The Chemical Nature of Metachromasy

Abstract

The phenomena of metachromasy are paralleled by analogous color changes which may be observed with aqueous solutions of dyes. It appears very probable that both types of phenomena arise from tautomerism in the structure of the dyes concerned. No adequate explanation of the behavior of dyes in these particulars has been proposed hitherto. A hypothesis is advanced which accounts for these phenomena in a satisfactory manner. It is held that the majority of dyes of aminated constitution are capable of undergoing a tautomerism which involves merely a redistribution of affinities within the dye molecule, resulting in a transition between structure of ammonium salt type and that of addition product type.