[f. as prec. + -ING2.] That colors: in senses of the verb.
1646. Sir T. Browne, Pseud. Ep., VI. xii. 334. The action of heat or fire, & colouring bodies objected.
1791. D’Israeli, Cur. Lit. (1866), 33/2. Conceptions … agreeably set off by a warm and colouring diction.
1801. Med. Jrnl., V. 199. Very little impregnated with colouring particles.
b. Coloring matter. [It is doubtful whether coloring is here originally the ppl. a. or the vbl. sb. used attributively.] Any substance coloring a natural body, or employed in the arts to color objects.
‘By chemists, however, the term is only applied to organic bodies, and not to mineral substances…. Colouring matter may be defined to be substances produced in animal or vegetable organisms, or easily formed there by processes occurring in nature, and which are themselves coloured, or give coloured compounds with bases, or with animal or vegetable fibre’ Ure, Dict. Arts).
1805. W. Saunders, Min. Waters, 69. A saline … water, will … produce material changes on the colouring matter.
1813. Sir H. Davy, Agric. Chem. (1814), 146. The colouring matters of flowers are the most permanent.
1831. Brewster, Optics, xxvi. 220. The colouring matter of the amethyst.
1838. T. Thomson, Chem. Org. Bodies, Contents p. xi. Of Blue colouring matters, Of Indigo, Litmus or turnsole, Blue flowers.
