One autumn day in 1772, Parisians walking near the Louvre, in the garden of the Infanta, along the Seine embankment, could see a strange structure resembling a flat cart in the form of a wooden platform on six wheels. It had huge windows. The two largest lenses, which had a radius of eight feet, were fastened together to form a magnifying glass that collected the sun's rays and directed them to a second, smaller lens, and then to the surface of the table. Scientists in wigs and black glasses, engaged in the experiment, stood on the platform, and their assistants scurried around like sailors on the deck, setting up this entire complex structure in the sun, continuously keeping the luminary floating across the sky “at gunpoint”.
Antoine Laurent Lavoisier was among the people who used this facility - the "elementary particle accelerator" of the 18th century. He was then interested in what happens when a diamond is burned.
It has long been known that diamonds burn, and local jewelers asked the French Academy of Sciences to investigate if there was any risk involved. Lavoisier himself was interested in a somewhat different question: the chemical nature of combustion. The whole beauty of the "fire glass" was that it, by focusing the sun's rays at a point inside the container, heated everything that could be placed at that point. The smoke from the vessel could be directed through a tube into a vessel of water, the particles contained therein were precipitated, then the water was evaporated and the residue analyzed.
Unfortunately, the experiment failed: the glass constantly burst from intense heating. However, Lavoisier did not despair - he had other ideas. He proposed to the Academy of Sciences a program to study "the air contained in matter" and how it, this air, is related to combustion processes.
Newton managed to direct the development of physics along the right path, but in chemistry in those days things were very bad - she was still a prisoner of alchemy. “Henna dissolved in a well deflegmented spirit of saltpeter will give a colorless solution,” wrote Newton. “But if you put it in good vitriol oil and shake it until it dissolves, the mixture will first turn yellow and then dark red.” The pages of this "cookbook" did not say anything about measurements or quantities. “If the spirit of salt is placed in fresh urine, then both solutions mix easily and calmly,” he noted, “but if the same solution is dropped onto evaporated urine, then hissing and boiling will follow, and volatile and acidic salts coagulate into a third after some time. a substance resembling ammonia in nature. And if a decoction of violets is diluted by dissolving in a small amount of fresh urine, then a few drops of fermented urine will acquire a bright green color.
Very far from modern science. In alchemy, even in the writings of Newton himself, much resembles magic. In one of his diaries, he conscientiously rewrote several paragraphs from the book of the alchemist George Starkey, who called himself Philalethes.
The passage begins: "In [Saturn] is hidden an immortal soul." Lead was usually understood as Saturn, since each element was associated with some planet. But in this case, the silvery metal known as antimony was meant. "Immortal Spirit" is a gas that ore emits when heated strongly. “Mars is tied to Saturn with bonds of love (this meant that iron was added to antimony), which in itself devours a great power, whose spirit divides the body of Saturn, and from both together wonderful bright water flows into which the Sun sets, releasing its light” . The sun is gold, which in this case is immersed in mercury, often called an amalgam. "Venus, the brightest star, is in the arms of [Mars]." Venus was called copper, which is added to the mixture at this stage. This metallurgical recipe, most likely, is a description of the early stages of obtaining the "philosopher's stone", which all alchemists aspired to, since it was believed that with its help it was possible to turn base elements into gold.
Lavoisier and his contemporaries managed to go beyond these mystical incantations, but chemists even at that time still believed in alchemical ideas that the behavior of substances is determined by three principles: mercury (which liquefies), salt (which thickens) and sulfur (which makes the substance combustible). ). The "sulphurous spirit," also called terra pingua ("fatty" or "oily" earth), has occupied the minds of very many. At the beginning of the 18th century, the German chemist Georg Ernst Stahl began to call it phlogiston (from the Greek phlog - referring to fire).
It was believed that objects burn because they contain a lot of phlogiston. As objects are consumed by fire, they release this combustible substance into the air. If you set fire to a piece of wood, then it will stop burning, leaving behind only a pile of ash, only when it uses up all its phlogiston. Therefore, it was believed that the tree consists of ash and phlogiston. Similarly, after calcination, i. strong heating, the metal remains a white, brittle substance known as scale. Therefore, the metal consists of phlogiston and scale. The rusting process is a slow combustion, like breathing, i.e. reactions that occur when phlogiston is released into the air.
The reverse process was also considered. The dross was believed to resemble ore mined from the earth, which was then refined, undergoing reduction, or "revival", by heating next to charcoal. The charcoal gave off phlogiston, which combined with the dross to restore the shiny metal.
In itself, the use of a hypothetical substance that cannot be measured, but can be assumed, does not contain anything wrong. In our time, cosmologists also operate with the concept of “dark matter”, which must exist so that galaxies do not scatter into pieces during rotation under the action of centrifugal force, and that antigravitational “dark energy” is behind the expansion of the Universe.
