VISIBLE AND NEAR-VISIBLE RADIATION 



165 



5 6 



Ultraviolet Violet Green Yellow Red 



Fig. 13. — Filters recommended by R. W. Wood. (Wood, 68.) 1. Cobalt chloride in 

 alcohol. 2. Potassium film (see his paper on Optical Properties of Metals). 3. Praseodym- 

 ium chloride. 4. Neodymium chloride. 5. Uranine (Na salt of fluorescein). 6. Cupram- 

 monium. 7. Cobalt glass. 8. Corning signal red glass. 9. Corning G34 glass. 10. 

 Corning sextant green. 11. Signal green glass. 12. Sodium nitrate (saturated solution 

 2 cm.). 13. Corning glass 984B. 14. 985B. 15. G986A. 16. Cyanosine. 17. Potas- 

 sium chromate. 18. Copper nitrate. 19. Corning glass G586J. 20. Cobalt chloride in 

 acetone. 21. Cobalt sulphate in water. 22. Nickel chloride. 23. Iodine in CCI4. 

 24. Nitrosodimethylaniline in water. 25. Bromine vapor. 26. Chlorine. 



