4 Morris, Modem Theory of Solutions. 



the H ion is in some way combined with the water it is 

 difficult to sec how this could occur. It is easy to imagine 

 a loose combination of HCl with HgO, such that a 

 hydrogen and a chlorine atom would be free enough to 

 exert independent kinetic pressures, but yet be bound to 

 move together as a physical whole. Indeed in the theory 

 of gases, the difficulty is to explain how the parts of a 

 molecule can be so lightly joined as not to exert these 

 independent pressures. Structural chemistry has taught us 

 that parts of a chemical molecule may enter into reactions 

 independently of the result of the molecule, and may be 

 more influenced by their environment than by the rest of 

 the molecules to which they are bound ; e.g., reduction of 

 nitro-ethane and nitro-benzene in acid or neutral solutions. 

 Such combinations would be a stage between mixtures 

 and chemical compounds that react as a whole. It is 

 precisely in such cases as the picric acid solution in silk, 

 that one would expect a large measure of independence 

 in the parts of the combination. On this view the HCl 

 and HoO combination would be regarded as in a strained 

 condition, requiring a further agent such as the electric 

 current, or the presence of a body like an ester, which 

 can combine with H and OH, and remove them from the 

 system and complete the decomposition of the water. 

 In conformity with this view I found that for the lower 

 esters of acetic acid the M of the formula of Harcourt and 

 Essen is about twice as great as that for hydrochloric 

 acid, and that, therefore, the heat change in the action 

 between HCl and water to form these combinations, is 

 about equal to that between the ester and these combi- 

 nations. Whenever the combination is broken up by the 

 ester, the liberated HCl would meet a water molecule in 

 an infinitesimal time, and the original number of combi- 

 nations be re-formed. 



