144 Dr. T. Ewan. On the 



n 



(1 X) MI X - <* 2 = x. 3 X aj4. 

 3 



As Arrheiiius* has shown, the values of i, a 2j &c., are to be ob- 

 tained from equations of the form 



w is the whole number of dissociated molecules of all kinds in the 

 solution, and KI, K 2 , &c., are the characteristic dissociation constants 

 for the four electrolytes. The values of a 2 and 3 are very small, so 

 that we have 



4 , the fraction of the hydrochloric acid dissociated, may be put 

 = 1, so that the equation becomes, putting n = 55'5/c, 



(1-aQ = JL??L ... (6). 



aj 2 c 55 '5 K 2 &i 



Neglecting small quantities, we have 



m = (l x) a,! -f x. 

 Substituting which in (5), 



1 



The values of a l5 the dissociation coefficients of ferric chloride, are 

 unknown. I have attempted to test the agreement of the experi- 

 ments with the Equations 6 and 7, thus : Each experiment gives a 



3 K 1 1 



value for __.. _2._= (say), or, writing the constant part 

 oo'o jL z a i b 



Substituting this in Equation 7, 



c6 2 

 j r-f cdx = 55*5 K^. 



(.V "^*" V 



From these equations d and KI can be found. The following 

 numbers were obtained : 



* ' Zeit. Phys. Chem.,' vol. 5, p. 1, 1890. Cf. J. J. van Laar, ' Die Thermo- 

 dynamik in der Chemie,' 1893, where a convenient collection of the formulae is to 

 be found. 



