Vol,. 7, 1921 
PHYSICS: W. DUANE 
271 
distribution of electrons described by the above equations consists of 
two electrons in an inner orbit: then two groups of eight electrons, each, 
each group on the surface of a sphere, the two spheres lying fairly close 
together. Considerably outside of these spheres are two spherical sur- 
faces, each containing eighteen electrons and lying fairly close together. 
Thus the distribution corresponds approximately with that described in 
the Lewis-Langmuir theory of static atoms. 
Bohr 2 has recently suggested an arrangement of orbits, one outside 
the other, that differs slightly from the arrangement adopted in the pre- 
ceding calculations. He assumes that the three quantum orbit or orbits 
lie between the two quantum orbits, and that for those elements which 
have four quantum electrons the four quantum orbits lie between the two 
three quantum orbits. This arrangement of electrons may be represented 
by the scheme 
tii = 2, n<i = 4, n% = 9, w 4 = 16, w 5 = 9, n& = 4, 
ri =1, r 2 = 2, t 3 =3, r 4 = 4, r 5 = 3, r 6 = 2. 
In order to test this distribution of electrons I have calculated the critical 
absorption frequencies of the chemical elements that lie just above the 
inert gases in the chemical tables. The critical absorption wave-lengths 
have not been measured for all the inert gases themselves. In making 
the computations I have assumed that the distribution of the electrons 
is the same as that in the inert gases, and that in each case the extra electron 
has been taken over by the other chemical element which forms the chemi- 
cal compound used in measuring the critical absorption wave-length. 
As a matter of fact, it makes very little difference what is done with this 
additional electron. Its influence on the critical absorption wave-length 
is, theoretically, very small. This distribution of electrons is the same 
as that employed above for all chemical elements up to and including 
argon (N = 18). I have, therefore, included in the computations only 
those chemical elements of higher atomic number than eighteen. In 
the case of niton (N = 86) the chemical element just above it is missing, 
and I have, therefore, calculated the critical absorption frequency for 
thorium. The data appear in table 3. As in tables 1 and 2 column 
3 contains the data computed on the supposition that the two one quantum 
electrons revolve in the same orbit, whereas for the data of column 5 
they are supposed to revolve in opposite directions in separate orbits, 
one just outside the other. It appears that the agreement between the 
calculated and observed values is much better for this distribution of 
electrons than for the preceding distributions, especially the data of 
column 3. Owing to the fact that the radius of the first three quantum 
orbits is much larger than that of the two quantum orbits inside them 
the correction for the mutual influence of these two and three quantum 
orbits becomes very small. 
