﻿Lioht Absorption and Fluorescence. 

 Table X. — m-Xylene absorption (Mies), 



235 



! o * in 









Infra-i 



ed bands. 



Angstroms. 



1/A. 



V'X. 



Mean v x . 



Calc. 



Obs. 



2802 



3569 



295 





3-39^ 



3-38 {i 



2721 



3675 



189 





5-29 



5-25 



F2716 



3682 



182 



181 



5-52 





2703 



3699 



165 



163-5 



612 



6-20 



2694 



3712 



152 





6-58 



6-77 



F2687 



3722 



142 



142 



7-04 





2684 



3726 



138 





7-25 



7-25 



2668 



3748 



116 





8-62 



8-70 



2663 



3755 



109 





917 



917 



2658 



3762 



102 



103 



9-70 



9-68 



2655 



3767 



97 





10-30 



10-20 



2648 



3776 



88 



87-5 



11-43 



11-42 



2640 



3788 



76 



74-5 



13-42 



13-00 



F2601 



3645 



19 



20 i 



50-00 





2588 



3864 













F2574 



3885 



21 



20 



50-00 





2540 



3937 



73 



74-5 



13-42 



1300 



2531 



3951 



87 



87-5 



11-43 



11-42 



2520 



3968 



104 



103 



9-70 



970 



F2496 



4006 



142 



142 



7-04 





2484 



4026 



162 



163-5 



6-12 



6-20 



F2473 



4044 



180 



1S1 



5-52 





The central line 3864 is almost exactly 13x297, and 

 12x297 = 3564, which should be the centre of the fluores- 

 cence. Dickson only finds three maxima of fluorescence, 

 and they all lie on the ultra-violet side of 35b4. If this be 

 correct, then allowing 14 units for the effect of the solvent 

 the fluorescence bands may be arranged as in Table XI. 



Table XI. — ?»-Xylene fluorescence (Dickson). 



o X in 



Angstroms. 



l/\. 



1/X4-14. 



! 



2802 

 2715 

 2685 



3569 



3683 

 3724 



3583 

 3697 

 3738 



19 (20) 

 133 (142) 

 174(181) 



It is, however, manifestly impossible to draw any definite 

 conclusion from only three maxima. 



There can be little doubt from the above results that the 

 conception of combining the frequencies of the short-wave 

 infra-red bands with those of central lines of absorption and 

 fluorescence bands is justified. In the five substances dealt 



