48 NOMOS. 



ment, and form the molecule of chloride of zinc, 

 C I z n. Passing to the left, the hydrogen which is 

 abandoned by the chlorine for the stronger attraction 

 of the zinc, is found to initiate a similar series of 

 changes. Abandoned in this manner, the H tends 

 to unite with Pt f , liberating p#; Ft tends to unite 

 with c ?/, liberating c u ; cu tends to unite with 

 z n' s and thus z n is left at liberty to unite with c I' 

 and form a molecule of cZ' zn. When the cir- 

 cuit is closed, therefore, we have to do, not only 

 with certain affinities, by which the cZ' and zn 

 incline to leave the elements with which they were 

 previously in combination, and to unite with each 

 other, but we have also a double transmission of 

 molecular changes around the circuit, by which the 

 cZ' and zn are left more at liberty to obey their 

 natural affinities by the withdrawal of the elements 

 which had previously occupied these affinities. But 

 when the circuit is left open the transmission of these 

 changes is impossible, and the cZ' and zn are there- 

 fore prevented from fully yielding to their natural 

 affinities, because these affinities are already occupied 

 by other objects. The case, in fact, is plain enough, 

 and the decompositions and recombinations must be 

 more energetic when the circuit is closed than when 

 the circuit is open; but in neither case is there any 

 necessity to invoke to the explanation the help of 

 other than simple chemical powers. 



Nor is there any reason to believe that the laws 

 of chemical affinity are ever suspended in the gal- 



