It has been shown that small amounts of sodium can be determined with fair rapidity through precipitation as a triple uranyl acetate, either by weighing the precipitate or by dissolving it and applying suitable volumetric or colorimetric procedures. However, where a large number of samples must be examined in a short period, as in biochemical investigations, a very rapid method for estimating small amounts of sodium would seem desirable, even though it involved some loss in accuracy. It has been found that measuring the amount of precipitate by collecting it in a capillary tube under centrifugal force and reading the volume leads to a satisfactory solution of the problem, since triple acetate precipitates are not only voluminous but, under proper conditions, can be obtained in minute uniform particles that pack in capillary tubes in a readily reproducible manner.