Atom Projector

At Purdue University (Lafayette, Ind.) Physicist Karl Lark-Horovitz last week showed big magic lantern pictures of atoms in action. In oldtime magic lanterns, a strong light shone through an illustrated glass slide. A lens projected an enlarged image of the picture upon a screen several feet away from the lantern. In Dr. Lark-Horovitz's arrangement the screen is a sheet of sensitive photographic film 9 ft. from the lantern light. The lantern light is a vacuum tube projecting a strong beam of x-rays. For slides he used a thin sheet of copper or shallow containers of volatile liquids. The copper slide yielded the most striking results.

When the x-rays strike the copper plate they pass through the submicroscopic lattice which the copper atoms form, cast a fencelike shadow upon the screen. When Dr. Lark-Horovitz adds energy to the copper plate by heating it, electrons jump from one energy level to another in the copper atoms, and the "pickets" in the x-ray picture shift a perceptible distance. Dr. Lark-Horovitz calculates the intra-atomic movements at one 200,000,000th part of an inch.

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