36 Larmor, Physical Aspect of the Atomic Theory. 



trollable, the duration of separate existence of the ions 

 depending on the obstacles to their finding new partners 

 In the case of gases in which the formation of ions is 

 stimulated by electric shock (Rontgen rays, etc.), know- 

 ledge is now highly developed (J. J. Thomson, Townsend 

 etc.) regarding their rate of formation, and its equilibrium 

 with recombination or with their extraction from the 

 region by an electric field : the processes in solutions are 

 much more rapid, and only resulting equilibria can be 

 directly investigated. The operations of inorganic chem- 

 istry consist largely in presenting to these ions of solutions 

 the possibility of taking on new partners, either by simple 

 admixture, or by pulling them away into a new environ- 

 ment by electric agency. The energy required for the 

 guidance of chemical processes is expended in this latter 

 way, perhaps none of it goes (except very indirectly 

 through thermal interchange) to the pulling asunder of 

 the ions in the atom ; that separation takes place spor- 

 adically, with purely local adjustment of energy, to an 

 extent dependent, however, on the environment and in 

 this way modifiable. 



Any intense motional disturbance liberated in such 

 ionisation lapses into mere thermal energy. But by 

 means of guiding control (constraints in bulk) little of 

 i,t may be left to this fate — e.g. in the Daniell voltaic cell, 

 as Lord Kelvin discovered half a century ago. Here 

 again we recall the emphasis placed by Helmholtz, in 

 1 88 1, on the inference that in a voltaic cell there is but 

 slight expenditure of energy in getting the current across 

 the solution, merely, in fact, the Joulean heat, while the 

 large amounts of energy which become available or stored 

 have their origin at the electrodes, in that process (often, 

 as will be seen, nearly statical) of passing over the Fara- 

 day unitary electric charge from atom to atom, which is, 



