4/6. Ionic Liquids. Twenty-five years ago, ionic liquids were just being talked about. Now these liquids are providing chemists with a green alternative to solvents used in chemical processes. They are molten salts - a mixture of positive and negatively charged molecules that are liquid at low temperature. There are up to a billion different combinations and the possibilities for their use are endless. Peter Evans finds out how they work and how they can make a greener future for the Chemical industry. Producer Helen Sharp