Measurement of Color Mixtures. 3 



demonstrated that thirty-six is the practicable limit, and 

 accordingly that number has been adopted.* If the 

 number of intermediate hues were equal in all cases 

 there would, in this scheme, be five between each 

 two adjacent fundamental colors of the spectrum; 

 but a greater number of recognizably distinct hues is 

 obviously necessary in some cases than in others ; for 

 example, spectrum orange is decidedly nearer in hue to 

 red than to yellow, and therefore the number of inter- 

 mediates required on each side of the orange is different, 

 being in the proportion of four for the red-orange series 

 to five for the orange-yellow, and similarly six are 

 required for the violet-red series, while four suffice for 

 the blue-violet hues. 



There is no known means by which we can measure 

 the proportion of two or more pigments in any given 

 mixture, "because color-effect cannot be measured by 

 the pint of mixed paint or the ounce of dry pigment ; "f 

 but, fortunately, we have a very exact method, in the 

 color- wheel and Maxwell disks, by which the relative 

 proportions of two or more colors in any mixture may be 

 precisely measured. This method has been used in the 

 painting of every one of the 1115 colors of the present 

 work, by means of one disk to represent each one of the 

 thirty-six colors (both pure and "broken"), together 

 with a black, a white, and a neutral gray disk, the last 

 being a match in color to the gray resulting from the 

 mixture of red, green and violet on the color-wheel ; % the 

 neutral gray disk, however, being used only for the 

 making of disks for the broken series of colors (', ", '", 

 "", and '"".) and for the scale of neutral grays (Plate 



*That is to say, the practical limit for pictorial representation of the colors in 

 their various modifications. 



tMilton Bradley: Elementary Color, p. 18. 

 JSee colored figure on frontispiece. 



