John Hadley (chemist) facts for kids
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John Hadley (born 1731, died 1764) was an English scientist. He was both a chemist, who studied chemicals, and a physician, meaning he was a doctor. He was born in London and went to Queens' College, Cambridge university, finishing his studies in 1753.
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A Career in Chemistry
John Hadley became a very important professor. In 1756, he was named the Professor of Chemistry at Cambridge University. This was a very old and respected position. It was the fourth time someone held this job at Cambridge. This chemistry teaching role is the oldest one that has been continuously filled in the United Kingdom!
Cool Experiments with Benjamin Franklin
While he was a professor, John Hadley worked with another famous scientist, Benjamin Franklin. This happened in 1758. They did some interesting experiments together. They wanted to learn about something called "latent heat." This is the hidden heat that is absorbed or released when something changes state, like from a liquid to a gas.
The Ether Experiment
In one experiment, they used a special thermometer. It was a mercury thermometer. They sprayed it with a liquid called ether. Then, they blew air on the ether. Blowing air made the ether evaporate, or turn into a gas, very quickly. This quick evaporation made the thermometer get super cold! It dropped to about -7 degrees Celsius (which is 19 degrees Fahrenheit), even though the room was warm. This showed how much heat ether takes away when it evaporates.
Becoming a Doctor
Being a chemistry professor was a big honor, but it didn't pay any money back then! So, John Hadley decided to study medicine too. He wanted to become a doctor.
Working at Hospitals
In 1758, he earned a special fellowship that allowed him to practice medicine. He then moved to London in 1760. There, he got a job as an Assistant Physician at St Thomas' Hospital. This was a very well-known hospital. Later, in 1763, he became a full Physician at Charterhouse School. He also became a Fellow of the Royal College of Physicians. This meant he was recognized as a top doctor.
A Short but Important Life
John Hadley was also chosen to be a Fellow of the Royal Society in 1758. This is a group of the most important scientists in the world. Sadly, he died in 1764. He was only 33 years old when he passed away from a fever. Even though he lived a short life, he made important contributions to both chemistry and medicine.
