Supersonic Measurements in CO2 at 0° to 100°C

Previous measurements are reviewed and curves are drawn for the velocity of low frequency and of high frequency sound waves in dry CO2 as functions of the temperature from 0 to 100°C. Another set of curves shows how the frequency producing maximum absorption per wave-length depends on the water vapor concentration in the CO2 at approximately one atmosphere pressure. Evidence is presented for two distinct relaxation times for each given concentration. Acetaldehyde is cited as a gas in which three relaxation times have definitely been found. Our recent measurements of the velocity at 98°C check well with the curve but the evidence for two distinct relaxation times was not more definite than at 28°C.