RECENT ADVANCES IN SCIENCE 203 



existence in certain circumstances. The pyramidal atom con- 

 sists of a nucleus, a ring of electrons in the form of a circle 

 on whose axis lies the nucleus, and in addition a single sta- 

 tionary electron situated on the axis, this latter electron 

 being the linkage by means of which binding with another 

 atom is effected on Stark's view. Now the objections urged 

 by Nicholson against Stark's model is a much more serious 

 matter than those proposed in the case of other model atoms. 

 No doubt a single ring of electrons in an atom on the Ruther- 

 ford idea cannot be stable, but the disturbances which break 

 up the atom on account of instability are those which are 

 least likely to occur, so that, in spite of this possibility, the 

 atom can have as long an existence in the form of an elec- 

 trically neutral system, as is demanded by its known pro- 

 perties. But in the Stark model something more funda- 

 mental than stability is involved. Nicholson shows that no 

 positively charged or neutral atom can exist in this form. 

 Quite apart from any question of stability, it is not possible 

 to satisfy the ordinary conditions for a steady rotation of the 

 ring in such pyramidal atoms even in the absence of all dis- 

 turbing forces. Besides, even though the atom may acquire 

 an electron on its axis, if it is neutral or negatively charged 

 before the operation, the ensuing structure is unstable as 

 regards some of its more important vibrations. Its stability 

 is not comparable even with that of a single ring, and it could 

 not be endowed with any permanence. Consequently such 

 atoms could never exist as positive or neutral systems, and 

 could only have a very transitory life as negatively charged 

 ones. As already stated, this conclusion is independent of 

 questions of stability, and would hold no matter what system 

 of dynamical reasoning is adopted, Newtonian or otherwise. 

 This would appear to vitiate entirely all molecular construc- 

 tions such as those of Stark. 



I 



PHYSICAL CHEMISTRY. By Prof. W. C. McC. Lewis, M.A., D.Sc, 

 University, Liverpool. 



False Equilibria. — The existence or non-existence of a false 

 equilibrium in a chemical process is one of those problems 

 which, after having attracted much attention and given rise 

 to considerable controversy, eventually comes to be regarded 



