Critical Behavior near a Vanishing Miscibility Gap

Abstract

We report measurements of the osmotic susceptibility and correlation length for the pseudobinary mixture of guaiacol ($o$-methoxy phenol) plus glycerol-water as a function of temperature and water content $x[x\ensuremath{\equiv}\mathrm{weight}\mathrm{of}\mathrm{water}/(\mathrm{weight}\mathrm{of}\mathrm{water}\mathrm{plus}\mathrm{weight}\mathrm{of}\mathrm{glycerol})]$. This system exhibits a limited two-phase region which vanishes for $x<{x}_{0}\ensuremath{\simeq}0.0137$. We observed a smooth transition from nearly Ising-type behavior for $x\ensuremath{\gtrsim}4{x}_{0}$ through a non-power-law regime to doubled exponents for $x\ensuremath{\simeq}{x}_{0}$ and saturating divergences with doubled exponents for $x<{x}_{0}$.