, without the necessity of drying it before using, as in 

 the case of gun-cotton, or having it ruined, as with gunpowder. 



♦'And, lastly, the difficulty of exploding it renders it the least 

 dangerous to human life." 



DYNAMITE. 



M. A. Nobel read, at the last meeting of the British Association, 

 a paper on " Dynamite, a recent preparation of the nitro-glycerine 

 as an explosive agent." 



"It is nothing but nitro-glycerine absorbed in highly porous 

 silica; and if I have given it a new name, it is not by way of dis- 

 guise, but that its explosive powers are so much altered as fully to 

 warrant a new denomination. 



"Dynamite consists of 75 per cent, of nitro-glycerine and 25 

 per cent, of porous silica. Hence it appears to possess only three- 

 fourths of the power of nitro-glj'cerine, the specific gravity of both 

 substances being very nearly the same. But practically there is 

 no advantage in the greater concentration of power of nitro-glyc- 

 erine. It cannot, or at least ought not to be poured direct into the 

 bore-hole, since it easily causes accidents by leakage into crevices, 

 where it explodes under the miners' tools. It must, tlierefore, be 

 used in cartridges, which leave considerable windage ; whereas 

 dynamite, being somewhat pasty, easily yields to the slightest 

 pressure, so as completely to fill up the sides of the bore-hole and 

 leave no windage whatever. For this reason a given height of 

 dynamite charge in a hole will contain quite as much nitro-glyc- 

 erine as when the latter is used in its pure, liquid state. 



*' Besides the security derived from its solid form, dynamite has 

 over nitro-glycerine other special advantages. Its sensitiveness 

 to concussion is, as I have already stated, reduced in a very high 

 degree, and, since fire does not cause it to explode, it offers great 

 security for transportation and stowage. Besides, it is quite natu- 

 ral that miners should prefer, as more practical, a solid to a liquid 

 explosive. Dynamite is now generally sold in ready-made car- 

 tridges, and nearly all the workman has to do is to put them in his 

 bore-hole and fire. 



"It would be a great drawback on advantages here set forth, 

 if, as has been sometimes asserted, the fumes of nitro-glycerine 

 or dynamite were of a noxious nature. The best ansvt^er, perhaps, 

 to those who maintain that opinion is, that a great number of 

 mines are daily using it for underground work, and that the miners 

 do not at all complain. The truth is, that when nitro-glycerine is 

 allowed to leak into the crevices of a bore-hole, it does not all ex- 

 plode, and, being dispersed in the atmosphere, causes a severe 

 headache. It is, however, easil}^ remedied by using cartridges, 

 which prevent leakage, and, in the case of dynamite, which is a 

 solid, that inconvenience falls away entirely." 



The following is from an English paper : — 



