THE STUDY OF SURFACE ANOMALIES OF FATTY SUBSTANCES 739 Figure 21.--Dilatometric curve (noir de carbone = carbon black heures = hours diminution du volume en % = % contraction of volume). Figure 22.--Appearance of freshly pre- pared Suppocire A-containing suppository Figure 24.--App. earance of Suppocire A- containing suppository after tempering at 29øC followed by four months' storage at room temperature (12X). Figure 23.--Appearance of Suppocire A- Figure 25.--Appearance of suppository containing suppository after 500 hours containing C•0-acid mono- and diglyceride storage at 25øC (12X). and Suppocire A (12X).

740 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS if the suppository is allowed to cool outside the thermostat, the exudates solidify, giving an "orange peel" texture (Fig. 20). The exudate which can then be separated is a fatty substance insoluble in water having a melting point of 28øC. On the other hand, the melting point of the solid substance of the suppository without the exudate was 38øC, higher than that of the initial mixture. Weighings of the exudate and of the solid substance indicate that the exuded liquid represents 4 to 5% of the total volume if the densities are identical. Since the increase in volume determined by dilatometry is only 0.35%, it must be assumed that the solid crystalline skeleton has diminished from 4 to 5%, thereby squeezing out part of the liquid phase at 28øC. (i) A fully saturated standard triglyceride, Suppocire A, melting at about 36øC, can be substituted for cocoa butter. The following mixture was examined: Suppocire A* ............................................. 100 g. Printex U--carbon black* .................................. 7 g. The expansion curve at constant temperature (25øC) is reproduced on Fig. 21. The reduction of volume is only -0.8%. Examination of samples in the course of storage in hermetically sealed flasks yielded the Figure 26.--Excrescence of a suppository having a low melting point after storage at room temperature (12X). following results: At the outset, time 0, the suppository is smooth and bright (Fig. 22) after 500 hours, no defects are detectable by the naked eye, but slight dullness develops (Fig. 23). In view of this favorable result, the products were examined after aging at 29øC. The expansion curve (dotted curve of Fig. 21) shows that over-all contraction is practically the same but is attained approximately 5 *Cf. Appendix I.