332 SCIENCE PROGRESS 



is hydrogen, which is shown to have an atomic weight of i-oo8 in close 

 agreement with the accepted value. 



An interesting discussion is given of the meaning of these results and 

 their bearing on modern atomic theory. Here Dr. Aston allows his imagina- 

 tion more freedom and has much that is interesting to say on such questions 

 as the structure of the nucleus, the meaning of the whole-number rule, and 

 the relation between atomic number and atomic weight. The author's 

 remarks on the question of the evolution of the elements at present existing 

 in the universe are sufficient to show what a far-reaching effect experiments 

 such as these considered in this volume may yet have on very fundamental 

 scientific questions. The discussion of the deviation of the atomic weight 

 of hydrogen from an exact integer is of particular interest. It is shown 

 that the apparent loss of weight and consequent emission of energy which 

 take place when four hydrogen nuclei or protons combine to form a helium 

 nucleus may possibly provide an explanation of the maintenance of solar 

 energy. This section of the book, while admittedly speculative, is full of 

 most inspiring suggestions. 



The concluding chapters are devoted to the consideration of the spectra 

 of isotopes, and their separation by other physical and chemical methods. 

 Emphasis is laid on the extraordinary difficulty of this separation when it 

 depends on deaUng with the average effects of vast numbers of atoms, and 

 not with the effect of individual atoms as is the case in the positive ray tube. 



Dr. Aston is to be congratulated on having produced a volume which 

 will not only be a valuable addition to the library of the specialist, be he 

 physicist or chemist, but which will also make a strong appeal to the general 

 reader who is interested in the present-day developments of science. This 

 can, unfortunately, be said of too few modern books on scientific subjects. 

 The copious illustrations, both plates and diagrams, and excellent type add 

 considerably to the pleasure to be derived from reading this volume. 



G. S. 



Organic Syntheses : An Annual Publication of Satisfactory Methods for the 

 Preparation of Organic Chemicals. By Roger Adams, Editor-in-Chief. 

 Vol. I. (Pp. vii + 84, with 7 illustrations.] (New York : John Wiley 

 & Sons ; London: Chapman & Hall, Ltd., 1921. Price 8s. 6d. net.) 



This book owes its origin to the fact that during the war the American 

 chemists were cut off from foreign supplies of research chemicals. As a 

 result the preparation of many organic chemicals was worked out in various 

 universities on a scale large enough for use as starting material for research. 

 The directions given in this volume are for the preparation of alkyl bromides, 

 aleyl alcohol, benzene sulphonic cliloride, benzil, benzilic acid, benzoin, 

 a-bromonaphthalene, ^-bromophenol, diacetone alcohol, furfural, mesityl 

 oxide, methylene iodide, methyl hexyl carbinol, anhydrous oxaUc acid, 

 thiophenol, trimethylamine, and trimethylamine hydrochloride. The 

 directions are clear and supplemented with diagrams of apparatus where 

 necessary. They are followed by notes on the process, other methods of 

 preparation are indicated, and full references to the literature up to January 

 192 1 are given. This volume should prove very useful to the research 

 chemist, who will look forward to other volumes in succeeding years. The 

 methods have been worked out in one laboratory, and checked in a second, 

 before being pubhshed. This makes the book the more valuable, as the 

 instructions may be relied upon to give the yields stated. The yields of 

 substances prepared vary from about 100 grams to 2,000 grams. 



In the preface the authors request that other research workers will assist 

 in the preparation of these volumes by sending particulars of preparations 

 of any other organic chemicals, which they have made on a fairly large 

 scale, for verification and pubhcation. J. N. E. D. 



