Science & People

Antoine Lavoisier | Discoveries, experiments, quotes, and death

When Antoine Lavoisier or Antoine-Laurent de Lavoisier started his chemistry studies in the 1760s, Aristotle's four-element theory (earth, water, air, fire) still dominated the discipline. At the time of Lavoisier's death thirty years later, this discipline was transformed into a science that was practiced in modern chemistry experiments.

Who is Antoine Lavoisier?

Antoine Lavoisier was the son of a wealthy attorney, received formal training at the College des Quatre-Nations in the city, usually known as College Mazarin. After completing his humanities education in 1760, he studied mathematics under the supervision of outstanding astronomer Abbe Nicolas Louis de Lacaille. Later in the years, he would explain his mathematician-like attention to detail and care in scientific studies with this occasion. "They never prove a proposition before the previous step becomes clear. Everything is linked, everything connected, from the definition of the point to the definition of the line and the supreme realities of transcendental geometry."

He left the college in 1761 and studied law to please his father, but his interest in science continued. He studied meteorology with Lacaille, and continued to work in this field even after his teacher died in 1762. After observing the northern lights (Aurora borealis), he published his first scientific paper in 1763. He attended chemistry courses given by pharmacist Charles Louis La Planche at the Pharmacists Association, public classes by Guillaume-François Rouelle on electricity, and Bernard de Jussieu's lectures on the plant kingdom. He studied mineralogy, geology, and chemistry with Jean-Etienne Guettard, a member of the French Academy of Sciences. He received a law degree in 1764 and was accepted as a lawyer. But he never worked as a lawyer. In fact, he was already planning for the transition to the republic of science.

The following year, in 1765, he presented his first paper on "analysis of gypsum" to the Academy of Sciences, where he went as a guest scientist. He showed how solid gypsum turns into powder when heated and creates steam during the process. He gathered the steam and found that it was pure water. This was crystallization water, equal to a quarter of its solid weight being heated. When he mixed the water with powdered gypsum, it turned into solid mass again. So, the source of the stiffness of gypsum was water. By weighing and measuring ingredients and products during synthesis and analysis, Lavoisier proposed the "double demonstration" method that he would use throughout his science career. His paper was published in the proceedings of the Academy. About a year later, he published a second paper on gypsum, showing that it consists of chalk and sulfuric acid and its solubility depends on acid concentration. Lavoisier insisted that the analysis of mineral substances is important to shed light on Earth's past.

Academician and tax collector

One of Lavoisier's human respiration experiments done with his colleague Armand Seguin.
One of Lavoisier's human respiration experiments done with his colleague Armand Seguin. In the drawing, Madam Lavoisier is depicted while taking notes on the nearby table

In 1776, the Academy announced a public competition for the best method to illuminate the city streets. The participants were required to present a theory adapted to calculation, physical and chemical experiments, and practice. Lavoisier studied all kinds of lighting meticulously, looked at lamps of different sizes and types, tested with oil and wax. In his report, he concluded that olive oil was the best fuel. The paper was awarded a gold medal. Antoine Lavoisier enthusiastically expressed his desire to dedicate his exuberance, intelligence, and knowledge to the service of the state.

In 1767, with a long field trip to the Vosges Mountains with Guettard, he collected data for his extraordinary work, "Mineralogical Atlas of France". For more than four months, they roamed the land by analyzing the soil, minerals, and water, taking samples from agricultural products. There were 26 maps, eight of which belonged to Lavoisier. He was elected to the Academy in 1768.

Lavoisier joined the private company Ferme generale (General farm) by purchasing shares, which also collected tax revenues on behalf of the king of France. The company was collecting tax on goods entering Paris such as salt, tobacco, alcohol, as well as the customs money, with a six-year revenue rental agreement with the king's Controller-General of Finances. They were paying a certain sum to the royal treasury in cash which is close to 150 million livres in 1770.

Lavoisier was particularly responsible for the Tobacco Commission, where he was tasked with preventing fugitives and cheating in retailers. Then he had much more important tasks. Jacques Paulze de Chastenolles was a strong and wealthy manager. In 1771, her 14-year-old daughter Marie-Anne Pierrette married 28-year-old Lavoisier. Maria brought lots of dowry with her and became the assistant of Lavoisier. She learned chemistry and took notes while Lavoisier conducting experiments. She also translated English chemistry books for him, and hosted many scientists who came to visit Lavoisier. They had no children.

