-44 Mr. W. E. Bousfield and Dr. T. M. Lowry. [June 19, 



of temperature at points not more than 50° below the freezing 

 point of water. The point of intersection is an important constant 



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Ira-. 1. — Influence of temperature on the conductivity of very dilute solutions. 



for any given solution, and we have been accustomed to refer to* 

 it as the conductivity zero of the solution. At this temperature, if the 

 observed relationship between conductivity and temperature should 

 continue to hold good, the conductivity of the over cooled solution 

 would become zero, and the conductivity zero may therefore be 

 satisfactorily compared with the absolute zero of a gas thermometer 

 at -273°. 



The influence of temperature on the conductivity of aqueous solutions, 

 has been investigated by Grotrian, Kohlrausch, Arrhenius, Deguisne,* 

 and others. In an important paper which has recently appeared, f 

 Kohlrausch has deduced from Deguisne's measurements the values 

 of the temperature coefficient in aqueous solutions of infinitely great 

 dilution, and has arrived at the important conclusion that the conduc- 

 tivity temperature curves for all such solutions would, if produced, cut 

 the axis of temperature at points lying within a degree or two of 

 - 38 '5° C, the differing slope of the lines being compensated by their 

 differing curvature (fig. 1). This temperature, which is almost inde- 

 pendent of the nature of the solute, is evidently a fundamental 

 constant of the solvent, and may be referred to as the " conductivity 

 zero of the solvent" 



The physical meaning of the conductivity zero is a matter of some 

 importance. Kohlrausch states that the viscosity of water may be 

 represented by the formula rj = 2'989 (t + 38"5) _1 * 40 , which leads to 

 an infinitely great viscosity at — 38° "5, and suggests that at this 



* ' Diss., Strassburg, 3 1895. 



f 6 Sitz. Prouss. Akad. Wiss.,' vol. 42, p. 1026, 1901. 



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