Properly Seasoned In the making of Table Tops for Laboratory Furniture, the proper drying and tempering of selected woods is of the greatest importance. Kewaunee Tops are constructed of Wisconsin hard woods, weather-cured for at least two years, then kiln-dried and tempered for a long time. It is the same method employed by the old masters in the preparation of woods for fine old furniture. It costs much more than the "modern rapid-fire" way-but it is one reason why Kewaunee stands supreme in endurance Kewaunee Biology Laboratory Table, No. 1009. Specially adapted for schools where sections are numerous. Kewaunee Laboratory Furniture is used by thousands of Schools all over America. It is selected where the highest educational standards in equipment are observed. If interested in equipment for Physics, Chemistry, Biology, Agriculture, Electricity, Domestic Science or Art, Manual Training or Kindergarten work in your school-ask for the Kewaunee Book. It is free. Address all inquiries to the factory at Kewaunee. Our Laboratory Spectrometers Are sold in competition with instruments of European make WM. GAERTNER AND CO. Physical and Astronomical Instruments 5345-49 Lake Park Avenue CHICAGO Eastman Organic Chemicals DURING the past month the following chemicals have become available: Of the above list all those distinguished by an asterisk have been prepared or purified in our laboratory. Palo Alto Calif 1129 Cowper Street, John F. Newsom, COLLIS AND GREENWOOD. The Health of the Industrial W HOOD AND CARPENTER. Textbook of Practical Chemistry. 8 Illustrations. fessor of Pre OOD, M.R.C.P. When 162 Illustrations. 8vo. xii + 527 pp. Cloth, $5.00 Postpaid. By G. F. HOOD, M.A. (Oxon), B.Sc. (Lond.), Chemistry Master Nottingham High School; and J. A. CARPENTER, M.A. (Oxon), Major, Late Science Master, St. Paul's School, and Lecturer in Physics, Royal Dental Hospital, London. MCGUIGAN. An Introduction to Chemical Pharmacology. Pharmacodynamics in Relation to Chemistry. By HUGH MCGUIGAN, Ph.D., M.D., Professor of Pharmacology, University of Illinois College of Medicine. 8vo. xii +418 pp. Cloth, $4.00 Postpaid. AUTENRIETH. Laboratory Manual for the Detection of Poisons and Powerful Drugs. 5th Edition. Revised. 25 Illustrations. 8vo. xv+342 pp. Cloth, $3.50 Postpaid. By DR. WILHELM AUTENRIETH, Professor in the University of Freiburg; Authorized Translation by WILLIAM H. WARREN, M.D. SMITH. Priestley in America, 1794-1804. An Account of the Life and Work of the Discoverer of Oxygen while in America. 16mo. v 173 pp. Cloth, $1.50 Postpaid. By EDGAR F. SMITH, University of Pennsylvania. COPAUX-LEFFMANN. Introduction to General Chemistry. 30 Illustrations. 12mo, x+195 pp. Cloth, $2.00 Postpaid. By H. COPAUX, Professor of Mineral Chemistry, School of Industrial Physics and Chemistry, Paris. Translated by and with Appendix by HENRY LEFFMANN, A.M., M.D., Member American Chemical Society and of the British Society of Public Analysts. An exposition of the principles of modern chemistry. BARNETT. A Textbook of Organic Chemistry. Illustrated. Cloth, $5.00 Postpaid. By E. DE BARRY BARNETT, B.Sc. (Lond.), Lecturer in Organic Chemistry, Sir John Cass Technical Institute, London. MOLINARI. General and Industrial Organic Chemistry. Part I. Cloth, $8.00 Postpaid. By ETTORE MOLINARI, Milan; Translated by T. H. POPE, B.Sc., University of Birmingham (Eng.). SCHNEIDER. The Microanalysis of Powdered Vegetable Drugs. 2d Edition. 237 Illustrations. 8vo. Cloth, $5.00 Postpaid. By ALBERT SCHNEIDER, M.D., Ph.D., Professor of Pharmacology, College of Pharmacy, University of Nebraska. P. Blakiston's Son & Co., Publishers, Philadelphia TOLMAN Theory of the Relativity of Motion With Appendix A supplement to this work, written by the author, has just been issued. Under the title, Relativity Theories in Physics this Appendix gives a general description of the nature of relativity theories, together with brief discussions of Tolman's theory of similitude or relativity of size, of Einstein's theory of the relativity of uniform motion, and of Einstein's theory of gravity and general relativity. ix +242 pages (including Appendix). Cloth, $1.75. Carriage extra. Weight, 14 pounds. Appendix only (paper), 25 cents. The University of California Press BERKELEY, CALIFORNIA Theory and Practice MILLIKAN: Mechanics, These books provide for course. GINN AND COMPANY Boston New York Chicago London A NEW WILEY BOOK Principles of Radio Communication TH By J. H. MORECROFT Associate Professor of Electrical Engineering, Columbia University Assisted by A. PINTO and W. A. CURRY HIS BOOK deals with all phases of the Radio Art, going completely into both theory and operation. The treatment is more thorough than is generally given, and for this reason the book will have a wide appeal among workers in this field, the importance of which is so rapidly increasing. The text of "RADIO COMMUNICATION" comprises 935 pages, 6 by 9 inches, and contains 788 illustrations, many of which are reproductions of oscillographic records of transient phenomena. All curves used to illustrate formulæ are carefully executed to scale and may be used as typical problems. The book is cloth-bound. $7.50 postpaid. Enter Your Order for a FREE EXAMINATION Copy JOHN WILEY & SONS, Inc. 432 Fourth Avenue NEW YORK PHYSICAL METHODS IN LABORATORY ANALYSIS It is a well-known fact that any measurement in any science involves the application of a physical method. The measurement may be mechanical, as with an analytical balance or a kymograph; it may be one of temperature or heat, as with a respiration calorimeter; it may be optical, as with a microscope, spectroscope or colorimeter; or it may be electrical, as of resistance, current or potential difference, any of which may have a definite, known relation to some biological characteristic that is being investigated. Leeds & Northrup Company has long specialized in electrical measuring instruments and their applications. A recent activity has been the development of suitable instruments for measuring the potentials of a hydrogen electrode, in solutions and media, which correspond to hydrogen-ion concentrations or pH values. The studies we have made on this subject are summarized in Catalogue S75, which gives a clear explanation of the principles involved in the measurements and describes how they are made. It also contains a representative bibliography of fifty titles, bearing on many scientific applications of the hydrogen electrode, and a descriptive price list of suitable electrometric apparatus. If you feel that the publication might be of service in your laboratory, we should be very glad to send you a copy gratis. Leeds Northrup Company Electrical Measuring Instruments 4901 Stenton Ave. Philadelphia, Pa. |