  A theory is presented which allows us to accurately calculate the surface
tensions and the surface potentials of electrolyte solutions. Both the ionic
hydration and the polarizability are taken into account. We find a good
correlation between the Jones-Dole viscosity $B$-coefficient and the ionic
hydration near the air-water interface. The kosmotropic anions such as
fluoride, iodate, sulfate and carbonate, are found to be strongly hydrated and
are repelled from the interface. The chaotropic anions such as perchlorate,
iodide, chlorate and bromide are found to be significantly adsorbed to the
interface. Chloride and bromate anions become weakly hydrated in the
interfacial region. The sequence of surface tensions and surface potentials is
found to follow the Hofmeister ordering. The theory, with only one adjustable
parameter, quantitatively accounts for the surface tensions of 10 sodium salts
for which there is experimental data.
