"Helium, nitrogen, carbon dioxide, and other gases suitable as reactor coolants were evaluated. It is shown that because of the helium conservation program, recently authorized by legislation, sufficient helium will become available for domestic power plants and for the requirements of the Euratom group. Tables of thermodynamic properties for helium and molecular nitrogen were computed from the Beattie-Bridgman equation of state. Specific enthalpy, specific entropy, isobaric specific heat, specific heat ratio, compressibility factor, specific volume, and acoustic velocity are tabulated over the range helium and molecular nitrogen are given."