  We study the propagation of electromagnetic waves in a chiral fluid, where
the molecules are described by a simplified version of the Kuhn coupled
oscillator model. The eigenmodes of Maxwell's equations are circularly
polarized waves. The application of a static magnetic field further leads to a
magnetochiral term in the index of refraction of the fluid, which is
independent of the wave polarization. A similar result holds when absorption is
taken into account. Interference experiments and photochemical reactions have
recently demonstrated the existence of the magnetochiral term. The comparison
with Faraday rotation in an achiral fluid emphasizes the different symmetry
properties of the two effects.
