Supplemental material to the 2025 article "Demonstration of dispersion gas barometry" by Y. Yang, J.A. Stone, and P.F. Egan.The archive file contains two-color data for the gases helium, neon, argon, and nitrogen. Two-color data means measured quadruplets of pressure and temperature together with refractivity at two wavelengths 1542.3912 nm (194.368624 THz) and 632.9919 nm (473.611873 THz).Two analysis scripts are included:1. plotHelium.py: performs the helium analysis to deduce the cavity distortion coefficient kappa and the conversion factor epsilon_p needed to realize the optical pressure scale. The script reproduces Fig. 2 from the article.2. plotGases.py: analyzes the gases neon, argon, and nitrogen and deduces the two parameters describing dispersion polarizability A_epsilon and A_2. The script reproduces Fig 3 from the article.Additionally, the script "pgtProp.py" is a library function, which offers best knowledge (as of January 2025) of gas properties to be used in Polarizing Gas Thermometry. The library functions synthesize the optical and thermophysical properties of helium, neon, argon, and nitrogen. The synthesis combines literature sources plus the measurement results from the main text.