Amplitude combinations in the critical binary fluid nitrobenzene andn-hexane

We have determined experimentally the amplitudes of the correlation length and susceptibility along the three principal trajectories: critical isochore, coexistence curve, and, for the first time in a critical mixture, critical isotherm. We have also determined the amplitude of the coexistence curve and that of the specific heat along the critical isochore. These amplitudes allowed us to compute several universal amplitude combinations, which are all in agreement with current theoretical predictions, except $\frac{C^{+}}{C^{-}}$ which agrees better with the renormalization-group value than with the high-temperature-series one. Moreover, linewidth measurements allowed us to determine the dynamic constant $R$, found to be close to unity.