THE SEDIMENTING DROPLET PROCEDURE FOR MEASURING FLUID DENSITIES (REPRINTED FROM ANALYT BIOCHEM, VOL 107, PG 25, 1980)

An apparatus is described which is used for the determination of veloc ities of falling droplets of small volumes (5 mul) through hydrophobic mixtures. From calibration curves with sodium chloride solutions of d ifferent molarities and specific gravities, the densities of the fluid in the droplets were obtained by interpolation. The density of the so lutions of proteins may be determined and used in the calculation of p artial specific volumes. The hydrophobic fluid used was a mixture of D ow Coming 200, kerosine to reduce the viscosity, and 1.2-dichlorobenzi ne to increase the specific gravity to approximately that of water.