NOMO8. 47 



case is not at all complex ; and a very little conside- 

 ration will serve to show that the chlorine C Z', and 

 the negative zinc element, zn, must have more 

 marked tendencies to unite with each other when 

 the circuit is closed than when it is open. When 

 the negative zinc element, zn, tends to unite with 

 the chlorine, cZ', it equally tends to leave the 

 positive zinc element, zn' 9 with which it was pre- 

 viously united; and this positive element is thus 

 left to exercise its peculiar affinities upon the con- 

 tiguous molecules. When, on the other hand, the 

 chlorine cZ', tends to unite with the negative zinc 

 element, zn, it equally tends to leave the hydrogen 

 with which it was previously united ; and this hydro- 

 gen is, therefore, at liberty to exercise its peculiar 

 affinities upon the contiguous molecules. And what 

 is the result ? The result is a series of decomposi- 

 tions and recombinations which travel simultaneously 

 in opposite directions around the circuit. Passing 

 to the right, the positive zinc element, zn', which 

 yields the negative zinc element, zn, with which it 

 was united, to the stronger affinities of the chlorine, 

 cZ', tends to unite with the negative element, cu, 

 of the contiguous copper molecule, liberating the 

 positive element, C u' ; this positive element tends to 

 unite with the negative element, Pt, of the con- 

 tiguous platinum molecule, liberating the positive 

 element, P^. This positive element tends to unite 

 with the contiguous hydrogen element, H, of 

 the hydrochloric acid; and thus the chlorine, cZ', 

 which was previously united with the hydrogen, is 

 left at liberty to unite with the negative zinc ele- 



