(glycolyl urea), C3H4N202 (glycoluric) acid,H 2 NCO-NH. CH 2 CO 2 H, which is readily soluble in hot water, and on heating with hydriodic acid decomposes into ammonia, carbon dioxide and glycocoll, CH2NH2C02H. Many substituted hydantoins are known; the a-alkyl hydantoins are formed on fusion of aldehydeor ketone-cyanhydrins with urea, the 13-alkyl hydantoins from the fusion of mono-alkyl glycocolls with urea, and the 'y-alkyl hydantoins from the action of alkalis and alkyl iodides on the a-compounds. y-Methyl hydantoin has been obtained as a splitting product of caffeine (E. Fischer, Ann., 1882, 215, p. 253).