  Two formulations of the Lorentz law of force in classical electrodynamics
yield identical results for the total force (and total torque) of radiation on
a solid object. The object may be surrounded by the free space or immersed in a
transparent dielectric medium such as a liquid. We discuss the relation between
these two formulations and extend the proof of their equivalence to the case of
solid objects immersed in a transparent medium.
