99 



TABLE 78.— NORMAL SPECTRAL EMISSIVITIES FOR SOME ELEMENTS 

 AND ALLOYS (concluded) 



Part 3. — Emissivities of tungsten™ 1 



For X = 1.27/i the spectral emissivity is constant and equals 0.335. 



Part 4. — Emissivities of some metals specially prepared by heat-treating and 



out-gassing " 



Element 

 Chromium . 

 Cobalt 



I ron a 



7 



5 



Molybdenum 



Nickel 



Niobium . . 



X in ii 

 .66 



Emis- 

 sivity 



.334 

 .327 

 .342 

 .344 

 .325 

 .337 

 .382 

 .350 

 .374 



Tempera- 

 ture 

 °K 



1050-1560 



1240-1378 

 1378-1450 

 below 1178 

 1178-1677 

 1677-1725 

 1300-2100 

 1200-1400 

 1300-2200 



Element 

 Palladium 



Platinum 



Rhodium 



Tantalum 



Thorium 



Tungsten 



Uranium 



X in /x 



.6605 



37 Private communication from Wahlin, taken from data by W'ahlin and Knop, L. V. Whitney, Wahlin 

 and Wright, Worthing, Fiske, Phys. Rev. 



TABLE 79.— CORRECTIONS IN °C TO ADD TO BRIGHTNESS TEMPERATURE 



READINGS, FOR DIFFERENT EMISSIVITY, TO OBTAIN THE 



TRUE TEMPERATURE* 



(continued) 



SMITHSONIAN PHYSICAL TABLES 



