264: Mr. L. 0. Jackson on a Mathematical Investigation 



(2) The a particle would then have atomic dimensions,, 



say 10 " 8 cm. It is inconceivable how a system of 

 atomic dimensions could travel through air distances 

 up to 7 cm., and on an average pass through 500,000 

 air molecules before being seriously deflected from 

 its original direction of motion. The photographs of 

 C. T. R. Wilson show very clearly the long straight 

 path of an a particle flying through air, and the 

 experiments of Rutherford on the structure of the 

 a particle are in accordance witli the view that the 

 diameter of the a particle is of the order 10~ 16 cm. 



(3) The change of an a particle into a helium atom would 



on this hypothesis be due to the loss of two positive 



charges and not to the gain of two negative charges. 



Rutherford's view that the « particle is a positive 



nucleus of charge -f 2e and that it becomes a helium 



atom by gaining two negative electrons seems far less 



artificial and more in accordance with the facts. 



It might be mentioned that Dr. Stewart's helium atom 



cannot explain the a particle as a helium atom minus two 



negative electrons, since the remaining two positives w r ould 



immediately fly apart. 



II. Lithium — group 1— no. of electrons three, no. of 

 valency electrons = one. 



In this system also we can find a configuration, at which 

 the constituents of the atom will arrive in the course of 

 their revolutions, and for which equilibrium cannot be 

 maintained. 



Fio-. 3. 



2lf N \ \ 



DfM — Si? H c f 



Lithium atom. 



Consider the equilibrium of the electron in the configur- 



ation shown in fig. 3. 