With the help of phlogiston, scientists could logically explain combustion, calcination, reduction, and even respiration. Chemistry suddenly made sense.
Nevertheless, this did not solve all the problems: the scale remaining after calcination weighed more than the original metal. How could it happen that after the release of phlogiston from the substance, it became heavier? Like "dark energy" a quarter of a millennium later, phlogiston, in the words of the French philosopher Condorcet, "was set in motion by forces opposite in direction to gravity." To make this idea more poetic, one chemist said that phlogiston "gives wings to the earth's molecules."
Lavoisier, like the scientists of that time, was sure that phlogiston was one of the main constituents of matter. But by the beginning of experiments with diamonds, he began to think: can something weigh less than zero?
His mother died when he was still a boy, leaving him an inheritance that was enough to enter into a lucrative enterprise called the Main Farm. The French government entered into an agreement with this consortium of private individuals to collect taxes, from which tax-farmers like Lavoisier had a certain share. This activity constantly distracted him from research, but gave him an income that allowed him, after a while, to become the owner of one of the best laboratories in Europe. Among the first experiments in 1769 was an experiment with which Lavoisier decided to test the then current idea that water could be turned into earth.
The evidence was convincing enough: water evaporating in a frying pan leaves a solid residue. But Lavoisier decided to get to the bottom of it using a distillation vessel known as a "pelican". Having a large round container at the base and a small upper chamber, the vessel was equipped with two bent tubes (a bit like a pelican's beak) through which the steam returned down again. For alchemists, the pelican symbolized the sacrificial blood of Christ, so it was believed that the “pelican” vessel had the power of transformation. Moreover, the water that boiled in the Pelican would continuously evaporate and condense, so that no substance - solid, liquid or gaseous - could leave the system.
Distilling pure water for a hundred days, Lavoisier discovered that the precipitate really existed. But he guessed where it comes from. As he weighed the empty Pelican, he noticed that the vessel had become lighter. After drying and weighing the sediment, Lavoisier saw that the weight of the sediment corresponded quite accurately to the decrease in the weight of the vessel, and this fact led him to the idea that the glass of the vessel became the source of the sediment.
Two years later, in 1771, Lavoisier was twenty-eight years old. In the same year he got married. His chosen one was Marie-Anne Pierrette Polze, the thirteen-year-old daughter of another farmer. (This rather pretty girl was engaged by that time, and her second potential fiancé was fifty.) Maria Anna liked her husband’s scientific studies so much that she quickly mastered chemistry and helped in any way she could: she took notes, translated English scientific literature into French and performed the most complex blueprints for an experiment so elegant that, like the philosopher's stone, it was destined to transform alchemy into chemistry.
The chemists of Lavoisier's generation already knew that, as the Englishman Joseph Priestley put it, "there are several kinds of air." The mephitic ("foetid" or "stale") air causes the flame to go out, and the mouse in it dies of suffocation. Such air makes lime water (calcium hydroxide) cloudy, forming a white precipitate (calcium carbonate). However, the plants felt good in this air and after a while made it breathable again.
Another suffocating gas was formed when a candle burned for some time in a closed vessel. This gas did not precipitate lime water, and, since it was quite obviously associated with the combustion process, it became known as phlogistic air, or nitrogen (from the Greek "lifeless"). The most mysterious was the volatile gas released when the iron filings were dissolved in dilute sulfuric acid. It was so combustible that it was called "combustible air". If you inflate a balloon with this air, it will rise high above the ground.
The question arose whether the new types of air were chemical elements or, as Priestley suggested, modifications of "ordinary" air obtained by adding or extracting phlogiston?
With difficulty restraining skepticism, Lavoisier repeated some of the experiments of his colleagues. He confirmed that the combustion of phosphorus to produce phosphoric acid or the combustion of sulfur to produce sulfuric acid results in substances whose weight exceeds the weight of the substances used, i.e. as in the annealing of metals. But why does this change occur? It seemed to him that he had found the answer to this question. Using a magnifying glass to heat tin, enclosed in a sealed glass vessel, he found that before and after the experiment, the whole installation weighed the same. Slowly opening the vessel, he heard the air rush in with a noise, after which the weight increased again. Maybe objects burn not because they emit phlogiston, but because they absorb some of the air?
If so, then recovery, i.e. smelting ore into pure metal leads to the release of air. He measured out a certain amount of lead scale, which is called "litharge", and placed it on a small platform in a vessel of water next to a piece of charcoal. Having covered all this with a glass bell, he began to heat the scale with a magnifying glass. From the displaced water, he could guess about the release of gas. Carefully collecting the released gas, he found that the flame goes out from this gas and lime water precipitates. It looks like the "stale" air was a product of the restoration, but was it just that?
