We may thus understand how black, in taking away some grey, imparts brilliancy, and how this grey, which may be considered as a tarnished or subdued blue, may, with yellow, produce an olive colour. It is also necessary to remark, that the gilt ornaments in question present an olive-grey tint, which, far from being diminished by the white ground, is exalted by it. Although the black ground lowers the tone of the colours, while white heightens them, it lowers yellow more in proportion than red, and consequently renders the ornaments redder than they appear upon a white ground; and, in taking away the grey, it purifies the colours, and acts also by giving them some red, or by taking away some green. _Metallic Gilt Ornaments._ 386. Gilt ornaments stand out better from black than from white, but the orange colour is weakened and really impoverished. The black ground then does not purify the real gilt ornaments as it does the painted imitation of gold. _Deep Red Ground._ The yellows are more luminous, the whole effect with the painted ornament is clearer, more brilliant, less grey than upon a white ground. Red much deeper than the ornament, lowers the tone of it; and this effect is also augmented by the addition of its complementary, green, a bright colour. This example is of much importance, enabling us to see how the red, which appears as though it could be of but little advantage to ornaments, because it tends to weaken them by making them greener, is notwithstanding favourable, because the lightening or weakening of the colour is more than compensated for by the brilliancy of the complementary of the ground which is added to the yellow. We shall return to this effect in a moment. There is this analogy between the influence of the red ground and that of the black ground, that the tone of the colour is lowered; but there is this difference, that the ornaments become green on the first, while they become orange upon the second. 387. The red ground is not so advantageous for gilt ornaments as it is for the painted imitations of them, because the metal loses too much of its orange colour, and appears inferior to gold upon a black ground. The red ground appears darker, and more violet than the ground upon which painted ornaments are placed. Grounds of a light-red are still less favourable to the gold than red grounds of a dark tone. _Orange Ground deeper than the Ornaments._ 388. The painted ornaments are bluer or rather greener than upon a white ground. The yellow and orange are singularly lower in tone. This ground, then, is very disadvantageous to ornaments, as might have been expected. 389. Orange is not favourable to metallic gilt. The metal becomes too white, while the orange ground is redder and more vivid than that upon which the painted ornaments are placed. _Yellow Ground of Chromate of Lead more brilliant than the Yellow of the Ornaments._