As a part of an international project, initiated by the Ruhrgas AG, the massic heat capacity c(p) and the Joule-Thomson coefficient mu (JT) were measured with flow calorimeters. Great effort was made in the designing and construction of the equipment and in the experiments to reach a high accuracy of the results. The pressure range of the measurements was 0.5 MPa. to 30 MPa and the temperature range 250 K to 350 K. The results are contained in the present paper. They yield the enthalpy as a function of temperature and pressure. Within the project they contribute to the experimental basis for a formulation of an equation of state.