Dispersion of Air*

New measurements of the infrared dispersion of air are reported. They agree with series I of the 1962 data of Peck and Khanna, but lie below Edlén's 1966 formula. A two-term Sellmeier formula suffices to fit the resulting infrared (ir) data as well as the data selected by Edlén in the visible and ultraviolet (uv), being valid down to nearly 0.23 μm. Other possible Sellmeier fits are discussed, including extension to 0.185 μm.