OZONE. 351 



ozone by the mercury, that is, the disappearance of the 

 ozone from the mixture, was accompanied by no diminution 

 of volume at all. In other words, returning to our illustrative 

 case, after the absorption of the ozone from the ninety -five 

 cubic inches occupied by the mixture, there still remained 

 ninety-five cubic inches of oxygen ; so that it seemed as 

 though an evanescent volume of ozone corresponded in 

 weight to five cubic inches of oxygen. This solution, of 

 course, could not be admitted, since it made the density of 

 ozone infinite. 



The explanation of this perplexing experiment is full of 

 interest and instruction. The following is the account given 

 by Mr. C. W. Heaton (Professor of Chemistry at Charing 

 Cross Hospital), slightly modified, however, so that it may 

 be more readily understood. 



Modern chemists adopt, as a convenient mode of repre- 

 senting the phenomena which gases exhibit, the theory that 

 every gas, whether elementary or compound, consists of 

 minute molecules. They suppose that these molecules are 

 of equal size, and are separated by equal intervals so long as 

 the gas remains unchanged in heat and density. This view 

 serves to account for the features of resemblance presented 

 by all gases. The features in which gases vary are ac- 

 counted for by the theory that the molecules are differently 

 constituted. The molecules are supposed to be clusters of 

 atoms, and the qualities of a gas are assumed to depend on 

 the nature and arrangement of these ultimate atoms. The 

 molecules of some elements consist but of a single atom ; 

 the molecules of others are formed by pairs of atoms ; those 

 of others by triplets ; and so on. Again, the molecules of 

 compound gases are supposed to consist of combination? 

 of different kinds of atoms. 



Now, Dr. Odling, to whom we owe the solution of the 

 perplexing problem described above, thus interpreted the 

 observed phenomena. A molecule of oxygen contains two 

 atoms, one of ozone contains three, and the oxidizing power 

 pf ozone defends on the ease with which it parts with its third 



