It’s well known nowadays that combustion — fire, for one — is a process requiring oxygen. It doesn’t need any phlogiston to work, although for a century before the 1770s, scientists thought “phlogiston” was some sort of substance, and if it was included in another substance (like wood), that’s what enabled burning. It’s thanks to Antoine-Laurent de Lavoisier that we know there’s no such thing as phlogiston. And August 26 is his birthday.
Lavoisier was a French nobleman born in 1743 in Paris, who was a (maybe the) central figure in what’s known as the “chemical revolution” of the 1700s. It was a time when virtually all the fundamental principles of modern chemistry were discovered. What made that possible was a shift from treating chemistry as a qualitative pursuit to a quantitative science, and Lavoisier was largely responsible for it.
Lavoisier came from a wealthy family and never had to work for a living, so he had plenty of time for his scientific pursuits. But initially he went in a different direction; he attended law school and was admitted to the bar (or the 18th-century French equivalent). He never practiced as a lawyer, though. He attended lectures about natural sciences — Paris was in the midst of the French Enlightenment, and there were lots of lectures available. He began to contribute, too, and published his first technical paper about chemistry in 1764 — by coincidence, the same year he became a lawyer. Just two years later he was awarded a gold medal by the King for his work on street lighting in cities. It was partially based on chemistry, but also focused on his interest in benefitting the public.
His next chemical/public works project was purifying drinking water — at the time, Paris used the Seine for water, and it was pretty much the opposite of sanitary. He developed ventilation systems, too, in order to provide fresh air inside buildings, and made numerous suggestions about improving the hygiene in Parisian prisons (his suggestions were mostly ignored).
At one point he bought a share in a tax collection company — in Paris, at the time, private companies could contract with the royal government to collect taxes in return for a percentage. In spite of Lavoisier’s public works, his role in tax collection didn’t help his standing a few years later during the French Revolution.
When he was 28 he got married, and his wife turned out to be an important part of his scientific career — she assisted in the laboratory, provided sketches and engravings of the scientific apparatus he owned (and often designed himself), and translated English scientific papers into French for him. But in 1793, when Lavoisier was 50, the French Revolution ordered everybody who’d been associated with private tax collection companies arrested, including him. Being a lawyer, he drafted the defense for himself and 27 others, but to no avail. In 1794 all of them were guillotined.
It didn’t help him, but just 18 months later the French government exonerated him and admitted he had been falsely convicted. The mathematician Joseph Lagrange said “It took them only an instant to cut off this head, and one hundred years might not suffice to reproduce its like.”
