Founder of Modern Chemistry: Antoine Lavoisier (1743 – 1794). His Biography, Execution and Anecdotes
Founder of Modern Chemistry: Antoine Lavoisier (1743 – 1794).
His Biography, Execution and Anecdotes
Prof. Dr. Kadircan KESKİNBORA
Bahcesehir U. Faculty Member of Faculty of Medicine
HBT Magazine Issue 96 – January 26, 2018
““I see nature as a huge chemical laboratory in which all kinds of combinations and dissolutions occur. Vegetation is the basic instrument that God uses to activate all of nature.””
Antoine Laurent Lavoisier
Antoine Laurent Lavoisier, the founder of modern chemistry, was the son of a wealthy Parisian family. Following family traditions, he studied law; But he had mathematics, astronomy and botany in mind rather than the rule of law. In 1764, he won first place with a project to illuminate the streets of Paris and won a gold medal from the French Academy of Sciences. Lavoisier, who published his first research in 1765, managed to become a member of the French Academy of Sciences with his studies in chemistry in 1768 at the age of 25.
- In the 18th century, chemistry was still under the influence of alchemy. However, chemists did not have a specific goal and no significant progress was made in this field. Lavoisier decided to reorganize chemistry. As he mentioned in a notebook he kept in 1773, he embarked on 'a series of experiments that were bound to bring about a revolution in physics and chemistry' and eventually succeeded.
Lavoisier's most famous contribution to chemistry was his demonstration of the nature of combustion, in which burning matter combines with oxygen (1775). .
Lavoisier's new system was based on the concept of new chemical elements. These elements were defined as substances that had not been broken down into simpler substances. Thus, Lavoisier accepted that there were 55 elements, as opposed to the previously accepted four or fewer elements. Together with his three friends, C. L. Berthollet, A. F. De Fourcroy and L. B. Guyton de Morveau, he created a new nomenclature for many compounds consisting of these elements (this nomenclature is still used today).
He defined oxygen and hydrogen accurately and brought them to chemistry with their modern names, explained the difference between elements and compounds, gave solidity, clarity and a method to the science of chemistry with his book Introduction to Chemistryand brought it to the modern age, and was the architect of the science of chemistry in Europe. The new system proposed by Lavoisier, which identified 20 of the elements and was soon accepted, led to the initiation of various studies in the field of chemistry. There were thousands of items to be analyzed qualitatively and quantitatively, and the results were to be written in Lavoisier's terms. Approximately twenty years later, the emergence of Dalton's atomic theory allowed these results to be expressed more precisely, and modern chemistry was established on solid foundations.
Phlogiston Theory
Lavoisier became known in the scientific world with his work on combustion. Many rules and regulations that modern chemistry has today were developed by Lavoisier.
The phlogiston theory was first put forward by Johann-Joackin Becher (1635-1682), developed by Georg-Ernst Stahl (1660-1734) and remained active in chemistry for about a quarter of a century until the discovery of oxygen. According to this theory, during combustion, the object released a substance called phlogiston, but its identity was unknown. Although it was accepted by the majority, this theory was opposed by some scientists, claiming the necessity of air.
. This tireless researcher was not satisfied with just chemistry. The most prominent subject of his scientific interest was the process of breathing. Lavoisier determined that oxygen is taken in and carbon dioxide is given out during respiration. Lavoisier, who revealed that breathing occurs with the slow burning of carbon and hydrogen and that this is similar to the burning in a candle or gas lamp, measured the heat of chemical reactions with the calorimeters he used. He did not stop there and discovered that the redness called calx (mercury oxide) was formed by the combination of air and metal. He discovered that during the reactions in which calcium deposits were formed, a gas, which he later named oxygen, was released. He met in Paris with the famous chemist Priestley, who had previously discovered oxygen and called it the "perfect gas". After that, he found it during his experiments on mercury; After listening to the properties of this perfect gas, he continued Priestley's experiments. However, after weighing the mercury oxide formed after combustion, Lavoisier went one step further than Priestley and heated the mercury oxide further. He determined that the red oxide, which turned into ember, was gradually disappearing, leaving behind mercury grains and some "elastic flow". This remaining substance was what Priestley called perfect gas. He determined that the weight of this substance remaining in the vessel was equal to the weight of air reduced from the initial heating of the mercury. The discovery of oxygen also enabled the combustion-oxidation phenomenon to be explained scientifically: "Combustion occurs not by the release of phlogiston of the burning substance, but by its combination with oxygen."
