514 TABLE 530.— TRANSMISSION OF RADIATION BY JENA GLASSES 



Part 1 



Coefficients, a, in the formula It =Ioa', where U is the intensity before, and U after, trans- 

 mission through the thickness /. 



Coefficient of transmission, a 



^_ \ 



Unitf=l dm .375/1 390/t .400/1 .434/1 .436a -455/t .477// .503// .580/1 .677// 



O 340, Ordinary light flint 388 .456 .614 .569 .680 .834 .880 .880 .878 .939 



O 102, Heavy silicate flint - .025 .463 .502 .566 .663 .700 .782 .828 .794 



O 93, Ordinary " " - - - - .714 .807 .899 .871 .903 .943 



O 203, " " crown 583 .583 .695 .667 .806 .822 .860 .872 .872 .903 



O 598, (Crown) — - - — .797 .770 .771 .776 .818 .860 



L'nitr=lcm 0.7// 0.95// 1.1/t 1.4/t 1.7/1 2.0/1 2.3/1 2.5/1 2.7/1 2.9/1 3.1/1 



S 204, Borate crown 1.00 .99 .94 .90 .85 .81 .69 .43 .29 .18 — 



S 179, Medium phosphate crown. - .98 .95 .90 .84 .67 .49 .87 .18 — — 



1143, Dense borosilicate crown.. .98 — .97 - .95 .93 .90 .84 .71 .47 .27 



1092, Crown 99 .96 .95 .99 .99 .91 .82 .71 .60 .48 .29 



1151, " 98 - .99 .99 .98 .94 .90 .79 .75 .45 .32 



O 451, Light flint 1.00 - .99 - .98 .95 .92 .84 .78 .54 .34 



O 469, Heavy " 1.00 — .98 — .99 .98 .98 .97 .90 .66 .50 



O 500, " " 1.00 — 1.00 — 1.00 — 1.00 .99 .92 .74 .53 



S 163, " " 1.00 — .98 - .99 - .99 — .94 .78 .60 



Part 2 



R is reflection factor yellow light for two surfaces. Values of transmission are for 1 mm 

 thickness. Ordinary figures refer to wavelengths in //, -281 to .775, black-faced infrared. 



U G 1 dark purple (uv„ extreme red). B G 1 blue (uv.. extreme red). B G 4 blue (ir.). B G 10, light blue 

 green, ir. absorption. V G 1 yellow-green. G G 2 colorless, uv. absorption. G G 4 almost colorless, strong uv. 

 absorption. G G 11 dark yellow for contract niters. R G 2 pure red. R G 5 dark red. N G 5 light neutral. 



OPTICAL CRYSTALS 



Not so many years ago physicists had to depend upon natural crystals for their various 

 optical instruments. Now, owing to a great deal of work in this field, it has been found 

 possible to grow artificial crystals of various materials for this purpose. Data on some of 

 these artificial crystals are given in the following tables and the spectral transmission of 

 some of them is shown in figure 26. 



SMITHSONIAN PHYSICAL TABLES 