Antoine Lavoisier and the Four Elements

Antoine Lavoisier spent most of his life in this laboratory setting. It is currently stored in the Paris Musee des Arts et Metiers.
Antoine Lavoisier spent most of his life in this laboratory setting. It is currently stored in the Paris Musee des Arts et Metiers.

Lavoisier installed a well-equipped laboratory in his first house in Paris, Rue des Bons-Enfants. The distinctive feature of his work was the quantitative approach based on the constant use of chemical balance. The law of conservation of mass had long been the basic principle. He would later say in his textbook: "The whole art of experimenting in chemistry rests on this principle; in all experiments one is obliged to assume an actual equality between the principles (that is, elements) of substances examined and those obtained by the analysis of these substances."

He applied the axiom for the first time in his paper "Nature of Water" dated 1770. At that time, many chemists believed that water could be turned into soil. Because when the distilled water was evaporated in the glass container, it was known that there was always a soil residue. Lavoisier weighed the glass container called "pelican" and poured in water that he distilled eight times and measured its weight. He kept the container at 70 degrees Reaumur (80 degrees Reaumur is the boiling temperature of water). After 101 days, he began to identify dust particles in the container, but there was no change in the temperature of the water. Also the weight of the container had decreased, and the weight loss was equivalent to the weight of the powder particles. It was clear that the powder on the surface of the glass container was dissolved by water. Moreover, Antoine Lavoisier found that water did not turn into soil.

From the four elements of Aristotle, Lavoisier stopped experimenting on earth and water and now switched to air and fire. He decided to find out what happened to the air during combustion. By using air and water, he would also examine a second process called calcination. When metals are heated a lime-like substance forms on the surface of the metal; chemists thought this type of calcination was kind of slow burning. The fire, or rather its main component, phlogiston—the mysterious substance named by German chemist Georg Ernst Stahl—was thought to be responsible for both calcination and burning. Nobody had detected phlogiston, but it was thought to be present at everything that was burning, at different rates. Oil and coal were said to be almost pure phlogiston.

When substances burned, phlogiston was released from the substance, producing fire. The same process was thought to produce calx during calcination. But Lavoisier wasn't too happy with this statement as the final weight of the burned metal was more than the weight of the initial metal when its weight and calx's weight were added together.

If phlogiston was thrown out of the metal, then how the burned metal could be heavier? Antoine Lavoisier suspected that something was added to the metal to form calx and it could be the air.

The birth of Modern chemistry

"Planche XIII. Des fourneaux" written by Madam Lavoisier for the Traite elementaire de chimie (Elementary Treatise on Chemistry), showing various furnace and distillation apparatus.
"Planche XIII. Des fourneaux" written by Madam Lavoisier for the Traite elementaire de chimie (Elementary Treatise on Chemistry), showing various furnace and distillation apparatus.

Antoine Lavoisier delivered a sealed envelope to the Academy of Sciences on November 1, 1772, to be opened in 1773. He found that when sulfur and phosphorus were burned with air, their weight would never decrease, in fact, it would actually increase. Moreover, when the lead calx, called litharge, was treated with charcoal, it was losing weight and releasing a large amount of air. Early in the next year, he wrote the memorandum of a long series of experiments that he intended to begin to clarify the role of gases in chemical combustion. One of his aims was to discover whether the air involved in combustion and calcination was atmospheric air or a special kind of air, which then known as "fixed air", that was named by Scottish chemist Joseph Black (we know it as carbon dioxide today). The answer to this question would revolutionize chemistry.

British scientist Joseph Priestley helped Lavoisier in initiating this revolution. In 1774, he went to Lavoisier's house in Paris for a dinner and told him that he had discovered a new kind of air. While working on the mercury calx, he had found that air was extracted from calx as it turned back into metal, and this air had completely different properties than Black's "fixed air". Priestley called it "air without phlogiston". But Lavoisier did not resort to phlogiston, as he understood the meaning of this phenomenon better than Priestley. Unlike other calxes, this new gas could not come from charcoal, as mercury calx did not require charcoal to return to metal; it should have come from the calx itself.

