46 



NOMOS. 



the positive zinc element in the zinc molecule. But 

 all is changed when the circuit is completed by bring- 

 ing the zinc and platinum plates into metallic con- 

 tact, for then the molecular changes of which we 

 have just been speaking are transmitted simulta- 

 neously in both directions along the circuit ; and the 

 result is that, at one and the same time, the chlorine 

 is more or less liberated from the hydrogen with 

 which it was previously united, and the negative 

 zinc element is more or less liberated from the posi- 

 tive zinc element with which it was previously 

 united ; and being thus liberated, the chlorine and 

 the negative zinc element are more at liberty to obey 

 those mutual tendencies which would cause them to 

 unite in a molecule of chloride of zinc. All this 

 will appear more intelligible with the help of the 

 two following diagrams : 



Fig. 11. 



Fig. 12. 



The first of these diagrams represents the circuit 

 open ; the second represents the circuit closed. The 



