Jan Ingenhousz

Infobox Scientist
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birth_date = December 8, 1730
birth_place = Breda
death_date = September 7, 1799
death_place = 1799
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nationality = Dutch
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field = physiology
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known_for = photosynthesis
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Jan Ingenhousz or Ingen-Housz (December 8, 1730, Breda - September 7, 1799) was Dutch physiologist, biologist and chemist. He is best remembered for showing that light is essential to plant respiration, a vital step in the discovery of photosynthesis. He was a physician to the Austrian Empress Maria Theresa.

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. [Jan Ingenhousz, "Experiments upon Vegetables, Discovering Their great Power of purifying the Common Air in the Sun-shine, and of Injuring it in the Shade and at Night. To Which is Joined, A new Method of examining the accurate Degree of Salubrity of the Atmosphere", London, 1779. From Henry Marshall Leicester and Herbert S. Klickstein, "A Source Book in Chemistry 1400-1900", New York, NY: McGraw Hill, 1952. [http://web.lemoyne.edu/~giunta/ingenhousz.html Excerpts] . Accessed 2008-06-24.] He identified the gas as oxygen (for this discovery he is known affectionately as "the Oxygen man"Fact|date=June 2008). He also discovered that, in the dark, plants give off carbon dioxide. He realized 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 soil.

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.

References

*cite journal
quotes = yes
last=Beaudreau
first=Sherry Ann
authorlink=
coauthors=Finger Stanley
year=2006|month=
title=Medical electricity and madness in the 18th century: the legacies of Benjamin Franklin and Jan Ingenhousz
journal=Perspect. Biol. Med.
volume=49
issue=3
pages=330-45
publisher= |location = United States| issn = 0031-5982| pmid = 16960304
doi = 10.1353/pbm.2006.0036
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*cite journal
quotes = yes
last=Smit
first=P
authorlink=
year=1980|month=
title=Jan Ingen-Housz (1730-1799): some new evidence about his life and work
journal=Janus; revue internationale de l'histoire des sciences, de la médecine, de la pharmacie, et de la technique
volume=67
issue=1-2-3
pages=125-39
publisher= |location = NETHERLANDS| issn = 0021-4264| pmid = 11610754
bibcode = | oclc =| id = | url = | language = | format = | accessdate = | laysummary = | laysource = | laydate = | quote =

External links

* [http://www.newadvent.org/cathen/16046b.htm Entry at the Catholic Encyclopedia]
* [http://www.eleceng.adelaide.edu.au/Personal/dabbott/publications/EDU_abbott1996.pdf Ingenhousz's relationship to Brownian motion, see page 1]