316 CHEMISTKY. 



part of much of our food. We burn it to keep ourselves 

 warm and to do our cooking. We spread it out in huge 

 sheets to the wind in our boats and ships. 



433. Gun-Cotton. If any form of cellulose in a divided 

 state, as cotton, linen, saw-dust, etc., be submitted for a 

 short time to the action of strong nitric acid, it becomes a 

 more explosive substance than even gunpowder. When 

 the discovery was first made it was proposed to use it in 

 place of powder, but this was found impracticable on two 

 accounts. First, it ignites so readily that it is very apt to 

 explode when we do not wish it. Secondly, its explosion 

 is too forcible and rapid, or, in other words, the gases pro- 

 duced expand too rapidly four or five times more so than 

 they do in the case of gunpowder. The consequence of 

 this quick expansion is that there is danger that the gases 

 will not have time to escape, as in the case of gunpowder, 

 at the outlet of the gun-barrel, and therefore the barrel is 

 very apt to burst. Gun-cotton can be prepared by immers- 

 ing cotton for about five minutes in strong nitric acid, and 

 then washing it thoroughly, and drying it. Care must be 

 taken to use but a moderate heat in drying it, lest it should 

 explode. The explanation of its explosiveness is that the 

 cotton loses a portion of its hydrogen and takes in its place 

 nitric peroxide, thereby increasing the number of atoms in 

 the molecule and its consequent instability. 413. The 

 reaction is shown in the following equation : 



Cellulose. Nitric acid. Gun-cotton. Water. 



C 6 H 10 5 + 3(HN0 3 ) = C 6 H 7 (NO 3 ) 3 5 + 3H 3 O 



Gun-cotton is often called trinitro-cellulose on account of 

 its composition, as shown in the formula just given. It 

 contains much more both of oxygen and nitrogen than 

 common cotton does. It is, then, like potassium chlorate, 

 a substance highly charged with oxygen, and on that ac- 

 count explosive. It is the oxygen that produces the com- 



