How to remove the bottom of a bottle (Part 2)…. without breaking the rest of the bottle. This one takes some practice to get right, but the end result is pretty cool. By just using your hand, and some water, you can make the bottom of a beer bottle blow out, in a perfect circle without breaking the rest of the bottle.
Take the empty beer bottle and fill it with water until the water is halfway up the neck of the bottle. Place your hand around the neck of the bottle, so that your hand is flush to the top. So your hand and the bottle are almost flat at the top. With your other hand OPEN, smack the top of the bottle/hand combination. You need to do it pretty hard. DO NOT do this step over anything important, go find a nice grassy spot. If done correctly, the bottom of the bottle will fall to the ground without breaking the rest of the bottle. When you smack the bottle, leave your hand on top. Immediately lifting your hand will do nothing and just result in a bruised hand. By smacking the bottle, the glass moves down slightly. The water in the bottle moves up closer to the top and creates a vacuum at the bottom of the bottle. This water moves back down fast enough to break the bottom off. Therefore you must keep your hand on top long enough to let the air compress. Luckily that is not very long, because the whole reaction takes place very fast. Do not do this over anything that you may not want to get wet, because it will most definitely get wet, really wet. Be careful hitting the bottle multiple times. When it finally breaks, it could shatter all the way up to the hand holding the bottle and potentially cut your hand. Once the bottom is removed you could sand down the bottom edges to make them smooth!
To see a video of this being done go here: http://www.tvlesson.com/video/4500_party-trick-how-to-remove-the-bottom-of-a-bottle.html