198 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS fully accepted by doctors and bacteriologists as a satisfactory means of reducing the incidence of bacteria on the washed surface. Hexachlorophene, in shampooing conditions, is substantive to the hair. The reason for this is seen when the molecular structure is examined. It has the form of a synthetic tannin which is substantive to protein. On the other hand, for antiseptics without this substantive effect, the power of an antiseptic to kill organisms is dependent on time, temperature and concentration. Even with a reasonable concentration it is unlikely that the antiseptic could be very effective in the period of shampooing-- for it will be removed by the rinsing operation. Use of a shampoo with a cationic base (some risk to the eyes) can give effective bacteriostasis. After subsequent washing with an artionic shampoo, bacteriological examination of the hair will show bacteria still present. A medicated shampoo need not be confined to having only antiseptic properties. •lany people complain of itching of the scalp after shampooing. The inclusion of an antipruritic material may be a sensible addition--coal tar for example. A coal-tar-like odour is not sufficient. When using coal- tar in a shampoo, the odour survives after washing, indicating that here again there is some sorption on the hair and possibly on the scalp. What is expected of a medicated shampoo ? Normally, people expect it to have an effect on dandruff. They also expect it to have an effect on secondary kinds of infection, on any inflammatory condition, and on any pruritis either connected with or subsequent to dandruff. Time does not permit the discussion of the complicated question of dandruff. Suffice it to say that there are types connected with micro- organisms which are contagious. There is no doubt also that some types of skin-scaling are associated with over-washing and some consequent damage to the scalp. For the first type one should have an effective bactericide, substantive to the scalp. For the other, the shampoo should be as mild as possible, consistent with the removal of existent dandruff scales. One important advantage of treatment by shampooing is that the existing dandruff scales are removed so that an antiseptic is then more effective on the scalp. In panel tests, it is worth remembering that in age groups above 50 years, dandruff may be resistant to bactericidal treatment and easily aggravated by severe shampoos, whereas with younger people, say in their early twenties, there is much more response to bactericidal treatment. Question 10: If the skin needs water, why do wet hands chap more easily than thoroughly dried hands ? Answer: The back of the hands is noteworthy as having a rather poor supply of sebaceous glands. And those which are there are rather small

I•UESTION AND •ANSWER 199 and not quite so well developed as in other parts of the body where sebaceous glands are found. The sebum in the duct, at a temperature just below 30øC becomes pasty and solid. It cannot flow out of the duct on to the surface of the skin, even though there may be contraction of the arrector muscle which normally causes a squeezing of the sebaceous gland. When the hand is wet, dry cold wind will bring about a greater lowering of tem- perature of the surface of the skin because of evaporative effects. In these conditions the sebum fails to flow and protect the skin, and chapping occurs readily. (Sebum requires to be heated appreciably above its setting point before becoming fluid again.) Much has been said about the skin needing moisture, which it does. However, the skin needs moisture in special places. The skin becomes dry as the outer layer loses moisture. The cells dry out and become horny as they get nearer the surface and finally flake off. If the process starts too low down there is general deterioration, chapping and hardening of the skin. If water can be put back inside the cells so as to re-hydrate the plasma much can be done for the skin. It seems more important to retain the water already there by a protective layer of fatty matter. In this connection, care should be exercised in the application of humectants on the skin. If the atmosphere is dry such hygroscopic materials may extract moisture from the skin, doing more harm than good. Liquid water may not be very efficient in softening the top layers of the skin. Moisture or water vapour is better. From water-in-oil emulsions water is released gradually in the form of vapour, particularly when in thin films as rubbed on the skin. This moisture release takes place at the oil-skin interface as well as the oil-air interface. Therefore moisture is held at the skin surface for a considerable time. In this sense there is some virtue in the term "moisturising." (Received: 27th March 1962) Event No. Tu. 1 Second Congress of the International Federation of Societies of Cosmetic Chemists SCIENTIFIC SESSIONS TUESDAY, 3rd JULY 9.00 Openin• of Conl•ress: School of Pharmacy, University of London, Brunswick Square, W.C.1. (1) The Dean of the School of Pharmacy. (2) The President of the International Federation of Societies of Cosmetic Chemists. (3) The President of the Society of Cosmetic Chemists of Great Britain.