Quinone-imine Dyes 



105 



.9— 



450 



I t I 



^90 



I I I I I I I I I 



530 



570 



I I I I I I I l-l 

 610 650 690 



Fig. 11. Spectral curves of three thiazin dyes: 

 1. Methylene blue. 2. Thionin. 3. Methylene violet. 



the sake of uniformity the paraquinoid form will be shown in the 

 following pages wherever possible; but with the understanding 

 that the orthoquinoid form is equally permissible. 



