196 DISCUSSION OF EVIDENCE. 



We should, therefore, not expect the laws of gases to apply to such 

 solutions, when we had no idea what was their concentration. Now 

 that we know their concentration, we find that the laws of gases are 

 of as general applicability to solutions as to gases, holding not simply 

 for dilute, but also for concentrated solutions. 



The theory of electrolytic dissociation, supplemented by the theory of 

 salvation, is, then, not simply a theory of dilute or "ideal" solutions, but 

 a theory of solutions in general. 



DOES THE SOLVATE THEORY AID IN EXPLAINING THE FACTS OF CHEMISTRY 

 IN GENERAL AND OF PHYSICAL CHEMISTRY IN PARTICULAR? 



To answer this question at all fully would lead us far beyond the 

 scope of this monograph. A few facts bearing upon this question can, 

 however, be taken up. Take, for example, the action of the hydrogen 

 ion both in the formation and saponification of esters. In the presence 

 of the alcohols the hydrogen ion accelerates greatly the velocity with 

 which an ester is formed, while in the presence of water it causes the 

 ester to break down into the corresponding acid and alcohol. 



In terms of ordinary chemical conceptions it is difficult, not to say 

 impossible, to interpret these reactions, the hydrogen ion under one set 

 of conditions undoing what under other conditions it effected. 



In terms of the solvation theory these reactions admit of a very, 

 simple interpretation. While the hydrogen ion is not strongly solvated, 

 work in this laboratory has shown that all ions are more or less solvated. 

 In the presence of alcohol the hydrogen ion therefore combines with a 

 certain amount of this solvent. The hydrogen ion, plus the alcohol com- 

 bined with it, unites with the organic acid, forming complex alcoholated 

 ions which then break down yielding the ester. 



On the other hand, the hydrogen ion in the presence of water com- 

 bines with a certain amount of this solvent. The hydrated hydrogen 

 ion, together with the water united with it, combines with the ester, 

 forming a complex hydrated ion, which then breaks down into the 

 corresponding acid and alcohol setting the hydrogen free again. For 

 a fuller discussion of this reaction see the paper by E. Emmet Reid. 1 



A reaction analogous to the above is that of hydrogen ions on amides 

 in the presence of water on the one hand, and alcohol on the other hand. 

 In the presence of water the hydrated hydrogen ion combines with 

 the amide, forming a complex hydrated ion which then breaks down 

 yielding ammonia and acid, the ammonia, of course, combining with the 

 acid. 



In the presence of alcohol the alcoholated hydrogen ion combines 

 with the amide, forming a complex alcoholated ion, which then breaks 

 down into ammonia and the ester of the acid in question. 



Hydrogen ions in a mixture of water and alcohol, which would con- 

 tain both hydrated and alcoholated hydrogen ions, give both reactions 



Amer. Chem. Journ., 41, 504 (1909). 



