43. According to the law of the simultaneous contrast of colours, and the insensible gradation of modification, beginning at the contiguous edges of the colours in juxtaposition (11), we may show, by means of coloured circular spaces, the modifications which the principal colours induce in those which are contiguous to them. Place wafers, circular pieces of paper, or any other convenient material about an inch and a half in diameter, coloured red, green, orange, blue, greenish-yellow, violet, indigo, and orange-yellow, each separately upon a sheet of white paper; then tint the white paper around the circle with its complementary colour, gradually softening it off from the coloured circle, when it will be found that The Red circle tends to colour the surrounding space with its complementary Green. Green ” ” Red. Orange ” ” Blue. Blue ” ” Orange. Greenish-yellow ” Violet. Violet ” ” Greenish-yellow. Indigo ” ” Orange-yellow. Orange-yellow ” Indigo. These figures are designed to exhibit the effects of contrast to those persons who, not having studied physical laws, are, notwithstanding, desirous of understanding these effects. CHAPTER IV. _On the Juxtaposition of Coloured Surfaces with White._ 44. When white bodies are viewed simultaneously with coloured bodies contiguous to them, they are sensibly modified. I confess that the modification is too feeble to be determined with absolute certainty while we are ignorant of the law of contrast; but, understanding that, and knowing the modifications that white undergoes in connexion with certain colours, we shall not fail to recognise this modification in special cases, provided the colours opposed to the white be not too deep. _Red and White._ 45. Green, complementary to Red, being added to White, the Red appears more brilliant and deeper. _Orange and White._ 46. Blue, complementary to Orange, being added to White, the Orange appears more brilliant and deeper. _Greenish-Yellow and White._ 47. Violet, complementary to Greenish-yellow, being added to White, the Yellow appears more brilliant and deeper. _Green and White._ 48. Red, complementary to Green, being added to White, the Green appears more brilliant and deeper. _Blue and White._ 49. Orange, complementary to Blue, being added to White, the Blue appears more brilliant and deeper. [Illustration: PLATE IV.] _Indigo and White._ 50. Yellowish-orange, complementary to Indigo, being added to White, the Indigo appears more brilliant and deeper. _Violet and White._ 51. Yellowish-green, complementary to Violet, being added to White, the Violet appears more brilliant and deeper. _Black and White._