Dichloromethane (DCM or methylene chloride) is an organochloride compound with the formula CH2Cl2. This colourless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible with water, it is polar, and miscible with many organic solvents.
The chemical compound’s low boiling point allows the chemical to function in a heat engine that can extract mechanical energy from small temperature differences. An example of a DCM heat engine is the drinking bird. The toy works at room temperature. It is also used as the fluid in Christmas bubble lights that have a coloured bubbling tube above a lamp as a source of heat and a small amount of rock salt to provide thermal mass and a nucleation site for the phase changing solvent.