Homogeneous aqueous solutions of alcohols can be split in two liquid phases by pressurization with gases like carbon dioxide or ethene. At conditions near the critical point of the gas, the two liquid phases coexist with a gaseous phase. It has been proposed to use this effect for the separation of water and alcohols, but it might also be promising to use it for extracting products from aqueous solutions. For the design of such processes, data on the phase behavior of the gas-water-alcohol system is needed. In order to take such data, an analytical equilibrium apparatus was developed. To test this apparatus, three- and four-phase equilibria in the carbon dioxide-water-isopropanol system at temperatures between 303 and 333 K and pressures up to 13 MPa were investigated. The new apparatus is described and the results are critically compared to literature data.