THE HYDRATE THEORY OF SOLUTIONS 211 



must do so in virtue of the charge and not in virtue of their 

 monatomic condition. This implies, if the theory of electrolytic 

 dissociation be true, that enormous stores of energy must be 

 available from the combination of the atom with the ionic charge 

 of electricity. For instance, if Ostwald's value, — 600 cal., be 

 taken for the heat of formation of the hydrogen ion, that of the 

 chlorine ion must be 39,930 cal. ; and even this figure does not 

 represent the whole of the energy that must be postulated as 

 arising from the union of the atom with its charge, since the 

 conversion of chlorine gas into chlorine ions involves the 

 disruption of the chlorine molecule as well as the electrification 

 of the resulting atoms. We must therefore write 



CI + e = CI + 39,930 + x calories, 



where x is the heat of formation of chlorine molecules from 

 chlorine atoms. 



How far then is it legitimate to draw on this hypothetical 

 source of energy in explanation of the phenomenon of electrolytic 

 dissociation ? Attention may be directed in the first place to 

 the behaviour of gases. If so much energy were available from 

 the electrification of the atom the ionisation of a gas should take 

 place spontaneously as an exothermic action quite independently 

 of the presence of any solvent. Gaseous hydrogen chloride 

 should therefore not only conduct the current but — in view of 

 the exceedingly low viscosity of the gas — conduct it even more 

 readily than in aqueous solution. Actually, however, the ionisa- 

 tion of a gas appears invariably to be an endothermic process, 

 and one, moreover, that is only brought about to any marked 

 extent when energy of a very high order of intensity is available, 

 as for instance from radioactive matter (the most intense source 

 of energy that is known) from Rontgen rays, or from ultra-violet 

 light. Even these agents do not impart any high degree of 

 conductivity to the gas, and the removal of the source of energy 

 is at once followed by a more or less rapid " decay of ionisation." 

 The idea that the electrification of the atom may be regarded as 

 a source of energy is therefore one that receives conspicuously 

 little support from the experimental behaviour of gases. 



It is also not upheld by the behaviour of solutions. If, for 

 instance, the only difference between water and benzene con- 

 sisted in their widely divergent specific inductive capacities, it 

 might be expected that ionisation — if a spontaneous process — 



