Didactical Absolute Viscosimeter

A didactical apparatus for the absolute measurement of small coefficients of viscosity (1 centipoise) with an accuracy of 1%is presented. A W-shaped piece rotates about a vertical axis at a variable distance from the walls of an identically shaped vessel, containing the liquid sample. A wire wound on a drum attached to the axis, carries a mass, which accelerates the rotor when falling through a distance H in the time interval T. When completely unrolled the wire is rewound on the drum and the mass is lifted up to a smaller height H′ in a shorter time T′. The determination of both distances and time intervals permits calculation of the coefficient of viscosity.