IT has been established by earlier investigators that acetic acid has a destructive effect on the ascorbic acid in raw cabbage. This effect is somewhat surprising, since the lower the pH in the medium, the more stable is the ascorbic acid and, therefore, one would expect the acetic acid to have a preservative effect on the ascorbic acid in cabbage. However, in experiments carried out in the early months of 1951, we found that, in many fruits and vegetables, the ascorbic acid is to a remarkable degree oxidized into dehydroascorbic acid if slices are sprinkled with 5 per cent acetic acid and allowed to stand for two hours. This oxidation does not take place if water is used instead of acetic acid. Other lower fatty acids have a similar effect. The action of lactic acid is very slow and that of citric and tartaric acid practically negligible. © 1952 Nature Publishing Group.