300 



SCIENCE 



[N. S. Vol. XXV. No. 634 



Mathematical Analysis ' is a very encouraging 

 sign of the growing interest in higher mathe- 

 matics and these works will douhtless do much 

 towards increasing this interest. In following 

 the pages of Professor Pierpont's work one 

 feels that one is heing led by a master of his 

 subject and a sympathetic teacher, and these 

 elements combined with the nature of the sub- 

 ject make the present work one of the most 

 significant publications on pure mathematics 

 that have ever appeared in this country. 



G. A. Miller 

 University of Illinois 



Electrical Nature of Matter and Bttdioac- 

 tivity. By Harry 0. Jones. New Tork, 

 D. Van Nostrand Company. Pp. viii + 

 220. Price $2. 



Another semi-popular book upon a well- 

 worn subject, but a book which on the whole 

 justifies its existence by the treatment, found 

 in the last seventy-five pages, of the results of 

 investigations and discussions so recent that 

 they have not yet found place in other books 

 on radioactivity. Thus the discussions of 

 recent work on the origin and distribution of 

 radium, of the properties of the a and /3 rays, 

 as lately worked out by Rutherford and Bragg, 

 of the ' radiobes ' of Burke, of the decomposi- 

 tion products of actinium, and of radiotho- 

 rium, are all new and all thoroughly com- 

 mendable. 



The book as a whole lacks somewhat in 

 unity of treatment, the different sections dif- 

 fering considerably in value and in method of 

 presentation. The treatment of radioactivity, 

 which occupies all save the first third of the 

 book, although it is non-mathematical, is on 

 the whole thoroughly scientific, being char- 

 acterized by an admirable moderation of state- 

 ment, a scholarly collection of all the available 

 experimental data, evidently from the original 

 sources, and a judicious balancing of argu- 

 ments for and against rival hypotheses. It 

 will be read with interest and profit by physi- 

 cists and chemists. It contains a commend- 

 ably small amount of the sort of material 

 which seems to be designed chiefly as food for 

 the popular imagination. 



The chapters dealing with the electrical 



nature of matter seem, on the other hand, to 

 have been written largely for popular con- 

 sumption and their faults are those most com- 

 mon to literature of this type, namely, incom- 

 pleteness in the presentation of the facts and 

 a rather immoderate haste in arriving at posi- 

 tive conclusions, the author's attitude being 

 that of the ardent convert to the electrical- 

 nature-of -matter hypothesis rather than that 

 of the judicious disseminator of the present 

 state of scientific knowledge in this field. 

 Thus in discussing in the first chapter the 

 value of e/m for the corpuscle, he slurs over 

 the differences between the values found by 

 different observers working with cathode rays, 

 Lenard rays, photo-electric effects, the Zeeman 

 effect, and radium rays, and says simply that 

 the answer to the question as to the constancy 

 of e/m for negative corpuscles is unmis- 

 takably given by the results which have been 

 obtained. When it is remembered that these 

 values vary for slow-moving corpuscles from 

 4 X 10° to more than four times that number, 

 namely, 18.7 X 10°> the statement appears 

 rather too strong even for a popular article. 

 Thus far these differences are certainly not to 

 be explained by proiahle observational errors. 

 It is to be hoped that further experimenting 

 will soon reveal the causes of the discrepan- 

 cies. The value of e/m which the author 

 uses throughout the book is 7.7 X 10° instead 

 of 18.7 X 10°, the value given by the most 

 reliable experiments, especially those of Seitz 

 (An. d. Phy., Vol. 8, p. 223), who succeeded 

 in bringing the results obtainable by the three 

 different methods used in the study of cathode 

 rays into close accord. The value 7.7 X 10° 

 is, of course, inconsistent with Kaufmann's 

 measurements upon the variation of e/m with 

 speed according to which this quantity 

 changed from 6X10° to 13.1X10° as the 

 speed varied from .94 to .7 that of light. 



The feature of this part of the book, how- 

 ever, which is least commendable is the con- 

 fusion either of ideas or of terms involved in 

 such statements as the following : " Matter is 

 then a pure ' hypothesis ' — ' there is not the 

 least evidence for its existence.' Energy is 

 the only reality." Now, of course, every 

 trained reader knows that in the ultimate an- 



