Centrifuge

A centrifuge for use in the treatment of batches of liquid on an analytical scale including a body rotatable about an axis, said body comprising two parallel concentric arc-shaped chambers such that the chambers form concentric rings interrupted at one point, wherein said chambers have ends facing towards each other but not connecting at said one point, each of said chambers extending for a length around said body, said chambers being located at different radial distances from the axis of the body wherein said axis is a center of curvature for said arc-shaped chambers, said chambers communicating with each other through a narrow gap of capillary dimensions substantially over their entire lengths and said chambers being shaped so as to enable a free separation of a batch of liquid which is filling the chambers into a heavier component accumulating in the chamber radially further away from the axis and into a lighter component accumulating in the chamber radially closer to the axis, and said body further comprising input and output conduits for filling the chambers with a batch of liquid and for separately removing the lighter and heavier components, respectively as obtained in the separation, the conduits being connected to the ends of only the innermost chamber so as to enable removal of the lighter component from that chamber while holding the heavier component in the outer chamber with the aid of the surface tension acting in the gap between the chambers, the removal of the heavier component being then effected with an added pressure overcoming the surface tension.