TABLE 180. 



INDEX OF REFRACTION. 



Indices of Refraction of Liquids relative to Air. 



189 



* Weegmann gives p D = 1.59668 .000518*. Knops gives H F 1.61500 .00056*. 

 t Weegmann gives H D = 1.51474 .000665*. Knops gives H D = 1.51^9 .000644*. 

 $ Wiillner gives M C = 1.63407 .00078*; /*/= 1.66908 .00082 *; n h = 1.6921$ .00085*. 



Dufet gives H D = 1.33397 io~ 7 (125* + 20.6 ** .000435 P .00115**) between o and 50; and nearly the 

 same variation with temperature was found by Ruhlmann, namely, ^=1.33373 io~ 7 (20. 14** + .000494**). 



SMITHSONIAN TABLES. 



