112 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS several pharmacological effects of chemicals are straws in the wind which may encourage the belief that safety testing may eventually be a less for- midable and a less empirical procedure than it is now. Testing for efficacy has not been undertaken by our subcommittee. Creams and lotions are designed to produce diverse effects, many of which are extremely difficult to assess. An effect frequently sought is that of increasing water content of skin to which the cream or lotion is applied. Papers recently read before this Society may point the way to a practical method for determining how effective a preparation is in moistening the skin, and the standardization of such a test may well be a future under- taking of this subcommittee. The attractiveness or esthetic appeal of a cream or lotion has so many facets that it must be considered piecemeal. The color, gloss, opacity, surface finish, texture, consistency, odor and feel are all qualities which may affect esthetic appeal and some of them are very difficult to measure or evaluate objectively. Our subcommittee has made a modest start on this complex task by tackling the problem of setting up specifications which will result in reproducible viscosity readings on liquid emulsions. Samples of each of three liquid cosmetic emulsions were supplied to four laboratories by S. J. Strianse, a member of our subcommittee. Detailed instructions were issued for the viscosities of these emulsions to be read on given days, using Brookfield viscometers at given speeds for given lengths of time at a given temperature, etc. A very considerable amount of work was done by our subcommittee members in making the periodic readings stipulated, tabulating the results and reporting them. In spite of this ef- fort, all that we can now report is that our specifications were lacking in some of the details essehtial for consistent results. We shall have to spell out additional conditions before we have a standard method. It is to be expected that viscosity readings on liquid emulsions of the type we are considering should be affected by many factors. Not the least is the structural nature of the system, which carries with it the consequence that every time the system is made to flow, its structure and therefore its viscosity is altered. This results in different apparent viscosities for dif- ferent cylinder speeds. The theory of structure of soap-type gels, and the mechanism of forma- tion of such structures, appear not to have been adequately worked out. One possible approach is that of Bourgoin and Joly who developed a theory ofgelation for gelatin solutions.* By a process of elimination they reached the conclusion that flow during the first phase of sol-gel transformation involves deformation of a structure and breaking of bonds. They derived equations for the relationship of structural bond breakage and reformation * Bourgoin, D., and Joly, M., Kolloid Zeit., 146, 121 (1956).

EVALUATION OF SHAMPOO 113 to flow birefringence and viscosity. Joly expressed the opinion that an analogous treatment could be applied to a general theory of thixotropy, to interpret perturbation due to flow in the second phase of sol-gel evolution a truly quantitative expression, however, would involve great difficulties in calculation, due to the relatively large number of parameters involved. The thing we generally want to know about a liquid cosmetic emulsion is its viscosity after a long period of rest, not its viscosity after it has been shaken or has been otherwise made to flow. To be specific, we want to know that it will flow from its container after long storage. We may be able to predict its ultimate viscosity from a curve made on the basis of successive readings taken over a few months. In order to draw such a curve accurately, our readings should be made with all pertinent factors uniform. The subcommittee's work indicates that there are factors affecting the viscosity of liquid emulsions which have not been covered in our specifica- tions. Our next effort will be to discover these factors and to include them in new specifications to be made the basis of another attempt to develop a standard method for determining the viscosity of liquid cosmetic emulsions. SUBCOMMITTEE ON CREAMS AND LOTIONS Dr. Paul G.I. Lauffer, Chairman Gabriel Barnett Dr. Saul Bell Dr. L. I. Conrad S. J. Strianse Report on the EVALUATION OF SHAMPOO SINCE THE report of this subcommittee was given in September, 1957, a tentative method has been approved and is published below. TENTATIVE METHOD PH DETERMINATION ./lpparatus Required (1) pH Meter: Any suitable instrument capable of obtaining a precision of q-0.1 unit. (2) Glass Electrodes such as: General Purpose, Beckman Red Label, Beckman Catalog No. 4990-80 for measurements of pH 9 or below. Temperature range: 5 ø to 100øC.