Technical Chemistry. 481 
manner sulphate of baryta and other pulverulent mineral bodies may be 
mordanted and dyed with decoctions of dyewoods, 
With regard to the nature of the force which binds the coloring matter 
to the fibre—whether or no it be chemical attraction? Bolley concludes 
that there is no sufficient reason for accepting the view, principally devel- 
by Chevreul [and by Kuhlmann, Comptes Rendus, Tomes xlii, xliii e¢ 
xliv], that dyeing is a direct consequence of chemical affinity. He 
believes that the power possessed by fibres of attracting certain bodies— 
_ whether salts or coloring matters or both—from their solutions, belongs to 
that class of phenomena which results from the action of finely divided 
mineral or organic bodies (charcoal or bone black for example,) on such 
s. The distinction between the action of charcoal and of fibres 
: 
, 
: 
4 
great difference in the structure of cotton fibre as compared with that of 
the two substances last mentioned. It is well known that wool and silk 
_ danted cotton which is on a par with the fact observed b 
the decolorizing power of eos charcoal is considerably increased by 
e Author mordants act by producing insoluble colors 
(lakes), Their behavior towards coloring matters in solution must be 
ascribed to chemical affinity, with which however the fibres themselves 
@ so-called substantive dyes become insoluble from some other cause 
than the addition of a Fe yin for example oxydation of protoxyd of iron, 
indigo. 
