The apparatus and procedure are described in Ref. 1. The equilibration device is a capillary tube 1 mm in diameter containing an internal mixer which is moved up and down by means of an external, motor driven magnet. The capillary tube is sealed in a vertical position and connected to a gas and liquid charging system, pressure gauges, as well as a volume regulator to maintain a constant pressure and to determine the volume of gas charged.Graphs of liquid solution molar volumes are also given as a function of solution compositions, including those for critical values at high pressures.