Sodium sulfite (sodium sulphite) is the inorganic compound with the chemical formula NaSO. Dissimilatory oxidation converts sulfite to elemental sulfur. These include thiosulfate, sulfite, or elemental sulfur, as well as fumarate. This lime then reacts with the sulfur dioxide produced forming calcium sulfite. The sulfite ion is the conjugate base of bisulfite. Antioxidants such as sulfite and ascorbic acid are sometimes used. Examples of reducing agents include the earth metals, formic acid, oxalic acid, and sulfite compounds. The refractive index of ammonium sulfite is 1.515. The kraft process is the dominant chemical pulping method, with the sulfite process second. The sulfur dioxide emissions of kraft-pulp mills are much lower than those from sulfite mills. For example, on reaction between potassium and sodium sulfite. The specific gravity of ammonium sulfite is 1.41. Berkeley's formula contained pyrogallol, sulfite, and citric acid. The hydroxymethanesulfinate ion is unstable in solution towards decomposition to formaldehyde and sulfite. Eukaryotic nitrate reductases are part of the sulfite oxidase family of molybdoenzymes.