Jan Ingenhousz

January Ingenhousz ( born December 8, 1730 in Breda, † September 7, 1799 in Bowood Park ) was a Dutch physician and botanist.

Curriculum vitae

Ingenhousz came from a merchant family, studied at the Universities of Leuven and Leiden medicine and settled after graduation in 1753 in his hometown of Breda as a physician. The English physician John Pringle (then president of the Royal Society) invited him in 1765 one to come to London. There Ingenhousz learned personalities like Benjamin Franklin and Joseph Priestley know. Already in 1769 he became a member of the Royal Society.

Ingenhousz was an advocate of - already propagated by Mary Wortley Montagu - smallpox vaccination; he took patients who were suffering from a mild form of smallpox, serum ( with still live viruses ) and " inoculated " that's not sick people. Ingenhousz inoculated the family of George III. of Great Britain and the family of Empress Maria Theresa and worked from 1768 as a court physician in Vienna at an annual salary of 5,000 guilders.

Priestley had in 1774 the element oxygen ( air dephlogisticated ) isolated as a component of air and found that " foul air " could be replenished by plants again. Puzzling, however, was the conditions under which this happened. This was contrary to the observations of the chemist Carl Wilhelm Scheele, who stated that plants can degrade the air.

To clarify this difference in observations led Ingenhousz after his return from Vienna in 1779 extensive series of tests. The findings were published in the Scriptures experiment " upon ... " In it, he argued that plants give off carbon dioxide in darkness ( fixed air ), this action of light - take up and release oxygen - dependent on the intensity. He further showed that the carbon that plants need for growth, not removed from the soil (as previously assumed ), but comes from the ambient air. He had discovered the fact that light for growth, and air purification ( of animal breath) plants is required; this was the beginning of photosynthesis research.

Ingenhousz also provided a series of tests on materials of different electrical conductivity and magnetism. In 1766 he had constructed a generator of static electricity. In 1775 he reported on his studies of the electric ray (English: " Torpedo "). In 1785 he described the stochastic behavior of Holzkohlestäubchen on alcohol, making it the true discoverer of Brownian motion. In 1789 he performed the first reliable experiments on thermal conductivity of metal rods. " Besides, " he constructed a working with hydrogen lighter ( to make it unnecessary for the annoying Zündschwamm ) and experimented with an electrically ignited ether - gun, the electric also known gun became known.

In 1910 (9th district) was named the Willingen- Housz alley after him in Vienna Alsergrund.

Publications

• An Essay on the Food of Plants and the Renovation of soils (1796 ).
• Experiments on the Torpedo (1775 )

Quotes

Alexander von Humboldt in " Introduction of some items of plant physiology ," the German edition of " Essay on the food of plants and the renovation of the soil " (1798, translated by Johann Gotthelf Fischer von Waldheim ) preceded by "Lord Ingenhouszen belongs to the small number of working physicists who possess the fertile talent to pursue not only individual objects with admirable effort, but also a new phenomenon ( rather than observed isolated ) to harmonically with the older. His writings teach that he never loses sight of the great object of all natural science to investigate this interaction of forces, out of sight, ... "