ON THE BOILING POINTS OF AQUEOUS SOLUTIONS OF ELECTROLYTES. 235 



Lithium Nitrate. 



Grni. eqs. 

 per Litre. 



Total 



water of 



Hydration 



in Grms. 



Molecules of water of Hydration 

 on the assumption that 



Molecules 

 and Ions 

 hydrate. 

 Per Mol. 

 or Ion. 



Ions only 

 hydrate. 

 Per Ion. 



Molecules 



only 

 hydrate. 

 Per Mol. 



2-025 



2-788 



3-371 



4-118 



4-62 



5-39 



5-98 



6-52 



•3 

 •9 

 1-7 

 21 

 3-1 

 39 

 41 

 4-1 



■38 

 •84 



1-2 



1-2 



1-5 



1-6 



1-5 



1-3 



•66 

 1-5 

 2-8 

 2-4 

 3-9 

 4-0 

 3-6 

 3-3 



•88 

 1-9 

 2-6 

 2-3 



3-0 



2-8 

 2-5 

 2-2 



The hydration data just given show that, if hydration be molecular alone, 

 a maximum hydration per molecule is quickly attained and then gradually falls off 

 for all the salts considered. In several instances the highest hydration per molecule 

 is obtained for the most dilute solution used. 



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

 with increase of concentration, which for the ammonia salts continues steady for a 

 considerable range of concentration and thereafter falls off gradually. In the case of 

 the chloride and bromide of lithium the ionic hydration seems to increase with 

 concentration up to the limit of concentration reached. 



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

 molecule or ion is gradually reached which remains constant for a certain range of 

 concentration and then falls off, and seems to do so for all the salts for which hydration 

 data are given. 



It will be seen from the above tables that the number of molecules of combined 

 water is greater for the lithium salts than for the corresponding ammonia salts under 

 each hypothetical form of hydration. These high values might result in part from the 

 hydration of the lithium ion being greater than that of the ammonia ion in case the 

 hydration were only ionic, but the difference is so considerable for the chlorides and 

 bromides as to suggest that perhaps the molecules of these salts also hydrate, which 

 might also be suggested by these salts being deliquescent. 



With this portion of the subject I hope to deal more fully in a later paper on 

 Hydration. 



On the question of ionic hydration the results of Garrard and Oppermann * are 

 interesting. 



By an electrolytic process they find that the S0 4 ion takes up nine molecules of 

 water of hydration, the bromine ion four, and the chlorine ion five molecules, and the 



* Gottinger Nachrichten, p. 86 (1900, 1903). 



