Atoms and Molecules. 889 



their ratio being 3*058, the same as for the positive charge. 

 It is interesting to note that the diameter of the negative 

 electron obtained experimentally by Rutherford falls 

 between these values, namely 3\ r > xlO -13 cm. This may 

 well be a kind of mean between the figures above given. 

 It would make a difference how the electron is oriented 

 when hydrogen gas is bombarded with alpha particles. 

 Collision might occur at a distance of 6 '5, and again 

 it might not occur until the distance is reduced to 

 2'13xl0- 13 cm. 



The next atom, lithium, has been investigated by Aston * 

 and found to have two isotopes, the one with mass 6 and the 

 other with mass 7. The accuracy claimed for these values 

 is within about one part in one thousand. The isotope of 

 mass 7, Li-No. 2 in fig. 1, is represented as a ring or 

 hexagon, in which the positive individuals are arranged in an 

 equilateral triangle, each having two electrons, one on either 

 pole as in the hydrogen model or in the alpha particle. 

 There are also three connecting electrons to hold the 

 system together located in the same circle with the positive 

 charges, that is on the equator. These electrons approach 

 very close to but do not touch the adjacent electrons 

 occupying planes above and below them. They are each 

 attracted toward the doublet because it has an effective 

 charge of 3 — 2 = 1. The mass of this isotope is exactly 



3 x^ = 7, if according to Table I. the mass of the positive 

 o 



charge of three is 7/3. 



The other isotope of Li, namely Li-No. 1 in fig. 1, has but 

 a single positive charge of 5 units t situated in the centre of 

 the only doublet, and is surrounded by an equatorial ring 

 of three single electrons. The mass of the charge of 5 is 

 6 according to Table I., so that this form satisfies this 

 requirement. The official weight given for Li is 6" 94, 

 indicating that the isotope No. 2 is of the more frequent 

 occurrence. 



The next atom, glucinum also called beryllium, has not 

 vet been investigated experimentally for isotopes, so far 

 as known to the writer, but its official weight, 9*1. indicates 

 that isotopes are probable. The scheme followed here 

 enables one to construct possible forms of the isotopes of Gl, 

 and it will prove of interest if the masses corresponding to 

 the forms shown are later obtained experimentally. In 



* Phil. Mag., May and November 1920. 

 t See Note, p. 894. 



