Chemistry and Physics. 145 



making this mine of wealth more easily accessible that the edi- 

 tors are to be specially congratulated. 



The first, and more important, volume contains all the thermo- 

 dynamical papers, the principal of these, the famous paper on 

 "The Equilibrium of Heterogeneous Substances," occupying 

 three hundred out of the four hundred and thirty pages of the 

 volume. A very welcome feature in this first volume is the 

 inclusion of a biographical sketch by Professor H. A. Bumstead. 

 Those who, like the present writer, had not the honor of meeting 

 Gibbs, will welcome this opportunity of obtaining some slight 

 understanding of the personality of the great scientist : we wish 

 the biography had been more ample. 



The second volume contains all the non-thermodynamical 

 papers. An especially interesting part of this volume consists 

 of eighty papers devoted to a reprint of a pamphlet on vector 

 algebra, originally printed privately for Yale students of physics. 



Those who possess the volumes will have nothing but praise 

 for the way in which the editors and publishers have done their 

 work : the former are to be congratulated on the arrangement of 

 the papers : the latter on the printing and appearance of the vol- 

 umes. Both are to be thanked for their service to science. 



J. H. JEANS. 



9. The Electron Theory ; by E. E. Fournier d'Albe. Pp. 

 xxiv + 311. New York and London, 1906 (Longmans, Green & 

 Co.). — The electron, or indivisible atom of negative electricity, 

 has become within the last ten years the most trusted and useful 

 conception which the physicist has at his command for dealing 

 theoretically with the new and startling experimental discoveries 

 of which this decade has been so prolific. In addition to this, it 

 has in many cases helped to correlate and "explain" experi- 

 mental facts and laws which had been known for a long time but 

 had not previously found a place in any connected theory. The 

 present book is a popular introduction to this new theory. It 

 adopts the electron as a fundamental postulate and ascribes to it 

 the properties which experiment and speculation have shown to 

 be necessary; from these hypotheses are deduced, in successive 

 chapters, the facts of electrostatics, the electric discharge, 

 thermo-electricity, voltaic electricity, magnetism, radiation, elec- 

 tro-optic and magneto-optic phenomena and the relation between 

 conductivities for heat and electricity. As is perhaps inevitable 

 in a popular presentation, there are portions of the book where 

 the triumphs of the theory are stated with a confidence which is 

 probably not shared even by the men who have been most active 

 in its development. But even when allowance is made for this, 

 the results collected in this book make a very impressive demon- 

 stration of the service which this theory has done and a promise 

 of what may be expected of its further developments. The 

 work is written with admirable clearness and in an attractive and 

 interesting manner ; it is the best popular presentation of this 

 important theory which the present reviewer has seen. h. a. b. 



