Experimental investigation of the behavior of the specific heat in finite systems in the vicinity of the critical mixing point

The specific heat of a 2,6-lutidine-water mixture is measured in the vicinity of the lower critical mixing point in the bulk and in porous media. The results of the measurements are interpreted by finite-size scaling. In particular, a universal function of the ratio t/t* [t is the dimensionless deviation of the temperature from the specific-heat maximum T m (L), and t* is the characteristic dimensionless temperature, which depends on the pore size] describing the behavior of the specific heat in the vicinity of the critical point in porous media with different pore sizes is obtained. The results obtained are consistent with the predictions of finite-size scaling and with the data from a numerical calculation of the specific heat of the finite three-dimensional Ising model.