In his experiments, Cavendish obtained a "flammable" gas as a result of the effect of acids on metal, and he mistook it for "phlogiston". In this respect, Lavoisier was not the first to discover oxygen; but he was the first to realize the true importance of this gas. When Lavoisier presented his conclusion to the Academy of Sciences in a paper, he did not mention a single word about the contributions of Priestley and Cavendish.
Lavoisier was also the first to suggest that a substance must exist in one of the states of solid, liquid and gas. In his experiments, he analyzed the air and separated nitrogen and oxygen. Lavoisier managed to burn hydrogen in his advanced laboratory, and as a result, he obtained water. He developed the Chemical Nomenclature Method.
In fact, Lavoisier discovered neither a new chemical object nor a new chemical phenomenon in this regard. What he did was to explain the objects and phenomena discovered by others, to create a theory that clarified chemical composition, and to establish a new and functional system for naming chemical objects. However, his work "Fundamentals of Chemistry (Traite Elementaire de Chimie)", published in 1789, became Newton's Principia in its field. While Newton laid the foundation of modern physics, he also laid the foundation of chemistry.
Three groundbreaking foundations of Fundamentals of Chemistry:
1) He showed in many experiments, both through analysis and synthesis, that air, water and many other substances are not elements, but compounds consisting of different elements. Thus, he definitively eliminated the four element theory, which had been going on since ancient times and claimed that air, water, earth and fire were elements. At the same time, he put an end to the phlogiston theory by showing through experiments that the phenomenon of calcination was not the removal of phlogiston from the metal, but its combination with oxygen.
2) In his work, Lavoisier laid the foundations of the modern chemical language by creating a dictionary of chemical concepts and terms. He proposed names such as oxygen, hydrogen and nitrogen for the first time in this work. In his book, he gave a list of substances that he saw as the cornerstones of the new chemistry. Under the title "Table of simple substances", he gave the new names of 33 simple substances, which he suggested, in addition to their old names.
3) Law of Conservation of Mass:Based on meticulous observations of experimental results, Lavoisier proposed the law of conservation of mass in chemical reactions. Thus, he turned chemistry into both a physical and mathematical science. This law he proposed caused the development of chemistry to gain great momentum. Lavoisier said that the weight of the products should be equal to the weight of the reactants. In other words, during a chemical change, matter could neither be created from nothing nor destroyed once it existed! Lavoisier experimentally proved the Law of Conservation of Mass with his studies on this subject. He found that the increase in the mass of phosphorus burned in an air-filled tube was equal to the amount of air consumed. He also performed the same experiment in reverse and determined that by heating HgO (mercury oxide) in a closed container, the increase in the air mass inside the container was equal to the decrease in the mass of the reacting substances.
Lavoisier also worked on improving social and economic conditions and made scientific contributions to the developments in agriculture. His studies include many issues such as the creation of the metric system, the creation of the geological map of France, and efficiency in agriculture.
Lavoisier's scientific studies ended before they could mature, with the French Revolution. He was actively involved in politics during the French Revolution. Lavoisier participated in political activities by serving in a special commission of the government, and examined the social conditions and agricultural fields of the period in the committees he was elected to. He worked to create a geological map of France and to increase productivity in agriculture. During these periods, he carried out projects such as old-age insurance and tax reform, which would later become widespread. He also took part in the defense of his country and undertook the production of gunpowder.
1789 French Revolution and Towards Execution
The institution where Lavoisier worked, "Ferme Generale (General Farm)", was a private organization that collected taxes (acted as a tax farmer) on behalf of the government before the French Revolution of 1789. Lavoisier, who had one of the largest laboratories of the period, established this laboratory by selling the shares of Ferme Generale that he had purchased in 1768. However, Ferme Generale was an institution that was not liked by the public at that time. He was collecting taxes from the poor by force.
When the French Revolution took place, Lavoisier was among the liberal and reformist people. When the Etats-generaux convened, he was elected as a reserve public representative and prepared the statute of the Assembly. He was also elected to the Paris Commune and joined the 1789 Association.
