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CflAPTEK III. 



EXPLOSIVE OASES AND DETONATING GASEOUS MtXTtJRES. 



1. DIVISION OF THE CHAPTER. 



THIS chapter comprises the study of definite explosive gases ; 

 of detonating gaseoUs mixtures formed, for instance, by the 

 association of oxygen with a combustible gas ; of liquefied 

 mixtures of gas ; and, finally, of the mixtures of gas with com- 

 bustible dust. The Study of all these systems is connected 

 with that of the gases themselves. 



2. EXPLOSIVE GASES. 



1. There exists a certain number of definite gases, capable of 

 transforming themselves with explosion under the influence of 

 a shock, sudden compression, heating, the electric spark, etc. 

 Such are ofcone and the oxygenated compounds of chlorine, 

 which explode through sudden compression or heating. These 

 bodies are characterised by the fact that their formation, either 

 from ordinary oxygen, as in the case of ozone, or from their 

 elements, as in the compound gases, takes place with absorption 

 of heat. 



This last characteristic belongs also to other gases, whose 

 explosive decomposition could not be determined for a long 

 time, such as the oxygenated compounds of nitrogen, acetylene, 

 and some other hydrocarbon gases, arseniuretted hydrogen, 

 cyanogen, the vapour of hydrocyanic acid, cyanogen chloride, 

 the vapour of carbon disulphide. Latterly, however, the author 

 has succeeded in making gases of this kind explode under the 

 influence of mercury fulminate (p. 66). 



2. The heat liberated by the decomposition of explosive 

 gases is known. It is precisely equal to the heat absorbed in 

 formation (p. 115). Starting from this datum, we can then 

 calculate the pressure and the temperature developed by the 

 explosion according to Mariotte's and Gay-Lussac's laws, and 



