PURPOSE: Show the view of a slide through a prism and argue about color theory.

DESCRIPTION: A 60 degree prism is mounted in front of a slide projector lens such that it can be rotated. The slide used is that of a plain white surface with some marking to show orientation. When projected so that the prism disperses, it adds color only to the edges of the field of the projected slide At another prism angle a mirror image of the slide is seen due to internal reflection in the prism.

Because of the great contrast, the print on the slide cannot be seen in the photograph.

SUGGESTIONS: The German poet and naturalist Goethe expected to see the white walls of his room in brilliant colors when looking through a prism, and rejected Newton's color theory on the basis of this experiment.

REFERENCES: (PIRA unknown.)

EQUIPMENT: 35mm slide projector with slide 4-22 from the Berg and Stork slide collection, showing large colorless (white) surfaces with mounted equilateral prism.

SETUP TIME: 5 min.