  In a classical description, a neutral, polarizable object acquires a kinetic
momentum when exposed to crossed electric and magnetic fields. In the presence
of only a magnetic field no such momentum exists classically, although it is
symmetry-allowed for an object lacking mirror symmetry. We perform a full QED
calculation to show that the quantum vacuum coupled to a chiral molecule
provides a kinetic "Casimir" momentum directed along the magnetic field,
proportional to its rotatory power and the fine structure constant.
