  The breaking of parity and time-reversal symmetry in two-dimensional Fermi
liquids gives rise to non-dissipative transport features characterized by the
Hall viscosity. In magnetic fields, the Hall viscous force directly competes
with the Lorentz force, since both mechanisms contribute to the Hall voltage.
In this work, we present a channel geometry that allows us to uniquely
distinguish these two contributions and derive, for the first time, their
functional dependency on all external parameters. We show that the ratio of the
Hall viscous to the Lorentz force contribution is negative and that its modulus
decreases with increasing width, slip-length and carrier density, while it
increases with the electron-electron mean free path of our channel. In typical
materials such as GaAs the Hall viscous contribution can dominate the Lorentz
signal up to a few tens of millitesla until the total Hall voltage vanishes and
subsequently is overcome by the Lorentz contribution. Moreover, we prove that
the total Hall electric field is parabolic due to Lorentz effects, whereas the
offset of this parabola is characterized by the Hall viscosity. Hence, our
results pave the way to measure and identify the Hall viscosity via both global
and local voltage measurements.
