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 those over 15 watts on 1 October 2016. Another source, however, has indicated that by 1 October 2016, all incandescent light bulbs will be banned. According to this source, 1 November 2011 to 30 September 2012 will be a transitional period and as of 1 October 2012, imports and sales of ordinary incandescent bulbs of 100 watts or more will be prohibited. The first phase will be followed by a ban on 60-watt-and-higher incandescent light bulbs starting in October 2014. By October 2016, all incandescent light bulbs will be banned in China. The final phase may be adjusted according to