ference between the color effects produced by mixing two pigments and the mixing of the light reflected from similar colored surfaces is a very strong argument for a system of color instruction based on disk combinations, rather than on pigmentary mixtures.
In order to obtain the most truthful effects of color in nature the artist should have sufficient knowledge of the principles which govern the combination of colors by reflected light, so that his reason may aid his eyes.
A little experimenting with the rotating disks and with pigments will convince any one that the disk combinations form the only possible basis at present known for logical color instruction.
Having shown that the three colors, red, yellow and blue, can not be combined to make an orange, a green or a violet of a corresponding degree of purity, we will consider the other claim which is set up by the advocates of the Brewster theory, namely, that the secondaries are complementary to the primaries in pairs, the green to the red, the violet to the yellow and the orange to the blue.
As all color is contained in white light, if we take from white light any given color, the color remaining is the complementary. If a small disk of standard red paper is placed on a white wall and the eyes fixed intently on it for a few seconds, and then the eyes slightly moved back and forth, a ring of a bluish green tint will be seen surrounding the red paper, or if the eyes are fixed intently on the disk for a short time and the paper suddenly removed, a disk of the same blue green tint will be seen in place of the red disk. This is called the accidental color and is supposed to be identical with the complementary color, although the image is too faint to give any very exact effect, but it is sufficient to furnish a clue to the complementary, and we may infer that a color between green and blue is that which is required.
