SATURATION, OF COLORS.--In optics the degree of admixture with white, the saturation diminishing as the amount of white is increased. In other words, the highest degree of saturation belongs to a given color when in the state of greatest purity. SCALE.--A graded system, by reference to which the degree, intensity, or quality of a sense perception may be estimated. SHADE.--Degree or gradation of defective luminosity in a color, often used vaguely from the fact that paleness, or high luminosity, combined with defective CHROMA, is confounded with high luminosity by itself. See Color, Hue, and Tint. SPECTRUM.--In physics the continuous band of light showing the successive prismatic colors, or the isolated lines or bands of color, observed when the radiation from such a source as the sun or an ignited vapor in a gas flame is viewed after having been passed through a prism (prismatic spectrum) or reflected from a diffraction grating (diffraction or interference spectrum). See Rainbow. TINT.--A variety of color; especially and properly, a luminous variety of low CHROMA; also, abstractly, the respect in which a color may be raised by more or less admixture of white, which at once increases the luminosity and diminishes the CHROMA. TONE.--A sound having definiteness and continuity enough so that its pitch, force, and quality may be readily estimated by the ear. Musical sound opposed to noise. The prevailing effect of a color. ULTRAMARINE.--A beautiful natural blue pigment, obtained from the mineral lapis-lazuli. +VALUE.--In painting and the allied arts, relation of one object, part, or atmospheric plane of a picture to the others, with reference to light and shade, the idea of HUE being abstracted.+ VERMILION.--The red sulphate of mercury. VIOLET.--A general class of colors, of which the violet flower is a highly chromatic example. The sensation is produced by a pure blue whose CHROMA has been diminished while its LUMINOSITY has been increased. Thus blue and violet are the same color, though the sensations are different. A mere increase of illumination may cause a violet blue to appear violet, with a diminution of apparent CHROMA. This color, called violet or blue according to the quality of the sensation it excites, is one of the three fundamental colors of Young’s theory. A deep blue tinged with red. VIRIDIAN.--Same as Veronese green. WHITE.--A color transmitting, and so reflecting to the eye, all the rays of the spectrum, combined in the same proportion as in the impinging light. YELLOW.--The color of gold and of light, of wave length 0.581 micron. The name is restricted to highly chromatic and luminous colors. When reduced in CHROMA, it becomes buff; when reduced in LUMINOSITY, a cool brown. See Brown. VERONESE GREEN.--A pigment consisting of hydrated chromium sesquioxide. It is a clear bluish green of great permanency. Also called Viridian. INDEX BY PARAGRAPHS.