Who coined the term "gas"?

Jan Baptist van Helmont (1580–1644) was a Flemish chemist, physiologist, and physician. He worked during the years just after Paracelsus and the rise of iatrochemistry, and is sometimes considered to be "the founder of pneumatic chemistry". Van Helmont is remembered today largely for his ideas on spontaneous generation, his 5-year tree experiment, and his introduction of the word "gas" (from the Greek word chaos) into the vocabulary of science.