It turned out that the answer lay in a reddish substance called mercurius calcinatus, or mercury scale, which was sold by Parisian apothecaries as a cure for syphilis at a price of 18 or more livres per ounce, i.e. $1,000 if translated into today's prices. Any experiments with this substance were no less extravagant than experiments with burning diamonds. Like any other scale, it could be obtained by calcining pure metal in a strong flame. However, upon further heating, the resulting substance again turned into mercury. In other words, mercurius calcinatus could be regenerated even without the use of charcoal. But what then was the source of phlogiston? In 1774, Lavoisier and several of his colleagues at the French Academy of Sciences confirmed that mercury scale could indeed be reduced "without additional substances" with a loss of about one-twelfth of the weight.
Priestley also experimented with this substance, heating it with a magnifying glass and collecting the released gases. “What struck me so much that there are not even enough words to express the feelings that overwhelmed me,” he later wrote, “is that the candle burned in this air with a rather strong flame ... I could not find an explanation for this phenomenon.” Finding out that the laboratory mouse felt good in the magic gas, he decided to breathe it himself. “It seemed to me that after some time I felt an extraordinary lightness and freedom in my chest. Who would have guessed that this clean air would eventually become a fashionable luxury item. In the meantime, only two mice and myself have had the pleasure of inhaling it.
The gas in which one breathes well and burns easily, Priestley decided to call "dephlogisticated", i.e. air in its purest form. He was not alone in such reasoning. In Sweden, a pharmacist named Carl Wilhelm Scheele also studied the properties of "fire air".
By this time, Lavoisier was already calling the gas released during the restoration of mercurius calcinatus "extremely useful for breathing," or "living" air. Like Priestley, he believed that this gas was air in its original form. Here, however, Lavoisier ran into a difficulty. When he tried to recover mercury scale using charcoal, i.e. in the old, proven way, the same gas was released as during the restoration of litharge - it extinguished the flame of a candle and precipitated lime water. Why was “living” air released when mercury scale was reduced without charcoal, but when charcoal was used, suffocating “stale” air appeared?
There was only one way to clear everything up. Lavoisier took from the shelf a vessel called a flat flask. The lower part of it was round, and the high neck was heated and bent by Lavoisier so that it first curved down and then up again.
If in his experiment of 1769 the vessel resembled a pelican, then the current one looked like a flamingo. Lavoisier poured four ounces of pure mercury into the round lower chamber of the vessel (labeled A in the figure). The vessel was placed on the furnace so that its neck was in an open container, also filled with mercury, and then raised into a glass bell. This part of the setup was used to determine the amount of air that would be consumed during the experiment. Marking the level (LL) with a paper strip, he lit the stove and brought the mercury in chamber A almost to a boil.
It can be assumed that nothing special happened on the first day. A small amount of mercury evaporated and settled on the walls of the flat flask. The resulting balls were heavy enough to flow down again. But on the second day, red dots began to form on the surface of the mercury - scale. Over the next few days, the red crust increased in size until it reached its maximum. On the twelfth day, Lavoisier stopped the experiment and took some measurements.
At that time, the mercury in the glass bell exceeded the initial level by the amount of air that was used to form scale. Taking into account changes in temperature and pressure inside the laboratory, Lavoisier calculated that the amount of air had decreased by about one-sixth of its original volume, i.e. from 820 to 700 cubic centimeters. In addition, the nature of the gas has changed. When a mouse was placed inside the container containing the remaining air, it immediately began to suffocate, and “the candle placed in this air immediately went out, as if it had been put into water.” But since the gas did not cause settling in the lime water, it was more likely to be attributed to nitrogen than to "stale air."
But what did mercury get from the air during combustion? After removing the red coating that had formed on the metal, Lavoisier began to heat it in a retort until it became mercury again, releasing from 100 to 150 cubic centimeters of gas - about the same amount as mercury absorbed during calcination. The candle introduced into this gas "burned beautifully", and the charcoal did not smolder, but "shone with such a bright light that the eyes could hardly bear it."
It was a turning point. Burning, mercury absorbed the "living" air from the atmosphere, leaving nitrogen. The recovery of mercury again led to the release of "live" air. So Lavoisier managed to separate the two main components of atmospheric air.
To be sure, he mixed eight parts of "living" air and forty-two parts of nitrogen and showed that the resulting gas had all the characteristics of ordinary air. Analysis and synthesis: "This is the most convincing evidence available in chemistry: when it decomposes, air recombines."
In 1777, Lavoisier reported the results of his research to members of the Academy of Sciences. Phlogiston turned out to be a fabrication. Combustion and calcination occurred when the substance absorbed "living" air, which he called oxygen because of its role in the formation of acids. (Oxy is Greek for "sharp.") The absorption of oxygen from the air leaves only unbreathable nitrogen in the air.
As for the gas, which was called "stale" air, it was formed when the oxygen released during reduction combined with something in the charcoal, and what we today call carbon dioxide was obtained.
