107% 
be taken together with the first in p and also the second in 2 with 
the second in gp. The mean moment of the molecule and therefore 
also the moment of the unit of volume with respect to axes fixed 
in space have corresponding terms, but all with the period 
27 eager ees ips i 
—'), Hence the ratio of this moment to the electric force that excites it 
Ss 
has likewise corresponding terms; as this ratio determines the index of 
refraction, the latter must be expressed by an equation of the form : 
NS 
u, u, {ts 
piston po + (s+) en in? pi -(s—@)*} jn" pe + (e+) | npe 
or if we decompose each of the first two terms into terms with 
denominators of the second degree: 
n?—1 = 
! t ! 
ne (ey ee ass oe u, = + 
s s s 
1 — | —-—— 1— | — 1 — | ——_—— 
nDi—-W AB ND tw 
fia u 
ge np2\? y, s\? i. npe \* at 
Cay ( yO 
ov o 0) o 
NG i = de Pz 09200 AD 0,304 w?, the terms of 
this equation correspond to those of (1) in the same order. The 
determination of the numerators would only lead to an unnecessary 
repetition of the long calculations Dersie had to make. Without 
it we can see already that the second term points to resonance 
if sng, the first-if st w— np, the third if s—o—7p,, the 
fourth if s—w—inp,, the fifth if s + w —= np. Professor Lorentz 
pointed out to me that by attending to the dispersion formula 
we should expect the unstable character of the hydrogen molecule 
of Bonr—Drpie. 
If now an electric force has worked on this system in the way 
assumed by Drie, the electrons remain in positions and with 
velocities which necessarily must give rise to the modes of motion 
B, D, and D,. Hence, after having been exposed for some time to 
an external electric force the system would be destroyed. 
§ 4. Now we can try to limit the freedom of motion of the 
system in the plane of the path in such a way that the motion 
1) As soon as the mean value has been determined with respect to the different 
phases of the electronic motion, this result is obtained. 
