of Electricity through Hot Gases. 447 



action between the salt and the solvent, if the thermal effect 

 accompanying this action were to follow the logarithmic law, 

 that is if the thermal effect produced by increasing the 

 quantity of water by unity were inversely proportional to the 

 quantity of water already present. 



From the consideration of the preceding experiments we 

 may deduce, I think, the conclusion that it is the atoms, as 

 distinct from the molecules, which are instrumental in carrying 

 electricity from one place to another, and that the molecules 

 are electrically inactive. 



Many interesting questions arise as to how the atoms effect 

 this transference of electricity. Does each atom, for example, 

 carry a charge equal to that (10 — n in electrostatic units) 

 deduced from electrolytic considerations, and is this charge 

 unalterable ? 



In this connexion it is important to notice that all that 

 electrolysis teaches us is that each ion which comes up to the 

 electrode receives from it a definite and calculable charge. 

 It does not, however, give us any information about the 

 charges on ions under other circumstances. If we adopt the 

 view enunciated by v. Helmholtz, in the Faraday lecture, that 

 chemical forces are electrical in their origin, we must suppose 

 that the charges on the atoms are susceptible of change, for 

 the hydrogen ascending from the kathode is in the molecular 

 condition, each molecule consisting of two atoms with equal 

 and opposite charges ; the charges on one or both of these 

 atoms must have undergone some change, for when the atoms 

 were in contact with the kathode they were presumably in the 

 same electrical condition. It seems probable that when two 

 atoms come very near together they may affect the charges on 

 each other, the gain of the one being equal to the loss of the 

 other. To fix our ideas we may imagine that the electric 

 charge is measured by the momentum corresponding to some 

 coordinate helping to fix the configuration of the atom, and 

 that when two atoms come quite close together their momenta 

 change, the one gaining as much as the other loses. 



If we had a collection of charged atoms of this kind, even 

 though the charges might not all be numerically exactly 

 equal, if combination began the molecules formed would be 

 electrically neutral, for the potential energy, other things 

 being the same, is a minimum when this is the case. 



It may perhaps give a clearer idea of the theory we are con- 

 sidering if we take the particular case of a charged metal plate 

 and consider what are the conditions under which it can lose its 

 charge. According to our view the charge on the plate implies 

 the presence of atoms of the metal of which the plate is made; 

 and in order for the plate to lose its charge, these charged 







