202 d. D. Middleton and M. E. Roberts 0.55/0 pancreatic trypsin for 18 h at 37øC (2). After this, the softened underlying tissues could be scraped away and the resulting corneum was washed by immersion in distilled water for 2 h. It was solvent-damaged by immersion in diethyl ether at ambient tem- perature for 18 h, followed by immersion in distilled water for 6 h. This procedure re- moves lipids and hygroscopic substances and reduces the water-holding capacity in humid atmospheres (2). The solvent-damaged corneum was used in experiments designed to increase the water-holding capacity towards the level for intact corneum. ß The technique for measuring water-holding capacity has been described previously (2). Briefly, it consisted of equilibrating pieces of corneum at 815/o r.h. and ambient temperature to constant weight. The pieces of corneum were then transferred to a dry atmosphere over self-indicating silica gel and re-equilibrated before weighing. Both equilibria took about 6 days to attain. The water-holding capacity was expressed as mg water held 100 mg -x dry weight of corneum at 81• r.h. The effect on water-holding capacity of a skin cream containing 55/0 Na PCA (ACO Fuktr•im, ACO L•ikemedel AB, Solna, Sweden) was compared with that of a cream with the same formulation except that it contained no Na PCA. The corneum was treated by rubbing the cream for 90 seconds into both sides of a piece of corneum with the fingertips while wearing rubber gloves. Excess cream was removed by wiping with tissues and the treated corneum equilibrated at 815/o r.h. before weighing. No attempt was made in these experiments to quantitate the amount of cream deposited on the corneum, as preliminary gravimetric experiments showed this to be a highly variable quantity owing to the loss of loose corneum flakes while applying the cream. It was not considered that more elaborate experimentation to determine the quantity deposited would be justified as the in vitro technique was regarded as a simple screening test only. Results were obtained on the corneum from 15 guinea pigs. One piece from each animal was treated with the test cream containing Na PCA and the other with the control cream containing no Na PCA. The mean values for water-holding capacity for each cream were compared statistically by Student's 't' test for paired observations. EVALUATION OF SKIN DRYNESS AND FLAKINESS IN CONSUMER TESTS OF HAND CREAMS The effects of three hand creams were investigated in a 6 week home-use trial in which groups of panelists used each cream under test for consecutive 2-week periods in all possible orders of use. Trained assessors evaluated the degree of hand skin dryness and flaking after the use of each cream. The three hand creams were (a) the test cream containing 5• of Na PCA, (b)the control cream with the same formulation but containing no Na PCA and (c) an estab- lished marketed cream with an alternative humectant system containing urea. One hundred and fifty women took part in the trial. Each woman used each of the three creams for a period of 2 weeks. There were approximately equal numbers of women using the creams in each of the six possible sequences. Only women with some degree of hand skin dryness and flaking were selected to take part. In order to obtain a reasonable degree of dryness and flakiness, the trial was carried out in southern Scotland during the late winter and early spring of 1976. The method of assessing hand skin dryness and flaking has been reported previously

Effect of pyrollidone carboxylic acid 203 (7, 8). It consisted of a trained technician using a simple numerical scoring system to assess six areas of each hand according to the following scheme: 0=no relevant visible damage, 1 =slight dryness, 2=marked dryness and/or slight flaking, 3-----severe dryness and/or marked flaking, 4=severe flaking and/or slight cracking, 6=severe cracking. The areas of the hand assessed were: back of hand, thumb web, other webs, back of fingers, palm, front of fingers. The 12 areas on each panellist were summed to give a total hand score. For convenience, the panel was divided into two halves and each half saw a different assessor. Each panellist saw the same assessor throughout the trial. Panellists were allocated to one of the six possible sequences of hand cream usage according to their initial total hand score. The allocation was carried out so that there were equal numbers of women in each of the six sequences and so that the mean and range of hand scores in each sequence was approximately the same. The allocation was carried out separately for each assessors' half of the total panel. After allocation to one of the six sequences, each panellist was given the appropriate cream and asked to use it at home after wet operations and before going to bed. They were asked to return for assessment after 2 weeks and collect the next cream. They were instructed not to use any cream on the assessment days. Residues of cream obscure dryness and flaking and absence of cream from the hands during assessment means that any effect of cream is on the skin itself and is reasonably long-lasting and does not reflect the ability of the fatty components of the creams to stick down any'- scales and obscure dryness by optical effects. The assessors were not aware which panellist had been using which product. The panellists themselves received coded products and did not know which creams contained humectant. After the end of the trial, results were examined for statistically significant differences between creams by analysis of variance. Because the trial was balanced for initial hand scores and because all possible sequences of cream usage were employed, it is reasonable to calculate mean changes from previous hand scores at each assessment and for each cream. These changes were calculated and used as the data for the analysis of variance. The results for each assessor were calculated separately and then combined to give an overall mean. RESULTS WATER-HOLDING CAPACITY OF ISOLATED CORNEUM Table I shows the mean water-holding capacity at 81•o r.h. of guinea pig corneum treated with the cream with and without Na PeA. The cream with Na PeA resulted in