24 Mr W. JV". Shaw, On the relation between [Nov. 25, 



parallel to the axis of abscissae, others are inclined positively 

 to it, others again negatively ; but in all cases, with the possible 

 exception of acetic acid, which exhibits irregularity, the corre- 

 sponding curve for the other property is a curve which though not 

 coincident is very nearly parallel, and generally speaking when 

 there is a change in the inclination of the curve for one property 

 there is a corresponding change of inclination in the curve for 

 the other property. When we add to the general appearance of 

 parallelism for the lines which present no special peculiarity the 

 remarkable parallelism in the exceptional cases of NaHO, the 

 curves for which are both very steeply but equally inclined to the 

 axis, and of H 2 S0 4 , which furnishes two irregular but still parallel 

 curves each shewing a maximum for the same degree of concen- 

 tration, the evidence is convincing that there is a real relation 

 not of identity, but of parallelism between these temperature co- 

 efficients of the two quantities for different concentrations. 



Another means of altering the viscosity without altering the 

 other properties of a solution might be found in adding an inert 

 non-conducting liquid to the solution and thereby altering the 

 solvent. Experiments have been made in this direction by C 

 Stephan*, who has measured the viscosity and its temperature 

 coefficient for some mixtures of alcohol and water, and the con- 

 ductivity and its temperature coefficient for dilute solutions of 

 NaCl, KCL LiCl, Nal, KI in these mixtures. The investigation 

 differs from Grotian's inasmuch as the temperature coefficients 

 of fluidity are not determined for the solutions but only for the 

 solvents, so that while the fluidity temperature coefficient seems, 

 for the alcoholic solvents, again to be of the same order of 

 magnitude and to exceed the conductivity temperature coefficients 

 of the solutions, no precise comparison can be made. Stephan's 

 comparisons of results are mainly concerned with an enquiry as 

 to the constancy of the products of conductivity of the solution 

 and viscosity of the solvent for the different solvents ; the con- 

 stancy is not established though a limiting value is indicated for 

 very dilute solutions. 



E. Wiedemann -f* has moreover compared the conductivities of 

 corresponding solutions of NaS0 4 in water and glycerine, but again 

 no numerical relation between conductivity and resistance is 

 exhibited. 



The relation between resistance and viscosity seems therefore 

 not to be a simple one, though the relation between the tempera- 

 ture coefficients does seem from Grotian's observations to be 

 comparatively simple. With the view of exhibiting this aspect 



* Wied. Ann., vol. xvn., p. 673, 1882. 

 t lb., vol. xx., p. 537, 1883. 



