Crystallization of sulphur, time-lapse footage. Sulphur is insoluble in water, but can be dissolved in various non-polar solvents. The solvent used here is toluene, and the crystallization occurs at 55 degrees Celsius. Sulphur is a reactive chemical element that is a yellow solid at room temperature. It is mainly used in the production of sulphuric acid for the chemical industry. It is deposited in its solid form around volcanic vents.