1. Accurate measurements of the dielectric coefficient ofcarbon dioxide have been made at 8 different temperatures from +20° to +210° C. 2. The value of polarisation is constant within the limits of experimental error, indicating that the gas is non-polar within the temperature range employed. 3. The results of the present investigations do not support the possibility of a bent structure for the molecule ofcarbon dioxide above 145° C., as postulated by Ibbs and Wakemann from their measurements on thermal diffusion and viscosity. 4. Incidentally, accurate measurements of the dielectric coefficients ofmethane, have been made at four different temperatures in the range from +25° to +190° C.