The low-frequency oscillatory behavior of non-conducting ferromagnetic liquid (colloidal ferromagnetic suspension) in the state of saturated magnetization is explored. It is found that an incompressible ferrofluid is capable of transmitting disturbances by transverse ferrohydrodynamical waves slowly traveling along the axis of magnetic saturation. In this wave, the deviations in the magnetization and in the velocity of the rotational flow undergo coupled oscillations in the plane perpendicular to the applied magnetic field. The dispersion relation is obtained for the ferrohydrodynamical wave in bulk, followed by an analysis of ferrohydrodynamical vibrations of an isolated drop of ferrofluid freely levitating in a magnetic field.
