and its bearing on the Nature of Solutions. 495 



portion of 1*03 to 0*63; in other words, that the water molecule 

 is 1^ H 2 0, and that the atomic theory is wrong. 



The theory of dissociation into ions is, for many reasons, 

 inacceptable to most chemists, and its application to the 

 results at present under discussion affords, I think, some of 

 the strongest arguments against its acceptance. 



If the higher values in the case of water are due to dissocia- 

 tion, we must conclude that all the stronger acids (e. g. 

 hydrochloric, sulphuric, and nitric acids) are nearly entirely 

 dissociated, whereas the weaker ones (e. g. hydrocyanic, sul- 

 phurous, and boric acids) are not so ; and similar conclusions 

 must be drawn respecting the alkalies and salts. In fact, we 

 shall be driven to conclude that the more stable the compound 

 is the more easily is it dissociated, and that too by an agent, 

 water, which has, ex hypothesi, no action beyond the dilu- 

 ting effect of its mass. Is it possible to maintain that sul- 

 phurous acid exists intact in solution, while sulphuric acid, 

 which is formed from it and molecular oxygen, with the 

 evolution of 55,000 cal.*, and which must, therefore, be by 

 so much the stabler body of the two, is entirely dissociated ? 

 Is it possible to maintain that hydrochloric acid is entirely 

 dissociated at a pressure of three or four atmospheres when 

 we know as a fact that it can exist undissociated at a pressure 

 of only one atmosphere f ? 



Indeed, it appears to me that if we acknowledge such a 

 dissociation we must deny the principle of the conservation 

 of energy. Thus, to take one instance out of many, the 

 molecules of hydrogen and chlorine must J be formed from 

 their constituent atoms with a considerable development of 

 heat, say + x and +y cal. respectively, and they react with 

 each other to form 2H01 with a further development of 

 44,000 cal. ; if this 2HC1, when dissolved in water, be entirely 

 dissociated into its atoms, it must absorb 44,000 + x+y cal., 

 whereas, as a matter of fact, it evolves 34,630 cal. : hence there 

 has been a creation of (78,630 + x + y) cal. out of nothing, 



* If atomic oxygen were taken, as it should be, the heat evolved would 

 be much greater. 



t In acetic acid hydrochloric acid is, according even to the supporters 

 of the theory, not only not dissociated into its ions, but even not dis- 

 sociated into its fundamental molecules, it being present as 2HC1. 



X I think that we may say " must." If they were formed with absorp- 

 tion of heat it would mean that the atoms repel each other, and such 

 atoms would, therefore, never combine. When we call a molecule endo- 

 thermic, we merely mean that it is formed from its constituent atoms 

 with a smaller development of heat than some other compound of the 

 same atoms, not that it is formed from these atoms with an absorption 

 of heat. 



