ABSTRACT
An apparatus is described which is used for the determination of velocities of falling droplets of small volumes (5/xl) through hydrophobic mixtures. From calibration curves with sodium chloride solutions of different molarities and specific gravities, the densities of the fluid in the droplets were obtained by interpolation. The density of the solutions of proteins may be determined and used in the calculation of partial specific volumes. The hydrophobic fluid used was a mixture of Dow Corning 200, kerosine to reduce the viscosity, and 1.2-dichlorobenzine to increase the specific gravity to approximately that of water.