﻿240 Light Absorption and Fluorescence. 



In the case of ^-xylene the following values are obtained 

 (Table XV.). 



Table XV.— p-Xylene. 



Phosphorescence 

 (v. Kowalski). 



Cathodoluminescence 

 (Goldstein). 



l/\. 



v x . 



Mean v x . 



1/X. 



,, 



234 



22 



22 (22 - 2) 



176 



30 (29-8) 



239 



17 



17-5 (19 and 16) 



180 



26 (26) 



243 



13 



13-5 (13-8) 



184 



22 (22-2) 



249 



7 



8 (7-8) 



188 



18 (19) 



253 



3 



2-5 " 



| 192 



14 (14) 



(256) 









196 



10 (10-5) 



258 



2 



25 



200 



6 (5-9) 



265 



9 



8 (7-8) 



205 







270 



14 



13-5 (13-8) 



208 



2 (1-95) 



274 



18 



17-5 (16 and 19) 



212 



6 (5-9) 



282 



26 



? 



Central line 205'6. 



Central line 256 





| 



It is possible that there is an error in v. Kowalski s 

 measurement of the last maximum on his list. We thus 

 have for the fundamental frequency of p-xylenethe following 

 values : — 



Cathodoluminescence . 8 x 257 

 Phosphorescence . . 10 x 256 

 Fluorescence . . . 14 x 258 

 Absorption .... 15x258 



It is manifestly impossible to expect much accuracy from 

 the values of the phosphorescence maxima, seeing that the 

 measurements themselves of these are far from accurate, but 

 they certainly seem to give considerable support to the 

 theory put forward in this paper, a theory which would 

 appear to be proved correct from the absorption and 

 fluorescence measurements. 



Inorganic Chemistry Laboratory, 

 The University, "Liverpool. 



