584 Dr. A. C. Crehore on an Atomic Model 



the ring rather than retard its motion. It has been supposed 

 on this theorv that this accelerating force is opposed and 

 balanced by the retarding force of the selected electron upon 

 itself due to the radiation of energy. It should be pointed 

 out. however, that it has never been possible to arrive at any 

 equilibrium speed by means of this theory where the two 

 forces mentioned just balance, so as to permit of uniform 

 motion. 



On the other hand, the Saha equation applied to the ring- 

 leads to a tangential force in exactly the opposite direction 

 to the Larmor-Lorentz theory, a force due to the other elec- 

 trons that retards the motion of the selected electron. And, 

 of course, the force due to its radiation also retards it. 

 There is, therefore, on this theory no possibility of there 

 being an equilibrium velocity for a ring of electrons. 



This conclusion is of the utmost importance, and presents 

 a kind of ultimatum. Either one must abandon the use of 

 rings of electrons entirely in an atomic model, or one must 

 lay asidj the Saha theory as inapplicable. To many the 

 latter course has seemed the wiser ; but ; on the other hand, 

 there is a large group of chemists who have found much of 

 value in the use of such a model as that proposed by Lewis 

 and Langmuir, who have not hesitated to lay aside the ring 

 of electrons revolving completely around the centre of the 

 orbit. The ring atom has been of more especial use in 

 the phenomena of radiation, but has not helped the chemist 

 so much. The atomic model that the chemist has set up is 

 useful in fully as large a group of phenomena, and the 

 problems of chemistry are not to be lightly ignored. 



New ideas are obvioush required to harmonize the very 

 great differences that now exist in the different forms of 

 atomic models. These considerations warrant an examination 

 of the consequences of tracing tl:e Saha theory as far as 

 possible without prejudice as to the form of atomic model to 

 wdiich it leads. 



It seems unwise, however, to proceed along this road until 

 tin fundamental assumptions of the Bohr theory are re- 

 examined. A close examination of them shows at once 

 that the theory is broader and more comprehensive than 

 the model by which it was first introduced, so much so that 

 the requirements of Bohr's theory may be satisfied by other 

 conceivable atomic models. 



In his admirable discussion * of the Bohr theory Dr. Adams 

 says : " This investigation by Kramers furnishes almost con- 

 vincing proof of the general validity of Bohr's theory." Is 



* Bulletin Nat. Re-earcli Council, Oct. 1920, pp. 380, 321. 



