  The Foldy-Wouthuysen transformation for relativistic spin-1 particles
interacting with nonuniform electric and uniform magnetic fields is performed.
The Hamilton operator in the Foldy-Wouthuysen representation is determined. It
agrees with the Lagrangian obtained by Pomeransky, Khriplovich, and Sen'kov.
The classical and quantum formulae for the Hamiltonian agree. The validity of
the Corben-Schwinger equations is confirmed. However, it is difficult to
generalize these equations in order to take into account the quadrupole moment
defined by a particle charge distribution. The known second-order wave
equations are not quite satisfactory because they contain non-Hermitian terms.
The Hermitian second-order wave equation is derived.
