Mixture of malic acid, urea, erythritol, resorcinol and acetanilide crystals, polarised light micrograph. Malic acid is found in certain fruits and wines. It's used in foods and cosmetics, and sometimes as medicine. Urea is a waste product of many living organisms and is the major organic component of human urine. Erythritol occurs naturally in fruits and fermented foods. It is used as a sugar substitute. Resorcinol is an organic compound. It is used to treat acne, dermatitis, eczema and other skin disorders. Acetanilide is a synthetic organic compound which has analgesic and fever-reducing properties.