20 



Color Standards and Nomenclature. 



Chroma. — Degree of freedom from white light; 

 purity, intensity or fullness of color. 



Luminosity . —Degree of brightness or clearness . The 

 relative luminosity of the spectrum colors is as follows: 

 [Yellow (brightest) ?] , orange yellow; orange; greenish- 

 yellow, yellow-green, and green; orange -red ; red and 

 blue (equal); violet-blue, blue-violet, violet.* 



Warm Colors. — The colors nearer the red end of the 

 spectrum or those of longer wave-lengths (red, orange, 

 and yellow, and connecting hues) "and combinations in 

 which they predominate, "t 



Cool, or Cold, Colors. — The colors nearer the violet 

 end of the spectrum or those of shorter wave-length, 

 especially blue and green-blue. "But it is, perhaps, 

 questionable whether green and violet may be termed 

 either warm or cool." 



Complementary Color. — "As white light is the sum of 

 all color, if we take from white light a given color the 

 remaining color is the complement of the given color." 

 When any two colors or hues which when combined in 

 proper proportion on the color- wheel produce, by rota- 

 tion, neutral gray, these two colors each represent the 

 complementary of the other. 



Constants of Color. — The constants of color are num- 

 bers which measure (1) the wave-length, (2) the chroma, 

 and (3) the luminosity. 



In addition to the terms defined above there are 

 many others, for which the reader is referred to the 

 chapter on "Color Definitions" on pages 23-30 of Milton 

 Bradley's excellent and most useful book "Elementary 

 Color." 



*Rood: Modern Chromatics, p. 34. 

 With the single exception of Vanderpoel (Color Problems, p. 28, plates 3, 4, 

 where yellow is given first in order of luminosity) all authorities on color-physics 

 that I have been able to consult very singularly ignore yellow entirely in their treat- 

 ment of the subject of luminosity. 



tAll quotations here are from Milton Bradley's "Elementary Color," ex- 

 cept where otherwise noted. 



