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Appendix to Chapter III.

False Color Balance. There is a widely accepted error An image should appear at this position in the text. that red, yellow, and blue are “primary,” although Brewster’s theory was long ago dropped when the elements of color vision proved to be Red, Grren, and Violet-Blue. The late Professor Rood called attention to this in Chapters VIII.—XI. of his book, “Modern Chromatics,” which appeared in 1879. Yet we find it very generally taught in school. Nor does the harm end there, for placing red, yellow, and blue equidistant in a circle, with orange, green, and purple as intermediates, the teacher goes on to state that opposite hues are complementary.

Red is thus made the complement of Green,
Yellow thus made the complement of Purple, and
[1]Blue is thus made the complement ofOrange.

Unfortunately, each of these statements is wrong, and, if tested by the mixture of colored lights or with Maxwell’s rotating discs, their falsity is evident.

There can be no doubt that green is not the complement of red, nor purple of yellow, nor orange of blue, for neither one of these pairs unites as it should in a balanced neutrality, and a total test of the circle gives great excess of orange, showing that red

  1. Ultramarine, the pigment often selected as a typical blue, has a violet or purple quality which makes it the complement of yellow, not of orange. Typical blue should contain no hint of violet or purple, and is best represented by Cerulean (cyan-blue), which is the true complement of yellow-red. See charts B and Y of the Color Atlas.