Harnessing electricity for light had been an ambition over a century ago. Edison had caught that rush for incandescent bulbs. A lasting incandescent bulb must have a filament that won't be burnt quickly and thus bear a long life. To have this, the filament has to be protected from chemical reactions that damage its property. At that time, vacuum is the choice. Edison first figured out the way to pump air and then looked for the desired filament and eventually found one, the bamboo ! Interestingly, it is also the same bamboo under the same arc that led Ijishima to his carbon nanotubes !
[http://www.wired.com/thisdayintech/2009/10/1021edison-light-bulb/]
Edison’s lab put a lot of effort into making a bulb with a platinum filament, but that work went nowhere, because platinum has a relatively low resistance. But gas bubbles in the platinum had led Edison to develop an efficient vacuum pump to remove the air from the inside of his bulbs. And that created a new opportunity: carbon. Carbon conducts electricity, has a high resistance and can be shaped into thin filaments. And it’s cheap. But it burns easily — unless there’s no oxygen around. The vacuum bulbs Edison had created for platinum were ideal for carbon.
Edison pushed hard on his research assistants, whom he more or less affectionately called “muckers.” After testing hundreds of materials, they baked a piece of coiled cotton thread until it was all carbon. Inside a near-vacuum bulb, it stayed alight for more than half a day. The “three or four month” project had taken 14 months.
Soon, the lab got a carbon-filament bulb to last 40 hours. It had cost $40,000 (about $850,000 in today’s money) and taken 1,200 experiments, but was ready at last for a public debut.
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