Question

How might you distinguish a sodium vapor street lamp from a mercury vapor steet lamp?


http://en.wikipedia.org/wiki/Sodium_lamp

http://en.wikipedia.org/wiki/Mercury-vapor_lamp

I think you would see colors better with the Mercury Vapor Light


You can distguish them by the color.
Low pressure sodium lamps (now seldom used for lighting) are bright yellow. High pressure sodium lamps are a warm pink-white (because the yellow sodium lines become broadened and Na2 forms).

Mercury vapor lamps are white with a bluish to violet tint.