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Night Blue

Night Blue

Ionisation: Basic

Chemical structure of Night Blue

Common Name: Night blue
Suggested Name: Night blue
Other Names:

C.I. Number: 44085
C.I. Name: Basic blue 15
Color: Blue
Solubility Aqueous: Readily
Solubility Ethanol: Readily
Absorption Maximum: 616 (Gurr)
Empirical Formula: C38H42N3Cl
Formula Weight: 576.2


Night blue has been recommended as a substitute for basic fuchsin in the demonstration of acid fast organisms, which would be coloured blue instead of red. While this dye is effective for that purpose, small blue organisms on a red background are not as easily seen as small red organisms on a blue background, and the method has gained very little favour.

Compare this dye to its close relatives, victoria blue 4R, victoria blue B and victoria blue R. If one of these dyes is required but is unavailable, it is worth trying one of the others as a substitute.


  1. R. D. Lillie.
    Conn’s Biological Stains
    Williams & Wilkins, Baltimore, MD., U.S.A.
  2. Edward Gurr, 1971
    Synthetic dyes in biology, medicine and chemistry
    Academic Press, London, England.