A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



" To the solid ground 

 Of Nature trusts the mind which builds for aye."- 



-WORDSWORTH. 



THURSDAY, MARCH 2, 1911. 



RESEARCHES ON RADIOACTIVITY. 

 Traite de Radioactivite. Bv Prof. Mme. P. Curie. 

 Tome i., pp. xiii + 426. Tome ii., pp. 548. (Paris : 

 Gauthier-Villars, 19 10.) Price, 2 vols., 30 francs. 



NO more effective illustration of the rapidity of 

 advance of accurate knowledge of radio- 

 activity can be taken than a comparison of the two 

 books published on the subject by Mme. Curie, at 

 an interval of seven years. The first, published as a 

 thesis for the doctorate of science in 1903, was a small 

 volume of 142 pages, and gave an account, not only 

 of her own work, but of most of the important facts 

 known in radio-activity at that time. The second, 

 published at the close of 1910, consists of two volumes, 

 containing in all nearly a thousand closely-written 

 pages, and giving an orderly and systematic account 

 of the large mass of data that has been accumulated 

 in the interval. The reniarkable rapiditv of advance 

 of this new branch of science largely results from two 

 factors — the discovery and isolation of radium by Prof, 

 and Mme. Curie, and the development of the trans- 

 formation theory in 1903. 



The discovery of radium gave an opportunity to the 

 investigator of obtaining intensely radio-active 

 material, in which the typical radio-active effects are 

 shown on a very marked scale. The remarkable pro- 

 perties of radium attracted the attention of the scien- 

 tific world, and gave a great impetus to the study of 

 radio-activity. On the other hand, the transformation 

 theory has proved an invaluable guide to the investi- 

 gator in disentangling the apparently complicated 

 processes occurring in radio-active matter. It offers 

 a rational explanation of practically all the experi- 

 mental facts that have been discovered, and has been 

 instrumental in bringing to light a number of unsus- 

 pected relations of great importance. 



This work represents, with additions, the course of 

 lectures on radio-activity given by Mme. Curie in the 

 Sorbonne. The first chapter is devoted to an account 

 of the conduction of electricity through gases, and 

 the second to a descri])tion of the methods employed 

 NO. 2I.'i7. VOL. 861 



in radio-active measurements. The latter contains a 

 somewhat detailed account of the theory of the elec- 

 trometer and of the quartz piezo-electrique devised by 

 J. and P. Curie. Chapters iii. and iv. include an 

 account of the general radio-active properties of 

 uranium and thorium, and of radio-active minerals, 

 and a very complete account of the methods of isola- 

 tion of radium and polonium and other radio-active 

 materials. This chapter will be read with especial 

 interest, as it is largely an account of- the author's 

 well-known discoveries. The next three chapters deal 

 with the radio-active properties of the emanations, and 

 of the active deposits which are derived from them. A 

 very full description is given of the methods employed 

 in determining the molecular weight of the emanation 

 by diffusion methods, and also a clear account of 

 recent work upon the purification of the radium 

 emanation, the determination of its volume, and of 

 its physical and chemical properties. In chapter viii., 

 after a review of the various theories proposed, the 

 transformation theory is adopted, and the mathematical 

 theory of successive .transformations is given. Then 

 follows a long chapter of more than 200 pages, giving 

 a systematic account of the nature of the radiations 

 from radio-active bodies, followed by a discussion of 

 the general physical and chemical effects shown^ by 

 the radiations, including the production of helium 

 from radio-active matter, and an account of the experi- 

 ments which have been made by Ramsay and others 

 to test whether the radiations from active matter 

 are able to transform inactive elements. After a dis- 

 cussion of the various experiments, Mme. Curie sums 

 up as follows :■ — 



"En resum6, on peut considerer qu'il n'y a pas 

 encore actuellement de raisons suffisantes pour 

 admettre que la formation de certains el6iients puisse 

 etre provoquee a volont6 en presence de corps radio- 

 actifs La production d'h^lium reste acquise ; mais 

 elle est reli6e k une propri(5t6 essentielle des elements 

 radioactifs et n'est pas influenc^e par I'intervention 

 de I'exp^rimentateur." 



Chapter xi. gives an account of the methods of 

 measurement of heat emission of the radio-active sub- 

 stances, while the next four chapters deal with suc- 



B 



