When we had the dry ice a couple of weeks ago we found an experiment in a book which said to add water and washing up liquid. The water heats the dry ice causing it to sublime and turn directly from solid into carbon dioxide gas. The gas then blows bubbles in the washing up liquid. We even added food colouring for effect. I realise now that I missed a trick: I should have added a burning match and watched it go out because carbon dioxide is a fire extinguisher. We noticed an odd phenomenon in that the bubbles stopped after a while. The water got so cold in contact with the dry ice that it turned into familiar water ice right around the dry ice pellets. This stopped the carbon dioxide escaping and occasionally there were odd sounds as it forced its way out.
