Meyer & Wood. 



Phil. Mag. Ser. 6, Vol. 30, PL VI. 



Fig. 1. — Commercial 

 nitrogen. 



Fig. 2. — Purified nitrogen. 

 First type of spectrum. 



Fig. 3. — Purified nitrogen. 

 Second type of spectrum. 



Fig. 4. — Purified nitrogen. 

 Jet-chamber open. 



Fig. 5.— Stream of dried air 



Source of moisture in 



jet-chamber. 



Fig. 6. — Iodine vapour 

 in nitrogen. 



Fig. 7. — Iodine vapour in nitrogen by Lit I row 

 spectrograph, with iron comparison spectrum. 



Fig. 8.- Transmission 



through tluorite. 



Fig. '.». -Refraction by 

 quartz prism. 



