Antoine Lavoisier 1743 - 1794 Born to Wealth.  Antoine-Laurent Lavoisier was born August 26, 1743, the son of a wealthy Paris family.  His father was a lawyer who had married a daughter of the wealthy Punctis family.  Louis XV was the King of France.  Most of Europe, and especially France, was in social upheaval.  Peasants faced continual famines and peasant revolts and mob violence were common.  Lavoisier's family were among the upper class so Lavoisier was able to complete a degree in law at the Collège Mazarin in fulfillment of his family's wishes.

Science.  Lavoisier never practiced law.  At age 21 began to fulfill his own dream — to study mathematics and science.  He studied astronomy, botany and geology under eminent scientists of the time.  His work with geology and his winning essay on the best means of lighting the streets of a large city at night gained him an elected membership at the age of 25 into France's prestigious Academy of Sciences.

Ferme Générale.  In 1768, Priestley bought into the Ferme Générale, a private company that collected taxes for the Crown.  Owners, called 'tax farmers,' were empowered to collect taxes of all kinds, but especially duties on imported goods.  The system was easily and often abused by the tax farmers who enriched themselves and lived in extravagance.  They were the target of popular hatred among the peasants and merchants alike.  All evidence suggests that Lavoisier discharged his duties honestly and without corruption.  Lavoisier seems to have justified his involvement in the Ferme to raise money for the pursuit of science.

Marie-Anne Pierrette Paulze.   In 1771, Lavoisier married 13-year old Marie-Anne Pierette Paulze, the daughter of a co-owner of the Ferme.  With time, she proved to be a scientific colleague to her husband by learning English so she could translate the writings of Priestley and others and by developing skills in art and engraving.  Madame Lavoisier drew the sketches of Lavoisier's apparatuses and laboratory, including all of the drawings in his book, Traité élémentaire de chemie.  She developed a scientific mind and was known to take lively part in discussions of writings on phlogiston and the chemical results of others.

Chemical Revolution.   Over the 20 year period 1770 - 1790, the science of chemistry experienced a revolution so fundamental and so complete that there has been nothing like it since.  The architect of the revolution was one man — Antoine Lavoisier.  Lavoisier believed that weight was conserved through the course of chemical reactions — even those involving gases.  He explained combustion (and respiration) in terms of chemical reactions that involve a component of air which he called oxygen.  His venue for the chemical revolution came in 1775, when he was appointed Commissioner of the Royal Gunpowder and Saltpeter Administration.  As such, he was able to build a fine laboratory at the Paris Arsenal and make important connections to the scientific community of all of Europe.  One of the first chemists to adopt Lavoisier's theories was Joseph Black who taught them as early as 1784.

Oxygen and the end of Phlogiston.  In 1774, Lavoisier was repeating Robert Boyle's tin calx experiments from the previous century.  Boyle knew the tin gained weight as the calx was formed.  The doctrine of Phlogiston explained that phlogiston was released upon calx formation.  While modern scientists recognize the implication that this: phlogiston must have a negative weight, early phlogistonists (Becker, Stahl) were not bothered as they considered phlogiston to be something of a philosophical concept.  Later phlogistonists such as Priestley did consider phlogiston to be a material substance (Cavendish believed it to be his inflammable air, now H2) but because the theory explained so many chemical phenomena, they were able to overlook its shortcomings.  But not Lavoisier!

     Lavoisier heated tin in air in a closed vessel.  The tin increased in mass upon forming the calx [now SnO] and air rushed into the vessel as it was opened.  At about the same time, in October, 1774 Priestley visited Paris and met with Lavoisier and told him at a dinner party of his discovery of dephlogisticated air.  By coincidence, Lavoisier also received a letter from Scheele (dated September 30, 1774) asking him to repeat one of his experiments that produced [oxygen].  In November 1774, Lavoisier repeated Priestley's experiment.
 

By this time Lavoisier was an affirmed anti-phlogistonist.  In 1777, Lavoisier conducted an experiment that established a fatal shortcoming of the phlogiston theory.  He heated mercury and air using a bell-jar for 12 days.  Red mercury calx (now HgO) formed and the volume of air decreased from 50 to 42 in3.  The remaining air was determined to be atmospheric mofette, and later renamed azote (now nitrogen).  The red [HgO] was heated in a retort producing 8 in3 of dephlogisticated air [O2].  The sequence of experiments established that heat caused formation of a calx (the doctrine of phlogiston explained phlogiston was released):  Hg(l) + O2(g)  HgO(s)   and then stronger heating reverted the calx back to the original substances (which the doctrine of phlogiston would predict to be impossible): HgO(s)   Hg(l) + O2(g)

Water.  Proof of the validity of Lavoisier's Oxygen Theory came when Lavoisier (a) decomposed water into two gases, which he named hydrogen and oxygen, and then (b) reformed them into water as had been previously done by Priestley (1781) and then quantitatively by Cavendish.

Traité élémentaire de chemie, 1789.  To spread his ideas and the Oxygen Theory, Lavoisier published Traité élémentaire de chemie in 1789.  In his book, Lavoisier named a total of 33 elements, most of which are still in use today.  It has been said that the book would be recognizable to a student of chemistry as is reads "like a rather old edition of a modern textbook."¹

French Revolution.  Lavoisier was a political liberal.  Through the events that led up to the French Revolution, Lavoisier contributed to the plans for reform — including the establishment of the metric system.  After the French Revolution, Lavoisier was a member of the Commission for the Establishment of the Metric System and was appointed Secretary of the Treasury in 1791.

A theorist.  Antoine-Laurent Lavoisier discovered no new substances.  He made few new improvements to laboratory methods.  Yet he will be remembered to the end of time as the father of modern chemistry.  He took the works of others, most notably that of Priestley, Black, Cavendish and Scheele and explained it.

Guillotined! Despite all of the contributions to science and France made by Lavoisier in his 51-year life, it was his connection with the Ferme Générale that the revolution zealots noted.  In November 1793, all 32 former members of the Ferme Générale were arrested and imprisoned.  After a trial by jury, Antoine-Laurent Lavoisier, along with his father-in-law and, were found guilty of conspiracy against the people of France.  He was guillotined on May 8, 1794.

Lasting accomplishments.

• father of modern chemistry — the concept of the chemical element

• metric system (replaced hundreds of archaic systems in use throughout France)

• other accomplishments are dwarfed by Lavoisier's oxygen theory which has changed the course of chemistry forever, but it need be mentioned that Lavoisier is also credited with other accomplishments, including the invention of plaster of Paris in 1768.
 

1 A Short History of Chemistry, J. R. Partington, 3rd edition, (1957)

2 Manual of Chemistry, Brande, 6th Ed, 1848.

3 Quote of Lagrange to Delambre, Famous Chemists, Sir William Tildon, London, 1921.