Nigrosin is a mixture of synthetic black dyes (CI 50415, Solvent black 5) made by heating a mixture of nitrobenzene, aniline and aniline hydrochloride in the presence of a copper or iron catalyst. Its main industrial uses are as a colorant for lacquers and varnishes and in marker-pen inks. Sulfonation of nigrosin yields a water-soluble anionic dye, nigrosin WS (CI 50420, Acid black 2
N 1616 (OTTO) Nigrosine (water soluble) Cas 8005-03-6 - used as a negative stain in place of India ink for spirochetes, bacteria, protozoa and fungi.
It is employed as a common biological stain for tissues and cells. N 1616 (OTTO) Nigrosine (water soluble) Cas 8005-03-6 - used to make inks and shoe-polish and for dyeing leather, wood, textiles, and plastics. The crude mixture of nigrosine hydrochlorides (Phenol Black L) is used to dye phenolic resins.