Chemical Affinity in terms of Electromotive Force. 389 



The solution diluted was found by analysis* to contain 

 16-525 per cent, of anhydrous CuS0 4 , corresponding with 

 2'231CuS0 4 100 H 2 ; hence there was employed altogether 

 53-781 x -16525 = 8-887 grammes of CuS0 4 , or : 0557 gramme - 

 molecule ; so that the contraction per gramme-molecule was 



= 7-58 cubic centim., the diluted fluid possessing the 



composition -362CuS0 4 100 H 2 0. 



In precisely the same way the following values were ob- 

 tained on diluting 2*231 CuS0 4 100 H 2 to other extents: — 



Solution ultimately obtained, 

 »CuSO 4 100H 2 O. 



n=l-328 



= -910 

 = -572 

 = -362 

 = -216 



Contraction in cubic centimetres 

 per gramme-molecule. 



2-76 

 4-40 

 6-19 



7-58 



Similarly the following values were obtained on diluting 

 5-247 ZnS0 4 100 H 2 to various extents :— 



n= 4-744 

 = 3-096 

 = 2-020 

 = 1-012 

 = -700 

 = -457 

 = -237 



0-96 

 4-78 

 7-59 

 11-23 

 12-63 

 14-03 

 15-69 



And the following, on similarly diluting 6 - 325CdS0 4 

 lOOHoO:— 



n=5-534 

 = 3-086 

 = 2-024 

 = 1-046 

 = -614 

 = -384 

 = -235 



1-23 



5-86 

 8-38 

 11-46 

 13-35 

 14-98 

 15-81 



On graphical representation on a large scale and interpo- 

 lation, the following values are deduced as the amounts of 

 contraction taking place on diluting to the strengths *25MS0 4 

 100 H 2 solutions of strength nMS0 4 100 H 2 0:— 



* The mode of analysis adopted was to evaporate to dryness a weighed 

 quantity of solution and weigh the residual anhydrous salt after continued 

 heating to 300°-400°, terminating in very gentle ignition for a minute 

 or two at a red heat barely visible in the dark. 



