Carbol fuchsin

Carbol fuchsin, carbol-fuchsin, or carbolfuchsin, is a mixture of phenol and basic fuchsin, used in bacterial staining procedures. It is commonly used in the staining of mycobacteria as it has an affinity for the mycolic acids found in their cell walls.
It is a component of Ziehl-Neelsen stain.  Carbol fuchsin is used as a dye to detect [acid fast bacteria] because it is more soluble in the cells wall lipids than in the acid alcohol. If the bacteria is acid fast the bacteria will retain the initial red color of the dye because they are able to resist the destaining by acid alcohol.
Carbol-fuchsin is also used as a topical antiseptic.