To definitively demonstrate that the structural heterogeneities observed from small angle scattering are dominated by critical fluctuations-and to measure the associated critical exponents-we investigate the temperature scaling of the extractant/diluent mixture having its critical point closest to room temperature. For this mixture, DMDBPMA and hexadecane, we select the composition with the strongest room-T critical fluctuations: φ E = 0.40. We measure the scattering at low Q while lowering T toward T C . In this regime, we can fit the data with Eq. 1 with B = 0. From critical point theory, the temperature scaling of ξ and I Q=0 are expected to follow power laws given by