Calcimeter

The calcium carbonate and magnesium carbonate are reacted with 10 percent Hydrochloric Acid to form CO2. This is done in a sealed reaction cell and the pressure build up due to the CO2 is measured using either a pressure gauge or a pressure recorder. The use of a Calibration Curve, Fig. 4, determined through the use of pure Calcium Carbonate reagent allows the pressure developed to be related to the weight of calcium carbonate in the calibration sample. Several weights of sample are suggested to assure an accurate curve. These tests can be conducted using either the pressure gauge or recorder with the reaction cell. The sample can be weighed on a portable balance (10 mg Precision or better). Refer to Section 5 for calibration procedure. The calcium carbonate content of the sample is determined by treating a 1 gm dried sample with hydrochloric acid (HCl) in an enclosed reactor vessel. Carbon dioxide gas is evolved during the reaction between the acid and carbonate fraction of the specimen. The resulting pressure generated in the closed reactor is directly proportional to the carbonate content of the specimen. This pressure is measured with a bourdon tube pressure gauge that can be pre-calibrated with reagent grade calcium carbonate. Refer to Section 5 for calibration procedure.