126 



INFRA-RED EMISSION SPECTRA. 



The voltage was obtained with a multiple-cell electrostatic voltmeter. The 

 curves for the intensest part of the spectrum pass through a double cur- 

 vature and have the general outline of that of platinum. The normal 

 burning is 80 watts and above that point the isochromatics appear to 



cm 

 1500 



1400 



10 20 30 40 50 60 70 80 90 100 Watts 



Fig. 95. Isochromatic radiation curves of Nernst glower. 



show a slight increase in curvature. The intersection of the graphs for 

 wave-lengths X= 1.206 [i and k = 1.633 P- at 73 watts 1 shows that the maxi- 

 mum of the spectral energy curve for this power consumption lies between 



1 None of the isochromatics, given in this paper, have been corrected for slit-width, 

 which would change the observed energy consumption a few per cent. 



