If your hair is brown, purple probably isn't going to show up very well. It's best to bleach your hair before dying it an unnatural color. Like I told you before, the box says 30-40 minutes, but the most I'd leave it on for is an hour. And that's at your own judgment, too.
But China's population statistics can be particularly misleading. Virtually overnight, Chongqing has become the largest city not only in China, but in the world, Time Magazine proclaimed in 2005. But it wasn't true-Chongqing is not the largest city in the world, or even in China.
As has been the case for nearly six decades, Tokyo remains the largest urban area in the world, with approximately 37 million. New York, which Tokyo displaced in 1955, has fallen to seventh largest and has the lowest population density of any megacity, at 4600 per square mile or 1800 per square kilometer (Note 2). London, which New York displaced in the 1920s never became a megacity due to the imposition of its greenbelt.