If it is true that the phenomenon of the after image is the cause of the peculiar effects expressed by the terms simultaneous, successive and mixed contrasts, and that by these effects all harmonies in color are governed, it is certainly profitable to understand them while using color material with the children, for their good as well as our own pleasure.
Returning to our classification of harmonies, already stated, we find the first to be Contrasted Harmony, which covers those combinations in which a positive color, as a spectrum color for example, is combined with white, black or gray, leaving out for the present silver and gold, which may be confusing, and can at best be used only as outlines.
The simplest combinations of colors are found in this class, all of which are not equally harmonious, and some may not perhaps be entitled to be classed as harmonies, although not positively inharmonious. In this class, as in all others, there is involved contrast of tone and contrast of color, which may best be considered in several divisions.
According to the results of Chevreul's elaborate experiments the effect of a combination of an active color with white is to render the color more brilliant and to give to the white the effect of the complementary of the active color. He admits that the modification of white is very indefinite, but claims that, knowing what to expect, a complementary effect may be seen which otherwise would not be noticed. There is also a contrast of tone which in all cases tends to strengthen a color when used with white.
White and black are both intensified by combination with each other, and this is the type of "contrast of tone." Contrast of tone is very clearly shown when two or more grays of different tones are placed contiguous to each other. This experiment is easily tried by mounting side by side several strips
