The liquid-liquid coexistence curves for (dimethyl adipate + n-hexane), (dimethyl adipate + n-heptane) have been measured, from which the critical amplitudes and the critical exponents are deduced. The critical exponent beta corresponding to the coexistence curves are consistent with the 3D-Ising value. The experimental results have also been analyzed to determine the critical amplitudes of Wegner-correction terms when beta and Delta are fixed at their theoretical values, and to examine the asymmetry of the diameters for the coexistence curves. (C) 2012 Elsevier Ltd. All rights reserved.