248 



EXPLOSIVES : MANUFACTURE AND USE. 



poles. One variety is the " collodion " of photographic plates; 

 another is the disruptive charge of torpedoes : from one arti- 

 ficial silk is made, and a similar one forms the base of nearly 

 all smokeless powders; one is the base of celluloid, out of which 

 most artistic articles are now made — even billiard balls — and 

 another is one of the two ingredients of blasting gelatine, of 

 which more is manufactured in South Africa than in any other 

 continent. Guncotton was discovered only one year before 

 nitro-glycerine, in 1846, by an Austrian chemist called Schon- 

 heim, and an Austrian military officer, called Von Link, dis- 

 played the greatest ingenuity in adapting it for firearms and 

 military purposes generally. He wove it into cloth, wound it 

 on reels for rifle charges, compressed it into slabs for cannon ; 

 tut all was of no avail, guncotton would not be tamed, and 

 after a series of most disastrous calamities, both in Austria and 

 in England, guncotton shared the same fate as nitro-glycerine; 

 It was apparently consigned to oblivion. 



I pass over all the pioneer work of Sir Frederic^ Abel, of 

 the British War Office, of Alfred Nobel, and merely say that 

 in due course these two remarkable bodies were tamed and 

 made amenable to ordinary manufacturing processes. Nowa- 

 days it is very seldom that an accident takes place during the 

 preliminary processes of manufacture of either. 



The chemical reactions involved in preparing these two 

 bodies are very similar. They are as follows : — 

 Chemical reactions involved in the making of Gun Cotton and Nitro-Glycerine. 



C,H,„0, + 3 HNO3 = CH; (NO,)3 + 3H,0. 



Cellulose + Nitric Acid = Gun Cotton + Water. 



C3H, (OH)3 + 3 HNO, = C3H, (ONO,)3 + 3 H,0. 

 Glycerine + Nitric Acid = Nitro Glycerine + Water. 



Composition of permanent gases produred on explosion. 



But I must abruptly leave these two most interesting bodies 

 to follow up another phase of explosives activity. Modern 

 explosives would be absolutely useless without caps, or detona- 

 tors. In general terms you all know what I mean by these. 

 The ordinary military and sporting cartridge is exploded by a 

 cap, which is in turn exploded by a striker or hammer. Shells, 

 shrapnel, and common and torpedo charges are exploded by 

 a more elaborate development of the same device; explosives 

 used for blasting purposes get their initial shock from a 



