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PRACTICAL ORGANIC CHEMISTRY MACMILLAN AND LONDON . CO., LIMITED BOMBAY CALCUTTA MELBOURNE . . MADRAS THE MACMILLAN COMPANY NEW YORK . DALLAS . THE MACMILLAN BOSTON CHICAGO SAN FRANCISCO . CO. OF CANADA, LTD. TORONTO C- '-0 BY JULIUS B: COHEN, PH.D., B.Sc., F.R.S. PROFESSOR OF ORGANIC CHEMISTRY, THE UNIVERSITY; LEEDS AND ASSOCIATE OF THE OWENS COLLEGE MACMILLAN AND ST. CO., LIMITED MARTIN'S STREET, LONDON 1920 COPYRIGHT. First Edition, 1900. Reprinted, Second Edition, 1904, 1907. 1908, 1910, 1913, 1915, 1916, 1918, 1919, 1920 (twice). PREFACE TO THE FIRST EDITION THE present volume is an enlarged edition of that published and has been completely rewritten. The preparations have all been carefully revised, some of the former ones omitted and many new ones introduced. The chief additions are the introductory chapters on organic analysis and molecular weight determinations, and an extension of the appendix. The book does not aim at being a complete laboratory guide, in 1887, but is intended to provide a systematic course of practical in- struction, illustrating a great variety of reactions and processes with a very moderate outlay in materials and apparatus. The objection may be raised that the detailed description of processes makes no demand upon a student's resourcefulness or ingenuity. It must be remembered, however, that the manipulative part of organic chemistry is so unfamiliar to the elementary student that he requires minute directions in order and to avoid waste of time considerable practical material. Until he has acquired he cannot accomplish the experiresearch, and repeated failures will be skill mental work requisite for apt to destroy his confidence in himself. To satisfy, to a legitimate extent, the prejudices of certain examining bodies, who still adhere to the old system of testing a student's knowledge of practical organic chemistry by means of the qualitative analysis of certain meaningless mixtures, the special tests for some of the more common organic substances have been inserted. At the same time, an attempt has been made at the end of the appendix to systematise the analysis of PREFACE TO THE FIRST EDITION organic substances on a broader and therefore more rational basis. The present occasion seems opportune to direct attention to the fact that one of the most familiar, most readily procurable and most cheaply produced of all organic materials is placed beyond the reach of many students by the heavy duty levied upon it. May I, in the name of teachers of organic chemistry, appeal to the Board of Inland Revenue, on behalf of scientific and technical education, to provide institutions for higher education in science with a limited quantity of pure alcohol of duty, thereby placing schools of chemistry in this free country in the same position as those on the Continent ? In conclusion I desire to thank Dr. J. McCrae, who has written the section on Ethyl Tartrate and the use of the Polari- meter, Dr. T. S. Patterson, who has been kind enough to look over the proofs, and Mr. H. D. Dakin, who has given me substantial assistance in the practical work of revision. J. THE YORKSHIRE COLLEGE, October, 1900. B. COHEN.