Nitro and Azo Dyes 85 



ly after adding it to the solution to avoid error due to this cause. 

 Carter (1933) has recently employed this dye in the vital staining 

 of protozoa. 



Dl THIAZINE RED R C, I. NO. 12-5 



Synonym : Chlorazol pink Y. Rosophenine lOB. 



OH 



N=: C_/~X_N = N_ 



/-v_ / \_/ 

 \_/ s I 



j SO3 Na 



CH3 SO3 Na 



C24Hi5N307S3Na2; Mol. Wt. 599.558 



{An add dye; absorption maximum 505) 



This dye has occasionally been used as a counterstain in animal 

 histology. It was introduced by M. Heidenhain (1903). It is 

 thought by some users to prove a satisfactory counterstain against 

 hematoxylin for skeletal and cardiac muscle. 



b. Dis-Azo AND PoLY-Azo Dyes 



d2 NAPHTHOL blue BLACK C. I. NO. 246 



Synonyms: Pontacyl blue-black SX. Buffalo black NBR. 



NH2 OH 



I / 

 N02_/-^_N = N_/\/\_N =- N_/— \ 



\_/ J I i \-/ 



NaSOs SOsNa 



Cr^HuNe O9 SaNaa; Mol. Wt. 616.505 

 {An add dye) 



This dye has rarely been mentioned for biological use; but it 

 has been referred to by Lillie (1945c) as a stain for collagen. See 

 Staining Procedures p. IB3IO. 



d3 brilliant CROCEINE C. I. NO. 252 



Synonyms: Croceine scarlet 3By MOO. 



NaSOa 



/-\_N = N_/- 



SOsNa 



C22H13N4 O7 S2 Naa; Mol. Wt. 555.-^82 

 {An acid dye) 



