Described is a way for an amateur to build a mercury-vapor ion laser which was devised by Dean Morelli. Morelli's laser emits bright pulses of green light and dimmer pulses of red-orange light and is the first gaseous-ion laser. (Author/DS)

Relates how Charles Martin Hall discovered the method of making pure aluminum metal in 1886. Retraces the events and steps that led to the process of aluminum purification. Includes diagrams of the apparatus used in the investigations. (ML)