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This paper concerns measurements on an electromagnetic six Degrees-of-Freedom (DoF) anti-vibration system that has been realized recently. The heart of this system is a fully passive permanent-magnet device which acts as a contactless magnetic spring. As such, the gravity force of a floating rigid metrology frame (730 kg) is compensated by the passive interaction between the permanent magnets in this device. The low position dependency of this force, or stiffness, is an important system property for floor vibration isolation. This 6-DoF system is stabilized by closed-loop controlled Lorentz actuators based on position feedback. The static force and torque of this system have been obtained experimentally to validate the modeling and design of the device. The results indicate a temperature sensitivity of 1.70/00/K which corresponds to -12.1 N/K compared to the vertical force of 7.2 kN. The passive force and torque produced by the gravity compensator have linear relation with translational and rotational displacements. The predicted low stiffness property of this system is validated by the stiffness matrix derived from static measurements. The total power consumption is position dependent and remains within a range of 0.3~6 W.