8 14 THE POPULAR SCIENCE MONTHLY. 



AKE BLACK AND WHITE COLORS? 



By HAERY AUSTIN DOTY. 



ALTHOUGH there is no general agreement as to whether black 

 and white are or are not colors, it is very commonly held both 

 by scientists and artists that they are not colors. Encyclopaedias, dic- 

 tionaries, and text-books usually class black and white separately from 

 colors, defining the former as the absence of all color and the latter as 

 the sum of all colors. Yon Bezold (" Theory of Color," p. 41) says, 

 "An object appears black if, in the light falling upon it, those species 

 of rays are wanting which alone it is capable of reflecting " ; and, 

 again, " White and black . . . which, indeed, are not colors at all in 

 the true sense of the word." But, on page 90 of the same work, the 

 heading of paragraph 48 is " White is a mixed color " ; and, again, 

 on page 113 it is stated that "white and all the very pale colors which 

 are closely allied to it must be counted among the cold colors." It is 

 not meant to attach much importance to such little inconsistencies in 

 this very excellent work, but simply to indicate an indecision regard- 

 ing the limitation of the word color. For another instance may be 

 quoted Field, an English artist, who says of black that the artist is 

 bound to regard it as a color ; that " it is colorless, but extinguished 

 light " ; that " to be perfect it must be neutral with respect to color 

 and destitute of sheen or reflective power in regard to light," and that 

 " there is no perfectly pure and transparent black pigment." And the 

 same author regards white light as colorless. These latter quotations 

 are not made to emphasize their obvious inaccuracies, but to further 

 illustrate the absence of anything like a unanimity of opinion regard- 

 ing the classification of black and white in the chromatic scale. Many 

 other opinions might be quoted, showing not only an indecision on 

 the particular point herein discussed, but also widely different ideas 

 concerning the nature of black and white. 



In endeavoring to answer the question propounded we can do little 

 more than test the propriety of restricting the application of the word 

 color to less than the entire range of visual impressions. It will be 

 necessary first to inquire just what relation black and white have to 

 other retinal impressions. 



At the outset it should be noted that we have no retinal standard. 

 An object may convey a color impression which varies in the same 

 individual with the conditions of rest or fatigue of the eye, with the 

 character of the prevailing illumination, and also according to the 

 influence of neighboring bodies which may produce effects of con- 

 trast. There is often a temporary or permanent difference in the 

 color-perception of the two eyes of the same person ; and among per- 

 sons there are of course still wider differences, even excluding abnormal 



