1072 
momentum with respect to the axis of the molecule must have the 
value Ee where / is PrLANCK’s constant. 
Under the same suppositions as Bonr made on the constitution 
of the molecule, Draijer has investigated the forced vibrations which 
the system can execute under the influence of the electric force of 
a transmitted light-beam *). Desise supposes the mass of the nuclei 
to be so great that their motion may be neglected and further that 
these vibrations can be calculated according to the laws of ordinary 
mechanics. If the forced vibrations are known, the mean electric 
moment of the unit of volume is found at the same time and from 
this follows again the index of refraction 7. 
For this Drsise finds: 
n?—1 e 2,97429 2,15347 | 
= Sn nt 
4AaN mw? a ia 8 a 1 8 2 
0,412375w 0,556397w 
0,246581 + 0,579918 (: as 2) 
0,0276447 
8 es a See 
Lm 0,304388 Ls 
(asso) + ( *) 
a. 
| 
| 
Sk 
0,246581 + 0,579918 (1 a “) 
ij Ef 
0,304388 + (: IE ) 
w | 
where: N is the number of molecules per unit of volume, 
—e the charge of the electron 
m the mass of the electron. 
By comparison with experimental data of J. Kocn or C. and M. 
Curaperson DeBiJR found: 
© — 4.64.10" or 5,01. 10%, 
m 
which value agrees very well with the data for the electrons from 
cathode rays (5,58.10), and for the moment of momentum of each 
that is, within the limits of error, just what Bonr 
, dad 
had assumed. 
Now we will consider, however, how the system behaves, firstly 
1) P. Denise. Die Konstitution des Wasserstoff-Moleküls. Sitz. Ber. München 1915 p.1, 