Although Lavoisier was not liked by the public because of the shares he owned, he started another business with the same institution. With Lavoisier's initiative, the walls around Paris were rebuilt, and the costs of the wall were covered by taxes collected from the public through the Ferme Generale. In fact, he approved the building of a wall surrounding Paris to prevent merchants from bringing their goods into the city and selling them without paying city taxes. That's why the people never liked this wall, and this wall was one of the first to collapse on the day the revolution started. All this caused the public to hate Lavoisier.
Lavoisier was an ardent defender of the state. He was a responsible director of the Gunpowder Commission when the 1789 revolution began, and some of the gunpowder was stored there just before the Bastille fell. It was claimed that he did this on purpose, that is, to blow up the arriving patriots. Among his official duties was the assistant of King Louis XVI's Minister of Finance, Necker.
Another important event that cost Lavoisier his life was his rejection of the book of young Jean Paul Marat, who participated in a competition organized by the academy. Marat wanted to make a name for himself in science in the pre-revolutionary years. In 1780 he wrote a book titled Physical Investigations on Fire. Here, he claimed that the flame of a candle in a closed container would go out because the hot air would put pressure on it, and that fire was a hot liquid. But people did not pay any attention to this booklet. Marat had a fake news published in the Jurnal de Paris stating that he"approved the views of the Academy of Sciences". The president of the academy at that time was Lavoisier. Lavoisier immediately denied this. Marat's views were a disguised form of the old phlogiston theory, and the Academy did not approve of it; He also wrote in the Jurnal de Paris that Marat followed an immoral way to get his book accepted.
Marat, whose book was rejected, became one of the most important figures of the revolution during the revolution and took his revenge on Lavoisier by paving the way for his execution. While the press was making publications against Lavoisier, Jean Paul Marat, who was a member of the French National Assembly at the time, worked to bring Lavoisier to trial and execute him. Around this time, Marat published a newspaper called Friends of the People. He violently attacked aristocrats and moderates. Of course, Lavoisier also had his share of this attack. What brought Lavoisier to an end was, to some extent, Jean-Paul Marat's grudge: "To be roped on the nearest lamp post..." This was Marat's wish for Lavoisier.
Following the revolution, Ferme Generale was closed in 1791. Lavoisier, whose gunpowder studies were terminated, was dismissed from his position in the gunpowder factories and removed from his laboratory. In November 1793, the managers of Ferme Generale were arrested and imprisoned along with 31 people, including Lavoisier and his father-in-law.
On May 8, 1794, he was brought before the Revolutionary Tribunal before a jury composed of people from various professions such as barber, coachman, jeweler, greengrocer and butcher. The presiding judge was lawyer Coffinhal. Starting from the very beginning, the defendants' answers to the president's questions were greeted with sardonic smiles. There was a very contradictory atmosphere in the court. The prosecutor began his case by making a series of accusations against the detainees. After some more questions, the prosecutor made his speech, accusing the detainees of regularly robbing the state and of being “perpetrators of all the evils that have been ravaging France for some time now.” The defense's hands were tied. They did not have the courage to defend the defendants strongly, and if they had done so they would most likely have found themselves in the dock right next to their clients. All they could do was put forward mitigating circumstances, such as Lavoisier's contributions to science, but these were also found to be irrelevant. It was at this point that Coffinhal said his shameful thought: "The Republic has no need for scientists!" The gagged, incompetent defense had no effect on the judge and jury, who had already made up their minds before taking their seats.
At the end of the trial, 8 people were acquitted. There were scenes of enthusiasm among the audience. The jubilant crowd followed the prisoners to the Conciergerie prison, where they were handed over to the executioner Sanson. In the evening of the same day, they were taken to Paris Revolution Square and executed one by one by guillotine. According to the mathematician Joseph Langrange, Lavoisier was reading a book while waiting to be beheaded. When the executioner came to take him to the guillotine, Lavoisier put a "bookmark" between the book so that he would not forget where he was staying.
Lagrange said about Lavoisier: “One minute was enough to tear off this head, but not even a whole century is enough to recreate such a head.” Lavoisier's search for proof is the torch of science that will last for centuries. But the bigoted heads who cut off his head will crawl in darkness for centuries, and they will make humanity crawl.”
If you are wondering about the end of Marat, who prepared the way for his execution, he was assassinated a short time later. If you ask what happened to the judge who sent Lavoisier to the guillotine: A few days after Robespier's fall, Coffinhal was also executed.
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