324 foote: luminosity and temperature of metals 



The integral of equation (1) obtained graphically using the data 

 of Ives, Nutting, and Hyde and Forsythe for visibility was 

 found to have the following form. 



where, for c 2 = 14450 



B = - 105.92 

 C = + 265.46 

 D = + 72.166 



The luminosity of a non-black body, such as a metal, is defined 

 by equation (3) where A is the emissivity coefficient of the non- 

 black material. 



(3) U = j™ AVJdX 



The writer has shown 2 that for most metals the emissivity co- 

 efficient can be accurately represented by equation (4) where 

 A', p, and q, are constants, X the wave length in microns, d the 

 true absolute temperature. 



(4) A = A'ex ee 



If equation (4) is substituted in (3) one obtains the following: 



(5) L' = A'e 9 f CiX _5 e~x^/^F(x) d\ 



(6) Let J> = - d - p 



(7) then L' = A' tf \ c, X~ 5 e~ xT' V (X) d X 



The integral in equation (7) is identical with that of (1) hence 

 from (2): 



2 This Journal, 6: 317-323. 1910. 



