Id est, initia physicæ inaudita. Progressus medicinæ novus, in morborum ultionem, ad vitam longam. Lyon: Jean Baptiste Devenet, 1655. Fourth collected edition, edited and published posthumously by Helmont's son, Franciscus Mercurius van Helmont. Approximately 13.5 x 8.25 inches. Quarto. , 487, [1, blank], 192, [57, indices], [1, Approbationes] pages. With engraved title-page. Contemporary full mottled calf, rebacked in brown calf, six raised bands. Binding worn, first several leaves a bit tattered, upper corner of page 145 in the second part is missing (not affecting text), a few ink notes and blots throughout. Overall, a good copy. Helmont (1577-1644) "devoted his life to exploring the first principles of nature through chemistry. He is best remembered as the discoverer of gas [derived from the Greek 'chaos'], a term he coined to described the 'specific smokes' that remain after the combustion of solids and fluids; among the gases he identified were carbon dioxide, carbon monoxide, chlorine gas and sulphur dioxide" (Norman Library). Ortus medicinæ "is our chief source for the discoveries of Helmont with regard to the chemical nature of living processes" (Printing and the Mind of Man). Opuscula medica inaudita (the second part of this book), originally published as a separate work in 1644, contains reprints of Helmont's treatises on the stone, on fevers, on the errors of humoral pathology, and on the plague. Garrison and Morton 665. Norman Library 1048. Printing and the Mind of Man 135. Waller 4307 and 4306. Willems 1066 and 1067. Estimate: $600 - up. Included in Heritage Auctions’ Rare Books Auction #6064, February 8-9, 2012, in Beverly Hills.