A Simple, Inexpensive Gas Discharge/Cathode Ray Tube Much of the information about atomlc structure was developed through successive modifications of the gas dischargelcathode ray tube. The apparent complexity of the equipment sometimes gives students the notion that science can only he done with fancy hardware and is somehow beyond the grasp of ordinary people. An extremely simple, inexpensive, and yet very effective gas dischargeleathode ray tube can be made from two large nails, two # 2 one-hole rubber stoppers, and a 250-mm condenser jacket (Kimble 18003-250). The components and assembly are pictured below. This apparatus works every hit as well ss commercially obtained vacuum discharge tubes and has the advantage that the components can be passed amund the class before demonstration. The simplicity of the apparatus tends to give students the idea that, "Maybe this stuff isn't so mysterious after all!"
to vacuum pump
clamp
The tube will serve as a gas discharge tube when the pressure is reduced to a few ton (adjustable by means of the screw clamp). When the pressure is further reduced (screw clamp closed completely) the tube may be used to show the cathode and anode glows, the Faraday dark space and the striated positive column. Any appropriate high voltage DC source will do. A high frequency induction coil of the Tesla type may also be used, though less satisfactorily. Roger L. Weichman Collage of Lake County 19351 W. Washmgton St. Grayslake. IL 60030
340
Journal of Chemical Education
