AND SCHONBEIN 75 



is decomposed by heat, I made the following experi- 

 ments. Ozone was produced in a large flask by the 

 usual chemical method in as large quantities as 

 possible, and a suitable arrangement was made 

 whereby the atmosphere charged with ozone was 

 caused to pass through a narrow glass tube into the 

 air. As long as the tube was not heated, the issuing 

 air had a smell quite indistinguishable from that 

 noticed in the neighbourhood of a point from which 

 electricity is being discharged, and it also produced 

 all the chemical and voltaic reactions which are 

 characteristic of chemical, voltaic and electrical ozone. 

 Thus it gave a negative charge to platinum, it turned 

 starch paste containing potassium iodide blue, it 

 destroyed vegetable colours, etc. But if about an 

 inch of the tube is heated by means of a spirit lamp 

 the peculiar smell disappears, and at the same time 

 the air loses all its peculiar properties. If the tube 

 is allowed to cool again, all these properties reappear. 

 Voltaic ozone of course behaves in exactly the same 

 way under the same conditions. The complete 

 similarity of the action of heat on chemical, voltaic 

 and electrical ozone may serve as a further proof of 

 the identity of these substances. 



A few days ago my friend Marignac l of Geneva 

 informed me of the results of the experiments which 

 he has carried out with a view to the isolation of 

 ozone and the determination of its properties. They 



1 Jean Charles Galisard de Marignac, born at Geneva in 

 1817, died in 1894. Professor of chemistry at the University 

 of Geneva from 1842 to 1878. 



