To increase the life of the bulb argon gas is used along with tungsten wire in an electric bulb. Argon gas is used in fluorescent and incandescent light bulbs to stop the oxygen in the light bulbs from corroding the hot tungsten filament. The use of argon in light bulbs prevents the evaporation of the tungsten filaments, which results in increased light bulb life. The bulb can't be filled with air because the presence of oxygen will cause the filament to burn, i.e. react with oxygen. The glass chamber can't be made vacuum as in vacuum condition, the filament will evaporate because of very high temperature, making bulb unstable. Pure tungsten has the highest melting point (3695 K), lowest vapour pressure, and greatest tensile strength out of all the metals. Because of these properties it is the most commonly used material for light bulb filaments. Argon is a non-metal gas at room temperature and is assigned the number 18 on the period table of elements.