YPE K POTENTIOMETER OUTFIT as used in PH measurements, with two Clark type of hydrogen electrodes and accessory glassware mounted on motor-driven shaking device. See Chapters XI and XII of Clark's "The Determination of Hydrogen Ions". The uniformly successful and satisfactory operation of the Type K Potentiometer with its accessories for Hydrogen Ion Measurements has made it a valued and important part of the equipment of many laboratories carrying on scientific investigations or controlling production processes. "Electrometric Methods and Apparatus for Determining Hydrogen Ion Concentratioms'-Leeds & Northrup Catalogue S75-will help you determine whether the Type K Outfit is adapted to your work, or whether some other combination of instruments would serve as well. If your work leads you into problems of acidity or alkalinity determinations, or of making accurate titrations under difficult conditions, reading of Catalogue S75 may represent time well spent. We shall be glad to furnish the catalogue. LEEDS & NORTHRUP COMPANY Electrical Measuring Instruments 4901 Stenton Avenue PHILADELPHIA, PA. Einstein's Own Explanation RELATIVITY By ALBERT EINSTEIN The Einstein law has been accepted by astronomers and physicists as an epoch-making discovery. Up to the present Newton's law of gravitation has been universally accepted, but the new theory goes farther, and, apart from supplying the laws of Newtonian mechanics when certain approximations are made, it enables us to predict the exact course of all motions resulting from gravitation. In this book Professor Einstein explains his famous theory. The author's aim has been to give an exact insight into the theory of relativity, and to present the main ideas in the clearest and simplest form. Five diagrams and portrait A Timely Study of Modern Industrialism Price $2.50 COAL, IRON AND WAR By EDWIN C. ECKEL Author of "Building Stones and Clays," "Iron Ores," etc. This is an important study of the industrial development of the leading nations from the beginning of modern industrialism until the close of the World War. "Particularly admirable," says The N. Y. Eve. Sun, "is Edwin C. Eckel's 'Coal, Iron and War,' since it possesses to rare degree that far-visioned objectivity which hectic today so sadly needs and so seldom finds. A study of the growth and future of industrialism, Mr. Eckel's book cuts under political and social facts to the material inferences which create them. 'Coal, Iron and War' is a book well worth the attention of all seeking perspective on the great problems of today and tomorrow." Price $3.00 Published by HENRY HOLT AND COMPANY 19 West 44th Street New York City Recommended PSYCHOLOGY: From the Standpoint of a Behaviorist By Dr. JOHN B. WATSON, Professor of Psychology, Johns Hopkins University, Baltimore. 429 Pages. Illustrated. $3.00. HIGH AND ADVANCED SCHOOLS. A TEXT FROM THE MODERN VIEWPOINT:-Every teacher of Psychology, whether or not he may favor the study of the subject from the objective standpoint, will read it with profound interest. From beginning to end a constructive attitude is maintained and, where possible, the material employed has been gathered by objective methods. No field, however, at present belonging to psychology, is neglected. The text takes the position that psychology is a scientific study of human behavior, of the acts that man does through his original nature and hence apart from training, the acts which he can later do by reason of the putting on and retaining suitable habits. The importance of studying the individual in the light of his instructive equipment, the environment in which he has had to grow up, the system of habit which he has had to put on, and the stability of his emotional life are all emphasized. The illustrations in the anatomical section have been prepared_with_great care and a number of the drawings were made under the direct supervision of Max Broedel. BRIGHTNESS AND DULNESS IN CHILDREN By HERBERT WOODROW, Ph.D. Assistant Professor of Psychology in the University of Minnesota. 13 Illustrations. 322 Pages. $1.40 net. The psychology of intelligence, the subject of which must form a large part of any thorough course in psychology, is not adequately treated in general texts. This volume covers the subject in a broad and systematic way and is a suitable textbook for courses in child psycholgy, mental diagnosis, mental development and education of children. It is of special value to teachers and school administrators, as it gives a thorough discussion of many of their fundamental problems. It gives the student an understanding of just how the most modern applications are made, in some very important instances, and a definite idea of the results achieved. The volume makes an excellent text for supplementing a course in general psychology or in any special branch where the scientific treatment of intelligence is regarded as important. CLOTHING: Choice Care Cost By MARY SCHENCK WOOLMAN, B.S. Illustrated. 