THEORETICAL CONSIDERATIONS. 449 



board vessels during long voyages, even in high temperatures in 

 the tropics. 



6. Gun-cotton is very susceptible to explosions by influence. 

 According to experiments made in England, a torpedo, even 

 placed at a long distance, may explode a line of torpedoes 

 charged with gun-cotton. 



7. The velocity of the propagation of the explosion in metallic 

 tubes filled with pulverised gun-cotton has been found to be 

 from 5000 to 6000 mms. per second in tin tubes, and 4000 in 

 leaden tubes (Sebert). 



Gun-cotton loosely exposed in the open air burns eight times 

 as quickly as powder (Piobert). 



8. It is admitted that the effect of gun-cotton in mines is 

 very nearly the same as that of dynamite for equal weights. It 

 requires stronger detonation, and it gives rise to a large quantity 

 of carbonic oxide, which is sometimes difficult to disperse, 

 because the earth remains impregnated with the gas. Carbonic 

 oxide being very deleterious, the use of gun-cotton is dangerous 

 to workmen in mines, But the form of compressed gun-cotton 

 is more convenient, because it does not require resisting 

 envelopes, and because it preserves the form which is given to 

 it. Besides, it is less sensitive to shock by reason of its special 

 structure. Its use for firearms has been abandoned. 



9. Let us now examine gun-cotton a little closer from a 

 theoretical point of view. Its force depends upon its composi- 

 tion, and upon the nature of the products, which vary with the 

 density of the charge; that is to say, with the pressure 

 developed. 



10. We have, at p. 288, given a summary of the very in- 

 teresting researches of Sarrau and Vieille on this question. 



Let us simply remember that the substance studied by these 

 authors contained 



C 24-4 



H 2-4 



N 12-8 



56-5 



Water 1-4 



Ash 2-5 



that is to say, abstracting the water and the ash 



C ... ... 25-4 



H 2-5 



N 13-3 



58-8 



the formula C 2 4Hi 8 (N0 3 H) 11 9 requires 



C ... 25-2 



H 2-6 



N 13-5 



58-7 



2 G 



