896 



SCIENCE. 



[N. S. Vol. XIX. No. 493. 



lar tissues. Mental capacity and vigor may 

 depend upon an upsetting of the physiological 

 balance and the aggrandizement of the central 

 nervous system at the expense of these other 

 processes. Great prosperity in the vegetative 

 functions — which we call physical health — 

 would thus be inimical to the highest intel- 

 lectual enterprise, and the case of D would be 

 made characteristic instead of anomalous. It 

 is at least suggestive that the eupeptic maxi- 

 mum in adults is found in connection with 

 the first stages of general paralysis. 



The gist of the figures contained in the 

 table, theorizing apart, is sufficiently indica- 

 tive of the importance of physical vigor as a 

 condition of mental activity to make the mat- 

 ter worthy of consideration in future study. 

 EoBERT MacDougall. 



New York University. 



THE ELECTRON THEORY. 



Professor J. J. Thomson in the March 

 number of the Philosophical Magazine dis- 

 cusses the theory of the stability of systems 

 of electrons. His conclusion is that a num- 

 ber of electrons constitute a stable system 

 when they are grouped in a series of con- 

 centric circular rings, very similar to Saturn's 

 rings, which rotate about a common axis. 

 Stability depends upon two conditions, 

 namely, (a) upon a certain minimum angu- 

 lar velocity of rotation of a ring, and (6) 

 upon the presence of at least f(n) electrons 

 at or near the center of a ring containing n 

 electrons. Stability increases when the angu- 

 lar velocity increases above the critical value 

 and when the number of internal particles is 

 greater than f (n) ; f(n) being a definite func- 

 tion of n. 



The first part of Professor Thomson's paper 

 is devoted to the establishment of the two 

 conditions of stability (a) and (&) and the 

 second part of the paper is devoted to the ap- 

 plication of these results to the theory of the 

 constitution of the atom. The features of 

 the second part are : 



1. A brief discussion of the tyijes of oscilla- 

 tion of systems of electrons and the applica- 

 tion of these results to the Tationalization of 

 spectra. Professor Thomson goes no farther 



than to show in a general way that the 

 spectral lines of a given element may be 

 grouped in a number of series of related lines, 

 and that the difFerent chemical elements of a 

 group or family, such as the alkali metals, 

 may have closely related series of lines. 

 This same idea has been advanced by H. 

 Nagaoka, of Tokyo, who promises soon to 

 publish a paper devoted to this method of 

 classifying spectra. 



2. A full discussion of the relations between 

 stable systems containing greater and greater 

 numbers of electrons, and the application of 

 these results to the rationalization of 

 Mendeleef's periodic law. In this section of 

 the paper Professor Thomson shows that a 

 system of electrons furnishes a dynamic model 

 which, with increasing numbers of electrons, 

 exhibits properties closely analogous to those 

 remarkable periodic variations of valency of 

 the chemical elements with increasing atomic 

 weight. This constitutes the first suggestion 

 of anything worthy to be called a rational 

 basis of Mendeleef's law, and its importance 

 can scarcely be overestimated. It is, per- 

 haps, the greatest contribution to theoretical 

 physics during a decade. In this section of 

 his paper Professor- Thomson discusses the 

 process of chemical combination in terms of 

 his theory and he siTggests an explanation of 

 the catalytic action of water and of a metal 

 such as platinum. 



3. An application of the fact that the 

 stability of a system of electrons depends 

 upon a certain minimum angular velocity of 

 the electron rings, to the explanation of radio- 

 activity. 



It is the purpose of this note merely to 

 call attention to Professor Thomson's paper, 

 which should be carefully read by every stu- 

 dent of chemistry, and to give to the reader 

 a sufficiently clear idea of the electron to en- 

 able him to fully appreciate Professor Thom- 

 son's theory of the structure of the atom. 



It is not to be expected, of course, that a 

 new hypothesis should lead at once to any- 

 thing approaching a completely consistent 

 theory and it may be helpful to readers of 

 Professor Thomson's article to point out the 

 weak points of his theory. 



