Xanthene Dyes 193 



r26 erythrosin, bluish c. I. NO. 773 



Synonyms: Erythrosin B, N, or JN. Pyrosin B. Eosin J. 



lodeosin B. Dianthine B. 



This is the tetraiodo compound corresponding to the tetrabrom 

 compound of typical eosin. 



NaO I I 



. O /\_0 



C= 



I 



COONa 



C2oH605l4Na2; Mol. Wt. 879.922 

 {An acid dye; absorption maximum 52^-527) 



w 



Solubility at 26°C: in water 11.10%; in alcohol 1.87% 



There is some uncertainty as to which of these two very similar 

 dyes is preferable in any given technic. At present, the latter, 

 erythrosin B, is ordinarily furnished by supply houses when 

 "erythrosin" is ordered. Its spectral curve is given in Fig. 25, 

 p. 194. 



Erythrosin has some use as an indicator. It is also employed 

 as a contrast stain for hematoxylin and certain blue and violet 

 nuclear stains. Thus, for example, Held (1895) used it, preceding 

 methylene blue, as a plasma stain for nerve cells. Similarly the 

 technic of Jackson (1926) calls for it as a counterstain to crystal 

 violet in plant histology. It was employed by Winogradsky (1924) 

 for staining bacteria in soil. Gellhorn (1931) applied it to the 

 vital staining of sea urchin eggs. These procedures are mentioned 

 merely by way of illustration; the uses of erythrosin are quite 

 numerous, and the list could be extended almost indefinitely. For 

 these purposes probably the tetra-iodo compound (i. e., erythrosin 

 bluish) is desired; but the literature is vague on the subject. 



A sample of erythrosin of pre-war origin that was labeled mag- 

 dala red has been examined by the Commission. This mislabeling 

 undoubtedly explains Chamberlain's results already mentioned 

 (page 133) in staining algae. Chamberlain, it will be recalled, was 

 able to obtain good results with a low-priced product called mag- 

 dala red but not with the high-priced stain called magdala red 

 echt. 



For technic of Jackson stain for woody tissue, see Staining Procedures, p. IIA-9. 



