Infinite-dilution activity coefficients were measured by g.l.c. over a range of 50 K for n-hexane, n-heptane, benzene, and toluene in n-hexadecane, n-octadecane, and n-eicosane; measurements for cyclohexane and tetrachloromethane in n-hexadecane are also discussed. The experimental results were fitted to an adaptation of the equation of Clarke and Glew, thus calculating partial molar excess enthalpies and heat capacities. The results are compared with those obtained by extrapolation from static results at finite mole fractions.