n6 



INFRA-RED EMISSION SPECTRA. 



Yttrium Oxide (Y 2 3 ). 

 (Curves a and b, fig. 83; curves a, b, c, fig. 84.) 



The surface color in the two cases (fig. 83) was a deep and a bright 

 red, corresponding to a temperature of 900 to iooo . The two curves 

 are similar in appearance, showing emission maxima at 2, 2.76, 3, 3.6, 4.6, 

 and 6.9 ft, respectively, the latter band being unusually sharp. It will be 



70 



4 5 



Yttrium oxide. 



shown presently, in fig. 92, that this sharp band may be due to a suppres- 

 sion of the radiation at 6 fi, caused by a band of metallic reflection at this 

 point. However, bands of metallic reflection are not common at these 

 short wave-lengths, so that the maximum at 6.9 // may be a true emission 

 band. 



In fig. 84 are shown the emission curves of three additional samples of 



