Nature of Solution. 



369 



water is to diminish it, as was to be expected, in the case of all 

 the salts when in a saturated solution. But in the case of the 



Table III. 



Salt. 



NaN0 3 

 KN0 3 ... 



Na.,C0 3 



K,C0 3 



MnSO, 



FeS0 4 



KNO3... 



FeS0 4 ... 



65 c 



3667 



1778 



i()94 



1178 



1889 



944 



75 c 



3879 

 2402 

 1744 



5872 

 1139 

 1039 



2028 

 890 



85°. 



4142 



2775 



1609 



6106 



898 



945 



2142 



899 



95< 



4329 



3302 



1549 



6214 



692 



735 



2149 



735 



o 

 X 



1 



NaNOg 

 KNO Q 



MnSO, 



FeS0 4 



27-1 

 135-3 



29-86 

 129-9 



32-82 

 126-2 



36-21 

 119-6 



22-08 



27-59 

 87-1 



33-65 



82-5 



40-24 

 82-1 



15-69 

 1133 



15-69 

 111-1 



15-59 

 103-3 



15-49 

 1000 





35-68 

 164-5 



37-51 



162-8 



39-33 

 158-0 



14-76 

 74-1 



14-76 



77-2 



14-71 

 61-0 



13-89 

 49-8 



15-43 

 76-3 



15-16 



68-6 



14-16 



66-7 



12-08 

 60-9 



mol. 

 mol. 

 mol. 

 niol. 

 mol. 

 mol. 



Solubility taken from Mulder {Bijdragen tot de Geschiedenis van het 

 scheikundig gebonden Water (Eotterdam, 1864). 



solutions of constant composition the attraction of salt for 

 water is increased with KN0 3 , and diminished with FeS0 4 ; 

 and this is also found with MnS0 4 at the temperatures 65° 

 and 75° — so long as the solubility remains constant the value 



P' 



of 1 — -p increases. Now KN0 3 has its solubility largely 



increased by rise of temperature, while that of FeS0 4 is 

 diminished ; and we have seen above that when n = constant 



F 

 1 — p- increases in the case of KN0 3 and diminishes in the 



case of FeS0 4 . The explanation of this apparently anomalous 

 behaviour must lie in a change in the molecular relations in 

 the solution. I have stated in previous papers that, from other 

 experiments, I have come to the conclusion that the solubility 

 of a salt is dependent on the attraction of salt for water and 

 of salt for salt : if the former increases faster than the latter 

 with the rise of temperature, then the salt is more soluble at 

 a high temperature than at a lower, and vice versa. Now in 



