Professor Olsen @ Large

On this date, the Dutch physician and scientist Jan Ingen-Housz was elected to the Royal Society of London. He is best known today for showing that light is essential to photosynthesis and thus having discovered photosynthesis. He also discovered that plants, like animals, have cellular respiration.

In the summer of 1771, Joseph Priestley had carried out experiments with air and jars, noting that a closed jar would eventually kill a mouse and extinguish a candle, but vegetation (he used mint) would allow the mouse to live and the candle to burn. Although he did not have the official names of the “types” of air he was observing, Priestly had discovered that mice and candles need something (oxygen), and plants are capable of using other things in the air (carbon dioxide) to produce that something. In short, plants restore to the air whatever breathing animals and burning candles remove.  However, Priestly…

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