side in contact, as shown in Fig. 9, duplicate strips being arranged in the field of view at some distance from each other. The tints of the two central strips were both altered; those placed at a greater distance apart suffered no change. In the experiment represented in Fig. 9, the central ultramarine by contrast is made to appear more violet, the central cyan-blue more greenish; the color of the outlying strips is scarcely affected.

As it requires a little consideration to predict the changes which colors undergo through contrast, we give below a table containing the most important cases:

Pairs of colors		Change due to contrast		Pairs of colors		Change due to contrast
${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Red.	becomes more purplish.		${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Orange.	becomes more yellowish.
	Orange.	"	yellowish.		Violet.	"	bluish.
${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Red.	"	purplish.	${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Yellow.	"	orange-yellow.
	Yellow.	"	greenish.		Green.	"	bluish-green.
${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Red.	"	brilliant.	${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Yellow.	"	orange-yellow.
	Blue-green.	"	"⁠		Cyan-blue.	"	blue.
${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Red.	"	orange-red.	${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Yellow.	"	brilliant.
	Blue.	"	greenish.		Ultramarine-blue.	"	"⁠
${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Red.	"	orange-red.	${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Green.	"	yellowish-green.
	Violet.	"	bluish.		Blue.	"	purplish.
${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Orange.	"	red-orange.	${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Green.	"	yellowish-green.
	Yellow.	"	greenish-yellow.		Violet.	"	purplish.
${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Orange.	"	red-orange.	${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Greenish-yellow.	"	brilliant.
	Green.	"	bluish-green.		Violet.	"	"⁠
${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Orange.	"	brilliant.	${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$	Blue.	"	greenish.
	Cyan-blue.	"	"⁠		Violet.	"	purplish.

It is easy and instructive to study the changes produced by contrast with the aid of a chromatic circle (Fig. 10), and it will Fig. 10.—Chromatic Circle. be found that alterations in color produced by contrast obey a very simple law: when any two colors of the chromatic circle are brought into competition or contrasted, the effect produced is, apparently, to move them both farther apart. In the case, for example, of orange and yellow, the orange is moved toward the red, and assumes the appearance of reddish-orange; the yellow moves toward the green, and appears for the time to be greenish-yellow. Colors which are complementary are already as far apart in the chromatic circle as possible, hence they are not changed in hue, but merely appear more brilliant and saturated. This is indeed the effect which a strict application of our rule