Year after year, Lavoisier's colleagues, especially Priestley, grumbled that he allegedly appropriated the primacy in the experiments they also carried out. Priestley once dined at the Lavoisier couple's house and told them about his phlogiston-deprived air, and the Swedish pharmacist Scheele sent Lavoisier a letter describing your experience. But with all this, they continued to think that oxygen is air devoid of phlogiston.
In the play Oxygen, which premiered in 2001, two chemists, Carl Gerassi and Roald Hoffman, came up with a plot in which the Swedish king invited these three scientists to Stockholm to decide which of them should be considered the discoverer of oxygen. Scheele was the first to isolate the gas, and Priestley was the first to publish a paper that spoke of its existence, but only Lavoisier understood what they had discovered.
He looked much deeper and formulated the law of conservation of mass. As a result of a chemical reaction, the substance - in this case, burning mercury and air - changes shape. But the mass is not created and does not disappear. How many substances enter into the reaction, the same amount should be obtained at the output. As a tax collector would say, the balance has to come together anyway.
In 1794, during the revolutionary terror, Lavoisier and Marie Anne's father, along with other tax farmers, were recognized as "enemies of the people." They were brought on a cart to the Place de la Revolución, where a wooden platform had already been built, the appearance of which, even in detail, resembled the platform on which Lavoisier burned diamonds. Only instead of huge lenses there was another achievement of French technology - the guillotine.
A message has recently slipped on the Internet that during the execution, Lavoisier managed to carry out his last experiment. The fact is that in France they began to use the guillotine, because they considered it to be the most humane form of execution - it brings instant and painless death. And now Lavoisier had a chance to find out if this was so. The moment the guillotine blade touched his neck, he blinked his eyes and did it as much as he could. There was an assistant in the crowd who had to count how many times he managed to blink. It is possible that this story is a fiction, but quite in the spirit of Lavoisier.
These words in the play are spoken by Marie-Anne Lavoisier.
Carbon (English Carbon, French Carbone, German Kohlenstoff) in the form of coal, soot and soot has been known to mankind since time immemorial; about 100 thousand years ago, when our ancestors mastered fire, they dealt with coal and soot every day. Probably, very early people got acquainted with the allotropic modifications of carbon - diamond and graphite, as well as with fossil coal. Not surprisingly, the combustion of carbonaceous substances was one of the first chemical processes that interested man. Since the burning substance disappeared, being consumed by fire, combustion was considered as a process of decomposition of the substance, and therefore coal (or carbon) was not considered an element. The element was fire, a phenomenon that accompanies combustion; in the teachings of the elements of antiquity, fire usually figures as one of the elements. At the turn of the XVII - XVIII centuries. the theory of phlogiston, put forward by Becher and Stahl, arose. This theory recognized the presence in each combustible body of a special elementary substance - a weightless fluid - phlogiston, which evaporates during combustion. Since only a small amount of ash remains when burning a large amount of coal, phlogistics believed that coal is almost pure phlogiston. This was the explanation, in particular, for the "phlogistic" effect of coal, its ability to restore metals from "lime" and ores. Later phlogistics, Réaumur, Bergman and others, have already begun to understand that coal is an elementary substance. However, for the first time "pure coal" was recognized as such by Lavoisier, who studied the process of burning coal and other substances in air and oxygen. In the book of Guiton de Morveau, Lavoisier, Berthollet and Fourcroix "Method of Chemical Nomenclature" (1787), the name "carbon" (carbone) appeared instead of the French "pure coal" (charbone pur). Under the same name, carbon appears in the "Table of Simple Bodies" in Lavoisier's "Elementary Textbook of Chemistry". In 1791, the English chemist Tennant was the first to obtain free carbon; he passed phosphorus vapor over calcined chalk, resulting in the formation of calcium phosphate and carbon. The fact that a diamond burns without residue when heated strongly has been known for a long time. Back in 1751, the French king Francis I agreed to give a diamond and a ruby for burning experiments, after which these experiments even became fashionable. It turned out that only diamond burns, and ruby (aluminum oxide with an admixture of chromium) withstands long-term heating at the focus of the incendiary lens without damage. Lavoisier set up a new experiment in burning diamond with a large incendiary machine, and came to the conclusion that diamond is crystalline carbon. The second allotrope of carbon - graphite in the alchemical period was considered a modified lead luster and was called plumbago; only in 1740 did Pott discover the absence of any lead impurity in graphite. Scheele studied graphite (1779) and, being a phlogistician, considered it to be a sulfur body of a special kind, a special mineral coal containing bound "air acid" (CO 2 ,) and a large amount of phlogiston.
Twenty years later Guiton de Morveau, by gentle heating, turned the diamond into graphite and then into carbonic acid.
