The law of Mass Conservation is a development of Lavoisier's experimental discovery that, when all substances were properly accounted for—specifically gasses, during the process of combustion—the total weight of a closed system is not changed by a chemical reaction. | The law of Mass Conservation is a development of Lavoisier's experimental discovery that, when all substances were properly accounted for—specifically gasses, during the process of combustion—the total weight of a closed system is not changed by a chemical reaction. |