in Vienna, where in 1775 he married Agatha Maria Jacquin. Work with photosynthesis In the 1770s Ingenhousz became interested in gaseous exchanges of plants. He did this after meeting the scientist Joseph Priestley (1733–1804) at his house in Birstall, West Yorkshire, on 23 May 1771. Priestley had found out that plants make and absorb gases. Ingenhousz' travelling party in northern England included Benjamin Franklin. They then stayed at the rectory in Thornhill, West Yorkshire with the polymath and botanist Rev. John Michell. In 1779, Ingenhousz discovered that, in the presence of light, plants give off bubbles from their green parts while, in the shade, the bubbles eventually stop. He identified the gas as oxygen. He also discovered that, in the dark, plants give off carbon dioxide. He realised as well that the amount of oxygen given off in the light is more than the amount of carbon dioxide given off in the dark. This demonstrated that some of the mass of plants comes from the air, and not only the water and nutrients in the soil. Other work In addition to his work in the Netherlands and Vienna, Ingenhousz spent time in France, England, Scotland, and Switzerland, among other places. He carried out research in electricity, heat conduction, and chemistry, and was in close and frequent correspondence with both Benjamin Franklin and Henry Cavendish. In 1785, he described the irregular movement of coal dust on the surface of alcohol and therefore has a claim as discoverer of what came to be known as Brownian motion. Ingenhousz was elected a Fellow of the Royal Society of London in 1769 and a member of the American Philosophical Society in 1786. In 1799, Ingenhousz died at Bowood House, near Calne in Wiltshire, and was buried in the churchyard of St Mary the Virgin, Calne. His wife died the following year. Tribute On 8 December 2017, Google Doodle commemorated his 287th birthday. References Further reading Norman and Elaine Beale, Echoes of Ingen Housz. The long lost story of the genius who rescued the Habsburgs from smallpox and became the father of photosynthesis. 630 pages, with a foreword by David Bellamy, Hobnob Press, July 2011, . Geerdt Magiels, From sunlight to insight. Jan IngenHousz, the discovery of photosynthesis & science in the light of ecology. VUB Press, 2009, . External links Experiments upon Vegetables, Discovering their Great Power of Purifying the Common Air in the