289 pages, including appendix, bibliography, glossary and index. 12mo. $2.00. Clothing, next to food, is a most vital problem. Heretofore it has been a neglected subject either for study or reading. This fact will emphasize the great value of this remarkable volume, to educators as well as to general readers. It gives complete information on clothing materials, their properties, values, and prices. How to ascertain by sight as well as by feeling the difference between fibres; between poor and good cloths; how to identify them; how to test their value for buying; and a general knowledge of the growth, manufacture, dyeing, and finishing of textiles in general. There are also chapters on the care, repair, and renovation of clothing; dyeing, laundering, and spot removal. This book will help solve the great problem of securing clothing to please the eye, to stand the wear of daily use, and at a cost within reason. AIRPLANE PHOTOGRAPHY By HERBERT E. IVES, Major, Aviation Section Reserve, Formerly Officer in Charge of Experimental Department, Photographic Branch, Air Service, U. S. A. 209 Illustrations. Octavo. $4.00. THE OUTLOOK, NEW YORK: "This thorough technical treatise may be used as a practical manual for class or self-instruction." JOURNAL OF OPTICAL SOCIETY OF AMERICA: "This book is sufficiently popular to interest anyone who reads simple English, and yet contains most of the essential scientific principles and technical data which are of importance to highly trained workers and students in this field. . . . It closes with chapters on the future developments in apparatus and methods, applications to technical and pictorial work and to exploration and mapping, all of which discloses the sound judgment and practical imagination of the author." J. B. LIPPINCOTT COMPANY PUBLISHERS PHILADELPHIA New Third Revised, Enlarged Edition Physiology and Biochemistry in Modern Medicine By J. J. R. MACLEOD, M.B., Professor of Physiology in the University of Toronto, Toronto, Canada; Formerly Professor of Physiology in the Western Reserve University, Cleveland. Assisted by Roy G. Pearce, M.D.; A. C. Redfield, M.D., and N. B. Taylor, M.D., and by others. 985 pages + xxxii, 6x9 inches, with 243 text illustrations, including halftones, charts, line drawings and tables, and 9 full-page plates in colors. Third edition, revised, Price, silk cloth binding with gold stamping, per copy, $10.00. ENTIRELY RESET, MOSTLY REWRITTEN, WITH 75 ADDITIONAL PAGES OF TEXT AND TEN NEW ILLUSTRATIONS. This book deals with the present-day knowledge of human physiology in so far as this can be used in a general way to advance the understanding of disease. It is an advanced text in physiology for those about to enter upon their clinical instruction, and at the same time a review for those of a maturer clinical experience who may desire to seek the physiological interpretation of diseased conditions. The former editions have been received with open arms by the profession and this edition has been completely revised. The section on the nervous system is unusually complete and includes an account of the fundamental principles of neuromuscular physiology. Much new matter has been added to this edition, including chemistry of respiration, measurement of functional capacity of heart, principles of ventilation and therapeutic value of oxygen, vitamines, capillary circulation, surgical shock, and interpretation of polysphymograms, and endocrine glands. Partial Table of Contents The physicochemical Basis of Physiological Processes; Circulating Fluids; Circulation of the Blood; Respiration; Acidosis; Hydrogen-Ion Concentration; Digestion; Urine; Metabolism; Ventilation; Endocrine Organs or Ductless Glands; Central Nervous Systern and Control of Muscular Activity. You should send for a copy of this epoch-making work. Teachers should write for special circulars and particulars, Circulars of other works sent on request. Molybdenum Wire Molybdenum Wire is a product of the General Electric Company's Research Laboratory Because of its resistance to chemical action Molybdenum Wire is capable of many uses in the industries. It is particularly adaptable to use as a heating element in muffle furnaces. The chemical properties are as follows: Slowly dissolves in hydrochloric acid at 110° C. It is not attacked by dilute sulphuric acid Dissolved slowly by concentrated nitric acid Dissolved rapidly by aqua regia Not attacked by hydrofluoric acid Not attacked by potassium hydroxide but is soluble in fused alkali Metal becomes coated after a time in acids, with an acid resisting oxide This wire can be furnished in standard diameter, .010" to .060". The melting point of molybdenum is approximately 2500° C. with oxidation occuring at red heat. Its resistivity at 20° C. is 4.1 microhms per centimeter cube and the temperature coefficient per degree between 0 and 170° C. is 005. For further details write our Schenectady (N. Y.) office General Electric General Office Company Sales Offices in 35B-22 |