Xitro-Glycerinf. Explosives. 97 



Some qualities of Kieselguhr will absorb as much as 80';^ nitro- 

 glycerine, but about 75% is the average, and this is the proiX)rtion 

 in which it is generally manufactured. 



Nitro-glycerine, as I have already mentioned, freezes at about 

 i2°C., and all explosives containing it are affected the same way. 

 When Dynamite freezes it is converted into a hard stony mass, and 

 to get the .same explosive effect, as from unfrozen, a detonator three 

 rimes as strong as the usual must be used. It is very dangerous 

 to ram frozen Dynamite into a bore-hole, and it should always be 

 thawed before use, but many accidents happen through the care- 

 less performance of this simple operation. At Parma, in 1878. a 

 cavalry lieutenant killed and wounded 80 people l)y neglecting 

 ■ordinary precautions in thawing a little over 2 lbs. of Dynamite. 

 I have already referred to its one great drawback, viz.. the dis- 

 placement of the nitro-glycerine when it comes into contact with 

 water, and this as much as anything has led to its gradual extinction. 

 In its favour, however, it must be stated that it requires a much 

 more violent shock than nitro-glycerine to explode it, and it is not 

 nearly so shattering, the explanation being that a part of the initial 

 heat of combustion is absorbed in heating up the Kieselguhr, thus 

 reducing the initial pressure. 



So much then for Dynamite, and now I shall say a few words 

 about Blasting Gelatine, which is from the scientific as well as from 

 the technical point of view, a much more interesting body in every 

 way. I have already outlined how Nobel first came to think of 

 substituting the Kieselguhr of Dynamite by a body actually explo- 

 sive in itself. The result was the most powerful explosive which 

 has ever yet been made or ever is likely to be made. Xitro-cellulose 

 had been know-n and used for various purposes long before Nobel 

 brought out his Blasting Gelatine, and about i860 the Austrian 

 Government actually went to the length of deciding to adopt one 

 form of it called Gun Cotton for small arms and field guns. Terrible 

 accidents in Austria, as also in England, however, put a complete 

 stop to these projects, but, as I have already remarked, it took a 

 good deal of danger to daunt Nobel. Another form of nitro- 

 • cellulose, generally known as Collodion Cotton, has come into great 

 use, in photography principally, in the production of wet plates. 

 Nobel found that this Collodion Cotton was soluble in nitro- 

 glycerine, which in consequence became thickened or gelatinous. 

 The method of producing a nitro-cellulose suitable for the manu- 

 facture of a good Blasting Gelatine is a secret very jealously guarded 

 by manufacturers, and although it is now 25 years since Nobel tiled 

 his patent, there is still something to learn. The chemistry of nitro- 

 cellulose belongs to that branch which we call obscure, but the 

 point which all manufacturers seek to arrive at in practice is to use 

 as little nitrocellulose as possible in their Blasting Gelatine. It 

 would serve no useful purpose to inquire into the reasons for this, 

 but I would only say that the health of the miner and immunity from 

 accidents depend to a great extent on a -f 2% of nitro-cellulose, 

 and that the gelatinous explosive which has the minimum of nitro- 



