Born at Brussels, 1577; died near Vilvorde, 30 December, 1644. This scientist, distinguished in the early annals of chemistry, belonged to a good Flemish family. He was brought up by his uncle, and studied humanities at Louvain, but refused to take his degree of Master of Arts, on the theory that it was a source of pride. The Jesuit order attracted him, but he did not enter it. He investigated the Stoic school of philosophy, and, to practice the evangelical counsel of poverty, he conveyed all his property to his sister. Urged on by a desire to relieve human suffering, he began to study medicine. He was appointed to the chair of surgery at Louvain. The course of his studies was interfered with by a sickness, scabies, which affected him. The Galenists treated him with purgatives, not recognizing that it was a parasitical disease. This disgusted him with the Galenists; and he began his travels through England, France, Switzerland, and Italy, for the purpose of investigating the practice of medicine in these different countries. Eventually he was healed by an Italian charlatan, who used sulphur and mercury. He practised as a physician and, instead of using plants, prepared his medicines in the laboratory of the day, in which the furnace, crucible, and retort were most largely employed; this made him known as the medicus per ignem. He departed somewhat from the counsel of poverty by marrying Margaret van Ranst, an heiress of Brabant, and settled down at Vilvorde. He had now acquired a wide reputation in medicine, and had received his doctor's degree at Louvain as early as 1599. Yet he failed in the treatment of his own family; and, in spite of his remedies, death carried off one of its members when attacked by scabies, the very disease of which he had been cured. His celebrity was now very great, and it is said that he was suspected of diabolism. A fantastic element appears in his work, largely due to the age in which he lived; but his scientific work is of a high order of merit. He investigated gases, notably carbon dioxide, which he discovered in various sources, and it was he who first applied the name gas (geist) to this family of substances. He applied the balance in his investigations. He discovered sulphuretted hydrogen in the human system, made hydrochloric gas, which he called gas of salt, explained the explosion of gun-powder on the theory of the expansion of gases, discovered or investigated sulphuric acid, nitric acid, and nitrogen oxide. He was one of the first to recognize the rôle played by acid in the gastric juice, attributing disease to an excess of the same. Like all other chemists of the time, he studied the transmutation of metals, naming his son Mercury, believing that he had succeeded in getting gold from mercury. His various books were published from 1622 to 1652. In 1648 a collection of his works was published posthumously under the auspices of his son.

POULTIER D' HELMOTH, Mémoires sur van Helmont et ses érits (Brussels, 1847); ROMMELAERE, Etudes sur Helmont (Brussels, 1868).

T. O'CONOR SLOANE