96 CONDUCTIVITY AND VISCOSITY OF SOLUTIONS 



SUMMARY. 



It has been our endeavor throughout this investigation to improve 

 the viscosity and conductivity methods wherever possible, in order to 

 eliminate the grosser errors which ordinarily creep in, for example: 

 temperature regulation; a more exact determination of the external 

 resistance in the circuit ; a change from suction to pressure as a means 

 of raising the liquid in the viscosimeters, etc. 



Instead of making up our solvents by the volume standard, as pre- 

 vious workers have done, we used the weight standard. An equation, 



md'(p x) 

 xd =y 



was deduced and employed for determining the amounts by volume of 

 the water necessary to add to 100 c.c., or even multiples of this quan- 

 tity of alcohol, in order to make the required mixtures by weight. 



Viscosity and conductivity determinations were made with several 

 dilutions of potassium and sodium iodides, in a series of mixtures of 

 alcohol and water; and curves representing fluidity as ordinates and 

 percentages of alcohol as abscissas were drawn, as well as curves for 

 conductivity as ordinates plotted both against mixtures of solvent and 

 against temperatures as abscissas. 



CONCLUSIONS. 



We arrived at the following conclusions : 



1. The effect of sodium and potassium iodides on the viscosity of 

 ethyl alcohol-water mixtures is comparatively small for N/8 solutions. 



2. There is a marked increase in the viscosity of the solvents caused 

 by these salts in passing from the 100 per cent alcohol to the 60 per 

 cent alcohol. 



3. The shifting of the point at which the fluidity curve for the salt 

 crosses that for the solvent with rise in temperature, is to be accounted 

 for by the change in association of the solvent with rise in temperature. 



4. This change in association is greater for the water than for the 

 alcohol. 



5. The facts brought out in connection with the viscosity work were 

 in harmony with those discovered by previous workers, and therefore 

 can be explained in the same way. 



6. There is a continual decrease in the conductivity of N/8 sodium 

 and potassium iodides in passing from pure water to pure alcohol. It 

 is much more rapid in the large percentages of water than in the large 

 percentages of alcohol. 



7. This may be explained as due to the fact that the association of 

 alcohol is changed to a much smaller extent by adding small quantities 

 of water, than is water when to it small quantities of alcohol are added. 

 Moreover, since association and viscosity are so closely related, we 



