484 



On the Action of Electricity on Gases. [June 19, 



the conditions of the experiment, could not be exceeded. It occurred to 

 me as possible to replace the 80 per cent, of oxygen unaffected by the 

 action of the electricity by an indifferent gas, and thus to effect the 

 complete conversion of oxygen into ozone. This idea was the starting- 

 point of the following investigation. 



When pure and dry carbonic-acid gas is subjected in the induction-tube 

 to the electric action, a certain proportion of the gas is decomposed into 

 carbonic oxide and oxygen, a portion of which appears in the form of 

 ozone. The presence of this ozone may be detected by its odour and the 

 characteristic oxidations produced by it. 



It was a point of fundamental importance to determine whether the 

 ozone thus generated was the same in kind as that formed by the action 

 of electricity on pure oxygen, and whether the oxidations referred to were 

 exclusively due to it ; for it was quite conceivable that under the peculiar 

 circumstances of the experiment other substances capable of producing 

 similar oxidizing effects might be formed. Now, in the investigation 

 before referred to, I had discovered certain quantitative reactions of 

 ozone by which this substance is discriminated from all other known 

 gases, and by which its presence may be detected and its quantity 

 estimated. The electrized carbonic-acid gas was examined by the aid of 

 these reactions. 



When the electrized gas was passed through a solution of hyposul- 

 phite of soda, it was found to undergo a diminution in volume equal in 

 amount to twice the " iodine-titre " of the gas, the mean of twelve expe- 

 riments giving for this value 1*9, the "titre" being 1. The oxidation also 

 effected in the solution of hyposulphite of soda was equal to three times 

 the "titre" of the gas, the mean of a set of five experiments giving for this 

 value, according to one method of estimation, 2*72, and according to a 

 second and more exact method 3 - 01. Again, the oxidation effected by 

 the electrized gas in a solution of protochloride of tin was equal to three 

 times the "titre" of the gas, the value found as the mean of six experi- 

 ments being 2' 77. In two experiments also, in which both the oxidation 

 and contraction were respectively estimated, 2*75 and 2-69 were the 

 values found for the oxidation, and 1*9 and 1*8 the values found for the 

 contraction, the "titre" of the gas being in all cases assumed as 1. These 

 experiments conclusively demonstrate the identity of the ozone formed 

 by the action of electricity upon carbonic-acid gas with the ozone simi- 

 larly generated from pure oxygen. 



Various experiments were instituted with the view of ascertaining the 

 conditions most favourable to the conversion of a large proportion of 

 this oxygen into ozone. The conclusion at which I arrived was that the 

 greatest proportion of ozone in relation to the total oxygen was pro- 

 duced when a rapid current of dry carbonic-acid gas was acted upon at 

 a low temperature by electricity of feeble tension. When these condi- 

 tions were realized, it was found that 75 per cent, of the total oxygen 



