346 
Let v m be the value of the refractive index of a gaseous ele¬ 
ment in the standard state selected by Cuthbertson and Metcalfe; 
it is the state in which the number of atoms of the element per 
unit volume is equal to the number of atoms contained in unit 
volume of hydrogen at 0° C. and 760 millims. In the present paper 
a different definition of the standard state has been adopted. The 
standard state to which all values of v given above are referred 
is that in which, by Avogadro’s Law, the number of molecules per 
unit volume is equal to the number of molecules contained in unit 
volume of hydrogen at 0° C. and 760 millims. In order to reduce 
the data given by Cuthbertson and Metcalfe to our scale, let us 
write p for the number of atoms contained in one molecule of the 
gaseous element; if we assume that v — 1 varies directly as the 
density of the gas we have 
(1) v CM -l = ^(v-l). 
From this and from (5), § 15., we conclude that 
(2) A cm — \p A. 
Gaseous Zinc (p = Ï). From the following data (C. and M., 
1. c., p. 141) 
a) l = 5,183 . . . v CM = 1,002100 
b) 6,562 . . . 1960 
we obtain 
A cm = 3,64. 
It must be added that this figure is probably to small; C. and M’s 
results for zinc graphically smoothed seem to point to A CM lying 
in the proximity of 4. 
Gaseous Tellurium (p — 2). From the following data (C. 
and M., 1. c., p. 144) 
a) Â — 5,460 . . . v CM 
b) 5,893 . . . 
c) 6,562 . . . 
we find: (a) and (c) lead to A CM =b,8o 
(b) and (c) ... 5,69 
These results, however, are rather uncertain. 
= 1,002620 
2495 
2370 
