Jean Baptiste Van, a celebrated chemical inquirer, was born at Brussels in 1577. He was educated at Louvain, and began the study of natural science under the Jesuits in that city. Their hard and dry philosophy, however, had few attractions for a nature so ardent and imaginative as his. Turning for relief to other systems, he found no rest except in the mysticism of a Kempis and Tauler. From them he learned that wisdom is the gift of the Supreme Being; that it must be obtained by prayer; and that we must renounce our own will if we wish to participate in the influence of the divine grace. From this time he began a life of exemplary meekness and humility, made over his property to his sister, and retired from the high society in which he had hitherto walked. He sought relief in the study of medicine; pored over Galen and the Greeks; mastered them, and finding their inadequacy, abandoned them forever. He then turned to Paracelsus and the alchemists, and conferred a real boon on humanity by rescuing chemical science from the erratic absurdities of the post-Paracelsian alchemists, and applying to it the principles of the newly-discovered induction. He graduated as M.D. in 1599; and, after travelling through France and Italy, married a rich lady of Brabant, by whom he had several children. He died in Holland in 1644 in the sixty-seventh year of his age. Science is under real obligations to Van Helmont, though at one period of his life he was a sworn alchemist, and revived the old doctrine of Thales, that the material particles of the universe consist essentially of nothing but water. To him is due the invention, or at least the first application, of the term gas in the sense in which it is now used. He also discovered that gas was disengaged in abundance by the application of heat to various bodies, and during the solution of various carbonates and metals in acids. His theory of the formation of urinary calculi is also nearly correct.

The personal character of Van Helmont, as given by his biographer Lobkowitz, is interesting—"He was pious, learned, famous, a sworn enemy of Galen and Aristotle. The sick never languished long under his hands, being always killed or cured in three days." His works were published at Amsterdam in 1648 by his son Mercurius, who aspired to rival his father, and is described on his tombstone as being nil patre inferior. The best edition of these is that of Elzevir, 1652.