ards embraced in a given compound color can be expressed.
The Maxwell color disks are the only known means by which we may measure the relative proportions of color effect embodied in a given color, and therefore the eight color disks are the foundation of the original color nomenclature herein advocated.
Colored papers are chosen for primary color instruction because paper is a valuable medium for simple schoolroom manual training and because no other pigmentary medium is at once so economical and affords such pure colors as may be secured in specially prepared colored papers, without a glazed surface.
Before leaving this part of the subject we do well to remember that in the present conditions of chemistry as applied to the preparation of pigments it is not possible to establish any absolutely definite science of such color combinations. Nor is it possible to establish permanent pigmentary standards without great expense, but if the locations of the standard colors in the spectrum are established by wave lengths the pigmentary standards may be re-determined at any time and produced, in the purest pigments available at the time. In art or harmony effects, the purity of the pigmentary standard is not so important as its hue, i. e. its location in the spectrum, which may always be determined by the established wave length. This last statement may be illustrated by the investigations regarding complementary harmonies. Scientifically one color is not considered complementary to another unless when combined in equal quantities they produce white light, or in other words when combined by the rotation of disks each color must occupy a half circle and the result must be a neutral gray. But this is not essential in considering a complementary harmony, as harmonies in different tones and in various proportions are pleasing and as yet the proportions and tones which produce the best combinations have not been determined.
The entire question of harmonies or pleasing color effects is dependent on individual color perception, and the establishment of rules and laws on these points can result only from a
