18 CONDUCTIVITY AND VISCOSITY IN MIXED SOLVENTS. 



We need only mention in this connection the work of Strindberg * and of 

 Holland. 2 



Voilmer 3 investigated solutions of various salts in methyl and ethyl 

 alcohols. He found the temperature coefficients of conductivity and fluidity 

 to be very nearly identical. 



Kohlrausch and Deguisne 4 used the formula 



K t = K u [l + a(t - 18) + 0(t- IS ) 2 ] 



to represent the influence of temperature on conductivity, starting from 18 

 as a mean temperature. Kohlrausch 5 noted that on extrapolating this 

 curve, aqueous solutions would reach a zero value of conductivity at about 

 39, which is about the temperature where the fluidity would become zero. 

 Bousfield and Lowry 6 showed that the viscosity of water may be represented 

 accurately by a formula similar to the above, 



1713 = 17, [! + (- 18) +(- IS) 2 ] 



They found that the constants a and @ are the same in the two formulas, to 

 within the limits of experimental error. They believe, however, that these 

 formulas will not hold at low temperatures, and that the zero values can not 

 be experimentally realized. This belief is borne out by the work of Kunz. 7 

 In an exceedingly interesting paper, Kohlrausch 8 proposes the view that 



About every ion there moves an atmosphere of the solvent, whose dimensions are 

 determined by the individual characteristics of the ion. . . . The electrolytic resist- 

 ance is a frictional resistance that increases with the dimensions of the atmosphere. 

 The direct action between the ion and the outer portion of the solvent diminishes as 

 the atmosphere becomes of greater thickness. . . . For a very sluggish ion there will 

 be only the friction of water against water, and the electrolytic resistance will have the 

 same temperature coefficient as the viscosity of water, provided the atmosphere itself 

 does not change its dimensions with the temperature. If, however, the atmosphere 

 becomes, for example, smaller with increasing temperature, the temperature gradient 

 of the conductivity might be greater than that of the fluidity. According to observations 

 now at hand, this would seem to be the case for the slowest moving univalent ion, Li. 



Bousfield and Lowry 9 have gone farther and have shown that we should 

 also expect to find an upper limit of conductivity, on account of the decrease 

 in dissociation with rise in temperature. A maximum conductivity of this 

 sort has been observed by Franklin and Kraus 10 in liquid ammonia. Potas- 

 sium iodide gives a maximum in conductivity, in methyl alcohol, at 160. u 



1 Ztschr. phys. Chem., 14, 221 (1894). 7 Compt. rend., 135, 788 (1902). 



2 Wied. Ann., 50, 261 (1892). 8 Proc. Roy. Soc., 71, 338 (1903). 



3 Ibid., 52, 328 (1894). 9 Loc. cit. 



4 Dissertation Strassburg, 1893. 10 Amer. Chem. Journ., 24, 83 (1900). 

 6 Sitz. Berlin. (1901), 1028. Phys. Rev., 18, 40 (1904). 



6 Proc. Roy. Soc., 71, 42 (1902). 



