MODERN TRENDS IN COSMETIC FORMULATION 203 1. the effect on germination and growth of garden cress and lentils and the growth of yeast cells and various micro-organisms, 2. the effect upon the fatigue phenomena exhibited by frog muscle submitted to intermittent electrical stimulus, :3. the effect upon the oxidation-reduction process of various cells, 4. the estimation of phosphatases, 5. the exploration by paper chromatography of amino acid and polypeptide content, and 6. the estimation of the sodium: potassium ratio. These tests may indicate that the cells of the tissue have been extensively disrupted before extraction and that unstable compounds have been reasonably well preserved. They may also be called upon to show uniformity from batch to batch of extract, but there is no consensus of opinion as to the relative importance of the different tests. A number of the tests enumerated have been described as useless either on the grounds that effects produced upon the growth of cellulose structures cannot be used as an argument relating to the growth of protein structures, or because of the failure of the method to yield reliable and repeatable results. • There are many other sources from which new trends in formulation have arisen, for example the remarkable increase in the spending power of the teenagers in recent years has brought a demand for new and more exciting colours in lipstick, nail varnish and so on. The roll-on dispenser and the pressurized dispenser have brought new problems which have been solved by a revision in formulation to give the necessary properties and compati- bilities to adapt the product to the new conditions. [Received: 20th January 19601 REFERENCES Knight, S. G. J. Soc. Cosmetic Chemists 10 307 (1959) Cohen, S. Drug •, Cosmetic Ind. 81 306 (1957) U.S. Pat. 2,773,834 U.S. Pat. 2,607,658. U.S. Pat. 2,645,616 Patents held by Albright and Wilson (Mfg.) Ltd. Lubowe, I. I. and Mecca, S. B. Drug •, Cosmetic Ind. 84 36 (1959) Get. Pat. 840,542. Milling, B. Am. Perfumer Aromat. 39 (1958) (October) Conrad, L. I. ibid. 70 (1958) (June) Pickthall, J. J. Soc. Cosmetic Chemists 6 (1955) 263 U.S. Pat. 2,826,551 •Fr. Pat. 1,068,586 Brit. Pat. 767,840 Niisslein, J. Soap, Perfumary •, Cosmetics 32 283 (1959) U.S. Pat. 2,437,965

204 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Stricks, W., and Kolthoff, I. M. J. Am. Chem. Soc. 73 4569 (1951) U.S. Pat. 2,840,086 Jacobi, O.K. Proc. Sci. Sect. Toilet Goods Assoc. 31 22 (1959) (May) Bolliger, A. and Cross, J. R. Australian J. Sci. 16 190 (1954) Herd, J. K. and Marriott, R. H. J. Soc. Cosmetic Chemists 10 272 (1959) Filatov, V. P. and Biber, V. A. Doklady Akad. Nauk. S.S.S.R. 62 259 (19•18) Lapine, E.G. Cosmetologie. 15 (1959) 21 DISCUSSION F. RILEY: the lecturer referred to certain visual and physical advantages of sodium laury! ether sulphates over the older triethanolamine-laury! sulphate. I would be very interested to hear his views on how these two materials compare from detergency standpoint, in use and how they leave the hair. TaE L•CTUR•R: There are many different ways of applying a shampoo and in my opinion it is usually carried out with too much vigour and with too much shampoo material. In many instances I have noted that a deficiency in lather is tackled by adding more shampoo when in fact what is wanted is more water. When the shampoo is properly conducted, the lower sodium lauryl ether sulphates show a little better performance in the matter of lathering, detergency and in the condition of the hair than the triethanol- amine !auryl sulphates. How to make this advantage available to the mass of users is a different matter. The ether sulphates have, I think, a smoother feel to the hands during the application to the hair. DR. B. L. RAo: How does triacetin compare with the hydantoin deriva- tive as an antiseptic in cosmetic preparations ? T• L•CTUR•R: Both triacetin and monomethylol dimethyl hydantoin depend for their effect upon the slow breakdown of a complex compound and it is clear that both breakdown reactions may be influenced by catalytic substances of various kinds. The hydantoin derivative has been in use for a sufficient length of time to establish its general reliability. In the case of triacetin, however, work is still in progress in the United States and we have insufficient evidence to allow of a comparison of the two preservatives. DR. B. L. RAo: Would it be an advantage to use linoleic acid with an antioxidant (in cosmetics) instead of isopropyl !ino!eate. TaE L•CTUR•R: Linoleic esters applied to the skin are hydrolysed by enzymes either on the surface, or after penetration of the skin and would act like the free acid. Linoleic acid could be preserved from rancidity for some time by adding an antioxidant, but this will eventually be used up and protection will then cease. We a!so have to consider the possibility of the antioxidant having some effect upon the skin. The use of an ester is a more elegant solution of the problem.