140 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Hydrogen Iodide (Perkin). 



For a concentration of one mol per kg. water P X 100 = 11.3, 

 dv/dm taken as 0.2815 cc. (20°) or 0.282 true cc. 



It is interesting to note in the cases of potassium and sodium iodides 

 that the specific volume of the pure substance is greater than the par- 

 tial specific volume of the substance in solution, and in these cases 

 there is a slight but definite increase in the partial volume as the 

 solution becomes more concentrated, that is, as it approaches the pure 

 salt. Moreover, in the case of lithium iodide, although here the par- 

 tial volume in solution is greater than the volume of the pure sub- 

 stance it also approaches the latter as the solution becomes more 

 concentrated. 



9. Calculation of the Transference Number. 



Substituting for n its value, and for F the value 96580, equation 

 (2) may be written : 



' 4.895 X 10^0 E 



Using the average values of B/?}^ the transference number of the 

 cation T^. was calculated for each of the salts. The data and results 

 are given below : ^^ 



=c 



~, + M, (1 - Vj/A -r 31 (1 - vsd). 



^8 Tlic vahies of E/n"^ arc, of oour.'^e, all negative since the current tends to 

 flow from the outer to the inner electrode. 



