Distilling starts with a board of bubbles arranged in vertically-staggered colums. As time elapses, the far right column will either rise into the rum, or fall into the furnace. Which direction it goes is determined by whether there are more light or dark pieces in the column. Dark pieces are heavy, brown pieces are neutral, and white or burnt white pieces are light. If the column has at least one more dark piece than light pieces, it will go down. If a column has an equal number of light and dark pieces, it will go up. This includes having no light or dark pieces at all in the column. (Watching a purely brown column go up can be quite a rude surprise and it isn't good for your score, either.)