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Neder-Over-Heembeek is a northern part of the City of Brussels municipality in Belgium. It is a municipality which lost its municipality status when it was merged with the City of Brussels. Now it is a section of that municipality, and a predominantly industrial zone, remarkable principally for the Military Hospital, which is the National Burns and Poisons center.
It was once a small village, just named Heembeek on the edge of medieval Brussels, and was founded around a small church that became the center of a parish.
Later a second church was built around a growing hamlet, and the two parishes were separated, that became two villages: Neder-Heembeek ("Lower Heembeek"), and Over-Heembeek ("Upper Heembeek").
Finally the two parishes were merged when the first municipality appeared, but instead of taking back the older name Heembeek, the two adjectives were kept to preserve the identity of the two parishes.
Today, now as a part of in the City of Bruxelles, Heembeek is frequently used to name various civil and commercial services located in that area (such as transportation stops, or a school), ignoring the historic distinction of parishes.
Jan van Helmont and alchemy 
In 1618 or thereabouts, a most curious incident changed the course of scientific history here. In a farm near the church lived the local medic, one Jan van Helmont, a follower of the teachings of Paracelsus. His son Mercurius, a close friend, tutor and collaborator of Leibniz, records that one evening, a stranger knocked at the door and was admitted. The two men talked late into the night about alchemy, and on leaving, the stranger left van Helmont with some unusual powder: he immediately mixed it with eight ounces of mercury, sealed in a clay crucible which was heated over the fire for twenty minutes, and broke the pot - to find eight ounces of gold. There are some suggestions that this visitor may have been a researcher who had had a significant hand in events leading up to the execution of the Counts of Egmont and Hoorne for heresy in 1568. This opened van Helmont's eyes to the possibility of scientific process, and he went on to become one of the founding fathers of modern chemistry.
In 1843, the same farm became the residence of Count Gioacchino Pecci, the Papal Nuncio, who showed a more than passing interest in searching the place from top to bottom. Count Pecci became Pope Leo XIII in 1878.
See also 
- Alchemy Tried in the Fire: Starkey, Boyle, and the Fate of Helmontian Chymistry, Newman and Principe ISBN 978-0-226-57702-9