Molecular sieve is a material containing precise and single tiny holes that can be used to adsorb gases or liquids. Molecules that are small enough can be adsorbed through the orifice, while larger molecules cannot. Unlike a normal sieve, it operates at the molecular level. For example, a water molecule is small enough to pass through a molecule that is a little larger than it is. Therefore, molecular sieves are often used as desiccant. A molecular sieve absorbs water up to 22% of its own weight. Molecular sieves are often used in the oil industry, especially to purify gases. For example, silicone can be used to adsorb the corrosion of mercury in natural gas to aluminum pipes and other liquefaction equipment.