Mann’s eosin-methyl blue

45 mL aqueous eosin (C.I. 45380) (1% w/v)

35 mL aqueous methyl blue (C.I. 42780) (1% w/v)

100 mL H₂O

Combine above reagents. The stock solutions and the mixture can be kept for 2 yr. Precipitates may form in the mixture; they should be removed by filtration. Any water-soluble “aniline blue” (C.I. 42755) may be used in place of methyl blue.