SHEILA TERRY / SCIENCE PHOTO LIBRARY SHEILA TERRY / SCIENCE PHOTO LIBRARY
Jean Baptiste van Helmont (1579-1644), Belgian doctor and chemist. Van Helmont's work was part of the transition from alchemy to experimental chemistry. He invented the word "gas" (from Greek chaos). He identified carbon dioxide and monoxide, nitrous oxide, and methane. He was the first to use the boiling and freezing points of water as standards for temperature. In medicine, he used remedies specific to the disease, the affected organ, and the causative agent. He showed that acid is the digestive agent in the stomach. He realised that matter is indestructible and that metals dissolved in acid can be recovered.
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