The air density equation and the transfer of the mass unit

A formulation of the equation used for the calculation of air density was developed. The Quinn, Colclough, and Chandler value of the gas constant, currently accepted values of the atomic weights, and recent determinations of the abundances of the various constituents of air were used. The abundance of carbon dioxide was treated as a variable and a factor enabling convenient adjustment of the apparent molecular weight of air for deviation of carbon dioxide abundance from a background value was derived. A new table of compressibility factor for the range of pressure and temperature of interest in standards laboratories has been calculated using recently determined values of virial coefficients. The enhancement factor, which has usually been ignored in air density equations, has been explicitly included in the equation.