Basle blue

Methylene blue, new methylene blue, thionine blue, Capri blue, cresyl blue, brilliant cresyl blue, Nile blue, Basle blue, Mel-dola s blue, fast navy blue, new blue, metamine blue, naphthol u, blue, metaphenylene blue, paraphenylene blue, mdamine blue, indazine, neutral blue, muscanne, diphene blue, rhoduline blue, rhoduline sky blue frl ... 

This dyestuff is obtained by the action of nitrosodimethylaniline chlorhydrate on the ditolylnaphthylenediamine obtained by heating a-dioxynaphthalene (M.P. 180°) with paratoluidine and parato-luidine hydrochloride. The dyestuff forms a brownish crystalline powder, soluble in water with a bluish-violet colour. It dissolves in concentrated sulphuric acid with a greenish-blue colour, which on dilution changes through green to violet, a bluish-violet precipitate being formed. Basle blue is a basic dyestuff and is best dyed on cotton prepared with tannic acid and tartar emetic. 

Leonhardt was mentioned in connection with naphthol yellow, and Geigy of Basle in connection with methylene blue and auramine. 

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