A number of polymers that are commonly soluble in water and in alcohol, display a dramatic collapse when 10 molar % of alcohol is added to the polymer/water system. Various explanations for such co-non-solvency behaviour have been proposed, however the molecular origin of these phenomena remains a subject of speculation. But to further understand the molecular origin of cononsolvency, it would be useful to further explore inhomogeneous mixing in the MeOH/water solvent itself. tetrahedrality of the water structure is in fact enhanced at xm=0.27 and 0.54 in water/ethanol mixtures, with respect to pure water. In an effort to understand the ``minimal conditions required in order to observe co-non-solvency'' , we would like to continue our series of studies on the aggregation and solvation of an amphiphilic compound (tertiary butyl alcohol, TBA) in a water/methanol mixture.