“The vibratory movement” in flames

Heat

“…He claims that it shows higher temperatures than the calculated ' I theoretical " temperatures, which must themselves be upper limits ; if this is so, it is conclusive proof that the spectral line method does not give the temperature corresponding to the mean kinetic energy of the gas molecules, and hence that this energy and the excitation (electronic) energy of the sodium atom do not reach equilibrium under the circumstances of his experiments. Clearly this is a promising field for further research, both on the experimental and theoretical sides: It may be that the explanation lies merely in the fact that the spectral line method gives the maximum temperature, which may without inconsistency be higher than the average temperature over the cross-section, as calculated from theory, Indeed, a paper by Ellis and Morgan (18) on the temperature gradients in flames, shows that differences of the order of 200' C. can occur in explosive flames, and this would possibly be sufficient to explain the discrepancies noted by David. The fact that the spectral line reversal method gives the correct value for a mass of gas heated in a furnace, shows that whatever may be the case in a flame, equilibrium is ultimately reached between the two forms of energy when sufficient time is given.…”