and Two New Types of Viscosity, 9 



\r)/\ r} may be only a fraction expressing the dependence of 

 molecular conductivity upon viscosity of electric origin, 

 standing in fact for 



1 ^27r(A 1 + A 2 )Cv 1 v 2 \n(n 1 -£ w 8 )//t}* 3KI\ , 



while i itself is really 1. It will now be shown that this is 

 the case. The most satisfactory verification of (9) is to be 

 obtained by applying it to electrolytic solutions in general. 

 After a number of American investigators had opened np the 

 important experimental field of solutions other than aqueous, 

 Walden brought out his comprehensive researches on organic 

 ionizing solvents and certain inductive conclusions drawn 

 from them (ZeitscJi. f. phys. Chem. liv. 190(3, p. 129). He 

 investigated electrolytic solutions of tetra-ethyl-ammonium 

 iodide N(C 2 H 5 ) 4 I in 49 organic solvents of 14 chemical types. 

 From this wealth of data he made the discoA'ery that those 

 solvents whose solutions of N(C 2 H 5 ) 4 I have a given value of 

 i (that is, of X/\ ) exhibit the following principle, namely 

 that ~K/ni is constant. In general his solutions were so dilute 

 that v = Vo an d A 1 + A 2 =X . For example, with nitromethane 

 CH 3 N0 2 , for which K = 40, the value of i is 0'66 when 

 ^ = 1/28000, and for ethyl alcohol with K=217 the value 

 of i is 0'66 when n= 1/256000. For these two substances 

 K/ni has the values 1220 and 1390. Altogether Walden 

 gives 27 instances illustrating the correctness of his induction. 

 But the right interpretation of Walden's discovery is con- 

 tained in (13), which shows that the true degree of ionization 

 must be taken to be complete, that is 2 = 1, and that the usual 

 so-called degree of ionization i given by \r}/\ 7] will be the 

 same for a given solute in different solvents if n is chosen so 

 as to make ~K/m the same for all the solvents. The law of 

 Walden verifies (13) in a comprehensive manner. But his 

 data carry the confirmation farther. We can write it in 

 abbreviated form 



\ /\ = l/i = l + n*G/K, .... (14) 



where G is a constant for a given solute. That is to say, for 

 a given solvent A, /A- or 1/i is to be linear in ni. This for any 

 dilute solution is a more rigorous form of the law discovered 

 by Kohlrausch for dilute aqueous solutions. It holds so long- 

 as 7] for the solutions can be identified with that for the 

 solvent. For concentrations too strong to admit of this sim- 

 plification, the measured values of 77 must be used in (13). 

 To verify (14) two illustrative cases will be taken from 



