and Dispersion in certain Metals. 377 



numbers to be approximately correct; however, rather a large 

 range of error must be allowed in consequence of the diffi- 

 culties of observation. 



Our refractive indices are plotted as a function of the wave- 



Tablb IV. 



No. 





Refractive Index n. 



Colour 



Bed. 

 Li a. 



" Red." 

 64-4 



Yellow. 

 D. 



58-9 



Blue. 

 F. 



Violet. 

 G. 



43-1 







X x 10 6 centim. 



671 



48-6 



Iron. 



Fe. 



I. 



II. 

 III. 



0- 



170 

 20-9 

 260 



3-34 



3-01 

 3-00 



— 



303 



2-84 

 2-59 



261 



2-63 

 208 



2-23 

 2-15 

 1-78 



Means A... 

 Means B . . . 





312 



302 



306 



2-72 

 2-71 



243 



2-40 



205 



201 











Cobalt. 









Co. 



I. 



IT. 



III. 



|3. 



13-5 

 14-5 

 22-3 



3-02 

 3-42 

 3-22 



— 



2-42 



2-88 

 2-97 



2-23 

 2-41 



2-54 



2-01 

 214 

 216 



Means A. . 





322 



3-22 



310 



276 



2-86 



239 



2-41 



210 



2-11 



Means B.. 







Nickel. 



Ni. 



I. 



IL 



III. 



P. 



16-5 

 22-4 



27-7 



2-12 

 1-93 



2-08 



— 



1-89 

 1-78 

 1-85 



1 71 



1-74 

 1-68 



1-46 

 1-52 

 1-63 



Means A. . 

 Means B.. 





2 04 



202 



193 



1-84 



1-83 



171 



' 1-72 



154 



1-56 





