Text extracted from opening pages of book: COLLOIDS AND TOT ULTRAMICROSGOPE A MANUAL OF Colloid Chemistry and Ultramicroscopy BT DR RICHARD ZSIGMONDY Professor of Inorganic Chemistry in the university of Gdttingen AUTHORIZED TRANSLATION BY JEROME ALEXANDER, M. Sc. FIRST SECOND THOUSAND NEW YORK JOHN WILEY & SONS, LONDON: CHAPMAN & HALL, LIMITED 1914 Copyright, IP BT JEROME ALEXANDER BRAUNWORTM A CO. BOOK MANUFACTURERS IKL. VN, N. V. PREFACE TO THE ENGLISH EDITION THE expectation that this book would arouse the interest of a wider circle has been agreeably fulfilled. I am glad to be able to' state that Mr. Jerome Alexander, of New York, has undertaken to translate the book because of interest in its contents, and has carried out the work carefully and conscientiously. I have myself read over the whole translation and found it in excellent accord with the original text. In so far as concerns the experimental basis for answer ing' the fundamental questions of Colloid Chemistry, there is but little to be added to the German edition. In but few places has it become necessary to amplify the statements and extend the text because of later publications. . May the English edition receive the same friendly reception, as the German edition. R. ZSIGMONDY. GOTTINGEN, November 14, 1908. iii TRANSLATOR'S PREFACE AFTER discussing the basic principles governing the colloidal condition, and the classification of colloids, and reviewing the most important work already done in this field, the author describes the development ( upon the principle originally conceived by himself) of the ultramicroscope, which carries our range of vision well towards molecular dimensions; and he furthermore gives a detailedaccount of his own valuable pioneer researches with the new instrument. Giving as it does an actual insight into a sphere here tofore beyond the range of direct observation, the ultra microscope has proven to be a powerful weapon with which to attack numerous problems confronting the chemist, the physicist, and the biologist; and it will be of special value in deciding many mooted questions in theoretical and in technical colloid chemistry. As the far-reaching ramifications of colloid chemistry are better understood, its importance and the applicability of its principles to a great variety of industrial problems, become more and more evident. There might, for ex ample, be mentioned agriculture, tanning, dyeing; rubber, cement, ceramics; soaps, photography, sugar in fact, almost every industry is directly or indirectly involved. Professor Zsigmondy's work will, therefore, be of vital interest not only to scientists concerned with theoretical Vi TRANSLATOR'S PREFACE questions, but also to chemists, engineers, and others controlling technical processes. To physiological chemists and physicians it is indispensible. I must express my sincere thanks to Prof. Zsigmondy and also to Alexander D. Ross, M. A., B. Se, ( lecturer on Natural Philosophy in the University of Glasgow), both of whom read over the original manuscript of the translation and made valuable suggestions. In the English edition besides some additions to the text, there are included two beautiful colored plates originally pub lished in Professor Zsigmondy 's paper on Colloid Chemistry/' JEROME ALEXANDER. NEW YORK, February 24, 1909. PREFACE TO THE GERMAN EDITION SOME of the conclusions and observations herein set forth wereoriginally intended for the Zeitschrift fur physikalische Chemie; however, as the method of render ing visible ultramicroscopic particles which were developed by Siedentopf and myself, has awakened the interest of a larger circle, I have decided to m ke readily accessible to the representatives of other branches of science the results of my ultramicroscopic investigation of fluids, and the experiments associated therewith; all the more so because they may be of some use to other workers in the same field. Another reason that led me to take this step was the fact that