over the supporting point of the hook so that the batch of coiled wires is smoothly and reliably rotated in the circumferential direction while in this embodiment the rotating shaft of the rotary vibrator 9 is shown disposed on the central portion of the beam 2 widthwise and extending along the axis of the beam the position of the rotating shaft may be shifted widthwise of the beam without changing the axial direction the rotating shaft may also be set apart from the beam on either side by means of brackets shifting the position of the shaft in this way will produce the same effect as when the shaft of the vibrator is set on the central axis of the beam in other words the rotating shaft of the vibrator may be set in any plane parallel to the vertical plane containing the hook and the beam with this method of vibrating the coiled wires it is possible to uniformly treat the wires with the solution in the bath improving the work efficiency and the surface quality of the treated wires this method has a further advantage that since the coiled wires are not supported at the same points by the suspension hook for a long period of time the stress corrosion of the wires can be prevented the vibrating device for use in this method can be obtained simply by employing the rotary vibratory with its rotating shaft arranged as described previously and by providing the frequency converter so that this invention can easily be embodied by modifying the conventional facilities with little additional cost obviously numerous additional modifications and variations of the present.