650 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS PAPER II (Wednesday, 23rd June 1965.) Candidates should answer FIVE questions from not less than FOUR sections. SECTION A 1. What are the principal differences between lyophobic and lyophilic colloids ? A solution containing 1.2 x 10 -3 equivalents/1 of dissociated non- diffusible carboxymethylcellulose is equilibrated across a semiperme- able membrane with a solution cont{ining 6.0 x 10 -8 mole/1 of sodium salicylate. The membrane allows free passage of the salicylate ion. Calculate the ratio of salicylate on the two sides of the membrane at equilibrium. 2. Describe the practical and theoretical details of the Maximum Bubble Method for the determination of surface tension. How does this method compare with other methods commonly used for the measurement of surface tension ? SECTION B 3. Discuss the autoxidation of long-chain materials and its relation to the development of rancidity in toilet products. Describe protective methods used in final products and outline the manner in which various treatments of raw materials can have a useful combating effect. 4. Describe the properties of long-chain materials that are useful in cosmetic preparations. Describe the structure and outline the way in which these materials such as oils and fats, waxes, petroleum products, silicones are effective for different purposes. SECTION C 5. Discuss the characteristic advantages of (a) liquid chromatography, and (b) gas-chromatography as separation methods. Give examples of applications of these methods which you consider to be of importance to cosmetic chemists. 6. What is meant by the Beer-Lambert law? Give a brief description of a spectrophotometer suitable for making transmission measure- ments of solutions in the visible spectrum, and outline how it could be used to determine the concentration of a coloured substance present in a solution.

SOCIETY OF COSMETIC CHEMISTS OF GREAT BRITAIN 651 SECTION D 7. Describe as fully as possible how two important series of perfumery raw materials are obtained from citronella and lemongrass oils. Indicate briefly how these raw materials can now be manufactured by alternative synthetic processes. 8. (i) Discuss the problems encountered in formulating suitable perfumes for (a) toilet soaps, (b) lipsticks, (c) aerosols. (it) Suggest one simple basic formula of at least four constituents for a rose and for a jasmin perfume. Include if possible an approximate indication of the proportions of those constituents mentioned. SECTION E 10. 9. State, with reasons, for what type of rheological measurement the Ostwald (U-tube) viscometer is suitable and describe the experimental procedure you would follow in using it to determine the viscosity of a given liquid. "Emulsions are thermodynamically unstable." Discuss this state- ment with reference to creaming, flocculation, coalescence and in- version. Successful Candidates Ten out of seventeen candidates were successful. awarded to the following: S. R. Ahmad *Miss H. C. Birrell W. T. Charville *oe5 prize. W. A. de Alwis E. H. Dudman Miss M. Markogiannis R. S. Phillips Diplomas were D.C. Unsworth J. A. Watts U. Wickramasekera