The standard directions for the preparation of phenylacetic acid specify that the benzyl cyanide is to be treated with dilute sulfuric acid prepared by adding three volumes of sulfuric acid to two volumes of water. There action, however, goes so vigorously that it is always necessary to have a trap for collecting the benzyl cyanide which is blown out of the apparatus. The use of the more dilute acid, as described in the above directions, is more satisfactory. The phenylacetic acid may also be made by boiling under a reflux condenser for eight to fifteen hours, without a stirrer, but this method is not nearly so satisfactory as that described in the procedure. When only small quantities of the acid are required, the following modified procedure is of value. One hundred grams of benzyl cyanide are added to a mixture containing 100 cc. of water, 100 cc. of concentrated sulfuric acid, and 100 cc. of glacial acetic acid. After this has been heated for forty-five minutes under a reflux condenser, the hydrolysis is practically complete. The reaction mixture is then poured into water, and the phenylacetic acid isolated in the usual manner. The odor of phenylacetic acid is disagreeable and persistent. 3. Other Methods of Preparation The standard method of preparation of phenylacetic acid is by the hydrolysis of benzyl cyanide with either alkali[1a] or acid.[2a] The acid hydrolysis runs by far the more smoothly and so was the only one studied. There are numerous other ways in which phenylacetic acid has been formed, but none of them is of practical importance for its preparation. These methods include the following: the action of water on phenyl ketene;[3a] the hydrolysis and subsequent oxidation of the product between benzaldehyde and hippuric acid;[1] the reduction of mandelic acid;[2] the reduction of benzoylformic acid with hydriodic acid and phosphorus;[3] the hydrolysis of benzyl glyoxalidone;[4] the fusion of atropic acid with potassium hydroxide;[5] the action of alcoholic potash upon chlorophenylacetylene;[6] the action of benzoyl peroxide upon phenylacetylene;[7] the alkaline hydrolysis of triphenylphloroglucinol;[8] the action of ammonium sulfide upon acetophenone;[9] the heating of phenylmalonic acid;[10] the hydrolysis of phenylacetoacetic ester;[11] the action of hydriodic acid upon mandelonitrile.[12] [1a] Ann. 96, 247 (1855); Ber. 14, 1645 (1881); Compt. rend. 151, 236 (1910). [2a] Ber. 19, 1950 (1886). [3a] Ber. 44, 537 (1911). [1] Ann. 370, 371 (1909)a [2] Chem. (2) 1, 443 (1865); Ber. 14, 239 (1881). [3] Ber. 10, 847 (1877) [4] J. prakt. Chem. (2) 82, 52, 58 (1910). [5] Ann. 148, 242 (1868). [6] Ann. 308, 318 (1899). [7] J. Russ. Phys. Chem. Soc. 42, 1387 (1910); Chem. Zentr. 1911 (I) 1279. [8] Ann. 378, 263 (1911). [9 Ber. 21, 534 (1888); J. prakt. Chem. (2) 81, 384 (1910). [10] Ber. 27, (1894). [11] Ber. 31, 3163 (1898)