482 



with sodium carbonate solution, in order to free it from all traces 

 of the acids. 



Nitroglycerine explodes violently, often from the slightest shock. 

 It owes this power to the fact that its carbon and hydrogen can 

 combine with the oxygen it contains to form carbon dioxide and 

 water: 



2C 3 H 5 (N0 3 )3 -> 6CO 2 + 5H 2 + 3N 2 (+O). 



The latter are very stable substances and much heat is liberated 

 in forming them. They are both produced as gases and, at the 

 high temperature of the action, they and the nitrogen tend to 

 occupy a great volume or to exert an enormous pressure in the 

 effort to do so. 



The explosion is also so sudden, compared with that of gun- 

 powder, that nitroglycerine would shatter the breech of a rifle 

 before the bullet had time to move. It also pulverizes rock, 

 instead of breaking it into fragments of usable size. For these 

 reasons, as well as on account of the danger in handling, and 

 impossibility of safely transporting the substance, it is made into 

 blasting gelatine (see below). The old form of dynamite was 

 made by soaking a porous earth (infusorial earth, kieselguhr) 

 with nitroglycerine. 



Guncotton. When cotton is steeped for half an hour in 

 a cooled mixture of nitric and sulphuric acids, it is converted into 

 cellulose trinitrate or guncotton : 



C 6 H 7 2 (OH) 3 + 3HN0 3 -> C 6 H 7 O 2 (NO 3 ) 3 + 3H 2 O. 



The equation, as written above, shows that three hydroxyl groups 

 OH in the empirical cellulose formula C 6 Hi 5 are replaced by 

 three nitrate groups N0 3 , with simultaneous formation of three 

 molecules of water. The sulphuric acid hastens the reaction and 

 carries it to completion by acting as a dehydrating agent and re- 

 moving this water (see p. 270). The fibers have the same appear- 



