This experiment was written or modified by participants of the TOPS program. It has been field tested and revised during the program, and an intensive effort has been made to minimize any possible hazards associated with the experiment. Nevertheless, it is impossible to foresee every problem that could conceivably arise. No laboratory activity should be undertaken by a teacher or student unless he/she has a full understanding of the chemical phenomena involved, adequate protective equipment, a willingness to observe all necessary safety precautions and a feeling of confidence and personal security in doing the activity. The contributors, editors, and sponsoring agencies accept no moral or legal responsibility for injuries that may result from laboratory activities based on this information.