NATURE 



[March 2, 191 1 



cessive transformations occurrinf^ in uranium, thorium, 

 radium, and actinium, followed by an account of the 

 origin of radium and the discovery of ionium, and 

 the discussion of the general connection between the 

 radio-active series. The last chapter is devoted to a 

 consideration of the radio-activity of the earth and 

 atmosphere. 



An excellent portrait of Pierre Curie is given in the 

 frontispiece. Several interesting reproductions are in- 

 cluded at the end of the volume in illustration of the 

 photographic effects of the various radiations. Care- 

 fully prepared tables are included in the text, giving 

 the important radio-active constants, while a table of 

 exponential values is added for convenience in calcu- 

 lating the decay and growth of the radium emanation. 



In these two volumes, written in a clear and inter- 

 esting manner, Mme. Curie gives a full and com- 

 plete account of practically all the work of import- 

 ance that has been done in radio-activity. It is a 

 storehouse of accurate information. The author has 

 shown judgment in the selection of data and in dis- 

 cussion of points at issue. The chemical methods of 

 separation of radio-active products are in most cases 

 briefly given, while a detailed account is included of 

 the methods of separation of radium and of polonium. 

 This is excellent so far as it goes, but it does not fill 

 the pressing need at the present time of a practical 

 book on the methods of separation and purification of 

 the numerous radio-active products. Such an account 

 should prove of the greatest value both to chemists 

 and physicists, for it is becoming more and more im- 

 portant in many lines of work that the investigator 

 should be able to separate and concentrate the various 

 radio-active products. Such an account can only be 

 written by an expert both on the physical and chemical 

 side who has himself worked over the subject, for 

 more than a compilation of chemical methods is re- 

 quired. 



It is always a difficult matter in a work of this 

 character, which treats of a rapidly growing subject, 

 to give full credit to pioneer discoveries, and at the 

 same time to do justice to later work of a more de- 

 tailed and accurate character. Mme. Curie has, to a 

 large extent, overcome this difficulty by giving a fairly 

 detailed account of the original experiments, and a 

 more condensed statement of subsequent work. 



There is very little to criticise and much to admire 

 in this notable work. It is remarkable what little 

 difference of opinion exists among radio-active workers 

 on the interpretation of the main phenomena. This 

 is no doubt mainly a result of the general adoption of 

 the theory of atomic disintegration, for on this theory 

 only one explanation is in most cases admissible. 

 While there is a general agreement on the funda- 

 mental points, there is naturally room for wide differ- 

 ence of opinion on matters still under investigation. 

 This is well illustrated by the conflicting views that 

 are at present held on the difficult question of the 

 nature of the emission and of the absorption of the 

 » and 7 rays by active matter. The advocacy of rival 

 views on such questions is in many cases a great 

 advantage, for it gives an incentive to a more accurate 

 and complete investigation of the problem under con- 

 sideration. 



x\0. 2157, VOL. 86] 



While the reviewer finds that he is in substantial 

 agreement with all the main conclusions of Mme. 

 Curie, there are a few minor points to which attention 

 may be directed. Mme. Curie includes radio-uranium 

 as a possible product of uranium, although a note of 

 interrogation is attached. She certainly makes a 

 better case for its existence than is given in the 

 original publication ; but until more definite informa- 

 tion is forthcoming it does not appear desirable to in- 

 clude it in the uranium series. The products radium 

 Ej and radium E, are retained, although later work ot 

 Antonoff has indicated conclusively that only one pro- 

 duct of period about five days which emits ^ rays can be 

 present. The discovery of ionium is credited to Ruther- 

 ford and Boltwood ; it should be Boltwood. The original 

 suggestion that lead is a final product of the trans- 

 formation of radium is attributed to Rutherford, li 

 should be Boltwood. The term "radio-active induite " 

 is used widely throughout the work. While the use 

 of this expression is historically justified, it is a 

 misnomer, especially when used in reference to radio- 

 active matter deposited from the emanation. The 

 term "active deposit," which has come into general 

 use, is a very convenient substitute, and it is desirable 

 that the original names, "induced," or "excited," 

 activity, should disappear from the literature. 



The lack of a name- or subject-index is a serious 

 drawback to the usefulness of this treatise. The 

 references to literature are incomplete, the name of 

 the journal and the year of publication alone being 

 given. 



As an account of a youthful branch of science, the 

 present treatise may appear somewhat lengthy ; but it 

 must not be forgotten that the subject of radio-activity 

 now covers a very wide field of work. It has to treat, 

 not only of the nature of remarkable types of radiation 

 which are emitted, but also of the origin and physical 

 and chemical properties of more than a score of new 

 transition elements. In addition, it has to deal with 

 the distribution of radio-active matter in the earth and 

 atmosphere, and its bearing on atmospheric electricity 

 and on problems connected with geology. Unless this 

 treatise is to become unwieldy in size, it will be 

 necessary in future editions, where much new work 

 has to be included, to adopt a policy of more rigid 

 selection and compression of the experimental data to 

 be discussed. No doubt as our knowledge of the 

 various questions becomes more definite, it will not 

 be so difficult as at present to give a complete review 

 of theory and experiment within reasonable limits of 

 space. 



The present work will be read with the greatest 

 interest by all workers in radio-activity as an authori- 

 tative account of the subject from one who has made 

 notable contributions to its history. The book is 

 essentially written for the investigator rather than for 

 the ordinary student, and will be of the greatest 

 service to the former as a complete and accurate re- 

 view of all important publications on the subject. 

 Every reader will recognise the great labour and 

 patience involved in writing a complete treatise on 

 such a rapidly growing subject, and Mme. Curie is 

 to be congratulated on the success of her efforts. 



This treatise is a noteworthy contribution to the 



