brilliancy tenfold. The reason for this apparent change in the colors, is that after looking upon a colored object for some minutes, that part of the retina of the eye upon which the color makes an impression becomes fatigued, and the complement of that color takes its place upon the retina. It is a fact that from the instant that we first look upon any color, its complement immediately begins to take its place upon the retina of the eye, and the longer we look upon a color, the duller it will become, and the stronger its complement will appear when we look upon a white surface; and if we look upon a color which is the complement of the color first looked at, the effect is just the same as when we print a transparent red over red, or a transparent bine over bine, etc.; the color will appear much more brilliant. This experiment can be tried with Figs. 242 and 243 with a pleasing result.
We will now give an experiment for the purpose of showing that a mixture of prismatic complementary colors will produce white light. The tint which comes into view after looking at a colored object, is really the same as a prismatic color, only it is not so strong. The reader will again cover all of the figures on Plate 31 except 239 and 240. Then look at the dot on Fig. 239 for a second, then at the dot on Fig. 240 for a second, and keep shifting the eyes at regular intervals of a second each, from one to the other for a half minute; then suddenly look at the dot between the two figures, and there will be seen a clear white figure surrounded by gray. The white is produced by an equal mixture of the complements of the colors in Figs. 239 and 240 upon the retina of the eye. The reader will observe that the colors in the two figures are purposely reversed for the benefit of some of the experiments. This experiment can also be tried with Figs. 242 and 243 with a pleasing result.
If the same experiment be applied to the three primary colors properly balanced, the result will be white; also the secondaries properly balanced will produce white by this experiment.
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