522 JOURNAL OF THE SOCIETY OF COSMETICr CHEMISTS required to do this was measured with a tension cell and the load-extension curve was plotted automatically on a recorder. Extensibility was calculated from the initial part of the curve and expressed as percentage extension 100 g4 load. Measurements were carried out at ambient temperature and in a controlled atmosphere at 81•o r.h. This was achieved by enclosing the jaw assembly of the Instron in a polythene cabinet and recirculating air which was pre-equilibrated at 81 •o r.h. by passing it through columns of saturated potassium bromide solution. After measuring extensibility, the water holding capacity was measured with the same pieces of corneum. The two pieces of corneum from the same animal were kept together. One was subjected to the treatment under investi- gation and the other served as a control. For statistical analysis the corneum from a number of animals was used. Each animal was taken as a statistical block and significant differences between treatment and control were assessed by analysis of variance. Adsorption studies The adsorption of materials by corneum was determined by measuring the decrease in concentration of an aqueous solution of the material in contact with corneum. Weighed pieces of dry corneum were immersed in solutions of the material under investigation using a solid-solution ratio of approximately 10 mg in 1 cm a of solution. At the end of the experimental period the mix- tures were centrifuged and the supernatants analysed for the material under investigation. Sorbitol and glycerol were analysed by a periodate titration method (10) and aromatic carboxylic acids by measuring their ultra-violet absorption at the wavelength of their absorption maxima using an Optica CF 4R spectrophotometer. Lactate was determined by the method of Barker and Summerson (11) or by using sodium DL lactate-2C x4 (Radiochemical Centre, Amersham) and determining the concentration by comparing with standards in a Packard Liquid Scintillation $pectrophotometer model 3224 with 1 cm a of lactate solution added to 10 cm a of Bruno-Christain scintil- lator (12). Control aliquots which had not been in contact with corneum were analysed using the same solution in each case. The results were expressed as mg of material adsorbed mg 4 dry weight of corneum under the conditions of the experiment.

SKIN CREAM FOR DRY AND FLAKY SKIN 523 Consumer tests with lotions Three consumer tests were carried out, each comparing the effects of three lotions on housewives' hands. In each test, all three had the same oil phase and two of the lotions contained humectant in the aqueous phase and the third did not and served as a control. At least 100 women took part in each test. Each woman used each of the three lotions for a period of 2 weeks. There were equal numbers of women using the lotions in each of the six possible sequences. The amount of hand dryness and flaking was assessed at the start of the test and after two weeks' use of each lotion and the effects of the lotion were compared. In order to assess the effect of a lotion on skin dryness and flaking there must be some initial dryness and flaking. The hands of about double the number of women required were examined and those with the most hand skin dryness and flaking were selected. The tests were all carried out in winter to obtain the maximum amount of skin dryness. The method of assessing hand skin dryness and flaking has been reported previously by Gibson (13). It consists of a trained assessor scoring six areas of each hand according to the following scheme :--0 = no relevant visible damage 1 = slight dryness 2 = marked dryness 3 = slight flaking 4 = marked flaking/slight cracking 6 = severe cracking. The areas of the hand assessed are: back of hand, thumb web, other webs, back of fingers, palm, and front of fingers. There is no clear distinction between any of the grades of dryness and flaking, but with practice, assessors can become consistent in their scoring. The 12 areas on each panellist are summed to give total hand score. To obtain a proper statistical balance for the experiment, the women who were to take part in the test were arranged in decreasing order of hand score. They were then allocated to one of the six possible sequences of hand lotion usage by taking the first six on the list and allocating them at random to one of the six sequences. This process was repeated down the list. In this way the mean and range of hand scores in each sequence was approximately the same. In each test the same person assessed the hands and did not know which lotion the panellists had been using. Also the panellists themselves received coded products and did not know which lotions contained the humectants. Using the six possible sequences of hand lotion usage allows the statis- tical analysis of the results to take account of any variations in the overall mean hand score with time. Such variations may occur as the result of