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XLIII. JVotes on the Viscosity of Liquids. By Alfred W. 

 Porter, F.R.S., Fellow of and Assistant Professor of 

 Physics in University College, London *. 



1. The Variation of Viscosity with Temperature. 



WHEN two liquids are examined throughout a sufficient 

 range there can, in general, be found a temperature 

 for the second liquid at which its viscosity is the same as that 

 for the first liquid at any given temperature. Let this tempe- 

 rature, when the standard liquid is at'T , be represented by T. 



T 



Then if ^ be plotted against T, I find that the curve obtained 





 is practically a straight line. This statement is illustrated 



for the case of mercury with water chosen as the standard 



substance in fig. 1. 



Fig. 1. — Mercury and Water. 



n 











^ 









s 



/ 



/ 





i-O 





/ 



/ 









S 

















0° 



00" l 



03° 1 



50" \ 



00° 



The values obtained by interpolation from the data given 

 by Landolt and Bornstein are as follows : — 



Viscosity. 



Water. 

 To. 



Mercury. 

 T. 



T 



•0181 



0°C. 



- 16° C. 



•942 



•0133 



10 



4- 68 



1206 



•0102 



20 



+ 194 



1-593 



•0090 



25 



+340 



2-06 



Communicated bv the Author. 



