A SPECTROPHOTOMETRY STUDY OF FLUORESCENCE. 



In addition to the measurements on fluorescein the fluorescence spectra 

 of solutions of eosin and naphthalin-roth were also studied by the method 

 already described, and the transmission curves of the solutions were taken. 



30 



60 



to 



20 



.430// 40 50 60 TO 80 90 .500," 10 



Fig. 8. Fluorescein. 



20 



30 



40 



Intensity of fluorescence as a function of wave-length of exciting light. Ordi- 

 nate's give the intensity of luminescence and abscissas the wave-length of the 

 exciting light. A refers to Nernst glower as source, B to acetylene flame. 



Dilute solutions in alcohol were made, that of the naphthalin-roth being 

 about , rj saturated. The results obtained with these solutions, which are 

 shown in Figs. 9 and 10, afford additional corroboration of the statements 



.5/1 



.6/4 



Fig. 9. Eosin. 



Fluorescence spectra observed when the exciting light lies in different 

 regions of the spectrum. Curve .4 was obtained when the excit- 

 ing light was confined to the region marked .1 on the axis of wave- 

 lengths, etc. Vertical scales arbitrary. 



