ERYTHROSIN, YELLOWISH 



C. I. NO. 772 



Synonyms: Erythrosin R or G. Pyrosin J. Dianthine G. lodo- 



eosin G. 



This is a fluorescein in which there are two substituent iodine 

 atoms instead of four bromine atoms as in yellowish eosin. 



O 



_0 



I 

 COONa 



{An acid dye; absorption maximum about 510.5.) 



ERYTHROSIN, BLUISH 



C. I. NO. 773 



Synonyms: Erythrosin B. Pyrosin B. Eosin J. lodo-eosin B. 



Dianthin B. 



This is the tetraiodo compound corresponding to the tetrabrom 

 compound of typical eosin. 



I I 



NaO I I 



O /\_0 



COONa 



{An acid dye; absorption maximum about 524--) 



Erythrosin has some use as an indicator. It is also em- 

 ployed as a contrast stain for haematoxylin and certain blue and 

 violet nuclear stains. Held uses it, preceding methylene blue, as 

 a plasma stain for nerve cells. It is employed by Winogradsky for 

 staining bacteria in soil. For these purposes probably the tetra- 

 iodo compound (i.e., erythrosin bluish) is desired; but the litera- 

 ture 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 57) 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. 



81 



