494 L. P. Wheeler — Dispersion of Metals. 



of the optical constants is incapable of yielding dependable 

 re suits. 



On the other hand, since, as has been pointed out above, the 

 data at our command as to the relative values of the optical 

 constants at different wave lengths are in general of a higher 

 order of precision, it would seem that a comparison of these 

 results with the dispersion formulae yielded by the electron 



Fig. 2. 





9 



\ 













/ 



ISO 





8 



r 











y' 





160 





7 



\ 









y 



s' 





140 





6 



\ 









/' 







120 





3 



\ 







/ 



y 







^100 





A 



\ 



\* 





/ 



*' 









80 





3 





V\/ 



„/ 











60 





2. 



j-y 















40 













/ 







r 



20 





V. 



< 



>, 













J* 















>, 



\ 



A 



>/ 



















&\ 



s 













075 







1 "^Ir 





















Jk? / 



















r^^ 





.jjns*^ 



i__^- — ■"" 











t 





















r 



-»A 0.25^0. O.SO/L 07S/U. I.OO/a. l.2S/fe. I 60yC«. 1 7»><- 2.00,0. 2.29/«- 



Fig. 2. Copper. 



theory should yield results of some value. To make such a 

 comparison is the object of this paper. 



It may be mentioned in passing that it would seem to be 

 possible to obtain accurate absolute values really representing 

 specific properties of the substance in the case of mercury ; for 

 the author* has shown that in the case of this metal it is possible 

 to reproduce exactly, surface conditions entirely free from all 

 films of impurity. The possibility of different states of surface 

 strain at different times would also, of course, be eliminated. 

 Work on the dispersion of mercury is now under way in order 



* Wheeler, Phil. Mag., xxxi, p. 229 ; also this Journal, xxxii, p. 85, 1911. 



