Sodium Alginate is the purified carbohydrate product extracted from brown seaweeds by the use of dilute alkali. It consists chiefly of the sodium salt of Alginic Acid, a polyuronic acid composed of -D-mannuronic acid residues linked so that the carboxyl group of each unit is free while the aldehyde group is shielded by a glycosidic linkage. It contains not less than 90.8 percent and not more than 106.0 percent of sodium alginate of average equivalent weight 222.00, calculated on the dried basis.