The international name Carboneum comes from lat. carbo (coal). The word is of very ancient origin. It is compared with cremare - to burn; the root of the sagas, cal, Russian gar, gal, goal, Sanskrit sta means to boil, cook. The word "carbo" is associated with the names of carbon in other European languages (carbon, charbone, etc.). The German Kohlenstoff comes from Kohle - coal (Old German kolo, Swedish kylla - to heat). The Old Russian Ugarati, or ugarati (burn, scorch) has the root gar, or mountains, with a possible transition to a goal; coal in Old Russian yug'l, or coal, of the same origin. The word diamond (Diamante) comes from the ancient Greek - indestructible, adamant, hard, and graphite from the Greek - I write.
At the beginning of the XIX century. the old word coal in Russian chemical literature was sometimes replaced by the word "coal" (Sherer, 1807; Severgin, 1815); since 1824 Solovyov introduced the name carbon.
One autumn day in 1772, Parisians walking near the Louvre, in the garden of the Infanta, along the Seine embankment, could see a strange structure resembling a flat cart in the form of a wooden platform on six wheels. It had huge windows. The two largest lenses, which had a radius of eight feet, were fastened together to form a magnifying glass that collected the sun's rays and directed them to a second, smaller lens, and then to the surface of the table. Scientists in wigs and black glasses, engaged in the experiment, stood on the platform, and their assistants scurried around like sailors on the deck, setting up this entire complex structure in the sun, continuously keeping the luminary floating across the sky “at gunpoint”.
Antoine Laurent Lavoisier was among the people who used this facility - the "elementary particle accelerator" of the 18th century. He was then interested in what happens when a diamond is burned.
It has long been known that diamonds burn, and local jewelers asked the French Academy of Sciences to investigate if there was any risk involved. Lavoisier himself was interested in a somewhat different question: the chemical nature of combustion. The whole beauty of the "fire glass" was that it, by focusing the sun's rays at a point inside the container, heated everything that could be placed at that point. The smoke from the vessel could be directed through a tube into a vessel of water, the particles contained therein were precipitated, then the water was evaporated and the residue analyzed.
Unfortunately, the experiment failed: the glass constantly burst from intense heating. However, Lavoisier did not despair - he had other ideas. He proposed to the Academy of Sciences a program to study "the air contained in matter" and how it, this air, is related to combustion processes.
Newton managed to direct the development of physics along the right path, but in those days things were very bad in chemistry - it was still a prisoner of alchemy. “Henna dissolved in a well deflegmented spirit of saltpeter will give a colorless solution,” wrote Newton. “But if you put it in good vitriol oil and shake it until it dissolves, the mixture will first turn yellow and then dark red.” The pages of this "cookbook" did not say anything about measurements or quantities. “If the spirit of salt is placed in fresh urine, then both solutions mix easily and calmly,” he noted, “but if the same solution is dropped onto evaporated urine, then hissing and boiling will follow, and volatile and acidic salts coagulate into a third after some time. a substance resembling ammonia in nature. And if a decoction of violets is diluted by dissolving in a small amount of fresh urine, then a few drops of fermented urine will acquire a bright green color.
Very far from modern science. In alchemy, even in the writings of Newton himself, much resembles magic. In one of his diaries, he conscientiously rewrote several paragraphs from the book of the alchemist George Starkey, who called himself Philalethes.
The passage begins: "In [Saturn] is hidden an immortal soul." Lead was usually understood as Saturn, since each element was associated with some planet. But in this case, the silvery metal known as antimony was meant. "Immortal Spirit" is a gas that ore emits when heated strongly. “Mars is tied to Saturn with bonds of love (this meant that iron was added to antimony), which in itself devours a great power, whose spirit divides the body of Saturn, and from both together wonderful bright water flows into which the Sun sets, releasing its light” . The sun is gold, which in this case is immersed in mercury, often called an amalgam. "Venus, the brightest star, is in the arms of [Mars]." Venus was called copper, which is added to the mixture at this stage. This metallurgical recipe, most likely, is a description of the early stages of obtaining the "philosopher's stone", which all alchemists aspired to, since it was believed that with its help it was possible to turn base elements into gold.
Lavoisier and his contemporaries managed to go beyond these mystical incantations, but chemists even at that time still believed in alchemical ideas that the behavior of substances is determined by three principles: mercury (which liquefies), salt (which thickens) and sulfur (which makes the substance combustible). ). The "sulphurous spirit," also called terra pingua ("fatty" or "oily" earth), has occupied the minds of very many. At the beginning of the 18th century, the German chemist Georg Ernst Stahl began to call it phlogiston (from the Greek phlog - referring to fire).
It was believed that objects burn because they contain a lot of phlogiston. As objects are consumed by fire, they release this combustible substance into the air. If you set fire to a piece of wood, then it will stop burning, leaving behind only a pile of ash, only when it uses up all its phlogiston. Therefore, it was believed that the tree consists of ash and phlogiston. Similarly, after calcination, i. strong heating, the metal remains a white, brittle substance known as scale. Therefore, the metal consists of phlogiston and scale. The rusting process is a slow combustion, like breathing, i.e. reactions that occur when phlogiston is released into the air.
