  Heterodyne polarometry is used to measure the frequency dependence in the mid
IR from 900 to 1100 cm$^-1$ and temperature dependence from 35 to 330 K of the
normal state Hall transport in single crystal, optimally doped
Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. The results show a simple Drude behavior in
the Hall conductivity $\sigma_{xy}$ which stands in contrast to the more
complex, extended Drude behavior for the longitudinal conductivity
$\sigma_{xx}$. The mid IR Hall scattering rate $\gamma_{xy}$ increases linearly
with temperature and has a small, positive, projected intercept at T=0. The
longitudinal scatter rate, in contrast, is much larger and exhibits very little
temperature dependnece. The Hall frequency indicates a carrier mass which is
6.7 times the band mass and which decreases slighly with increasing frequency.
These disparate behaviors are consistent with calculations based on the
fluctuation-exchange interaction using current vertex corrections.
