Helmont, Jan Baptista van (yän bäptĭs`tä vän hĕl`mônt), 1577–1644, Flemish physician, chemist, and physicist. He attributed physiological changes to chemical causes, but his conclusions were colored by his speculative mysticism. He discovered carbon dioxide, distinguished gases as a class of substances (as contrasted with solids and liquids), and is credited with introducing the term gas in its present scientific sense. His chief work is Ortus medicinae (1648).

Helmont, Jan Baptista van

(born Jan. 12, 1580, Brussels, Belg.—died Dec. 30, 1644, Vilvoorde, Spanish Netherlands) Belgian chemist, physiologist, and physician. Though he tended to mysticism, he was a careful observer and exact experimenter. The first to recognize gases other than air, he coined the word gas and discovered that the “wild spirits” (carbon dioxide) produced by burning charcoal and by fermenting grape juice were the same. For applying chemical principles to digestion and nutrition, he has been called the “father of biochemistry.” His collected works were published in 1648.