John Hadley (chemist)

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John Hadley in 1759

John Hadley (1731 – 5 November 1764) was a British chemist and physician.

Born in London to Henry Hadley, he was educated at Queens College, Cambridge, graduating B.A. in 1753. [1]

In 1756 he was appointed the fourth Professor of Chemistry at Cambridge University, the oldest continuously occupied chair of Chemistry in the UK. During his time there he co-operated in 1758 with Benjamin Franklin on a series of experiments to investigate latent heat. They found that a mercury thermometer sprayed with ether which was then evaporated by blowing could fall to −7 degrees Celsius in a warm room.

The Professorship was unpaid so Hadley studied medicine and obtained in 1758 a Physick Fellowship. He then moved to London in 1760 and got a post as Assistant Physician at St Thomas' Hospital. In 1763 he became full Physician to Charterhouse School and became a Fellow of the Royal College of Physicians.

In 1758 he was elected as a Fellow of the Royal Society. He died in 1764 of a fever at the age of 33.


  1. ^ Biographical account of John Hadley ... and of his brothers, George and Henry. p. 32.
  • L.J.M.Coleby Annals of Science, Vol VIII, pp 165–174