ON THE BOILING POINTS OF AQUEOUS SOLUTIONS OF ELECTROLYTES. 239 



varying from two to six gramme equivalents per litre. But generally, when a certain 

 concentration is reached, which varies for different salts, the value of the elevation 

 constant increases with concentration when computed in the ordinary way. 



(3) Molecular weight determinations have been successfully made for several salts, 

 and are in striking contrast with those which have been made by other observers by 

 the boiling-point method, these varying by as much as 20 per cent, as obtained by 

 different observers. Those I have obtained only differ from the international atomic 

 weight values by from one to one-tenth per cent. 



(4) An improved method of obtaining conductivity values at the boiling point of 

 the solvent has been given, and apparatus described. 



(5) The results of observations on concentrated solutions, with a view to find out 

 the meaning of the high values of the elevation constant for such solutions, are 

 given, alternative theories being tested, and finally, these high values are ascribed to 

 hydration. 



(6) A minimum has been found in the curves obtained by plotting elevation per 

 gramme equivalent against gramme equivalents per litre, which is in harmony with the 

 results obtained both from the elevation of the boiling, and depression of the freezing, 

 points of view, as given by other observers. 



(7) Some salts commence to hydrate at a much greater dilution than others, as is 

 shown by a comparison of the elevation constant obtained for the lithium and cadmium 

 salts (pages 220 and 221). The indications are that those which ionize least commence 

 to hydrate at the higher concentration. 



(8) The hydration figures obtained indicate that, if association is molecular alone, its 

 amount quickly reaches a maximum per molecule for the ammonia salts, and decreases 

 gradually for higher concentrations. 



If the hydration be ionic only, the maximum hydration per ion is reached gradually, 

 which is steady until high concentrations are reached and then it decreases for the 

 above salts. 



If the hydration be that of both molecules and ions, a maximum hydration per 

 molecule or ion is gradually reached which continues constant until considerable con- 

 centrations are reached. 



(9) The molecular, the ionic, and the molecular ionic theories have been considered, 

 and the conclusion arrived at that the ions hydrate, and probably the molecules also, 

 in the case of deliquescent salts. 



(10) The curves giving the relation between elevation of boiling point and grammes 

 of combined or associated water show that between elevation of boiling point and 

 association a linear relation exists for all the salts considered. 



(11) The curves with values of m v //"°° as ordinates and elevation of the boiling-point 

 constant as abscissae are made up of two portions. One approximately along the 520 

 elevation line, the other receding from this line, each portion being approximately 

 a straight line. 



