The
number of coal-tar colours is thus very great, and the variety also.
_Adjective Colours._--As regards the artificial coal-tar adjective
dyestuffs, the principal are Alizarin and Purpurin. These are now almost
entirely prepared from coal-tar anthracene, and madder and garancine are
almost things of the past. Vegetable adjective colours are Brazil wood,
containing the dye-generating principle Brasilin, logwood, containing
Haematein, and santal-wood, camwood, and barwood, containing Santalin.
Animal adjective colours are cochineal and lac dye. Then of wood colours
we have further: quercitron, Persian berries, fustic and the tannins or
tannic acids, comprising extracts, barks, fruits, and gallnuts, with
also leaves and twigs, as with sumac. All these colours dye only with
mordants, mostly forming with certain metallic oxides or basic salts,
brightly-coloured compounds on the tissues to which they are applied.
LECTURE XI
DYEING OF WOOL AND FUR; AND OPTICAL PROPERTIES OF COLOURS
You have no doubt a tolerably vivid recollection of the illustrations
given in Lecture I.
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