The Pharmaceutical era . ced by mixing any of the others; hence, accordingto Youngs theory of color vision, these are the threeprimary color sensations, and all other color sensationsare combinations of these. Mixed all together in properproportion the sensation is white, or if any two aremixed the intermediate sensations are produced. According to this theory, color blindness is due to theabsence of one of the primary color sensations, usuallyred, so that the color blind person is able to distinguishonly green and violet and the colors produced by theirintermixture. Color by Absorption. Thoor
The Pharmaceutical era . ced by mixing any of the others; hence, accordingto Youngs theory of color vision, these are the threeprimary color sensations, and all other color sensationsare combinations of these. Mixed all together in properproportion the sensation is white, or if any two aremixed the intermediate sensations are produced. According to this theory, color blindness is due to theabsence of one of the primary color sensations, usuallyred, so that the color blind person is able to distinguishonly green and violet and the colors produced by theirintermixture. Color by Absorption. Thoory of Pigments.—The color of anolgict depends upon the relation of the absorbedand reflected rays. If all the rays are equally reflectedthe sensation of white light is produced and the objectis called white. If the waves are largely absorbed andabsorbed equally so that there is but little reflection, theobject is said to be black. If the red waves are mainlyreflected, and the others absorlied the object is called PURPLE. N33U0 Fig. 57.—Compleuieutary Colors. red, and so on. In applying paint, we select the pig-ment which has the property of reflecting the waveswhich produce the color sensation desired, and of ab-sorbing the others. It must be noted, however, that mixing colors, and mix-ing pigments may yield different results. Thus, whileblue light and yellow light will combine to form white,blue and yellow pigments mixed will prodtice green. Thisis explained by the assumption that the l)Iue pigmentabsorbs the red, orange and yellow rays, and the yellowpigment the lilue and violet. The green rays being ab-sorlied by neither, are reflected, and give their own colorto the mixture. Reflection of Light, Mirrors.—Objects with roughened sur-faces diffuse the light which falls upon them, or re-flect it irregularly in all directions. If the surface besufiiciently smooth the light is reflected regularly andimages are formed. Such reflecting surfaces are knownas mirrors, and may lie
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