526 Prof. J. J. Thomson on the Relation between the 



neighbouring H atom, and also that required to separate the 

 + charge on the CI atom from the — charge on the atom 

 with which it is paired. Thus this disposition of molecules, 

 by diminishing the electrostatic attractions, increases the 

 chance for the — H and 4- CI to interchange their charges in 









Fig. 5. 









CI 



CI 



H 



4- 



H CI 



- 4- 



CI 



H 



4- 



H 





+ 

 H 









Cl 



""+ 



H 



Cl 



+ 



CI H 



4- 

 H 



CI 









(a) 









Cl- 



CI 



H 



4- 



H CI 

 4- — 



CI 



H 



4- 



4-H 



H+ 



+ 

 H 



Cl 









-CI 





4- 

 CI H 



4- 

 H 



Cl 





response to the " Volta effect : " after this interchange has 

 taken place the adjacent H and CI atoms will have respectively 

 4- and — charges, i. e. charges suitable for the formation of 

 the HC1 molecule ; if such molecules form, the ring will be 

 disposed as in fig. 5, b. This disposition will not be stable, 

 since the lines joining the negative to the positive atoms in 

 the molecule do not all point in one way ; the ring will 

 consequently break up into separate HC1 molecules. 



Thus, on this view the chemical combination consists in the 

 formation of an aggregate of a large number of H and CI 

 molecules, then the interchange of the charges on some of the 

 atoms, then the formation of an aggregate of HC1 molecules, 

 and finally the breaking up of this aggregate into a number 

 of separate molecules of HC1. It will be noticed that there 

 are no atoms set "free" during the whole of the process. 

 The presence of free charged atoms during the progress of] 

 chemical combination between gases could be detected by ex- 

 periments made on the electric conductivity of the mixture 

 whilst the combination is proceeding. If free charged atoms 

 are present they will move under electromotive forces, and 

 will cause the mixture of gases to act as a conductor of elec- 

 tricity. A method of testing the conductivity of gases and 

 the results of experiments made with it are given in a paper 



