GUN COTTON. 103 



exploding with fearful violence on the contact of any 

 oleaginous body, and the latter by the smallest elevation 

 of temperature : both of them destroying the vessels in 

 which they may be contained. 



Gun cotton presents some peculiar phenomena 

 which may merit brief attention. This peculiar com- 

 pound is prepared by the action of nitric acid on 

 cotton fibre. The general appearance of the cotton 

 is not altered, but a remarkable physical change 

 has taken place. It is now soluble in ether, and 

 forms a gelatinous compound : it explodes violently 

 at a temperature which is insufficient for the combustion 

 of gunpowder. Indeed, from, as it would appear, slight 

 electrical disturbances taking place in the gun cotton 

 itself, it not unfrequently explodes spontaneously. These 

 fearful disturbances of the forces which hold bodies in 

 combination are explained with difficulty. May it not 

 be, that an enormous quantity of the calorific and 

 chemical principles is held in a state of extreme tension 

 around the particles of the compound, and that the 

 equilibrium being destroyed, the whole is developed in 

 destructive rapidity ? 



The fact of great heat being evolved during the con- 

 version of a body from a solid to a gaseous state, as in 

 the explosion of gunpowder or gun cotton, which is a 

 striking exception to the law of latent heat, as it prevails 

 in most cases, admits of no more satisfactory explanation. 



As mechanical force produces calorific excitation, so 

 we find that every movement of sap in vegetables, and 

 of the blood and fluids in the animal economy, causes a 

 sensible increase of heat. The chemical processes con- 

 stantly going on in plants and animals are another 

 source of heat, in addition to which nervous energy and 

 muscular movement must be regarded as producing the 

 caloric which is essential to the health and life of the latter. 

 Digestion has been considered as a process of combus- 

 tion ; and the action between the elements of food, and 



