May, 1926.] BOOK REVIEWS. 653

BOOK R E V I E W S . RECENT ADVANCES IN PHYSICAL AND INORGANIC CHEMISTRY. By Alf red W.

Stewart, D.Sc., Universi ty of Glasgow. Fi f th edition, xi-312 pages, 8vo, plates and illustrations in text. New York, Longmans, Green and Company, I926. Price, $6.50.

This is an excellent summary of the data that have accumulated in the inorganic field of physical chemistry in recent years. A dozen new chapters have been written, giving in clear and concise form the facts concerning haf- nium, mass-spectroscopy, segregation of isotopes, atomic structure, active hydrogen, new hydrides, intense drying and the Tesla luminescence spectra. The author states that only three chapters have been left in the form in which they were in the previous edition. A large part of the volume has been devoted, as might be expected, to the researches that have increased the knowledge of the structure of the atom. The author leans decidedly to the static theory of atomic structure which is treated at considerable length. The final chapter gives ~ most interesting and valuable historical review of the atomic theory from its origin in the dawn of scientific speculation among the Greeks to the elaborate experiments and theories of to-day. A paragraph, covering the years f rom I914 to I918, gives a painful reminder of the war, s ta t ing that Bri t ish scientists were, during those years, so occupied in other channels than pure research that little was accomplished in the latter field, but that in the " undisturbed atmosphere of the United States " such work was possible, and during this period G. N. Lewis put forward his cubical atom theory with its concomitant view that the valency bond could best be represented by a pair of electrons held in common by two united atomic systems. Even this work was but little noticed in the stress of war.

All through the book are to be found these instructive historical notes. together with descriptions of the methods now used in studying the nature of the atom and the phenomena of atomic action. A striking chapter is that on the effect of thorough drying on the properties of substances. Many years ago Wanklyn showed that perfectly dry chlorine does not act on perfectly dry fused sodium. Later, Dixon showed that a perfectly dry mixture of carbon monoxide and oxygen cannot be exploded by an electric spark, but a trace of moisture will activate the mass. Recent researches have gone much fur ther and this book describes many of these, showing the drastic influences of thorough drying on melting and boiling-points. Baker found that the vapor density of ether and methanol were very much higher when they were perfectly dry than when in the ordinary condition.

The book is eminently adapted to enable the more mature chemist to " catch u p " with the modern knowledge of physical chemistry and atomic theories in the inorganic field. HENRY LEFFMANN.

X X e SALON INTERNATIONAL DE PHOTOGRAPHIE, 1925. SociGt6 Franqaise de Photographie, Paris. I5 pages, 48 plates, 9 ~ x i 2 ~ inches, stiff paper.

The present issue of this annual is somewhat more elaborate in point of mechanical execution than that of the preceding year in that the plates are printed on one side of the paper. There is also a marked difference in the color of the paper, which is white or nearly so, instead of the buff t int of

654, BOOK REVIEWS. [J. F. L

last year's production, which is especially pleasing for art studies. Nevertheless the tableaux, which include still-life, figures in motion and portraits, are of the usual high standard of excellence of the productions of this Society. Gray, blacks and sepia tones are employed with good effect in keeping with the nature of the subject.

Apart from their artistic merit, the plates constitute examples of superior press-work scarcely distinguishable from photo-prlnts.

Luc~N E. PICOLET.

IL VOLO TRANSPOLARE. By Col. Ing. Umberto Nobile, Director of the estab- lishment for aeronautic construction in Rome. Pamphlet, 27 pages, illus- trations and maps, 8vo. Rome, 1925.

This is a dissertation upon the plan for a transpolar journey starting from Rome. A concise account is given of the earlier voyages to the North Pole, from which it appears that in the fifteenth century, the brothers Zeno and Pietro Querini began such journeys, the main object being to obtain a route to India. Another Italian explorer took up the work in the latter part of the sixteenth century, but lost his life in the attempt. Henry Hudson's voyage in I(x)7 was the next in importance. Later voyages are noted, but there seems to be no reference to Elisha Kent Kane's expedition in 1853.

Numerous photogravures give details of the dirigible which is to be used for the journey, and several excellent maps show the routes pursued by the more recent polar travellers, including Peary's famous journey.

HENRY" LEFFMANN.

P ~ s s m ~ DE LA LUMII~RE. Par Pierre Lebedef. Traduit du Russe par T. Kousmine, Chef de Travaux de Physique ~ l'Universit6 de Lausanne. 7I pages, 9 x 6 inches, paper. Paris, Librairie Scientifique Albert Blanchard,

I926. Price, 7f.5o. Of the many persons who have a little more than a casual interest in

striking phenomena of physical science, there are perhaps few who have not noticed the little apparatus devised by Crookes many years ago to demonstrate the pressure of light that is to be found in the ~hop-window of nearly every dealer in optical goods. Most of the text-books of physics describe it, but in general do not dwell upon the subject at more than brief length. Crookes' demonstration was in the main qualitative. Though numerous other investi- gators earlier and later than Crookes occupied themselves with the subject, to Maxwell is generally accorded the credit of demonstrating the relation between radiant energy absorbed, the velocity of light and the pressure exerted upon the absorbing surface.

The present pamphlet is a record of the investigations of the late Professor Lebedef on this important phenomenon of radiation. There are three main divisions of the work: First, on the repulsive force of radiating bodies; second, experimental research on the pressure of light; third, experimental researches on the pressure of light upon gases. A biographical sketch of the author is given at the end. The account of these experiments and their results is given in full detail with numerous references to the work of other investi- gators. The pamphlet is No. IX of a collection of monographs from foreign