We have designed and constructed an isochoric apparatus for fast and accurate pressure-volume-temperature (pVT) and phase equilibrium measurements. The apparatus allows isochoric (p, T at constant V) measurements for noncorrosive fluids over a wide range of pressures (7-105 MPa) and temperatures (100-450 K). Densities can be derived from densities determined at one isotherm (p, V at constant T) with another apparatus, such as a pycnometer or a Burnett apparatus. Temperatures are accurate to +/-10 mK and precise to +/-1 mK on ITS-90. Pressure measurements are accurate to +/-10 kPa and precise to +/-2 kPa. This apparatus requires about 20 min for temperature equilibration for measurements 2 K apart and about 50 min for measurements 10 K apart. We have measured 23 phase boundary points for three mole fractions, x(1) = 0.3991, 0.4459, and 0.5037, for CO2 (1) + N-2 (2) at temperatures from 207 to 268 K and pressures from 10.8 to 21.5 MPa. The estimated accuracy is +/-40 mk in temperature and +/-17 kPa in pressure. The isochoric measurements used to obtain these phase boundary points extend from 205 to 300 K and from 8 to 80 MPa. We have determined the saturation density for 20 of the phase boundary points. The saturation densities and the densities along the isochores were derived from density measurements at 300 and 285 K measured with a pycnometer estimated to be accurate to +/-0.1%. The behavior of the solid + fluid phase boundary is discussed.