296 MR. W. R. BOUSFIELD AND DR. T. M. LOWRY ON THE ELECTRICAL 



the convergence of the conductivity-temperature curves was simply the viscosity of 

 the solvent. We are indebted to Dr. LAKMOR for the suggestion that this result may 

 be indicated by factorising the equation K, = K O (1 -\-at + ftt 2 ) and writing it in the 

 form K t =s * (1 +at) (1 +bt), where a is a coefficient depending on the (viscosity of 

 the) solvent, whilst 6 is a specific constant of the electrolyte under consideration, 

 both a and 6, however, being constant only over a narrow range of temperature. 



A fuller study of the influence of temperature on the conductivity of composite 

 electrolytes led to the conclusion that it was possible to represent all the experimental 

 data by means of a generalised conductivity-temperature curve having the form 

 shown in fig. 6 ( BOUSFIELD and LOWRY, loc. dt., p. 52). The most important 



Fig. 6. 



features of this curve are (l) a more or less tangential approach A to the axis of 

 temperature, (2) a point of inflexion S, (3) a maximum conductivity at M, and (4) a 

 rapid fall almost to zero in the neighbourhood of the critical temperature Z of the 

 solution, with possibly a second point of inflexion T. In addition to the evidence 

 brought forward at the time, confirmation of this view has been afforded by the 

 measurements by KUNZ (' Comptes Rendus,' 1902, vol. 105, p. 788; ' Zeit. Phys. 

 Chem.,' 1903, vol. 42, pp. 591-596) of over-cooled aqueous solutions, which show that 

 the conductivity-temperature curves, instead of cutting the axis of temperature as is 

 indicated by the parabolic formula K t = *r (I -\-at-\- fit 2 ), approach it nearly tangen- 

 tially; in the other direction, NOYES and COOLIDGE ('Zeit. Phys. Chem.,' 1903, 

 Jubelband, p. 372), working with aqueous solutions under high pressures, have shown 

 that even powerful electrolytes like sodium and potassium chlorides reach a maximum 

 conductivity at high temperatures ; in decinormal solutions this occurs at about 

 280 C., and above that temperature these salts exhibit negative coefficients. As 

 regards non-aqueous solutions, the measurements by EVERSHEIM (' Ann. Physik,' 

 1904, iii., vol. 13, pp. 492-511) of the conductivity of liquid ammonia, of ammonia 

 containing 1 per cent, of copper nitrate, and of sulphur dioxide, have yielded 

 additional evidence of the correctness of the curve at the upper temperature limits 

 of conductivity. 



The original object of the investigation described below was to obtain evidence of 

 the correctness of our view that the point of inflexion S was a normal feature of the 



