406 DEFINITE NON-CAEBUKETTED EXPLOSIVE COMPOUNDS. 



temperature and pressure. The initial pressure will therefore 

 at once attain its maximum, and nitrogen chloride at once yield 

 the whole work of which it is capable, whether in dislocating 

 the materials on which it acts, or by crushing them, if they are 

 not sufficiently compact, or, lastly, by communicating to them its 

 energy under the form of movements of projection and rotation. 



Moreover, the pressure will decrease very suddenly, as much 

 by the fact of these transformations as by that of the cooling 

 and of the expansion of the gases ; and it will decrease without 

 any fresh quantity of heat, gradually reproduced, intervening to 

 moderate the rapid fall in pressure. An enormous initial 

 pressure, becoming almost suddenly lowered, are conditions 

 eminently favourable to the rupture of vessels containing 

 nitrogen chloride. 



These conditions contrast with those which accompany the 

 combustion of powder, as in the latter the final state of combina- 

 tion of the elements is not produced at the very first in a com- 

 plete manner, but becomes more advanced according as the 

 temperature falls. The initial pressure could therefore be less 

 with powder than with nitrogen chloride. But, to compensate 

 this, it decreases less quickly, owing to the intervention of the 

 fresh quantities of heat produced during the period of cooling. 

 These considerations have already been insisted upon (p. 12). 



In order to fully explain the differences observed between the 

 properties of nitrogen chloride and those of ordinary powder, 

 the duration of the molecular reactions must also be taken into 

 account. 



The almost instantaneous transformation of nitrogen chloride 

 develops pressure of which the sudden increase does not give 

 the surrounding bodies time to put themselves into motion, and 

 thus gradually yield to these pressures. It is well known that 

 a film of water on the surface of nitrogen chloride is sufficient 

 to produce such effects. 



11. This would be the proper place to speak of nitrogen 

 iodide, a compound so sensitive to shock and to friction that it 

 is hardly possible to isolate it. Everybody has seen the experi- 

 ments of which this body is the subject in public lectures. 

 But it is so unstable that up to the present it has not been 

 possible to determine its composition with certainty. No 

 attempt has been made to measure its heat of formation. 



4. POTASSIUM CHLORATE: C10 3 K 



1. Potassium chlorate is not explosive by simple shock or 

 friction at the ordinary temperature. However, the powdered 

 salt, wrapped in a thin piece of platinum foil and strongly struck 

 with a hammer on an anvil, yields some chloride; that is to 

 say, it undergoes partial decomposition. 



