Norman and Elaine Beale

Ingen Housz was born in Breda, the son of a leather merchant. His high intellect was recognised as a schoolboy and he went on to study medicine at the Catholic University of Louvain, qualifying in 1753. He established a family medicine practice in Breda, alongside his brother, a pharmacist.

In 1764 Ingen Housz travelled to London to study smallpox inoculation (the precursor of vaccination as pioneered by Edward Jenner later in the century). Medical colleagues in London saw the young Dutch doctor as a very safe and effective inoculator, especially of children, and he was ‘head hunted’ to go to Vienna in 1768 when Empress Maria Theresa requested an ‘English’ inoculator to save the rest of her smallpox-ravaged family. Ingen Housz successfully inoculated many royals and aristocrats across the Empire. The Empress awarded him a very generous pension and set him free to use his time in scientific endeavour unless called upon – a meteoric rise from general practitioner to roaming royal physician and freelance investigator.

Of the many subsequent scientific discoveries of Ingen Housz, the most outstanding was made at a rented private villa to the west of London during the summer of 1779 – the essentials of what we now call photosynthesis. He was able to demonstrate, using eudiometry, a volumetric analysis of oxygen, that the green parts of plants release the gas during (and only during) exposure to sunlight. He published his findings in his most important book (1).

He returned to Vienna in 1780 where he continued his experiments on plants but also studied magnetism, heat conduction in metals, static electricity, microscopy (he invented the cover slip) and, later back in England, the importance of manures in plant husbandry. In fact, it was in travelling back to England in 1789, bearing the passport of a royal courtier, that he ran into danger and difficulties. He managed to elude the revolutionary mobs in Paris and escaped on Bastille day. His last decade was spent stranded in England despite his wife and all his personal effects being at Vienna.

In England, Ingen Housz was a close friend and confidant of the First Marquess of Lansdowne (British Prime Minister 1782/3) and it was at his Lordship’s country estate in Wiltshire in 1799 that Ingen Housz died. He was buried in a vault under the church at nearby Calne.

For more details of the fascinating and inspiring life of Jan Ingen Housz there is a thorough and fully referenced biography (2).

(1) Ingen Housz J. Experiments Upon Vegetables. Hansebooks, Edinburgh (modern reprint) 2017. 396 pages. ISBN 3337373488.

(2) Beale N and Beale E. Echoes of Ingen Housz. Hobnob Press, East Knowle, Salisbury 2011. 632 pages. ISBN 978-1-906978-14-3.