The　composition　adsorption　isotherms　(y(a)　similar　to　x(g)　curve)　for　toluene-n-hexane,　benzene-n-hexane,　acetone-n-hexane　and　n-pentane-n-hexane　vapor　mixtures　on　lamp　black　with　different　surface　coverages　(theta)　at　25　degrees　C　were　measured.　The　experimental　results　indicate　that　the　y(a)　similar　to　x(g)　curves　approach　gradually　up　to　their　binary　liquid　vapor　equilibrium　with　increasing　surface　coverage,　Therefore,　the　binary　gas　phase　and　adsorption　phase　at　equilibrium　are　similarly　with　the　binary　gas　liquid　phase　equilibrium.　The　composition　adsorption　isotherms　of　the　four　binary　gases　adsorption　on　lamp　black　systems　are　in　accordance　with　simulated　equation　of　relative　volatility.