74 



INFRA-RED EMISSION SPECTRA. 



in the region of 4.5 \x. The purity of this material may be judged from 

 the entire absence of the sodium lines; only the violet carbon bands were 



4 



Cm 



u 



c 



._ 2 



o 



/ 



<D 

 Q 



ATi 



2 3 4 



Fig. 50. Emission of carbon arc. 



CM 



visible. The lower curves are for a current of 7 amperes (120- volt cir- 

 cuit), while the two upper curves are for a current of 8 amperes, all of 



6mm 



z 4 



E 2 

 .5 3 



C 2 

 o 



. / 



<J 



2 



Q / 



- 1 * * 



. 



. ' 



2mm 



1 

 2mm 



I 



O 



I 



3 4 5 6JU 



Fig. 51. Emission of graphite arc (8 amperes). 



which were obtained under various conditions. On account of the diffi- 

 culty in maintaining a steady arc, no attempt was made to map a strong 

 emission band extending from 1.2 to 1.7 fx and a second band extending 



