Jan Baptist van Helmont

Jan Baptist van Helmont (1580–1644) was a Flemish physician and chemist whose experiments on gases, plant growth, and chemical reactions helped shape early modern science.

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Pneumatic chemistry: The study of gases as distinct substances with measurable properties and roles in chemical reactions. Van Helmont’s investigations helped establish gases as subjects of chemical study.
Quantitative experiment: An investigation that uses numerical measurement to test or characterize a phenomenon. He weighed soil and a growing willow to support a claim about the source of plant mass.
Flemish science: Scientific work produced in the historical region of Flanders and its surrounding Low Countries. Van Helmont’s research emerged from the intellectual networks and institutions of this region.
Gas (word): The term for a state of matter, introduced into scientific usage by van Helmont. He coined the word from a form of the Greek word chaos to name substances such as spirit of wildness.
Alchemy: A historical body of practices and theories concerning the transformation of matter and the preparation of substances. His chemical work grew from alchemical traditions while introducing experimental approaches.
Carbon dioxide: A colorless gas with the formula CO₂, produced by respiration, combustion, and other processes. He identified the gas arising from burning charcoal and fermenting materials as a distinct substance.
Paracelsianism: A medical and natural-philosophical tradition inspired by Paracelsus, emphasizing chemical processes and remedies. He adopted chemical medicine while reshaping Paracelsian ideas through experiments.
Joseph Priestley: An English natural philosopher who isolated and studied several gases, including oxygen. His eighteenth-century gas experiments developed a field van Helmont had helped establish.
Combustion: A chemical reaction in which a substance reacts rapidly with an oxidant, usually releasing heat and light. His observations of burning helped him distinguish air from the gas produced by combustion.
Fermentation: A metabolic process in which microorganisms convert sugars into products such as acids, gases, or alcohol. His studies treated fermentation as a chemical transformation that produced an identifiable gas.