Page:The color printer (1892).djvu/20

 The of a color are the various degrees of color produced by the mixture of a full color with black. For example, Figs. 35 and 36 on Plate 4, are two of the dark tones of red.

By is meant all of the different tones of a color, ranging from the darkest shade to the full color, and from the full color to the lightest tint.

A is any color in which red or yellow predominates.

A is any color in which blue predominates.

—Any color is complementary to another, when by a mixture of the two, prismatically, white light is produced.

—A spectral color is the tint which is seen upon a white surface, after looking upon a colored object for some minutes. The tint will in every case be exactly complementary to the color looked upon.

—The different colors produced by the refraction of the sunlight as it passes through a triangular piece of clear glass called a prism.

The is a delicate membrane inside of the eye, upon which is projected by the crystalline lens, the image of any object coming before it. In operation the eye is similar to that of the photographic camera. It is said that the retina is composed of three sets of fine nerve-fibres intermixed; one set being sensitive to the action of red, another to yellow, and the other to blue. These nerve-fibres unite in the back part of the eye, forming what is known as the optic nerve, which connects The eye with the brain.