On April 26, 1775, Lavoisier proudly reported to the Academy of Sciences: "The principle [substance] which combines with metals during their calcination is the purest part of the air. That…fixed air…results from the combination of the highly respirable part of the air with charcoal." He later called this "purest part" as "oxygen" which means "acid producer" in Greek, because he (wrongly) thought that all acids contain oxygen.

In 1783, British scientist Henry Cavendish burned hydrogen in a closed container to obtain water. He accurately concluded that water created from the burning. But since he still believed that oxygen does not contain phlogiston, he thought the missing substance was supplied by hydrogen. In the presence of many members of the Academy, Lavoisier repeated Cavendish's experiment and showed that hydrogen and oxygen form water when burned together. He argued that water is a combination of two gases, not one element. In 1785, he carried out a major experiment on the analysis and synthesis of water, the experiment both validated his discovery and enabled the development of hydrogen on a large scale production method. (Soon after, Lavoisier would realize how hydrogen was a better lifting gas while refereeing a hot air balloon competition between Montgolfier brothers and another inventor.)

There was nothing left of Aristotle's theory of the four elements of earth, water, fire, and air and there was no such thing as phlogiston. The chemical elements needed a new definition and in 1787 Lavoisier, Claude Berthollet, Antoine François de Fourcroy, and Louis Bernard Guyton de Morveau published the new Chemical Nomenclature that would change our understanding of chemistry. Two years later, Lavoisier summarized his ideas in his work Traite elementaire de chimie and presented a list of the known elements.

The chemistry of life: oxygen

During the french Revolution, Jacobean Terror led to the execution of intellectuals such as Antoine Lavoisier.
During the French Revolution, Jacobean Terror led to the execution of intellectuals such as Antoine Lavoisier.

Lavoisier was now exploring the physiology of the human respiratory. He concluded that breathing was kind of slow burning. Therefore, the oxygen in the air must be essential for the chemistry of life. Lavoisier invented the calorimeter with Pierre Simon-Laplace to measure the heat emitted from an animal. He compared this with the heat released in the combustion of coal and actually determined the animal's energy consumption. He then compared animal and human oxygen consumption while inactive and also on the move. Lavoisier created two papers on the physiology of animal respiration.

Lavoisier was one of the first to predict the value of the chemical approach to the physiology of nutrition and the mechanisms of tissue anabolism. In the 1790s, he was ready to start a second scientific revolution in biology. He sensed the vital role of the liver in synthesis. In fact, he had created a conceptual study program and it would take almost 100 years for science to develop it.

Why was Antoine Lavoisier executed?

The French Revolution began in 1789, and Lavoisier was drawn into the process of demolition of the General Farm, which was thought to represent the worst excesses of the regime and hated by revolutionaries. All his contributions in other areas had been forgotten:

  • Significant progress in gunpowder production in his management
  • Agricultural reform thanks to his model farm in Frenchies, the first scientific farm
  • Efforts to enforce the metric system
  • Participation in the Art and Trade Advisory Board
  • Deep thoughts on public education
  • Efforts to save France from bankruptcy
  • His collection of memories, Regional Welfare of the French Kingdom, a touchstone in the history of economics

During the hottest days of the Terror Period on May 28, 1794, the Jacobins—assuming that all officers of the tax farm were anti-revolutionary—caught 28 government representatives of the national treasury, and judged them in the Revolutionary Tribunal. All were found guilty and executed with a guillotine at the Place de revolution. Antoine Lavoisier was the fourth. The great mathematician Joseph Lagrange commented on this event: "It took only a moment to cause this head to fall and a hundred years will not suffice to produce its like."

Antoine Lavoisier quotes

  • "In nature nothing is created, nothing is lost, everything changes."
  • "Life is a chemical process."
  • "Nothing is born, nothing dies."
  • "This theory [the oxygen theory] is not as I have heard it described, that of the French chemists, it is mine (elle est la mienne); it is a property which I claim from my contemporaries and from posterity."