2-Naphthalenesulfonic acid, 4-hydroxy-7-((((5-hydroxy-6-((2-methoxy-4-sulfophenyl)azo)-7-sulfo-2-naphthalenyl)amino)carbonyl)amino)-3-((6-sulfo-2-naphthalenyl)azo)-, sodium salt, compd. with 2,2,2-nit