Test method makes quantitative determination of calcium carbonate (CaCO3) content of soils. Test is a gasometric method that utilizes a simple portable apparatus. The test method is quickly performed on soils containing calcium carbonate. One gram of dried soil specimen is treated with hydrochloric acid (HCl) in an enclosed reactor vessel. HCl reacts with soil carbonates to produce carbon dioxide gas (CO2). CO2 Pressure is measured with a bourdon tube pressure gauge pre-calibrated with reagent grade calcium carbonate. Results show presence and quantity of calcium carbonate in marine soil samples. Calcium carbonates are water soluble cementing agents at a pH less than 7 (soft on the Mohs scale) compared to other soil minerals. Acrylic chamber is 2.5 inch ID x 5.5 inch (63.5 x 139.7) mm long and sealed with anodized end caps. Unit comes complete with 10 psi test gauge, bleed valve and 20 mL cup with handle.