Sodium silicate is a generic name for chemical compounds with the formula Na ₂ₓSi yO ₂y₊ₓ or ₓ· y, such as sodium metasilicate Na ₂SiO ₃, sodium orthosilicate Na ₄SiO ₄, and sodium pyrosilicate Na ₆Si ₂O ₇. The anions are often polymeric. Wikipedia