3H 



Tables 328-330 



TABLE 328. — Percentage Emissivities of Metals and Oxides 

 Emissivity of black body taken as ioo 



True temperature C. 



Ref. 



60 FeO.40 Fe203 Total 



= Fe heated 



in air X = 0.65 fi 



NiO Total 



X = 0.65 n 



Platinum: 

 True temp. C. . . 

 App* temp. C. . 

 Total emiss. Pt. 



1000 



486 

 12.4 



1700 

 1005 

 17-5 



Tungsten: 



True temp. K (abs.) . 



X = 0.467 



X =0.665 



2200 



47.0 



43-3 



3800 

 39-5 



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



References: (1) Burgess and Foote, Bui. Bureau of Standards, 12, 83, 1915; (2) Burgess and Foote, loc. cit 

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



TABLE 329. — Emissivities, Metals (Black body — 1) 



(Worthing, Phys. Rev., 28, 174, 1926.) 



t"C 0.460/i 0.5351U 0.665m 



t°k. 



0.460^ o.535m 0.665m 



Gold 



Nickel 



Tantalum. 



20 0.635 °-35 2 0.062 



" 45 375 



" 48 



1275 



1 200- 1 650. 



1 400 



2 1 00 



2800 



0.632 0.448 0.140 

 •45 -425 -375 



442 



415 



390 



Platinum 



0.665 

 •463 



noo°K. 0.292 



1300 0.297 



1500 0.302 

 1500 .370 



1700 0.307 

 1700 .381 



1900 0.312 

 1900 .392 



Total radiation = C'T" watt/cm 2 , nichrome values poor. Suydam, Phys. Rev., 5, 497, 1915. 



Ag 6io°- 

 9 8o°K. 

 C 3.0 X 10- 1 

 n 4.1 



Pt 640 - 



H50°K. 



2.3 X io 15 



5-o 



Ni 463 - 



i28o°K. 



1.0 X 10-" 



4-65 



Fe 700 °- 



i300°K. 



3.2 X io 1 ' 



5-55 



Nichrome 325 - 



i3io°K. 



1.8 X io 12 



4.1 



Specific values are given in this paper for various temperatures of both radiator and 

 absorber. Also for electrical resistances. 



TABLE 330.— Total Radiation from Bare and Soot-Covered Nickel (Watts/cm 2 ) 



(Barnes, Phys. Rev., 34, 1026, 1929.) 



400 500 600 700 800 900 1000 1200 1400 



Soot-covered Ni 0.096 0.28 0.59 1.87 3 3 4.8 



Polished Ni initial heat 0092 .032 .079 .166 .31 .55 .91 2.17 4.49 



" " after above 0066 .023 .058 .123 .24 .44 .76 2.04 4.49 



Smithsonian Tables 