The reverse process was also considered. The dross was believed to resemble ore mined from the earth, which was then refined, undergoing reduction, or "revival", by heating next to charcoal. The charcoal gave off phlogiston, which combined with the dross to restore the shiny metal.
In itself, the use of a hypothetical substance that cannot be measured, but can be assumed, does not contain anything wrong. In our time, cosmologists also operate with the concept of “dark matter”, which must exist so that galaxies do not scatter into pieces during rotation under the action of centrifugal force, and that antigravitational “dark energy” is behind the expansion of the Universe.
With the help of phlogiston, scientists could logically explain combustion, calcination, reduction, and even respiration. Chemistry suddenly made sense.
Nevertheless, this did not solve all the problems: the scale remaining after calcination weighed more than the original metal. How could it happen that after the release of phlogiston from the substance, it became heavier? Like "dark energy" a quarter of a millennium later, phlogiston, in the words of the French philosopher Condorcet, "was set in motion by forces opposite in direction to gravity." To make this idea more poetic, one chemist said that phlogiston "gives wings to the earth's molecules."
Lavoisier, like the scientists of that time, was sure that phlogiston was one of the main constituents of matter. But by the beginning of experiments with diamonds, he began to think: can something weigh less than zero?
His mother died when he was still a boy, leaving him an inheritance that was enough to enter into a lucrative enterprise called the Main Farm. The French government entered into an agreement with this consortium of private individuals to collect taxes, from which tax-farmers like Lavoisier had a certain share. This activity constantly distracted him from research, but gave him an income that allowed him, after a while, to become the owner of one of the best laboratories in Europe. Among the first experiments in 1769 was an experiment with which Lavoisier decided to test the then current idea that water could be turned into earth.
The evidence was convincing enough: water evaporating in a frying pan leaves a solid residue. But Lavoisier decided to get to the bottom of it using a distillation vessel known as a "pelican". Having a large round container at the base and a small upper chamber, the vessel was equipped with two bent tubes (a bit like a pelican's beak) through which the steam returned down again. For alchemists, the pelican symbolized the sacrificial blood of Christ, so it was believed that the “pelican” vessel had the power of transformation. Moreover, the water that boiled in the Pelican would continuously evaporate and condense, so that no matter - solid, liquid or gaseous - could leave the system.
Distilling pure water for a hundred days, Lavoisier discovered that the precipitate really existed. But he guessed where it comes from. As he weighed the empty Pelican, he noticed that the vessel had become lighter. After drying and weighing the sediment, Lavoisier saw that the weight of the sediment corresponded quite accurately to the decrease in the weight of the vessel, and this fact led him to the idea that the glass of the vessel became the source of the sediment.
Two years later, in 1771, Lavoisier was twenty-eight years old. In the same year he got married. His chosen one was Marie-Anne Pierrette Polze, the thirteen-year-old daughter of another farmer. (This rather pretty girl was engaged by that time, and her second potential fiancé was fifty.) Maria Anna liked her husband’s scientific studies so much that she quickly mastered chemistry and helped in any way she could: she took notes, translated English scientific literature into French and performed the most complex blueprints for an experiment so elegant that, like the philosopher's stone, it was destined to transform alchemy into chemistry.
The chemists of Lavoisier's generation already knew that, as the Englishman Joseph Priestley put it, "there are several kinds of air." The mephitic ("foetid" or "stale") air causes the flame to go out, and the mouse in it dies of suffocation. Such air makes lime water (calcium hydroxide) cloudy, forming a white precipitate (calcium carbonate). However, the plants felt good in this air and after a while made it breathable again.
Another suffocating gas was formed when a candle burned for some time in a closed vessel. This gas did not precipitate lime water, and, since it was quite obviously associated with the combustion process, it became known as phlogistic air, or nitrogen (from the Greek "lifeless"). The most mysterious was the volatile gas released when the iron filings were dissolved in dilute sulfuric acid. It was so combustible that it was called "combustible air". If you inflate a balloon with this air, it will rise high above the ground.
The question arose whether the new types of air were chemical elements or, as Priestley suggested, modifications of "ordinary" air obtained by adding or extracting phlogiston?
With difficulty restraining skepticism, Lavoisier repeated some of the experiments of his colleagues. He confirmed that the combustion of phosphorus to produce phosphoric acid or the combustion of sulfur to produce sulfuric acid results in substances whose weight exceeds the weight of the substances used, i.e. as in the annealing of metals. But why does this change occur? It seemed to him that he had found the answer to this question. Using a magnifying glass to heat tin, enclosed in a sealed glass vessel, he found that before and after the experiment, the whole installation weighed the same. Slowly opening the vessel, he heard the air rush in with a noise, after which the weight increased again. Maybe objects burn not because they emit phlogiston, but because they absorb some of the air?
