Percolation involves having a solvent go through a permeable substance, with the idea that filtering will occur during the process. This idea is in play during processes as diverse as film development, petroleum movement and coffee making.
The percolator consists of a few different parts. At the bottom, there is a heat source usually plugged into a wall outlet. The pot which goes on top of this heat source has multiple chambers in it. At the bottom of the pot, closest to the heat, there's a small chamber for water with a tube sticking out of it that extend to the top of the pot. Just below the top of the tube, the coffee grounds are placed on top of a grate.
How Does It Work?
The water is poured into the water chamber and the coffee grounds are loaded up top and the heat is turned on. The heated water boils and rises through the tube into the upper chamber with the grounds. This water builds up in the top and the pressure rises as more and more is pumped through the tube. When the pressure gets high enough, the water is then pushed back down and seeps through the coffee grounds, where it is infused with the coffee. This newly cooled down water will then be heated at the bottom and this process is then repeated again and again until the desired flavor intensity is achieved. Some percolators are automatic and turn off before the coffee is ruined, but manual ones must be checked to be sure.