  Weyl semimetals are topological materials that provide a condensed-matter
realization of the chiral anomaly. A positive longitudinal magnetoconductance
quadratic in magnetic field has been promoted as a diagnostic for this anomaly.
By solving the Boltzmann equation analytically, we show that the
magnetoconductance can become negative in the experimentally relevant
semiclassical regime of weak magnetic fields. This effect is due to the
simultaneous presence of the Berry phase and the orbital magnetic moment of
carriers and occurs for sufficiently strong intervalley scattering.
