CATIONIC EMULSIFIERS IN COSMETICS 27 effect of the tertiary amine is very much reduced compared to the primary amine. The chain length also has an effect and the lower fatty derivatives have a higher sensitizing effect than the longer chain materials. MR. C. PARRY: In Table I the reputed phenol coefficients for the quaternary ammonium compounds are given. I agree that the gram-positive organisms such as staphylococcus are more susceptible to the quarternary ammonium compounds, but the use of phenol coefficients for these quaternary ammonium compounds has been shown to be meaningless in these cases. This is indicated by the fact that British Standards Specification 3286, which is used for the evaluation of the quaternary ammonium compounds, specifies that the Rideal Walker coefficients should, in fact, be used solely for phenolic derivatives. Have you any further comments on this ? THE L•CTURER: Apart from accepting your comment in the spirit in which it is given, the figures here are given purely as a guide, and I have tried to emphasize how meaningless figures of this type can be. Apart from the method of evaluation, it is a fact that any formulated product must be considered as a whole and no results for any one component can be accepted as such. I agree that the R.W. figures in themselves do not mean a great deal in today's thinking, but they do at least allow us to form some sort of comparison between one compound and another. They are not absolute values. MR. I•. F. L. THOMAS: A number of papers have recently been written on the inactivation of germicides in conjunction with nonionic emulsifiers. Have you any experience of this, and do you feel that in relation to cattonics there is a drop in bactericidal activity in the presence of the majority of nonionic emulsifiers ? THE LECTURER: I think there is. If one considers the actioh of a quaternary to be adsorption on to the bacteria surface, it is reasonable to expect that in the presence of a nonionic the adsorption equilibrium would move towards the aqueous phase and the concentration at the surface would be reduced. In the presence of nontonics the position of the equilibrium must therefore shift away from adsorption and hence affect the efficiency of the materials as bacteriocides. MR. R. L. STEVENS: Could you please expand a little more on the subject of w/o emulsions manufactured with quaternary ammonium compounds? Perhaps some of the references which you cite give further information. TH• LECTURER: I would suggest (17) and (23). In general, the HLB value must be reduced and the materials of particular interest are the difatty quaternaries, and the ethoxylated difatty quaternaries. Long chain fatty derivatives with a small degree of ethoxylation, or short chain difatty quaternaries are materials of particular value. DR. B. A. SCOTT: IS the deposition of oil on substrate dependent on the concentra- tion of cationic ? For example, do you see a bimolecular film which is positively charged at high concentrations of cattonics ? Does the oil deposit on the substrate in these circumstances or is it affected by electrostatic repulsion ? TH• LECTURER: One can build up double layers and the quantity of material is fairly critical. On most plain surfaces the amount of material required to build up this level is very small, and so the amount of surface sensitive emulsifier used must be kept very low. The rate of deposition will be affected by the level of use but deposition will still occur at a high level of surface active material. The mechanism could then be related to degree of hydration rather than to electrostatic forces.

J. Soc. Cosmetic Chemists 17 29-44 (1966) ¸ 1966 Society of Cosmetic Chemists of Great Britain Some principles and difficulties of topical treatment in dermatology G. HODGSON* Presented at the Symposium on "Emulsions", organised by the Society of Cosmetic Chemists of Great Britain at Harrogate, Yorks, on $1st March 1965. Synopsis--The majority of dermatological topical treatment is used for alleviation of symptoms. These arise from systemic disease, or a. re just temporary, or longer lasting, individual variations in functions of the skin from the physiological mean. The efficacy of established topical treatments is discussed, including the use of anti-perspirants and detergent ache preparations. Antipruritic agents usually act by anaesthetizing pain fibres or reducing bacterial degradation of protein to polypeptides, which provoke itching. Both local procaine-type anaesthetics and antibiotics, especially the 'mycin' group, are liable to cause sensitization. Topical steroids used under occlusive polythene dressings to increase hydration and permeability in established eczema or psoriasis may cause severe local degeneration of collagen with epidermal thinning, skin stretching ('striae') and bruising, in addition to systemic absorption effects. The treatment of melanosis with bleaching agents, or hydroquinone monobenzyl ether, is clinically and cosmetically unsatisfactory, as is that of depigmentation with methoxy psoralens or disguising agents as dihydroxy acetone. THE CHANGING FACE OF DERMATOLOGY The practice of dermatology does not depend as much as formerly upon topical applications. Those days were without antibiotics, anti- histamines, steroids, and other agents to be effectively administered systemically. These older medicaments were both complex and simple complex because of the polypharmacy of the ingredients, of which few chemists will mourn the passing, and simple because the vehicles had not yet seen the transformation to the more pleasant and effective emulsified and water-washable applications for which we owe so much to the cosmetic industry. *Lecturer in Dermatology, Welsh National School of Medicine, Cardiff. 29