GO 



and although we can point to some animal substances of a very 

 permanent character which contain nitrogen, nevertheless I am afraid 

 we must admit that on the whole the subject of our lecture is a fickle 

 and unreliable element. It is a constituent of almost every explosive, 

 and these owe their effectiveness to the ease with which nitrogen and 

 its associates part company and resolve themselves into gases, the 

 sudden production and expansion of which fractures and ruins their 

 environment, whatever that may be, unless properly confined or 

 regulated. The chief raw material for the old explosive gunpowder 

 was, as you know, saltpetre, but now, for the high explosives so-called, 

 nitric acid is employed. The aim of the manufacturers of these new 

 explosives, whose name is legion, is to get rid of all unnecessary 

 constituents and employ only such as will resolve themselves com- 

 pletely into gas, and as much of that as can be produced. In place of 

 sulphur and charcoal used of old in making gunpowder, cotton and 

 various forms of cellulose, glycerine and even sugar have been 

 substituted and nitrified or nitrised by nitric acid. In this way gun- 

 cotton is produced as well as nitroglycerine. The latter substance is 

 composed of C a H- N 3 9 and when exploded 2 molecules of it yield 6 of 

 carbonic acid, 5 of water, 1 of nitrous oxide and 4 of nitrogen, one part by 

 bulk will yield on combustion. 



554 volumes of aqueous vapour 



469 " carbonic acid 



39 oxygen 



236 " nitrogen 



1298 volumes in all. 

 But M. Noble tells us that the heat set free by explosion causes 

 the gases to expand to eight times their bulk ; so that one volume of 

 nitroglycerine will yield 10,384 volumes of gas while one part by bulk 

 of ordinary gunpowder yields only 800 volumes. Noble was not the 

 discoverer of nitroglycerine. The first inventor was Sobrero, in 1S47 

 while a student in the laboratory of Pelonze at Paris. Noble began its 

 manufacture 15 years afterwards in 1S62. From that sleep of 15 

 years it has awakened with such violence as almost to make people 

 wish it had never been invented. 



(Continued on page 69.) 



