44 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS long as three years afterwards. With a winter eczema the vessels underneath it are equally unstable, and will flush up and leak more easily. In front of a fire the vascular changes may themselves increase the temperature and congestion, which will press on nerve fibres and cause itching. You are quite right- itching is much more easily elicited at high than at low temperatures. MRs. H. BUTI, ER: Why does this only happen during frosty weather ? THE LECTURER: The skin gets dehydrated and therefore little spicules of keratin are standing up, thus the skin is non-intact and more easily injured by the friction of the clothes. MR. A. G. McGEE: Would you care to expand on your statement in page 35 that "phenol and other coal tar distillates are much less likely to irritate though a few are intolerant" ? T-HE LECTURER: Phenol and coal tar distillates can be both irritants and sen- sitizers, but are mainly irritants. The majority of individuals are unable to tolerate tar on skin. The problem is that the more you remove the phenol, which has an anaesthetic effect upon the nerve fibre, the less anti-itching effect is obtained. People who are intolerant of the tar acids are not going to be helped by removing the phenol component, because it is going to be less effective for them. Summarizing, crude coal tar is by far the most effective antipuritic agent- but the more it i• purified the less anaesthetic effect does it have upon the nerve fibres. MR. C. PARRY: What is your opinion about the suitability, and the possible mode of action of the purported hormone creams ? THE LECTURER: There is no doubt that hormones are very easily absorbed through the skin, and as they are absorbed they can produce both local and systemic effects if a patient is taking hormones for any other reason, you may get a summational effect. I believe I am right in saying that at the control trial of release bleeding at the menopause with hormone cream, and an emolient alone, the results did not seem to be very significant. It was thought that the main effect of the hor- mone cream related to the hydration effect of the keratin of the collagen. I fail to see how you are going to alter the collagen degeneration a great deal in the older person, though I think you can do something in the younger person.

J. Soc. Cosmetic Chemists 17 45-56 (1966) ¸ 1966 Society of Cosmetic Chemists of Great Britain The subjective assessment of the consistency of materials in relation to physical measurements G. W. SCOTT BLAIR* A lecture delivered before the Society on 7th October 1965. 1tlr•01•si•--In all traditional, and even in some modern industries, the properties of materials and products are assessed by experts handling them. This is not in itself a bad thing but experts are becoming increasingly difficult to find and it is useful both for the craftsmen themselves and for those working in their absence to be able to compare such subjective assessments with physical measurements and chemical analyses. This paper is concerned with one group of "properties" commonly called "consistency." One must first ask whether the sensations perceived by the experts are themselves quantitatively measurable and, if not, how do we regard the judgements which they are undoubtedly able to make? A second question follows: By what combinations of stresses, strains and times do people assess consistency when they squeeze materials by hand ? Are such combinations dimensionally similar to those which we use to define such physical properties as viscosity and elastic moduli? What mathematical and statistical techniques are required to describe the judgements offered ? Finally, the implications of psychorheology to the practical chemist or physicist working in a traditional industry are discussed. Some years ago, I had the privilege of addressing you on the rheology of pastes, etc. (1) and now I should like to discuss how physical, and particularly rheological properties of materials, as measured by instruments, may be related to the subjective assessment of con- sistency by handling materials. Consistency has been defined as "that property of a material by which it resists permanent change of shape ß . . defined by the complete flow-force relation" but, in fact, the word is often used in an even wider sense. I have argued elsewhere (2) that rheologists require two types of technical terms-those which express precisely in c.g.s. units the properties of materials, such as *National Institute for Research in Dairying, Shinfield, Reading. 45