230 Proceedings of the Royal Society of Edinburgh. [Sess. 
In the case of hydrogen, the electrostatic moment of the doublet is 
given as 
•75 x 10 -18 = (i)ft in electrostatic units. 
•75 x 10~ 18 
w h = 
2-62 
2*63 
in electro-magnetic units. 
o X 1 U 1 
. CO,* = 2*5 X 1CT 29 . 
2-5 n 
x 10 
-29 
The r th electron in the 2nd atom, whose displacement is £' r , is displaced 
an amount £' r — x x relative to atom 1. 
Force in direction of axis of 
2wje 
I)r- 
i'r - *i Y 
D. 
2 
where 0 is small and is 
on average zero 
2-64 
Taking D / r = 2 x 10 8 , we have 
2*65 
<MD'r) = *i = 1-5. ^-lO" 17 - 
Force on doublet —e(j; r — x 2 ) due to charge -f-se at distance D, 
2se 2 
3 (i r “ x t) — 120 r ~ x i)’ 
2*66 
12 
— 6*5 . s . lO" 17 . 
In general 
6*5s <c 
T5 n 
and we shall therefore assume 
2-67 .... 
and 
02lB 
ft 
T5n a 
~ft" 
10- W 4^r s 
We proceed to modify our notation in order to make explicit the con- 
tribution to P due to the interaction of the atoms. 
j. n, o 1 , O 1*5010 1 1 
■ f 1 =f 1 -/3 v where ft, - ^ ; ^ = m , 
• ^<1. 
/ 1 
^.e. /3 j<1. 
2*08 
