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The W/12 gels look turbid over the entire range of compositions in which they can be produced, because of the difference in the values of refractive indices of the cubic phase and water. The refractive index of the continuous 12 phase is higher than that of the dispersed water phase. Replacing water partially with glycerol increases the refractive index of the dispersed phase. Figure 22 shows the refractive index of water + glycerol as a function of glycerol concentration. The dashed line (Fig. 22) indicates the refractive index of the 12 phase of the composition Si25C3E015.8/D4 = I : 1. So it is observed that the refractive indices of the 12 phase and dispersed phase match each other when the water-glycerol weight ratio is l : I. A photograph of a transparent W/12 gel emulsion of the composition 90 wt % aqueous phase (water-glycerol = 45 : 45) 10 wt % 12 phase (Si25C3E015.8/

weight fraction of glycerol FIG. 22 Refractive index of water + glycerol as a function of glycerol concentration. The dashed line indicates the refractive index of the 12 phase of composition 50 wt % ShsC3E01s.s-SO wt % D4.