Because the yellow color of the lamp’s rays acts upon the color of the silk, forming a third color. Blue silk becomes green by lamp-light, and red silk becomes orange.
Are all persons able to distinguish one color from another?
No; some are color-blind. To such persons all colors appear to be alike.
What curious instances of color-blindness may be mentioned?
Dr. Mitchell tells of an officer who bought a blue coat and a red waistcoat, thinking them to be of the same color. He also tells of a tailor who patched a black waistcoat with a piece of crimson; and of another, who put a red collar on a blue coat. Dr. Dalton lost a piece of red sealing-wax in the grass, and he could not find it because it and the grass seemed of the same color to him.
Refraction of Light.
How do the rays of light from the sun come to us?
They come to us in straight lines.
When the rays of light pass from one substance to another more dense, what takes place?
They are bent or turned from a straight course.