Nigrosine

noun

Ni·gro·sine

ˈnīgrəˌsēn,

-sə̇n

variants or nigrosine or less commonly Nigrosin

-sə̇n

or nigrosin

plural -s

often capitalized

: any of several azine dyes closely related to the indulines: such as

or Nigrosine Base B : an oil-soluble bluish black dye obtained as the free base by heating aniline and aniline hydrochloride and nitrobenzene or nitrophenol in the presence of iron and used chiefly in coloring waxes, shoe polish, plastics, and lacquers and as wood stains

or Nigrosine Spirit Soluble : a chloride of the free base that is soluble in alcohol and is used similarly

or Nigrosine Water Soluble : a water-soluble sulfonation product of the free base or of its chloride used chiefly in dyeing leather and paper and as a biological stain