Minecraft wiki entry for Tips_and_tricks, associated text: For this trick, the player should hold a torch, and use it to break the bottom-most block if a stack then immediately place a torch on the floor of the newly empty space. The column should collapse into a scattering of items. If you placed the torch too fast, the sand, etc. might not have time to start falling, and the torch will just hold them up -- in this case just break the next block above the torch as well.