422 NITKIC ETHERS. 



8. Permanent pressure, at (the liquid water occupies 

 237 c.c.) 



440 atm. 455 kgm. 



n - 0-237 ' C n - 0*237' 



a value only applicable to low densities of charge. 



9. Pressure at the theoretical temperature calculated accord- 

 ing to the laws of gases 



734 



273 / 22170 atm. 



n . n 



or 22,910 kgm. per square centimetre. 



5. NITROGLYCERIN: C 3 H 2 (N0 3 H) 3 . 



1. Nitroglycerin is considered the most powerful of explosive 

 substances. In spite of terrible accidents, its extraordinary 

 properties have been taken advantage of for industrial purposes. 

 The manufacture of nitroglycerin in France commenced on a 

 large scale during the siege of Paris, at the instance and under 

 the direction of the Scientific Committee of Defence. Since 

 then it has assumed an ever-increasing importance, dynamite 

 tending to replace blasting powder in the greater number of its 

 uses. 



It is not our intention to make here a complete study of 

 nitroglycerin and dynamites, nor of their industrial or military 

 applications ; but it enters into the scope of the present work 

 to present the figures which express the heat and pressure 

 developed by the explosive decomposition of nitroglycerin. 



We shall, therefore, devote a paragraph to pure nitroglycerin, 

 reserving the study of dynamites for the following chapter. 



2. Formula: C 3 H 2 (N0 3 H) 3 . 

 Equivalent, 227. 



3. Composition 



C = 159 



H = 22 



N = 185 



= 634 



1000 



4. Nitroglycerin is liquid, but solidifies at -f- 12. These 

 circumstances play an important part in the properties of 

 dynamite. 



The density of liquid nitroglycerin is T60. 



This body is very soluble in alcohol or ether, but only very 

 slightly soluble in water. Nevertheless, in presence of a 

 sufficient quantity of water, it is entirely dissolved, which does 



