Phenyl Methane Dyes 173 



A mixture of rosolic acid and pararosolic acid, with oxidized and 

 methylated derivatives of the latter. This product is of consider- 

 able use as an indicator. 



This dye was employed by Pappenheim (1898) in a decolorizing 

 solution following carbol fuchsin. The method was intended to 

 safeguard against confusion of the smegma and other acid-fast 

 bacteria with the true tubercle bacillus. After the usual carbol 

 fucnsin stain, the decolorizing was done with 1% rosolic acid in 

 absolute alcohol, saturated with methylene blue and containing 

 20% glycerol. 



No other dyes of this group have biological use. Two others 

 perhaps deserve mention: 



n93 red CORALLIN C. I. NO. 72.6 



Synonym: Aurin R. 



Probably a pararosolic acid salt of pararosanilin, forming an 

 intermediate stage in the conversion of pararosolic acid into 

 pararosanilin. 



n95 chrome violet CG C. I. NO. 7I7 



A carboxyl derivative of pararosolic acid : 



COONa 



/ 

 /~\_0H 



o_/--\_c 



"\_0H 



/ \_/ 



COONa \ 



COONa 



C22Hii09Na3; Mol. Wt. 488.299 



{An acid dye) 



3. DIPHENYL-NAPHTHYL METHANE DERIVATIVES 



P5 VICTORIA BLUE R C. I. NO. 718 



Synonyms: New Victoria blue B or R. Corn blue B. 



C29H32N3CI; Mol. Wt. 458.027 



{A basic dye; absorption maxima 61Jf.7 [558]) 

 Solubility at 26°C: in water 0.54.%; in alcohol 3.98% 



