The "magnesia alba" (magnesium carbonate) was already commercialized in Rome about 1700; the term "magnesia alba" was used in contrast with "magnesia nigra", the black manganese oxide. In 1755, J. Black clearly distinguished magnesia from lime, showing that the first tend to form a soluble sulfate and the latter tend to produce an insoluble one. In 1808, Sir Humphrey Davy isolated the metal (not pure) and called it "magnium". At the time, the terms "magnesium" and "manganese" were used to denominate the manganese, obtained from the mineral pyrolusite (manganese dioxide) and the name magnesium to denominate the magnesia alba. To avoid confusions, the term "magnesium" is used refering to the existent element in the magnesia alba and "manganese" for the existent element in the pyrolusite.