Van Krevelen coefficients for protonated monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA), the carbamates of MEA and DEA, and the bicarbonate ion have been determined experimentally from measurements of the solubility of N2O at 25-degrees-C and atmospheric pressure in aqueous solutions of these ions. Measured values differ significantly from values recommended by others in the absence of experimental data. By analogy with N2O, the solubility of carbon dioxide in the same solutions can be estimated.