Silk, wool, fur,
etc., act like fibre and mordant together, for they absorb and fix the
substantive colours firmly. In our experiments we saw that turmeric is
one of the few substantive colours fixing itself on both cotton and
wool, without any aid from a mordant or fixing agent. Magenta was also a
substantive colour, but Alizarin was certainly not one of this class.
_Adjective Dyestuffs._--Some of these substances are definitely coloured
bodies, but in some of them the colour is of no consequence or value,
and is quite different and distinct from the colour eventually formed on
the fibre, which colour only appears in conjunction with a special
mordant; but, again, some of them are not coloured, and would not colour
the fibre directly at all, only in conjunction with some mordant. All
the polygenetic colours are, of course, comprised in this class, for
example Alizarin and logwood (Haematein), whilst such monogenetic colours
as annatto and turmeric are substantive, for they will fix themselves
without a mordant on cotton and wool.
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