Belgian doctor who was the first to realize that there are gases other than air, and claimed to have coined the word 'gas' (from Greek cháos).
Helmont identified four gases: carbon dioxide, carbon monoxide, nitrous oxide, and methane. He was the first to take the melting point of ice and the boiling point of water as standards for temperature and the first to use the term 'saturation' to signify the combination of an acid and a base. In medicine, Helmont used remedies that specifically considered the type of disease, the organ affected and the causative agent. He demonstrated acid as the digestive agent in the stomach.
Helmont was born in Brussels, studied at Louvain, and 1600-05 travelled to Spain, Italy, France, and England. From 1621 to 1642 he was persecuted by the Roman Catholic Church for his views on the cure of wounds by applying ointment to the weapon rather than the wound, which was then common. Although he did not reject the belief, he insisted that it was a natural phenomenon with no supernatural element, as set out in his treatise De magnetica vulnerum ... curatione 1621.
Taking care to weigh the materials he used in chemistry, Helmont gained insight into the indestructibility of matter and the fact that metals dissolved in acid were recoverable, not destroyed or transmuted. He believed that all matter was composed of water and air, which he demonstrated by growing a willow tree in a measured quantity of earth, adding only water.
His works were collectively published posthumously as Ortus medicinae 1648.