COBALT GLASS. 



103 



emission spectrum is conspicuous for two regions of strong emissivity at 

 1.6 and 5 n, respectively, with a deep depression at 3.5 pt. The emission 

 bands at 1.6, 2.7, 5, 5.5, and 7.1 /1 are not well resolved, but their presence 

 can not be doubted. 



2 3 4 5 6 



Fig. 70. Glass (a); Magnesia. 



9/1 



Glass (Cobalt Blue). 

 (Rod 12 by 2 mm. Energy supplied, 5.4 and 7.5 watts. Curves a and b, fig. 71.) 



This rod was heated to a dull red. The emission spectrum is quite 

 different from that of soft glass, but there are not such prominent bands 



>6 



14 



12 



10 



X 



OJ o 



2 3 4-5 



Fig. 71. Cobalt glass. 



&JM 



