Sec. 184.1191 Calcium carbonate. (a) Calcium carbonate (CaCO3, CAS Reg. No. 471-34-1) is prepared by three common methods of manufacture: (1) As a byproduct in the "Lime soda process"; (2) By precipitation of calcium carbonate from calcium hydroxide in the "Carbonation process"; or (3) By precipitation of calcium carbonate from calcium …