Rose bengal is an organic potassium salt that is the dipotassium salt of 2,3,4,5-tetrachloro-6-(2,4,5,7-tetraiodo-6-hydroxy-3-oxoxanthen-9-yl)benzoic acid. It has a role as a fluorochrome and a histological dye. It is a xanthene dye and an organic potassium salt. It contains a rose bengal(2-). It is functionally related to a fluorescin.