A mixture of 212 g. (1 mole) of benzoin (Note 1), 110 g. (1.8 moles) of urea and 800 cc. of glacial acetic acid in a 2-l. round-bottomed flask is heated under a reflux condenser for seven hours (Note 2). The hot solution is quickly poured into a 2-l. beaker (Note 3) and allowed to stand at least three hours. The cold mixture is then transferred by means of a large wooden spoon or spatula to a 30-cm. Büchner funnel and sucked as dry as possible with the help of a rubber dam. The crystals are pressed down during the suction filtration. The filtrate is discarded. The crystals are returned to the beaker, stirred mechanically with 500 cc. of ether for thirty minutes, filtered again by suction (Note 4), and spread out to dry at least overnight (Note 5). The product is dissolved by heating with 1 l. of glacial acetic acid in a 2-l. round-bottomed flask attached to a reflux condenser (Note 6), and the clear solution is poured, with mechanical stirring, into 2.5 l. of water in a 4-l. (1-gal.) crock. Stirring is continued for thirty minutes (Note 7). The mixture is filtered on a 30-cm. Büchner funnel and pressed and sucked as dry as possible. The crystals are transferred to the 2-l. beaker and stirred mechanically for ten minutes with 1 l. of water. After filtration, the washing with water is repeated. The product is then returned to the beaker, stirred with 750 cc. of ether, and filtered again. The material is then air-dried to constant weight. The yield of white fluffy crystals of diphenylglyoxalone melting at 330–335° (corr.) (Note 8) is 220–230 g. (93–97 per cent of the theoretical amount).