Jan Baptist van Helmont was a chemist, physiologist, and physician from Brussels. He worked during the years just after Paracelsus and the rise of iatrochemistry, and is sometimes considered to be "the founder of pneumatic chemistry". Van Helmont is remembered today largely for his 5-year willow tree experiment, his introduction of the word "gas" into the vocabulary of science, and his ideas on spontaneous generation.
Portrait of van Helmont by Mary Beale
The Romanesque tower of the old church in Neder-Over-Heembeek and house where van Helmont performed an alchemical transmutation. Drawing by Leon Van Dievoet, 1963.
Posthumous portrait of van Helmont
Monument for Jan Baptist van Helmont in Brussels
In the history of science, pneumatic chemistry is an area of scientific research of the seventeenth, eighteenth, and early nineteenth centuries. Important goals of this work were the understanding of the physical properties of gases and how they relate to chemical reactions and, ultimately, the composition of matter. The rise of phlogiston theory, and its replacement by a new theory after the discovery of oxygen as a gaseous component of the Earth atmosphere and a chemical reagent participating in the combustion reactions, were addressed in the era of pneumatic chemistry.
Robert Boyle's air pump
The pneumatic trough, invented by Stephen Hales in the 1700s. This was the initial model, used for the collection of airs (gases) produced by combustion.