Swelling Solution

The Swelling Solution makes whatever it touches swell in size, which is straightforward enough in a bottle and considerably less so when a cauldron of it goes over. Dried nettles and puffer-fish eyes are crushed together to a medium-fine powder and stirred into the cauldron with water, heated on a medium temperature for twenty minutes and left to brew; a bat spleen goes in afterwards, with four stirs anti-clockwise and half a minute on a low heat to finish. Hogwarts students brew it in Potions.