Antoine Lavoisier (1743-1794) was a French aristocrat, businessman, and chemist best known for his successful attack on the Renaissance theory of phlogiston and his contributions to the law of conversation of mass, the periodic table of elements (in his time, only existing in list form), and the metric measurement system. He was executed for alleged fraud in the aftermath of the French Revolution.
– Youth and Education –
Lavoisier was born to a wealthy and aristocratic Parisian family, and grew up with a substantial inherited estate after the early death of his mother.
He spent seven years studying scientific subjects – at the College Mazarin, where he was introduced to the heady brew of Enlightenment political and scientific thought. By the 1760s, when he was only in his 20s, he was already publishing new works on chemistry and was admitted to the prestigious French Academy of Sciences. (Even today, the Academy has only a couple of hundred members.) His early work was on a wide range of subjects, ranging from streetlights to cartography.
– Scientific Career –
Lavoisier’s most important studies, however, began with the newly discovered substance oxygen. In England, Joseph Priestley had just isolated and “discovered” oxygen, which he called “dephlogisticated air.” Operating on the basis of a Renaissance theory of fire, Priestley believed that phlogiston was an invisible substance contained in flammable objects which burst forth as fire. His dephlogisticated air seemed to make objects more flammable – so, he reasoned, it must have no phlogiston of its own, and therefore be prone to absorb it rapidly from other substances. Curiously, Priestley found, dephlogisticated air was also very pleasant to inhale.
We now realize that Priestley had discovered not dephlogisticated air, but oxygen, and that fire is the result of chemical reactions involving oxygen. This realization is due to Lavoisier. Both men had discovered that Priestley’s dephlogisticated air could be combined with another special type of isolated “air,” “inflammable air” (what we now know as hydrogen), to produce water. Lavoisier rushed this discovery into publication, apparently in an attempt to take credit for Priestley’s innovation. Lavoisier went further, however. Noting some experiments involving dephlogisticated air and acid, he argued that the substance was actually the cause of fire – and called it “oxygen.” The new air had not simply been stripped of its phlogiston, Lavoisier argued; instead, it was an identifiable chemical substance in its own right.
This discovery was not the only component of Lavoisier’s work, but it paved the way for the most important. He subsequently pioneered vital methodological techniques of stoichiometry, establishing that total mass does not change during chemical reactions – a consequence of what we now know as the law of conservation of mass. This, coupled with the disproving of phlogiston, paved the way for a new era in the study of chemistry – and, indeed, Lavoisier is often regarded as the father of modern chemistry.
– Aristocratic Businessman –
Befitting his noble birth, Lavoisier was never solely a chemist. He actually studied law and became a lawyer, although he never practiced the profession actively. In his 20s he was given a position as private tax collector (in pre-revolutionary France, tax collection was a privatized industry subsisting on royal collection contracts). It was during this work that Lavoisier assisted in the development of metric measurements, believing it would provide objective standards for French weights and measures.
– Death –
Given his position as a tax collector, it is perhaps not surprising that Lavoisier was one of the many alleged traitors condemned by the revolutionary government of 1790s France. That he attempted to rescue a number of foreigners from asset seizure or imprisonment did not help. In May 1794, Lavoisier was formally charged with diluting tobacco prior to its sale. A defence on the grounds that he was a famous scientist was rejected on the grounds that the new nation needed justice more than it needed science. He was killed by guillotine.
The government soon realized it might have made a tactical error in executing such an accomplished Enlightenment figure. Lavoisier was posthumously pardoned soon after his execution. Much later, the French government commissioned a statue of him, which incidentally was modelled after the Secretary of the French Academy of Sciences during Lavoisier’s life, rather than after Lavoisier himself. The statue was destroyed during World War II.