WOOD. 355 



sively for scenting soap. -Its vapor, mixed with air, is 

 also burned as gas. The heavy oil may be converted 

 by a different action of the same acid, into beautiful 

 lemon-colored crystals of carbazotic acid, a substance 

 now used in France as a yellow dye for silks and wool. 



894. OILS FROM COAL. The oils may 



How are oils ,,';"", 



produced from be directly produced from bituminous coal 

 itself, and in much larger quantities than 

 from tar, by avoiding the high temperature to which 

 coal is subjected in the production of tar and gas. 

 The production of oils by this means promises to 

 be a very important branch of industry. 



895. GUN-COTTON. This material, so 



How is gun- 

 cotton pre- entirely harmless in appearance, has an 



pared? explosive energy superior to that of gun- 



powder. It may be prepared by immersing ordinary 

 cotton, for the space of five minutes, in the strongest 

 nitric acid. It is then to be washed thoroughly, and 

 dried at a moderate heat, for fear of explosion. The 

 material is found to have lost a certain portion of its 

 oxygen and hydrogen, in the form of water, and to 

 have assumed nitric acid, in its place. It is not how- 

 ever changed in its appearance. A mixture of nitric 

 acid with two-thirds of its volume of oil of vitriol, is 

 found to be preferable to pure nitric acid, in the above 

 experiment. The oil of vitriol assists in abstracting 

 from the cotton the water which it is desired to replace 

 by nitric acid. Gun-gotton is also called pyroxyline. 

 Similar compounds, which are less explosive, may be 

 prepared from sugar and starch. 



