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.

THE STUDY OF SURFACE ANOMALIES OF FATTY SUBSTANCES 741 times faster. The samples are then taken out of the thermostat and kept in the laboratory at room temperature. After four months (Fig. 24) they appear slightly bleached and velvety. Fine white spheroid excrescences are formed, but on a white suppository they would be scarcely visible to the naked eye. (j) If to the same glyceride is added 10% of a mixed mono- and di- glyceride derived from pure C•0- acid, the defects observed after seven months storage at laboratory temperature are more noticeable (Fig. 25). (k) A suppository comprising $uppocire L* and Printex U carbon* black exhibits small excrescences after seven months' storage at room temperature. These are similar to those of Fig. 24 but touch each other. With a mixture of Suppocire BS2X* and 10 to 12% essential oils (melt- ing point 33.5øC) typical excrescences (Fig. 26) were obtained. In this case, the melting point of the mixture studied is evidently too low, and it contains too great a proportion of liquid phase, even at room temperature. CONCLUSIONS According to the observations presented here surface defects can be classified as follows: 1. Excrescences due to crystals: These are unrelated to the fatty base. Instead, the foreign substance diffuses toward the surface and crystallizes. This difficulty can be avoided by wrapping the suppository in a hermeti- cally sealed film (e.g., aluminum foil) touching its surface. 2. Molds: They can be avoided by introduction of an antifungal agent. 3. Excrescences of solid fatty substances: They may be circinate or have wart forms. Crystallization starts from crystalline nuclei. A partial correction may be achieved as follows: The mixture is kept for several days in a pasty form in order to "temper" it and convert the fatty sub- stance into the stable crystalline 3-form then the mass is liquefied slightly at the lowest possible temperature, while keeping the walls of the container below the melting temperature the mass is then poured. This treatment is obviously very time-consuming. 4. Formation of wrinkles: These are due to spontaneous polymorphic changes. Unstable a- and •'-forms are transformed into denser stable 3- form. A possible correction consists of bringing the fatty substance into the 3-form and then injecting the mass, at low temperature, into a mold by means of an injection press. The suppositories obtained are softer than those prepared according to the standard process. 5. Exudates of Liquid Substances: These are due to the presence of too much of the liquid phase and to shrinkage of the crystalline solid skeleton. It seems difficult to correct this anomaly a priori at best one can recom- mend aga. inst storage of the "tempered" fatty substance at too high a temperature. *Cf. Appendix I,