1889.] Viscosity and Conductivity of Electrolytes. 



25 



of the question we may consider some of Grotian's observations 

 a little more closely. 



I have reproduced in fig. 1 the curves of temperature co- 

 efficients for NH 4 C1 plotted from his tables (reducing the abscissae 

 to gramme equivalents per litre) and placed them on the diagram 

 with the curves for fluidity and conductivity already alluded to. 

 The curves for KC1, KBr and KI are strictly analogous, so that 

 the diagram may be taken as exhibiting the comparison for a 

 group of salts which seem to form a special class of solutions with 

 respect to conductivity and fluidity. 



Strict parallelism of the plotted curves would correspond of 



course to a constant difference between the corresponding values of 



1 df 1 dk 



10% -4- and 10 4 -r -=r. These differences are tabulated below, by 

 f at k at 



interpolation, for the four salts. 



Table I. 



The differences are very nearly the same for all the salts for 

 concentrations between 10 and 20 p. c, but the two values ap- 

 proach one another slightly when the concentration is large. As 

 a simple assumption we may take however that the relation 

 between the temperature coefficients of fluidity and conductivity 

 is one of a constant difference <r, independent of the concentration 

 and of the nature of the salt for this particular group of salts. 

 It may vary with the temperature and with the nature of the 

 solvent, but we will assume for the moment that it is a constant. 

 We then get 



1 df_ 1 dk 



fdt kdt 



+ a- 



•(1), 



where a is a small quantity (about 30 x 10 4 ) independent of 



