Chlorazol Black E as a Vital Dye

Abstract

THE use of chlorazol black E as a stain for general purposes in ordinary microscopical technique was suggested by Prof. H. Graham Cannon in NATURE some years ago¹. This nearly black substance agrees with many vital dyes in being a sulphonated acid azo-compound; but whereas trypan blue, trypan red, vital new red, diamine fast scarlet, benzo–purpurine 4B, the various Niagara blues, new Bordeaux L, Congo rubine, afridol blue, Baumwoll-rubin, etc., all possess two azo-linkages, chlorazol black E has three. It was thought interesting to try the trisazo compound as a vital dye, and the results suggest that it may be a useful one.