Incandescent light bulb granted a Hungarian patent (No. 34541) for a tungsten filament lamp that lasted longer and gave brighter light than the carbon filament. Tungsten filament lamps were first marketed by the Hungarian company Tungsram in 1904. This type is often called Tungsram-bulbs in many European countries. Filling a bulb with an inert gas such as argon or nitrogen slows down the evaporation of the tungsten filament compared to operating it in a vacuum. This allows for greater temperatures and therefore greater efficacy with less reduction in filament life. In 1906, William D. Coolidge developed a method of making "ductile tungsten" from
Phase-out of incandescent light bulbs special purpose bulbs including those used in devices such as household appliances, traffic lights, infrared lamps and automotive lighting. The sale of the most inefficient bulbs was phased out. The first types to go were non-clear (frosted) bulbs, which were taken off the market in September 2009. Also from September 2009 clear bulbs over 100 W were made of more efficient types. This limit was moved down to lower wattages, and the efficiency levels raised by the end of 2012. In practice, some manufacturers and retailers have found a loophole in the new rules so that some incandescents are still