Sodium vapor lamp
A sodium vapor lamp is a kind of gas discharge lamp. It produces a yellow or orange light. There are two types; the high pressure lamp and the low pressure lamp. The high pressure one is very energy-efficient and is the orange light in streetlights. The low pressure one is yellow. These lights contain sodium metal in them. They operate by a spark through a tube that contains the sodium. The sodium emits a yellow color, which produces the light. Because the lamp contains highly flammable sodium as well as toxic mercury, it should not be placed in the trash and must be disposed of properly at the end of its life.