Hoff; the theory of electrolytic dissociation to Arrhenius; and the theory of the voltaic cell to Nernst; but it is Ostwald who has taken these theories, has developed them and has forced the world to accept them. No one else could have fought the good fight as Ostwald has done. He has founded a distinct school, the Leipzig school as it is sometimes called. A large majority of the active physical chemists of today have worked in Ostwald's laboratory at one time or another; but his influence is not confined to his pupils. There is probably no man living whose opinions have so much immediate weight in the world of chemists as does that of Ostwald.
Ostwald's record during the last twenty-one years is an extraordinary one, whether judged by quality or quantity of work. The first edition of the 'Lehrbuch der allgemeinen Chemie' consisted of two substantial volumes; but it is dwarfed by the second edition which runs to over thirty-four hundred pages and is not yet finished. The other books on chemistry include a short introductory volume on physical chemistry, a laboratory manual of physical chemistry, a history of electrochemistry, a volume on the scientific principles underhung analytical chemistry, a text-book of inorganic chemistry, and an elementary book in dialogue form. All this is in addition to lectures, laboratory work and editorial duties. This last item is a serious one, because a large percentage of the papers published in the Zeitschrift für physikalische Chemie come from Ostwald's laboratory and because he reviews all the new books, and has, until the last few years, written critical reviews of many of the current articles on physical-chemical subjects appearing in other journals. Over and above this, Ostwald is the editor of a series of reprints of important chemical papers.
Mention has already been made of the fact that Ostwald at one time gave lessons in music and painting. As results of this we have an unpublished course of lectures on the theory of harmony and a book on painting. Every year Ostwald spends a large part of his vacations in sketching, using a modified form of pastel which is his own invention.
A very natural result of Ostwald's literary work in chemistry has been his growing interest in the theory of knowledge. Beginning as an ardent admirer of Mach, he has devoted more and more time in recent years to philosophy. With characteristic energy he has started a journal of philosophy and has published in book form a course of lectures on philosophy delivered in Leipzig in 1901. It must be admitted that Ostwald ranks higher at present as a chemist than as a philosopher; but it was as a philosopher that Ostwald attended the International Congress of Arts and Science at St. Louis, and he is to lecture at Harvard both on chemistry and on philosophy.
THE ECLIPSE OF THE SUN.
A total solar eclipse is an event which appeals in equal measure to the scientific investigator and to the popular imagination. Yet the interest is not only different, but to a certain extent conflicting. The astronomer is concerned with certain technical problems, such as the composition of the corona, which have less connection with human welfare than most scientific questions. The popular interest is largely due to the awe-inspiring character of the event, a survival perhaps from the time when this was the occasion of portents and omens. It may be assumed that the simple explanation of the moon's shadow will gradually do away with the apparent marvel of this phenomenon, though the accuracy with which it can be foretold will continue to impress the unlearned with the wonders of the science, which has been called both 'the queen of the sciences' and the 'science of pure curiosity.'
The eclipse of August 30 was for
