Sodium silicate is a common name for chemical compounds represented by the general formula Na2 (SiO2) nO. The best known member of this series is sodium metasilicate, Na2SiO3. These materials, also known as water glass or liquid glass, can be used in aqueous solution or in a solid. Pure compositions are colorless or white in color, but commercial examples are usually greenish or blue because of the presence of iron-containing foreign materials.