309 



Tables 378-379. 



REFLECTION AND ABSORPTION OF LONG-WAVE RADIATIONS. 



TABLE 378. — Long-wave Absorption by Gases. 



Unless otherwise noted, gases were contained in a 20 cm long tube. Rubens, Wartenberg, Verb. d. Phys. Ges. 



* Tube 40 cm long. 



t Pentane vapor, pressure 36 cm. 



TABLE 379. — Properties with Wave-lengths 108 =*= /*. 



Rubens and Woods, Verb. d. Phys. Ges. 13, p. 88, rgii. 

 With quartz, 1.7 cm thick: 60 to 8o;U, absorption very great; 63;z, gg%; 82JU, 97.5; 97JU, 83. 



(a) Percentage Reflection. 



Wave-length, ^gp^"*^ Marble. 



X = 82M*. . 

 X = ioSm t- 



43.8 



Rock 

 salt. 



25. 8 

 20.3 



Syivite KBr 



36 o 

 19-3 



82.6 

 3I.I 



Kl 



29.6 

 35-5 



Fluo- 

 rite. 



19.7 

 20. 2 



Glass. Water. Alcohol 



9.6 

 II. 6 



1.6 



* Restrahlung from KBr. 



t Isolated with quartz lens. 



{b) Percentage Transparency. 

 Uncorrected for reflections. 



Solid. 



Paraffin 



Mica 



Hard rubber. . . 

 Quartz || axis . 

 Quartz, amorph 



Rock salt 



Fluorite 



Diamond. . . . . . 



Quartz J_ axis . 



Thickness. 



3 03 



0.055 



0.40 



2.00 



3.8s 



o. 21 



0.S9 



1.26 



4 03 



7.26 



11.74 



14.66 



Transparency. 



57-0 

 16.6 

 39 o 

 62.6 

 o 



21-5 



5-3 

 45-3 

 81.3 

 66.4 

 49.8 

 355 

 29.0 



Liquid. 



Benzene 



Ethyl alcohol 

 Ethyl ether . . 



Water , 



Water 



Vapors: 

 Alcohol . . . , 



Ether 



Benzene . . , 

 Water 



CO2 



Thickness. 



1.00 



0.158 



0.158 



0.029 



0.044 



Thickness 



precipi- 



table 



liquid. 



0.023 

 0.350 

 0.063 



Trans- 

 parency. 



S6.8 

 7.9 

 37.1 

 25.8 

 13.6 



33. 5 

 100 



19.6 

 100 



(c) Transparency of Black Absorbers. 



Method and wave-length. 



Spectrometer 



Fluorite "restrahlung" 

 Rock salt "restrahlung' 

 Quartz lens isolation 



2M 



4 

 6 



26 



S2 

 108 



Black silk 



paper, 



.025 mm thick 



0.9 



8.2 

 24. 2 

 46.0 

 <5t.5 



Opaque black 



paper, 

 o.ii mm thick 



1.4 



3-2 



151 

 33.5 



Black card- 

 board, 

 0.4 mm thick. 



1.6 



Candle lamp- 

 black, 

 10 cm2= 1.8 

 mg 



0.5 

 8.6 

 t6.o 

 37-6 

 76.7 

 91-3 

 91-5 



Smithsonian Tables. 



