The Variation of the Specific Heats (Cp) of Oxygen, Nitrogen and Hydrogen with Pressure

The specific heats, $C_p$ of oxygen at 26° and 60°C, nitrogen at 26° and 60°C and hydrogen at 50°C have been measured as a function of pressure over the pressure range 10 to 130 kg/${\mathrm{cm}}^2$. A continuous flow method is used, by which the ratio of $C_p$ at a pressure $p$ to ${\left(C_p\right)}_0$ of the same gas at a pressure of one atmosphere is measured. The theory of the method shows that the experimental results are practically independent of the usual errors arising from heat leakage and the Joule-Thomson effect. Complete experimental curves as well as tabulated values are shown for $\frac{C_p}{{\left(C_p\right)}_0}$ as a function of pressure. Details of construction and use of the apparatus are given.