a yellow dye that is visible even when highly diluted; used as an absorption indicator when silver nitrate solution is added to sodium chloride in order to precipitate silver chloride (turns pink when no chloride ions are left in solution and negative fluorescein ions are then absorbed)
Any of a class of yellow xanthene dyes which are visible when highly diluted; used forensically to detect traces of blood, and in analytical chemistry as an indicator in silver nitrate titrations