884 THE BOILING AND FREEZING POINTS OF AQUEOUS SOLUTIONS. 



conclusive, but for some it would seem that hydration ceases with ionization, and for 

 these the indication is that there is only ionic hydration. 



(10) The maximum hydration for some salts remains constant; for others there is a 

 maximum point in the hydration curve. 



(11) The curves for which equivalent elevation values are plotted against con- 

 centration may be quite similar in form for a salt and an acid (CaBr 2 and H 2 S0 4 , 

 fig. 2). 



(12) For the most concentrated solutions of nitric and hydrochloric acid the per- 

 centage hydration falls off when computed from observations made at the freezing 

 point. From computations made at the boiling point it appears that equivalent 

 elevation falls off for hydrochloric acid as the concentration increases, after a certain 

 concentration is reached (fig. 2). 



(13) Values of Mv/m^ are greater at the lower temperature for the same concentra- 

 tion for dilute solutions than at the higher temperatures ; the reverse is true for the 

 concentrated solutions ; that is, the isothermals cross each other (fig. 6). 



My warmest thanks are heartily given to Professor MacG-regor for his kindly 

 interest in this research. 



I wish also to express my gratitude to the Moray Endowment and Carnegie Trust 

 for grants towards the expense of this research. 



Physical Laboratory, 



Edinburgh University. 