If so, then recovery, i.e. smelting ore into pure metal leads to the release of air. He measured out a certain amount of lead scale, which is called "litharge", and placed it on a small platform in a vessel of water next to a piece of charcoal. Having covered all this with a glass bell, he began to heat the scale with a magnifying glass. From the displaced water, he could guess about the release of gas. Carefully collecting the released gas, he found that the flame goes out from this gas and lime water precipitates. It looks like the "stale" air was a product of the restoration, but was it just that?
It turned out that the answer lay in a reddish substance called mercurius calcinatus, or mercury scale, which was sold by Parisian apothecaries as a cure for syphilis at a price of 18 or more livres per ounce, i.e. $1,000 if translated into today's prices. Any experiments with this substance were no less extravagant than experiments with burning diamonds. Like any other scale, it could be obtained by calcining pure metal in a strong flame. However, upon further heating, the resulting substance again turned into mercury. In other words, mercurius calcinatus could be regenerated even without the use of charcoal. But what then was the source of phlogiston? In 1774, Lavoisier and several of his colleagues at the French Academy of Sciences confirmed that mercury scale could indeed be reduced "without additional substances" with a loss of about one-twelfth of the weight.
Priestley also experimented with this substance, heating it with a magnifying glass and collecting the released gases. “What struck me so much that there are not even enough words to express the feelings that overwhelmed me,” he later wrote, “is that the candle burned in this air with a rather strong flame ... I could not find an explanation for this phenomenon.” Finding out that the laboratory mouse felt good in the magic gas, he decided to breathe it himself. “It seemed to me that after some time I felt an extraordinary lightness and freedom in my chest. Who would have guessed that this clean air would eventually become a fashionable luxury item. In the meantime, only two mice and myself have had the pleasure of inhaling it.
The gas in which one breathes well and burns easily, Priestley decided to call "dephlogisticated", i.e. air in its purest form. He was not alone in such reasoning. In Sweden, a pharmacist named Carl Wilhelm Scheele also studied the properties of "fire air".
By this time, Lavoisier was already calling the gas released during the restoration of mercurius calcinatus "extremely useful for breathing," or "living" air. Like Priestley, he believed that this gas was air in its original form. Here, however, Lavoisier ran into a difficulty. When he tried to recover mercury scale using charcoal, i.e. in the old, proven way, the same gas was released as during the restoration of litharge - it extinguished the flame of a candle and precipitated lime water. Why was “living” air released when mercury scale was reduced without charcoal, but when charcoal was used, suffocating “stale” air appeared?
There was only one way to clear everything up. Lavoisier took from the shelf a vessel called a flat flask. The lower part of it was round, and the high neck was heated and bent by Lavoisier so that it first curved down and then up again.
If in his experiment of 1769 the vessel resembled a pelican, then the current one looked like a flamingo. Lavoisier poured four ounces of pure mercury into the round lower chamber of the vessel (labeled A in the figure). The vessel was placed on the furnace so that its neck was in an open container, also filled with mercury, and then raised into a glass bell. This part of the setup was used to determine the amount of air that would be consumed during the experiment. Marking the level (LL) with a paper strip, he lit the stove and brought the mercury in chamber A almost to a boil.
It can be assumed that nothing special happened on the first day. A small amount of mercury evaporated and settled on the walls of the flat flask. The resulting balls were heavy enough to flow down again. But on the second day, red dots began to form on the surface of the mercury - scale. Over the next few days, the red crust increased in size until it reached its maximum. On the twelfth day, Lavoisier stopped the experiment and took some measurements.
At that time, the mercury in the glass bell exceeded the initial level by the amount of air that was used to form scale. Taking into account changes in temperature and pressure inside the laboratory, Lavoisier calculated that the amount of air had decreased by about one-sixth of its original volume, i.e. from 820 to 700 cubic centimeters. In addition, the nature of the gas has changed. When a mouse was placed inside the container containing the remaining air, it immediately began to suffocate, and “the candle placed in this air immediately went out, as if it had been put into water.” But since the gas did not cause settling in the lime water, it was more likely to be attributed to nitrogen than to "stale air."
But what did mercury get from the air during combustion? After removing the red coating that had formed on the metal, Lavoisier began to heat it in a retort until it became mercury again, releasing from 100 to 150 cubic centimeters of gas - about the same amount as the mercury absorbed when calcined. The candle introduced into this gas "burned beautifully", and the charcoal did not smolder, but "shone with such a bright light that the eyes could hardly bear it."
It was a turning point. Burning, mercury absorbed the "living" air from the atmosphere, leaving nitrogen. The recovery of mercury again led to the release of "live" air. So Lavoisier managed to separate the two main components of atmospheric air.
