Gaseous combustion at high pressures.—Part XIII. The molecular heats of nitrogen, steam, and carbon dioxide at high temperatures

The only information available concerning the internal energy of gases at temperatures higher than 2000° C. or so is that provided by the results of explosion experiments in which the energy liberated during the combustion serves to raise the products and any other gases that may be present in the medium to some definite maximum temperature. By varying the proportions of the reacting gases, or by adding suitable quantities of some diluent gas, this temperature may be varied between comparatively wide limits. In a previous paper of this series the method of calculating the mean maximum temperature attained during a gaseous explosion in a closed vessel was discussed, and those calculated from our experiments for theoretical CO-air and H2 -air explosions at initial pressures of between 3 atmospheres and 175 atmospheres were given. At Prof. Bone's request I have recently reviewed and analysed the mass of data accumulated during these researches, together with others resulting from the supplementary experiments described herein, with a view to seeing how far it is possible to deduce, not only a quantitative estimate of the energy distribution at the moment of maximum pressure in typical explosions at high pressures, but also the mean heat capacities of the various explosion products over a temperature range from 15° C. up to various definite points between 2600° and 3000° C. The results of this investigation are described in the present paper.