316 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS TAsLe 3 Material Trade Mark Manufacturer or Distributor Beeswax Beehive Brand Cetyl Alcohol .......... Cottonseed Oil Wesson Oil Lanolin, anhyd., U.S. P ........... Mineral Oil, heavy Nujol Mineral Oil, light Marcol GX Paraffin Paraseal Petrolatum, white White Perrecta Stearic Acid, D.P. Emersol •so Will and Baumer Candle Co., Inc. E. I. du Pont de Nemours & Co., Inc. Wesson Oil and Snowdrift Sales Co. Botany Mills, Inc. Stanco Distributors, Inc. Stanco Distributors, Inc. Socony-Vacuum Oil Co., Inc. L. Sonneborn Sons, Inc. Emery Industries, Inc. with the water. After a few minutes the emulsion was reshaken and then stored overnight. Storage was again either at room temperature for oils or at 60-70øC. for waxes. Observa- tions (and pictures) were usually taken after twenty-four hours. Further storage appeared to affect results little. In a few cases the ob- servations were taken before 24 hours due to the poor quality of of emulsions in an entire series. Since the data are comparative this is considered permissible when an entire series is handled as a unit. O/W or W/O emulsions may result and this behavior must be checked. Usually the difference is readily ap- parent, in fact is expected depending upon the HLB of the emulsifiers. Figure l.--Effect of ratio of low and high HLB emulsifiers on emulsi- fication (the same weight per cent of emulsifier is not best)

CLASSIFICATION OF SURFACE-ACTIVE AGENTS 317 The amount of emulsifier used in these tests, 10 gm. for 95 gin. of oil, is much more than is usually re- quired to obtain emulsification. Usually in a given system, the de- gree of emulsification increases with increasing amounts of emulsifier to a point. Beyond this point, the ad- dition of emulsifier does not im- prove or harm the emulsion. The high proportion of emulsifier was selected as providing maxim ex- pected emulsification from the agents under test so that those hay-. ing a poor over-all efficiency would indicate trends. The oils and waxes usually included in an evaluation series are listed in Table 3. These values may be utilized more completely than for a gross estimate of the behavior of the emulsifier. In Fig. 1, we show sev- eral series of samples in which heavy mineral oil is emulsified with several combinations or blends of emulsi- fiers. In each series, the only differ- ence is the types of emulsifiers em- ployed. Two emulsifiers are used in each row, one having a low and one a high HLB. The samples on the extreme left are emulsified with 100% of low HLB agents the samples on .the extreme right are emulsified with 100% of high HLB agents. Blending permits coverage of the complete range of values be- tween the two emulsifiers. From top to bottom, the emulsifiers are blends of laurate, palmirate, stea- rate, and oleate ether-esters (the latter in addition being tri esters). You will note that the weight per- centages of the low and high HLB products required are not similar for best emulsification and that the ß 25'1,'•. __ :'%' .. • • .. , . Figure 2.--Behavior of various oils with one pair of emulsifiers (different ratios best for different oils)