Two-fold Reflections.
Provide a circular piece of glass, and with a common awl, moistened with spirits of turpentine, pierce the center of the glass; hold it encircled with the fingers and thumb in the sunshine, or the strong light of a lamp, when these striking effects will be produced: If the glass be red, the hole pierced in the middle will be reflected green; if the glass be green, the spot will be red; if blue, orange; and if yellow, indigo.