Table 388 357 



DERIVATION OF PARTIAL DISPERSIONS OF GLASS FROM n F -n c 



(F. E. Wright, Journ. Amer. Ceramic Soc, 3, 783, 1920; Journ. Opt. Soc. Amer., 4, 148, 



195. 1920; 5, 389, 1921.) 



The optical constants of a glass are generally stated as the index of refrac- 

 tion n Dj and the partial dispersions between the A (.768/*), C (.856), 

 D (-5 8 9)> F (4 8 6) and G' (434/*) lines and its v value, (n -i)/(n F -n c ). 

 The reciprocal of v is called the average dispersive value. The following table 

 is computed from n Y —n x = a(n F — n c ) -b. The mean indices of refraction of 

 two sets of glasses from which a and b were derived are: 



«D »F 1lc' Mc — Ua no He Mf — Md hg' — Mf 



1.545958 1.552616 1.557994 a = .288936 .272167 .727833 .658443 



000529 .000219 — .000219 — .000843 



1-539909 I-543I 



1.588807 1.593565 1-597767 1.608201 1.616995 b 



Smithsonian Tables 



