162 JOURNAL OF COSMETIC SCIENCE I III II IV Figure 10. Microphotographs of phase changes for sample A during evaporation, starting from P-IV (Table II, Figure 5). Table II Composition of Sample A During Evaporation Sample no. Water White oil Laureth 4 ½x-hydroxyoctanoic (Figures 9, 10) No. of phases (%) (%) (%) acid (%) A 3 70.0 20.0 5.0 5.0 A-1 (A-l) 3 66.7 22.2 5.6 5.6 A-2 (A-II) 3 60.0 26.7 6.7 6.7 A-3 3 53.8 30.8 7.7 7.7 A-4 3 40.0 40.0 10.0 10.0 A-5 (A-Ill) 2 14.0 57.1 14.3 14.3 A-6 2 3.2 64.5 16.1 16.2 A-7 2 1.6 65.6 16.4 16.4 A-8 2 (two liquids) 0.5 29.5 35.0 35.0 A-9 (A-IV) 2 (solid + liquid) 0.0 35.0 35.0 30.0 These particles are extremely small (Figure 10-I), but during the final evaporation process with less than 30% of water left, the microemulsion droplets "burst" and the small crystals are dispersed into the oil phase. They now grow to large crystals

PHASE BEHAVIOR OF c•-HYDROXYOCTANOIC ACID 163 I II III Figure 11. Microphotographs of phase changes for sample B during evaporation, starting from I--III (Table III, Figure 5). Table III Composition of Sample B During Evaporation Sample no. Water White oil Laureth 4 tx-hydroxyoctanoic (Figure 11) No. of phases (%) (%) (%) acid (%) B 3 75.0 5.0 15.0 5.0 B-1 3 70.6 5.9 17.6 5.9 B-2 (B-I) 3 66.6 6.7 20.0 6.7 B-3 3 61.5 7.7 23.1 7.7 B-4 3 50.0 10.0 30.0 10.0 B-5 (B-II) 2 28.6 14.3 42.8 14.3 B-6 2 3.8 19.2 57.8 19.2 B-7 (B-III) 2 (two liquids) 1.0 35.0 29.0 35.0 B-8 (B-IV) 2 (solid + liquid) 0.0 35.0 35.0 30.0 (Figure 10-III). This growth is caused by the reduction of the solubility of the acid in the microemulsion phase (L2) , as is best observed in Figure 1. The final result (Figure 10-IV) consists of a dispersion of solids and particles in the surfactant/oil liquid (Figure 3). The small-angle x-ray diffraction data for the lameliar liquid crystal (Figures 6, 7) give information about the location of the water upon addition of the acid or white oil.