The Ultracentrifuge

Abstract

A centrifuge is described in which the rotor is both driven and supported by a whirling cushion of air. The apparatus is inexpensive, easy to construct, and may be operated from 10 to 150 lbs. per sq. in., air pressure. The max. rotational speed is limited only by the mechanical strength of the rotor. Rotational speeds of 500,000 revolutions per min. and centrifugal forces in excess of a million gravity have been obtained. The rotor is very stable and its design may be varied over wide ranges to suit the needs of the experimenter. Rotor designs by which it is possible to determine the rate of sedimentation by both transmitted and reflected light are described. Also a construction is described in which the lighter fractions are completely separated from the heavier.