Welcome to the Museum of Historic Discharge Lamps
Since Sir Humphry Davy demonstrated the first electric arc at the Royal Institution of Great Britain in 1802, electric discharge light sources have been intensely researched for one fundamental reason - that they create light from electricity more efficiently than any other kind of artificial light source.
Over time it was learned that the carbon arc discharge could be made still more efficient by arranging that it took place inside a rare gas instead of through the air. This led to the creation of gas discharge lamps which nearly always make use of the noble gases neon, argon, krypton or xenon. Carbon dioxide was also of considerable interest owing to its white light output.
The next great leap forward was made with the introduction of the metal vapour lamp, achieved by adding various metals to the discharge tube. The heat of the gas discharge serves to vaporise some of the metal, and the discharge is then carried almost exclusively by the metal vapour. Sodium and mercury are generally employed on account of their high vapour pressures and increased emission in the visible spectrum.