Set the beaker on a hot plate and turn the dial to medium high. Heat the mixture
for about 30 minutes in order to dissolve as much of the aluminum as possible. Stir
frequently in order to keep the metal pieces from floating to the top of the froth. If
necessary, add water to keep the volume constant. Do not allow bubbling to become so
vigorous that the froth spills over the side of the beaker. The hydrogen gas (flammable!)
generated by the reaction will be carried away by the suction of the fume hood. The
reaction may splatter so heating should be slow and care should be exercised at all times.