Jan Baptist van Helmont (January 12, 1580 - December 30, 1644) was a Flemish chemist, physiologist, and physician. He is sometimes considered to be the founder of pneumatic chemistry as he was the first to understand that there are gases distinct in kind from atmospheric air. The very word "gas" he claimed as his own invention, and he perceived that his "gas sylvestre" (carbon dioxide) given off by burning charcoal, was the same as that produced by fermenting must, which sometimes renders the air of caves unbreathable.