Humans have always known about certain elemental substances, such as gold and broken silver, that occur in nature and cannot be broken down into other substances. Other chemical elements were discovered gradually beginning in 1669, when a German merchant, Hennig Brand, accidentally found phosphorus while attempting to find a way to create gold out of more common metals. By 1809, the number of known elements had increased to 47. Chemists studying the elements began to notice patterns in the way chemicals reacted.