Supersonic Measurements in CO2 and H2O at 98°C

Measurements with CO2 at 98°C were made with the hope that the minor absorption peaks found earlier at 28°C might be made more prominent. At the higher temperature the CO2 holds more water vapor thus furnishing a longer range of relaxation times. The control and measurement of temperature and humidity were improved. Otherwise the procedure was that used at 28°C. The apparent change in relaxation times from 28°C to 98°C was not entirely the expected one and the minor absorption peaks were not as prominent as we hoped they would be. The velocity at high frequency and the change in velocity through the dispersion region and also the total absorption were found approximately as expected. The specific heat of CO2 calculated from our results agrees much better with the values calculated from spectroscopic data and with the most reliable calorimetric results than do the values obtained by some earlier investigators who used the velocity or the absorption of sound waves.