250 



Tables 279-281. 



RADIATION EMISSIVITIES. 



TABLE 279. — Relative Emissivities of Metals and Oxides. 



Emissivity of black body taken as loo. 



True temperature C. 



60 FeO.40 FesOa Total 



= Fe heated 



in air X = 0.65 n 



NiO Total 



X = 0.65 IX 



8S 



8S 



62 



800° 



87 



Ref. 



Platinum: 

 True temp. C. . , 

 App.* temp. C. . 

 Total emiss. Pt. 



1000 



4S6 

 12.4 



Tungsten: 



True temp. K (abs.) . 

 X = 0.467 



X = 0.66s 



2200 

 47 -o 

 43-3 



* As observed with total radiation pyrometer sighted on the platinum. 



References: (i) Burgess and Foote, Bui. Bureau of Standards, 12, 83, 1915; (2) Burgess and Foote, loc. cit 

 II, 41, 1914; (3) Foote, loc. cit. 11, 607, 1914; (4) Worthing, Phys. Rev. 10, 377, 1917. 



TABLE 280. — Temperature Scale for Tungsten. 



Hyde, Cady, Forsythe, J. Franklin Inst. 181, 418, 1916. See also Phys. Rev. 10, 395, 1917. The color temperature 

 temperature of black body at which its color matches the given radiation. 



TABLE 281. — Color minus Brightness Temperatures for Carbon. 



Hyde, Cady, Forsythe, Phys. Rev. 10, 395, 1917. 



Brightness temp. ° K. 

 Color — brightness 



1700 



7 



1800° 



1900 

 16 



2100 

 28 



2200 

 33 



Smmhsonian Tables. 



