January 26, 1905] 



NA TURE 



29t 



their form, composition and arrangement, together 

 with the general characters of their venation, surface 

 and texture ; nor has the author omitted to go into the 

 more detailed but equally important consideration of 

 the anatomical structure and physiological functions 

 of leaves. This part also contains many lists com- 

 prising those leaves which show the same common 

 features as regards arrangement on the twig, form of 

 venation, character of base, apex and margin of 

 lamina, &c. 



Part ii. of this volume, like that of vol. i., gives the 

 classification of trees and shrubs, but, in this case, 

 according to the character of their leaves. A useful 

 glossary is given at the end of the volume, so that the 

 beginner need have no difficulty in understanding the 

 few but necessary technical terms which are used in 

 the book. 



ADVANCES IN PHYSICAL SCIENCE. 

 The Recent Development of Physical Science. By 

 W. C. D. Whetham, F.R.S. Pp. xii + 344. 

 (London : John Murray, 1904.) Price 7^. 6d. net. 



IT is now nearly thirty years since Prof. Tait pub- 

 lished his lectures on " Recent Advances in 

 Physical Science." The period that has since elapsed 

 has been one of remarkable fruitfulness, and it is 

 a suggestive fact that the fundamental problems of 

 physical science which were dealt with by Prof. Tait 

 have to so large an extent supplied the motive for 

 the investigations now described by Mr. Whetham. 

 Foremost amongst these perennial problems must 

 be placed the structure of matter, the mutation of 

 energy, and the nature of comets and nebulae. Lord 

 Kelvin's vortex-ring theory of the atom, so lucidly 

 expounded by Prof. Tait, finds in the later volume its 

 analogue in the electrical or corpuscular atom of Prof. 

 J. J. Thomson, and the doctrine of the conservation 

 of energy, which occupies the foremost position in the 

 earlier volume, is again brought into prominence by 

 the recent suggestions that the internal motion of the 

 atom, be it that of a vortex ring or of a moving 

 electron, may perhaps be drawn upon to supply the 

 energy that is liberated from some hidden storehouse 

 by the radio-active elements. 



After an introductory chapter on the philosophical 

 basis of the science, Mr. Whetham devotes two 

 chapters to the liquefaction of gases and the pheno- 

 mena of fusion and solidification. These two chapters 

 afford striking examples of the way in which recent 

 years have added to the equipment of the experimental 

 sciences, not only by increasing the range of tempera- 

 tures within which investigations may now be con- 

 ducted, but also by providing the means of accurately 

 measuring these temperatures. Under the heading of 

 " Fusion and Solidification " Mr. Whetham has given 

 a concise and readable account of the knowledge 

 recently acquired with reference to the structure of 

 metals and alloys. The examples, already classical, 

 of the copper-tin alloys studied by Roberts-Austen and 

 by Heycock and Neville, and the iron-carbon alloys 

 studied by Osmond, le Chatelier, Roberts-Austen, and 

 others are described. Photomicrographs of the former 

 NO. 1839, VOL. 71] 



series of alloys are given. The most fascinating part 

 of the chapter, however, is that which deals with Mr. 

 Beilby's recent investigations of the surface structure 

 of solids. These investigations have shown that 

 even a brittle metal like antimony can be made at 

 ordinary temperatures to flow like a liquid, so that 

 when it is rubbed with fine emery paper the surface 

 produced is not jagged or crystalline, but under the 

 highest magnification appears rather like a freshly 

 painted surface on which the rounded streaks left by 

 the brush are still visible. 



In the chapter on the problems of solution, the 

 mechanism of electrolysis is discussed from the point 

 of view of Arrhenius's theory of electrolytic dissoci- 

 ation, but the arguments in favour of this theory 

 are stated with a moderation that is in marked con- 

 trast to the one-sided statements that have sometimes 

 been put forward by ardent supporters of the theory. 

 In considering the nature of colloidal solutions, a 

 purely physical explanation is given of the coagulation 

 of the proteids ; the observation that "the direction 

 of movement of certain proteids " under the influence 

 of an electric current " could be changed by changing 

 the solvent from a verv dilute acid to a very dilute 

 alkali " would be interpreted by the chemist as evidence 

 of their power, as amino-acids, to function either as 

 acid or as base, whilst the fact that " if the solvent 

 was very carefully neutralised an isoelectric point was 

 reached at which the solution became very unstable 

 and coagulation seemed to occur spontaneously " 

 would be ascribed to the tendency of the free amino- 

 acid to condense and form a more complex molecule 

 in the manner characteristic of this group of com- 

 pounds. 



The chapters on the conduction of electricity through 

 gases and on radio-activity contain a concise account 

 o? the series of investigations that have been co- 

 ordinated in the recently published works of Prof. 

 J. J. Thomson and Prof. Rutherford. The chapter 

 on atoms and sethcr derives its chief interest from the 

 inclusion in it of the results of Prof. Thomson's recent 

 investigations of the stability of a system of negatively 

 charged corpuscles revolving in orbits within a posi- 

 tively charged sphere. The atomic model suggested 

 by such a system gives, probably for the first time, a 

 clear representation of the periodic properties of the 

 elements, including the variation in valency, which is 

 the most characteristic of these properties. 



The final chapter, on astrophysics, contains an 

 account of the more recent results of spectroscopic 

 investigations of the sun and stars, and includes re- 

 productions of three of the most striking of Prof. 

 Hale's solar photographs. In the later part of the 

 chapter the pressure due to radiation is considered and 

 applied to the explanation of the curious phenomena 

 of comets' tails, whilst the mutual repulsion of radi- 

 ating particles is suggested as a possible explanation 

 of the permanence of Saturn's rings. 



The author has sought to express the results of 

 recent physical investigations in a form which " might 

 prove useful to students of science in general," and 

 " also appeal to those who, with little definite scientific 

 training, are interested in the more important con- 

 clusions of scientific thought." In the former part 



