Manchester ATemoirSy Vo/. /zi. (igoS), No. 1{^. 39 



nearest to expressing the true relation between [available] 

 chemical energy and heat, or, what amounts to the same, 

 between the magnitudes A and Q. In this direction we 

 can show that in reactions between solids, liquids, or 

 concentrated solutions, the values of A and Q approach 

 each other very closely, while on the other hand in dilute 

 solutions or with gases we actually find large differences 

 between the two quantities ;..."* The case of galvanic 

 cells operating even by dilute solutions is included in the 

 generalization for the reason given above. Obviously 

 also on the present view the unavailable part of the 

 energy should become steadily less at lower temperatures, 

 as Nernst concludes. The principle of Gibbs, that the 

 fraction of the energy of chemical combination that is 

 unavailable is equal to the ratio of the actual temperature 

 of reaction to the temperature of dissociation, pro- 

 vided correction can be made for work of expansion and 

 heat on change of state, etc., is seldom effective on 

 account of this latter complication. 



The Faraday unitary charges have now a specific 

 name, the electrons. Their unchanging magnitudes were 

 strong presumption from the first of their intrinsic atomic 

 existence : the Zeeman-Lorentz effect has almost exhibited 

 them to us in action in the molecule, as the agents 

 of radiation through their combined vibratory motions, 

 in the now familiar manner foreshadowed by the Maxwell- 

 Hertz theory of radiation. But the most far-reaching of 

 recent discoveries has been that not merely can they pass 

 at close quarters from molecule to molecule in some 

 hitherto inscrutable way, according to the Faraday law, 

 and also reveal their vibrations inside the molecule 

 through its spectrum and its magnetic modifications, 



* Nernst, /oc. cit. "Applications of Thermodynamics to Chemistry," 

 1907, p. 43, seq., where extensive examples are given. 



