in which 4 represents the wave-length in air. 
951 
differences between observed and calculated values: 
é 
f 
(air) 
0.64385 , 
0.54608 
0.50859 
0.47221 
0.43585 
0.40467 
In this 
even with only one 
and, 
neel 
n° 2 — 
erm 
CZ 
The following table gives 
It gives the following 
“cal) | 
0.99319 
I 
1.00338 
1.00745 
1.01258 
1.01811 
in the sum, 
As with hydrogen we obtain from it: 
(obs) 105A 
().99374 5 
| 
1.00539 a 
1.00742 | 3 
1.01259 — | 
1.01813 —2 
case, too, the theoretical dispersion formula *) 
gives quite good agreement. 
1 1 
n—l AE iS dy? 
7) oat ae a | 
Aa A 
taking 4 as the wave-length in vacuo, we calculate 2 = 0,07982 u. 
an idea of the degree of correspondence: 
an 
‘(vac.) | “(cal) “(obs) A0 
k Dt et ee. 
a | 0.64403 | 0.99391 | 0.99374 | + 17 
b | 0.54623 | 1 ! 
e | 0.50873 | 1.00934 | 1.00339 | — 5 
d | 0.47234 | 1.00741 | 1.00742 Pi 
| | 
e | 0.43597 | 1.01258 | 1.0129 | — 1 
f | 0.40478 | 1.01823 | 101813 iel 
| | 
A subsequent paper will deal with the absolute values of the 
refractive indices of air and of carbon dioxide. 
ik These proceedings If 
12 p. 602. 
