vy 
Dielectric Capacity of Atoms. 403 
the atom, I used Maxwell’s relation K,;=N,”, where N, is the 
refractive index of the stuff of the atom. For ten metallic 
ions, namely those of the Li family, those of the Be family 
from Mg to Ba, and for Zn, and for the six negative fatty 
acid radicals from formic to eaproic, the equation (16) was 
found to be verified in a broad way. But in the case of the 
halogens from F to I the relation seemed to break down 
completely, as also in the case of the ions H and OH. By 
means of further data I have found that Cd ranges itself with 
the metals mentioned, while Ag and Pb rank as further 
exceptions. In the case of the halogens it was suggested 
that, as their atoms are heptad as w ell as monad, we must 
imagine each halogen to have associated with it four negative 
electrons and three positive ones. Three of the negative 
electrons unite with the positive ones when the halogen atom 
acts as a monad, and so form inside the halogen atom three 
electric doublets. With a notation which I lave preposed 
this idea would be expressed by writing the following as the 
formula for the Cl ion: DCI((#);. In this way we ean 
briefly record the fact that Cl is a monad with heptad capa- 
bilities. Now, if the three electric doublets #p inside the 
halogen ion produce an abnormal effect on the propagation 
of light through the halogen ion, we shall not be justified in 
using Maxwell’s relation for finding the dielectric capacity 
from the refractive index. Just as water and a number of 
similar substances have two limiting dielectric capacities, 
namely 80 and 2 in the case of water, with every intermediate 
value for electric alternations of suitable frequency, so it 
seems to me that the halogen atoms have a dielectric capacity 
K, which is different from N,? for the conditions under 
which their ionic velocities are measured. Accordingly I 
propose to use equation (16) for finding the dielectric capa- 
cities of the halogen atoms and of atoms in general. By 
means of the data given on page 175 of the paper mentioned 
and the assumption that K,=N,’ on the average for the 
regular ions, the equation becomes one for K, in the following 
form : 
Kg 2800 fr, Bie ii ivy lee Te GR) 
where B is the volume of a gramme-atom of the ion. 
The following table contains the values of the ionic velo- 
cities given by Kohlrausch except for Cd aud Pb, the values 
of B taken from “Further Studies on Molecular Force” 
(Phil. Mag. [5] xxxix.), and also the values of K, calculated 
by (17), using for v the value 1 for the monad atoms and 2 