To be sure, he mixed eight parts of "living" air and forty-two parts of nitrogen and showed that the resulting gas had all the characteristics of ordinary air. Analysis and synthesis: "This is the most convincing evidence available in chemistry: when it decomposes, air recombines."
In 1777, Lavoisier reported the results of his research to members of the Academy of Sciences. Phlogiston turned out to be a fabrication. Combustion and calcination occurred when the substance absorbed "living" air, which he called oxygen because of its role in the formation of acids. (Oxy is Greek for "sharp.") The absorption of oxygen from the air leaves only unbreathable nitrogen in the air.
As for the gas, which was called "stale" air, it was formed when the oxygen released during reduction combined with something in the charcoal, and what we today call carbon dioxide was obtained.
Year after year, Lavoisier's colleagues, especially Priestley, grumbled that he allegedly appropriated the primacy in the experiments they also carried out. Priestley once dined at the Lavoisier couple's house and told them about his phlogiston-deprived air, and the Swedish pharmacist Scheele sent Lavoisier a letter describing your experience. But with all this, they continued to think that oxygen is air devoid of phlogiston.
In the play Oxygen, which premiered in 2001, two chemists, Carl Gerassi and Roald Hoffman, came up with a plot in which the Swedish king invited these three scientists to Stockholm to decide which of them should be considered the discoverer of oxygen. Scheele was the first to isolate the gas, and Priestley was the first to publish a paper that spoke of its existence, but only Lavoisier understood what they had discovered.
He looked much deeper and formulated the law of conservation of mass. As a result of a chemical reaction, the substance - in this case, burning mercury and air - changes shape. But the mass is not created and does not disappear. How many substances enter into the reaction, the same amount should be obtained at the output. As a tax collector would say, the balance has to come together anyway.
In 1794, during the revolutionary terror, Lavoisier and Marie Anne's father, along with other tax farmers, were recognized as "enemies of the people." They were brought on a cart to the Place de la Revolución, where a wooden platform had already been built, the appearance of which, even in detail, resembled the platform on which Lavoisier burned diamonds. Only instead of huge lenses there was another achievement of French technology - the guillotine.
A message has recently slipped on the Internet that during the execution, Lavoisier managed to carry out his last experiment. The fact is that in France they began to use the guillotine, because they considered it to be the most humane form of execution - it brings instant and painless death. And now Lavoisier had a chance to find out if this was so. The moment the guillotine blade touched his neck, he blinked his eyes and did it as much as he could. There was an assistant in the crowd who had to count how many times he managed to blink. It is possible that this story is a fiction, but quite in the spirit of Lavoisier.
(c) George Johnson "The ten most beautiful experiments in science."
The word "diamond" comes from the Greek language. It is translated into Russian as "". Indeed, to damage this stone, you need to make superhuman efforts. It cuts and scratches all minerals known to us, while itself remains unscathed. Acid does not harm him. Once, out of curiosity, an experiment was carried out in a forge: a diamond was placed on an anvil and hit with a hammer. The iron almost split in two, but the stone remained intact.
The diamond burns with a beautiful bluish color.
Of all solids, diamond has the highest thermal conductivity. It is resistant to friction, even against metal. It is the most elastic mineral with the lowest compression ratio. An interesting property of a diamond is to luminesce even under the influence of artificial rays. It glows with all the colors of rainbows and refracts color in an interesting way. This stone seems to be saturated with solar color, and then radiates it. As you know, a natural diamond is ugly, the cut gives it true beauty. A gem made from a cut diamond is called a diamond.
History of experiments
In 17th century England, Boyle managed to burn a diamond by shining a sunbeam on it through a lens. However, in France, the experiment with calcining diamonds in a melting vessel did not give any results. The French jeweler who conducted the experiment found only a thin layer of dark plaque on the stones. At the end of the 17th century, the Italian scientists Averani and Targioni, when trying to fuse two diamonds together, were able to establish the temperature at which a diamond burns - from 720 to 1000 ° C.
Diamond does not melt due to the strong structure of the crystal lattice. All attempts to melt the mineral ended in burning it.
The great French physicist Antoine Lavoisier went further, deciding to place the diamonds in an airtight vessel made of glass and fill it with oxygen. With the help of a large lens, he heated the stones, and they completely burned out. After examining the composition of the air environment, they found that in addition to oxygen, it contains carbon dioxide, which is a combination of oxygen and carbon. Thus, the answer was received: diamonds burn, but only when oxygen is available, i.e. on open air. Burning, the diamond turns into carbon dioxide. That is why, unlike coal, even ash does not remain after the combustion of diamond. The experiments of scientists confirmed another property of diamond: in the absence of oxygen, the diamond does not burn, but its molecular structure changes. At a temperature of 2000 ° C, graphite can be obtained in just 15-30 minutes.
