Dyeing, Witt theory

In 1890 Otto N. Witt advanced the theory that the dye dissolves in the fabric or the mordant, forming a solid solution. The chief argument in favor of this view was that the color of the dye on the fiber is that of the dissolved dye and not of the solid dye. Magenta, for instance, dyes a red and not a metallic green. Silk dyed with rhodamine fluoresces, while solid rhodamine does not, when obtained on a glass plate by evaporation of an alcoholic solution. 

Witt s theory of solid solutions in dyeing loses its only support as soon as one postulates that textiles and mordants may act as ionizing adsorbents. 

A further effort to establish a relationship between explosive properties and structure has been made more recently by Piets [2]. He proposed a theory of ex-plosophores and auxoploses in a way analogous to Witt s suggested chromo-phores and auxochromes in the dyes, and Ehrlich s suggested toxophores and autotoxes in chemotherapeutics. 

Chrysophenine shows a characteristic reaction with mineral acids witli which it turns a beautiful blue. It is of interest, theoretically, that chrysophenine is an extraordinarily strong dye even though it contains no auxocliroiue groups of the type required by tlie Witt color theory. 

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