40 Mayer — Note on the Analysis of Contrast- Colors. 



gray discs, there is, to my vision, no decided change in hue, 

 but only a deeper shading of the purple as you view deeper 

 and deeper grays. Now the maximum red of the purple con- 

 trast-color is given by gray No. 8 on a cyan-blue ground, while 

 the maximum violet-blue of the purple is given by disc No. 8 

 on a yellow ground, therefore the hue of each component is 

 equally affected, as the purple is mixed with more and more 

 black. To test further whether the darkening of the purple 

 causes a change in its hue, I obtained on the rotator a purple 

 similar to that seen by viewing disc No. 5 on the green ground, 

 and changed its illumination by rotating the plane of the discs, 

 on the rotator, away from the incident light. I also darkened 

 the purple by adding black on the rotator. In neither experi- 

 ment, to my vision, did the purple change its hue; it was only 

 darkened. 



Viewing in succession the gray discs on a violet surface, 

 numbers 1, 2, 3 and 4 appear greenish-yellow. No. 5 appears 

 as much green as yellow ; No. 6 appears yellowish-green. The 

 following discs in order of their number appear greener and 

 greener till No. 13 appears of a dark green almost devoid of 

 yellow. Here you have an analysis of the contrast-color by 

 viewing through the reflecting tube the gray discs on a violet 

 ground, for the maximum contrast-color of the yellow com- 

 ponent of the greenish-yellow is given by disc No. 4 on a blue 

 ground, while the maximum contrast-color of the green com- 

 ponent is given by disc No. 11 on a purple ground. 



In this matter of color perception the personality of the 

 observer enters as a very important factor ; especially when the 

 observer has reached an age when he knows that his color 

 sense must be somewhat deadened and he does not know how 

 much remains of the good perception of color which he once 

 possessed. I therefore do no: hesitate to say that I may be 

 somewhat in error in my observations and in the deductions 

 made from them. It may be that the whole matter of this 

 note will turn out to be nothing more than the effect of mix- 

 ing a color with black, as in Rood's experiments ; though to 

 my vision this is not so. 



