513 



TABLE 527.— CHANGES WITH TEMPERATURE IN ABSOLUTE INDEX OF 

 REFRACTION (n) AT 20°C FOR A NUMBER OF GLASSES *t 



* For references, see footnote 160, p. 509. 

 t In units of the fifth decimal place. 



TABLE 528.— INDEX OF REFRACTION OF GLASSES MADE BY SCHOTT AND 



GENOESSEN, JENA 



The following constants are for glasses made by Schott and Genoessen, Jena : Ha, tic, n D , hf, na, 

 are the indices of refraction in air for A = 0.7682/x, C — 0.6563m, D = 0.5893, F = 0.4861, G' = 

 0.4341, v= (n D — 1)/(m f — n c ). 



Percentage composition of the above glasses : 

 O 546, Si0 2 , 65.4 ; K 2 0, 15.0 ; Na 2 0, 5.0 ; BaO, 9.6 ; ZnO, 2.0 ; Mn 2 3 , 0.1 ; As 2 3 

 O 381, Si0 2 , 68.7 ; PbO, 13.3 ; Na 2 0, 15.7 ; ZnO, 2.0 ; Mn0 2 , 0.1 ; As 2 5 , 0.2. 

 O 184, Si0 2 , 53.7; PbO, 36.0; K 2 0, 8.3; Na 2 0, 1.0; Mn 2 3 , 0.06; As 2 3 , 0.3. 

 O 102, Si0 2 , 40.0; PbO, 52.6; K 2 0, 6.5; Na 2 0, 0.5; Mn 2 3 , 0.09; As 2 5 , 0.3. 

 O 165, Si0 2 , 29.26 ; PbO, 67.5 ; K 2 0, 3.0 ; Mn 2 3) 0.04 ; As 2 3 , 0.2. 

 S 57, Si0 2 , 21.9 ; PbO, 78.0 ; As 2 5 , 0.1. 



0.4 ; B 2 3 , 2.5. 



TABLE 529.— CHANGE OF INDICES OF REFRACTION FOR 1°C IN UNITS OF THE 



FIFTH DECIMAL PLACE 



Mean 

 No. and designation temp 



S 57 Heavy silicate flint 58.8° 



154 Light silicate flint 58.4 



O 327 Baryt flint light 58.3 



O 225 Light phosphate crown. . . 58.1 



-An 



100 



SMITHSONIAN PHYSICAL TABLES 



