Wiktionary
n. (context US English) (alternative spelling of mercury-vapour lamp English)
WordNet
n. ultraviolet lamp that emits a strong bluish light (rich in ultraviolet radiation) as electric current passes through mercury vapor
Wikipedia
A mercury-vapor lamp is a gas discharge lamp that uses an electric arc through vaporized mercury to produce light. The arc discharge is generally confined to a small fused quartz arc tube mounted within a larger borosilicate glass bulb. The outer bulb may be clear or coated with a phosphor; in either case, the outer bulb provides thermal insulation, protection from the ultraviolet radiation the light produces, and a convenient mounting for the fused quartz arc tube.
Mercury vapor lamps are more energy efficient than incandescent and most fluorescent lights, with luminous efficacies of 35 to 65 lumens/watt. Their other advantages are a long bulb lifetime in the range of 24,000 hours and a high intensity, clear white light output. For these reasons, they are used for large area overhead lighting, such as in factories, warehouses, and sports arenas as well as for streetlights. Clear mercury lamps produce white light with a bluish-green tint due to mercury's combination of spectral lines. This is not flattering to human skin color, so such lamps are typically not used in retail stores. "Color corrected" mercury bulbs overcome this problem with a phosphor on the inside of the outer bulb that emits white light. They offer better color rendition than the more efficient high or low-pressure sodium vapor lamps.
They operate at an internal pressure of around one atmosphere and require special fixtures, as well as an electrical ballast. They also require a warm-up period of 4 – 7 minutes to reach full light output. Mercury vapor lamps are becoming obsolete due to the higher efficiency and better color balance of metal halide lamps.
Usage examples of "mercury-vapor lamp".
The mass of tangled wires, the current leads, the mercury-vapor lamp up above meant nothing to it.
As soon as the RUM is submerged in the outer ocean I'll switch on the mercury-vapor lamp and we'll track by TV screen.
They put their heads down and scurried past the front of the diner, around the side, through the purple light under the single mercury-vapor lamp, and into the deep shadows behind the building.
He did not know if the world of 1960 they had entered when the arc-sodium light became a mercury-vapor lamp had been real or an illusion, but he knew it was gone.
The mercury-vapor lamp was reflected as a rich blue pool from the bodywork of metallic silver, a German hallmark which Japanese automakers attempted to match with less success than they showed in matters of pure mechanics.
A mercury-vapor lamp on a high pole flooded the entire yard, but Verona had run all the way down the lane without a flashlight.