40 NOMOS. 



sides at once, and pulled asunder with a double 

 power. This is the true conception, and this con- 

 ception it is which enables us to understand the 

 readiness with which the decompositions of which 

 we have spoken are effected. The hydrogen which 

 is liberated from the first molecule of hydrochloric 

 acid when the molecule of chloride of zinc is formed, 

 must decompose the second molecule of hydrochloric 

 acid ; not because its affinity for the chlorine of this 

 molecule is stronger than that of the hydrogen pre- 

 viously combined with it, but because the hydrogen 

 is being pulled away from the chlorine in the con- 

 trary direction by the attraction of the platinum 

 element beyond. It is difficult to explain this idea 

 in words ; but it is sufficiently simple in reality, and 

 there is nothing in it which is not quite consistent 

 with the chemical hypothesis. It is difficult to 

 explain the idea in words, but there is less difficulty 

 with diagrams, and we think the two following 

 diagrams, with a little attention, will serve to express 

 the changes of which we have already spoken. The 

 diagram on the left hand, which is merely a repe- 

 tition of the one already given, represents the time 

 before the formation of the molecule of chloride of 

 zinc ; the diagram on the right hand represents the 

 changes which have taken place after the formation 

 of this molecule. It is not possible to represent 

 these changes in progress, but it is enough to re- 

 member that, originating in the formation of the 

 chloride molecule, they start simultaneously from 

 each side of the molecule and travel in opposite 

 directions around the circuit to its other side, and 



