Percolation transition in Coulombic near-critical binary liquids?

We study the mobility of H + ions for the quasi-binary liquid mixture of water and isobutyric acid in the vicinity of the critical point T c of the mixture. In the one-phase region above T c , a continuous but very drastic decrease in ion mobility is observed for compositions in isobutyric acid exceeding the critical composition. The results are interpreted as the formation of dynamic clusters. The "percolation" line for cluster formation is found to start at the critical point and remains at the critical composition for all temperatures T > T c studied.