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Jan IngenhouszZoomA-Z


08. Dezember 1730 in Breda (The Netherlands)
07. September 1799 in Bowood (Wiltshire, England)

In London, Ingenhousz was an early champion of the inoculation against smallpox by taking small amounts of the live, unmodified virus from patients with mild cases of the disease. In 1768 he traveled to Vienna to inoculate the family of the Austrian empress Maria Theresa - including the young Marie Antoinette - and subsequently served as court physician for over ten years.

In 1774, while Ingenhousz was abroad, Joseph Priestley had discovered oxygen. However, Priestley had noticed that air made foul by burning a candle in it could only occasionally be re-vivified by plants, and could not explain the variations. Back from Austria in 1779, Ingenhousz worked to explain these mysteries. Over the course of four months he completed over 500 experiments to cover every possible contingency, and published them as 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.

It had been noticed that submerged plants gave off small bubbles and, if the plants were placed in the shade, these bubbles eventually stopped. Ingenhousz carried out a series of experiments to prove that the bubbles were independent of heat and that the cause of this phenomenon must be light. He further discovered that the accumulated gas re-lit a glowing splint, suggesting that the air was full of oxygen. In the dark, however, he found that the plants gave out less gas, but that that gas extinguished a flame, meaning that the air was rich with carbon dioxide. Therefore in light plants gave out oxygen, but in the dark they emitted carbon dioxide.

Ingenhousz's work, Experiments On Vegetables, Discovering their Great Power of Purifying the Common Air in Sunshine, and of Injuring it in the Shade or at Night, 1779, laid the foundations for the study of photosynthesis.


1730Geboren am 08. Dezember in Breda (The Netherlands)
studied at Louvain and Leiden and abroad at Paris and Edinburgh
established a private medical practice in Breda
1765He came to England to work at the Foundling Hospital, London where he successfully inoculated patients against smallpox (using the hazardous live virus).
1768He was sent to the Austrian court by George III, to inoculate the royal family.
1772 - 1779He was court physician there.
1799Gestorben am 07. September in Bowood (Wiltshire, England)