THERMAL DECOMPOSITION OF OZONE 443 



moisture on chemical change, being regarded in many quarters 

 as too speculative. 



Other gases and particularly those which might be expected 

 to be incapable of combining with ozone have been shown by 

 Jones and the writer to be without influence on the decomposi- 

 tion of ozone. In the presence of these gases, the rate of 

 decomposition of ozone is dependent only on the concentration 

 of the ozone and the temperature. It will be convenient to 

 consider separately the inert diluents, as our results are not in 

 all cases entirely in agreement with those of previous workers. 



Jahn maintains that his results demonstrate that the rate of 

 decomposition of ozone is inversely proportional to the con- 

 centration of the oxygen mixed with the ozone and he has 

 elaborated a theory of the mechanism of the decomposition of 

 ozone based on this alleged fact. His hypothesis is that there 

 exists between ozone molecules, oxygen molecules and oxygen 

 atoms an equilibrium expressible by the equation : 



3 $0, + 0; 



that this equilibrium is instantly established ; and that the 

 destruction of the ozone molecules is effected by interaction of 

 ozone and the oxygen atoms according to the equation : 



O, + O -> 20,, 



the last change being a slow one and irreversible at a low 

 temperature. 



The hypothesis is a plausible one but the fact on which it is 

 based is contested by Jones and the writer. The results (J.C.S. 

 1910, 97, 2470) of a series of experiments, in all of which compari- 

 son with a control experiment was made, demonstrate that the 

 concentration of the diluting oxygen is without effect on the rate 

 at which the ozone is decomposed. Therefore, in our opinion, 

 in accounting for the breaking up of the ozone molecules, the 

 oxygen molecules can be left out of consideration. 



Nitrogen and carbon dioxide have also been shown to be 

 inert in promoting the reconversion of ozone into oxygen. That 

 the latter gas should be inert is interesting, as it is proof that 

 the high percentage of ozone found in the oxygen obtained by 

 the decomposition of carbon dioxide by means of the silent dis- 

 charge is not due to the ozone being rendered more stable by 

 the presence of the carbon dioxide. 



By far the most interesting conclusion drawn from our work 



