358 



Tables 389 and 390 

 TABLE 389. — Index of Refraction of Glasses (American) 



Indices of refraction of optical glass made at the Bureau of Standards. Correct probably to o.ooooi. The com- 

 position given refers to the raw material which went into the melts and does not therefore refer to the composition of 

 the finished glass. 



TABLE 390.— Dispersion of Glasses of Table 389 



Melt. 



n F — n c 

 n D - 1 

 n F -n c 



«D - »j 



n F - n c 

 n n - n. 



1-51714 

 0.00868 



59-6 



0.00612 

 0.00492 

 0.00256 



1 52430 

 0.00820 



63 9 



0.00578 

 o . 00460 

 0.00242 



1.56819 

 0.01164 



48.8 



0.00827 

 0.00681 

 0.00337 



1 . 57406 

 0.01014 



56.6 



0.00715 

 0.00577 

 0.00299 



1 . 58038 

 0.01391 



41-7 



0.00991 

 0.00831 

 o . 00400 



1. 61756 

 0.01121 



55-1 



0.00792 

 0.00641 

 o . 003 29 



163 



1.62725 

 0.01700 



369 



0.01216 

 0.01032 

 o . 00484 



1.65548 



0.0190-1 



34-4 



0.01363 



0.01168 

 0.00541 



Smithsonian Tables. 



