Vapour-Liquid Equilibrium Data at Normal Pressures presents the direct experimental data of a set of selected systems and correlates the data with the aid of equations expressing the dependence of the activity coefficients or separation functions on the composition of the liquid phase. In the last columns of the tables, the deviations of the calculated from the direct experimental data are presented which give information on the quality of the data and on the flexibility of the correlation relations used. The text also describes the correlation of data in two-, three-, four-, and more than four-component systems.