184 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS essentially a teamwork proposition involving cosmetic chemists, pharma- cologists, and dermatologists. The most important aspect is a careful delineation of the objective which is being sought and a recognition of the limitations of whatever methods are being applied, whether to animals or to humans. Certainly most species have their place in the over-all program. We strongly recommend the use of animals for all of the preliminary screening and evaluation phases. This applies to irritation, sensitization and preliminary cosmetic aspects. To do otherwise poses an unnecessary hazard to the human test subject and severely limits the scope and volume of the screening which can be completed. In effect, our view is to know the advantages and limitations of each group of subjects and to use the animal wherever the use is practical, since if the cosmetic industry is to make the advances which the progress of chemistry has made available to it, both animal and human resources must be used to the ultimate maximum capacity. There is much work to be done with each species, and each has its place in the over-all program. TOWARD EMULSION CONTROL* By SYr)•E¾ Ross Rensselaer Polytechnic Institute, Troy, N.Y. ONLY WHEN THE control of any physical process is assured, when we are aware at all times of what is taking place, and can alter it at will, can we derive maximum utility from its application. In the field of emulsion technology we can report progress but we are still far from this ultimate goal. I propose to review briefly for you the methods that we can now summon to help us learn what is taking place during the formation and subsequent aging of emulsions. This is still only half the story, but we certainly cannot go on to effect alterations at will unless we first know the situation. A grand step forward in the control of emulsion formation was the recog- nition by Bancroft that the continuous medium will be the one in which the stabilizing agent is more soluble. This rule has recently been made quantitative by Griffin, with the introduction of the HLB system of choosing emulsifying agents (1). The very first question, that of emulsion type, is thus brought under control. There are still left many other pos- sible variables. The nature of the interface, the emulsion composition, Presented at the September 23, 1954, Seminar, New York City.

184 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS essentially a teamwork proposition involving cosmetic chemists, pharma- cologists, and dermatologists. The most important aspect is a careful delineation of the objective which is being sought and a recognition of the limitations of whatever methods are being applied, whether to animals or to humans. Certainly most species have their place in the over-all program. We strongly recommend the use of animals for all of the preliminary screening and evaluation phases. This applies to irritation, sensitization and preliminary cosmetic aspects. To do otherwise poses an unnecessary hazard to the human test subject and severely limits the scope and volume of the screening which can be completed. In effect, our view is to know the advantages and limitations of each group of subjects and to use the animal wherever the use is practical, since if the cosmetic industry is to make the advances which the progress of chemistry has made available to it, both animal and human resources must be used to the ultimate maximum capacity. There is much work to be done with each species, and each has its place in the over-all program. TOWARD EMULSION CONTROL* By SYr)•E¾ Ross Rensselaer Polytechnic Institute, Troy, N.Y. ONLY WHEN THE control of any physical process is assured, when we are aware at all times of what is taking place, and can alter it at will, can we derive maximum utility from its application. In the field of emulsion technology we can report progress but we are still far from this ultimate goal. I propose to review briefly for you the methods that we can now summon to help us learn what is taking place during the formation and subsequent aging of emulsions. This is still only half the story, but we certainly cannot go on to effect alterations at will unless we first know the situation. A grand step forward in the control of emulsion formation was the recog- nition by Bancroft that the continuous medium will be the one in which the stabilizing agent is more soluble. This rule has recently been made quantitative by Griffin, with the introduction of the HLB system of choosing emulsifying agents (1). The very first question, that of emulsion type, is thus brought under control. There are still left many other pos- sible variables. The nature of the interface, the emulsion composition, Presented at the September 23, 1954, Seminar, New York City.