168 Biological Stains 



tuted for anilin blue W.S., as in the Mallory connective tissue stain. 

 Such uses of this dye are too numerous to Hst, but one might men- 

 tion that of Dubreuil (see Krause, 1926-7, p. 1382) who employed 

 it, cpmbined with picric acid, in contrast to a red nuclear stain 

 such as carmine or safranin. One of its oldest and best known 

 uses is that of Mann (1894) who mixed it with eosin and showed 

 the value of the mixture in staining nerve cells. Recent workers 

 suggest it for other purposes: Clauser and Strani (1930) for stain- 

 ing unfixed tissue; Cumley (1935) for the negative staining of 

 bacteria; Monne (1935) in the vital staining of protozoa. 



For use in buffered Mann stain, see Staining Procedures p. IA4-I9; in technic 

 with Biebrich scarlet see p. IB3-I2. 



n65 anilin blue, w. s. (i.e., water soluble) c. i. no. 707 



Synonyms : China blue. Soluble blue 3M or 2R. Marine blue V. 



Cotton blue. Water blue. 



This is a mixture of the tri-sulfonates* of tri-phenyl para- 

 rosanilin (C. I. 706) and of di-phenyl rosanilin. The latter is: 



H 



NaSOj /""\=N_/— \_S03-Na 



H2N_/— \_C SO3 



CHj 



H 



N 

 C32H25N309S3Na2; Mol. Wt. 737.718 



{An add dye; absorption maximum of samples submitted for 

 certification 595-610 in alcohol) 



Anilin blue W. S. should be regarded as a group of dyes rather 

 than as a simple dye. The composition of the various commercial 

 products sold under this name is uncertain, and no method seems 

 to be known for controlling the process of manufacture so as to 

 yield a constant product. 



The spectrophotometric curve of a sample typical of those sold 

 as biological stains is given in Fig. 22. 



Certain dyes of this group (apparently only the rosanilin deriva- 

 tives, because they are most likely to be free from undesirable 

 colored impurities), have indicator properties, decolorizing almost 

 completely on addition of alkali, and slowly becoming blue again 



*The location of the sulfonic groups is uncertain. 



