A New Kind of Oscillating Crucible Viscometer

A new oscillating crucible viscometer, having a torus shaped crucible, is presented. The geometry of the torus allows a rigorous treatment of the fluidodynamical problem for an oscillating viscous liquid. The damping coefficient δ is shown to characterize two possible distinct zones of oscillation: In the first zone, δ rises when the viscosity η of the liquid rises; in the second one, δ is lowered by an increase of η. The second zone proves to be much more convenient for fixing the working point of the instrument because here the sensitivity is expected to be twice that of the first zone. Some preliminary experiments have confirmed the results of the theory.