Cork Heavier Than Lead
Let a large piece of cork be pendent from one end of a balance beam,
and a small piece of lead from the other; the lead should rather
preponderate. If this apparatus be placed under a receiver on the
pump, you will find that when the air is exhausted, the lead, which
seemed the heaviest body, will ascend, and the cork outweigh the lead.
Restore the air, and the effect will cease. This phenomenon is only on
account of the difference of the size in the two objects. The lead,
which owes its heaviness to the operation of the air, yields to a
lighter because a larger substance when deprived of its assistance.