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 and yellow usurp too great a portion of the circumference. Starting from a false basis, the Brewster theory can only lead to un-balanced and inharmonious effects of color.

The fundamental color sensations are, , and.

all of the hues in the right-hand column being compound sensations. The sensation of green is not due to a mixture of yellow and blue, as the absorptive action of pigments might lead one to think:, and not made by mixing any hues of the spectrum, while, but caused by the mingled sensations of red and green. This is easily proved by a controlled spectrum, for all yellow-reds, yellows, and ereen-yellows can be matched by certain proportions of red and green light, all blue-greens, blues, and purple-blues can be ob- tained by the union of green and violet light, while purple-blue, purple, and red-purple result from the union of violet and red light. But there is no point where a mixture gives red, green, or violet-blue. They are the true primaries, whose mixtures produce all other hues.

Studio and school-room practice still cling to the discredited theory, claiming that, if it fails to describe our color sensations, yet it may be called practically true of pigments, because a red, yellow, and blue pigment suffice to imitate most natural colors. This discrepancy between pigment mixture and retinal mixture becomes clear as soon as one learns the physical make-up and behavior of paints.