A diaphragm cell for diffusion measurements in liquids under pressure

Abstract

The design of a magnetically stirred diaphragm cell for diffusion measurements in liquids under pressure and the procedures for its use are described. The cell differs from the conventional diaphragm cell in two respects; (i) the bottom compartment of the cell incorporates a bellows to allow for changes in compressibility of the liquid in the cell; (ii) the stirrers inside the cell rotate in fixed bushes as opposed to floating or riding gently on the diaphragm surface. Calibration of the cell has been carried out at atmospheric pressure by self-diffusion measurements with benzene and carbon tetrachloride. Self-diffusion measurements made with the cell for benzene at 25 degrees C and pressures up to 635 atm are in good agreement with earlier data but are of significantly better accuracy ( approximately 1%).