L. P. Wheeler — Dispersion of Metals. 



495 



to obtain with this more promising material data which will 

 enable us to make a more satisfactory comparison with theory 

 than is possible with other substances. 



With regard to the properties of the metals revealed by the 

 data under discussion, it will be observed that all five of the 

 substances show in general a decrease of the absorption coef- 

 ficient (increase in transparency) with increasing frequency of 



Table II— Copper. 



Observer 



1 



n 



nk 



- l — (10)- 12 

 1? 



r 



ftV-1) 



A 



K 



Minor 



0-231// 



1-39 



1-46 



163- 



11-8 



0-19 



50-0 



49-8 



t < 



•257 



140 



1-42 



117- 



9-96 



0-06 



52-1 



520 



<< 



•298 



1-26 



1-32 



62-7 



7-31 



0-16 



515 



51-3 



i ( 



•347 



1-19 



1-47 



41-8 



597 



0-73 



56-7 



56-0 



a 



•395 



1-17 



1-76 



33-4 



5-34 



1-73 



66-1 



64-4 



a 



•450 



1-13 



215 



26-6 



4-77 



3-34 



766 



73-3 



Tate _ 



•460 



1-57 



2-26 













Tool 



•460 



119 



2-29 



27-9 



4-89 



3-72 



82-4 



7~8"-7 



< < 



•500 



1-17 



2-38 



22-2 



4-37 



4-30 



86-9 



82-6 



Tate. 



•500 



1-50 



2-37 





... 



... 







Minor 



•500 



110 



2-34 



20-6 



419 



4-24 



8~3~-2 



79 



Tate 



•540 



1-38 



2 46 













Tool 



•540 



1-07 



2-41 



16-4 



3-13 



4-66 



84-1 



79-4 



Minor 



•550 



0-892 



2-23 



12-0 



3-20 



4-18 



77-0 



728 



Tool 



•560 



0-855 



2-42 

















Tate 



•580 



1-07 



2-84 













Tool 



•580 



0-600 



2-79 



8-60 



2*71 



7-44 



72 4 



650 



Drude 



•589 



0641 



262 







_ 









Minor 



•589 



0-617 



2 63 



7-90 



260 



652 



71-6 



65-1 



Tate 



•600 



0-980 



319 









. 





Tool 



•620 



0-580 



3 32 



8-10 



263 



10-9 



80-4 



69 5 



Drude .. 



•630 



0-580 



3 04 













Tool 



•640 



0-615 



3-58 



8-40 



2-68 



12-4 



87-5 



75-1 



Tate 



•640 



0-958 



3-53 













Ingersoll.. 



•65 



0-44 



3-26 



5 21 



2-10 



10-4 



70-5 



60-1 



Tool 



•660 



0-655 



3-78 



8-64 



2-72 



139 



94-1 



80-2 



Tate 



•660 



0-996 



370 















n 



•700 



1035 



3-82 















Ingersoll . 



•87 



0-35 



3 85 



2 : 05 



1-32 



14-7 



79-4 



64-7 



c< 



1-25 



0-56 



7-28 



2-09 



1-33 



52-7 



165- 



113- 



u 



1-75 



0-83 



9-46 



1-47 



1-12 



90-7 



273- 



182- 



(« 



225 



1-03 



11-7 



1-06 



1-02 



136- 



420- 



284- 



the incident light. In the cases of silver and gold and, with 

 less certainty, copper, there is a minimum in the curve followed 

 by a feeble maximum further up in the spectrum. Thus for 

 silver there is a distinct " transmission " band in the ultra- 

 violet with its center at about 0*316//, ; for gold, a less distinct 

 one in the visible spectrum central at about 0480/li ; while for 

 copper there are apparently two minima of absorption, one in 



