The outlines of physics: an elementary text-book . and violet, blueby the absorption of the redand green. Measurements of the differ-ent wave lengths reflected bythree typical pigments, andexpressed graphically bymeans of curves, are shownin Fig. 391. None of thecolors produced in these casesare pure; that is to say, thereis, in all cases, a considerableadmixture of light other thanthat which gives the prevailing color tone. Purity of colordenotes absence of these admixtures. The only perfectlypure colors are those of the spectrum formed by a narrowslit. Colors differ also in saturation. This
The outlines of physics: an elementary text-book . and violet, blueby the absorption of the redand green. Measurements of the differ-ent wave lengths reflected bythree typical pigments, andexpressed graphically bymeans of curves, are shownin Fig. 391. None of thecolors produced in these casesare pure; that is to say, thereis, in all cases, a considerableadmixture of light other thanthat which gives the prevailing color tone. Purity of colordenotes absence of these admixtures. The only perfectlypure colors are those of the spectrum formed by a narrowslit. Colors differ also in saturation. This term denotesthe absence of admixture of white light. In proportion asthe white light is done away with, and the tint becomesmore and more intense, it is said to be more and moresaturated. There is, in all ordinary cases, a considerableamount of white light present in the rays reflected bypigments, because not all the light penetrates the sub-stance, and thus a considerable portion is reflected fromthe surface, and this does not suffer VISION AND THE SENSS OF COLOR 419 385. Dependence of Color upon the Character of the IncidentLight. — Colored objects are capable of modifying the lightwhich falls upon them only by process of absorption. Theycan therefore reflect back no rays which do not reach colors which they present contain no light which hasnot been thrown upon them from without. In proportionas the source of illumination is rich, the effect will bevaried upon the bodies which it illuminates. Daylight,for example, is richer in violet and blue rays than anyartificial light. Colors seen by daylight, therefore, sendthe eye a larger proportion of these tints. If, for daylight,we substitute gaslight, which is comparatively weak inviolet rays, objects of a bluish cast tend towards in the color of bodies, which are perfectlyobvious by daylight, are scarcely to be distinguished whenthe bodies are seen by lamplight. If, for lamplight, wesubst
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectphysics
