Lavoisier calcination of tin and mercury. "Ten Most Beautiful Experiments in the History of Science"
In 1764, the Paris Academy of Sciences announced a competition on the topic “To find the best way to illuminate the streets of a large city, combining brightness, ease of maintenance and economy.” The project with the motto “And he will mark his path with lights” (words from Virgil’s “Aeneid”) was recognized as the best. The project scientifically substantiated various street lighting devices: oil lanterns and tallow candles, with and without reflectors, etc.
On April 9, 1765, the winner was awarded the Academy's gold medal. He turned out to be twenty-two-year-old Antoine Laurent Lavoisier - the future pride of French and world science.
He was born on August 26, 1743 in the family of a lawyer in the Parisian court. His father wanted to see Antoine as a lawyer and sent him to the old aristocratic educational institution, Mazarin College, then his studies were continued at the law faculty of the university.
Antoine, who was distinguished by excellent abilities, studied easily, since from a young age he developed the habit of hard, systematic work. At the university, in addition to legal sciences, Lavoisier also studied natural sciences, which he became increasingly interested in. He listens to a course of lectures on chemistry from the famous chemist G. Ruel, studies mineralogy from J. Guettard, and botany from B. de Jussier.
In 1764, Lavoisier graduated from the university with the title of lawyer, and in February of the following year he presented his first work on chemistry, “Analysis of Gypsum,” to the Paris Academy of Sciences, in which his independence and originality of thinking were revealed. If before this the composition of minerals was judged mainly by the “action of fire,” then he studied “on gypsum the effect of water, this almost universal solvent”; studied the crystallization process and found that when gypsum hardens, it absorbs water.
In 1768 he was elected to the Academy of Sciences as an adjunct in the class of chemistry. French scientists had high hopes for him, and they were not mistaken.
In the same year, Lavoisier became general tax farmer. As one of the members of the General Taxation Company, he received the right to collect taxes and duties from the population. While carrying out Company assignments, he inspected tobacco factories and customs offices in western France. The income went mainly to the purchase of expensive instruments for scientific research. Participation in the General Farming became the reason for the tragic death of the great scientist during the bourgeois revolution.
Having many responsibilities for farming matters, Lavoisier studied chemistry only from 6 to 9 am and from 7 to 10 pm every day and once a week (on Saturdays) all day.
Since 1772, Lavoisier began to study the combustion and roasting of metals, intending to “repeat with new precautions in order to combine everything that we know about the air that binds or is released from bodies (we are talking about CO 2 - B.K.), with other acquired knowledge and create a theory." In the same year, he began experiments on combustion and calcination of metals. The first experiment was burning a diamond. Lavoisier placed it in a closed vessel and heated it with a magnifying glass until the diamond disappeared. Having examined the resulting gas, Lavoisier determined that it was “bound air” (CO 2). Then the scientist burned phosphorus and sulfur in hermetically sealed flasks, having previously weighed them. Analyzing the results of the experiments, he became convinced that the weight of phosphorus and sulfur increased during combustion, and this “increase occurs due to the enormous amount of air that binds during combustion.” This leads Lavoisier to believe that air is also absorbed during the calcination of metals. As proof, he will carry out special experiments next year (again, carrying out careful weighing). Various metals were heated in closed vessels: tin, lead, zinc. At first, a layer of scale (oxides) formed on their surface, but after some time the process stopped. However, the scale is heavier than the original metal, and the weight of the vessel before and after heating remained the same. This means that the increase in weight of the metal could only occur due to the air present in the vessel, but then there must be a rarefied space there. And indeed, when the vessel was opened, air rushed into it and the weight of the vessel became greater (remember the experiments of M.V. Lomonosov).
Why doesn’t all the air combine with metals? Which of its components reacts with substances? These questions worried Lavoisier. The answers to them came after a meeting with Priestley.
Repeating the experiments of the English scientist, Lavoisier stated that 1/5 of the air combines with mercury, turning it into scale (mercury oxide), and the remaining 4/5 of the air does not support combustion and respiration. When the oxide is heated, the same volume of air is released, which, mixing with the remaining, gives the original air. Therefore, ordinary air consists of two parts: “clean air” and “suffocating air”.
In 1775, Lavoisier became the “chief manager of gunpowder” (manager of the saltpeter and gunpowder industry). He moves to the Arsenal, where he sets up an excellent laboratory; He worked there almost until the end of his life.
The work carried out led Lavoisier to the idea that “clean” or “life-giving” air, and not fantastic phlogiston, plays an important role in the combustion of substances. The scientist summarized all his rich experimental material in three articles, which he presented to the Academy.
The first examined the interaction of mercury with “vitriol acid” (sulfuric acid) and the roasting of the resulting mercury sulfate. The second article, “On Combustion in General,” was the most important, since in it Lavoisier proposed a “new theory of combustion.” According to this theory, combustion is the process of combining bodies with oxygen with the simultaneous release of heat and light. The resulting products are not simple substances, but complex ones, consisting of body and oxygen. When burning, the weight of substances increases. The third article was entitled “Experiments on the respiration of animals and the changes that occur in the air passing through the lungs.” In it, the author noted that animal respiration is identical to combustion, only it occurs more slowly, and the heat generated during this process maintains a constant temperature in the body.
These works were highly appreciated by F. Engels, who wrote that Lavoisier “for the first time put on its feet all chemistry, which in its phlogistic form stood on its head.”
The oxygen theory of combustion refuted the phlogiston theory. It is not for nothing that the greatest chemists of that time were adherents of phlogiston, and among them Scheele, Cavendish, Priestley refused to recognize it. In Germany, fans of the “fiery matter” even burned a portrait of Lavoisier as a sign of protest...
For his innovative research, Lavoisier was elected academician of the Paris Academy of Sciences in 1778.
In 1789, the “Elementary Course of Chemistry” was published in three parts - one of the most important works of the scientist. That same year, the bourgeois revolution began in France. In March 1792, tax farming was liquidated, and the following year the Convention decided to arrest tax farmers, including Lavoisier. After the trial, all tax farmers were sentenced to death. On May 8, 1794, Lavoisier was guillotined. He was paying, in the words of K. A. Timiryazev, “for the sins of entire generations of predators who sucked the life juice out of the French people.”
Eighteenth century, France, Paris. Antoine Laurent Lavoisier, one of the future creators of chemical science, after many years of experiments with various substances in the quiet of his laboratory, is convinced again and again that he has made a genuine revolution in science. His essentially simple chemical experiments on the combustion of substances in hermetically sealed volumes completely refuted the generally accepted theory of phlogiston at that time. But strong, strictly quantitative evidence in favor of the new “oxygen” theory of combustion is not accepted in the scientific world. The visual and convenient phlogiston model has become very firmly ingrained in our heads.
What to do? Having spent two or three years in fruitless efforts to defend his idea, Lavoisier comes to the conclusion that his scientific environment has not yet matured to purely theoretical arguments and that he should take a completely different path. In 1772, the great chemist decided to undertake an unusual experiment for this purpose. He invites everyone to take part in the spectacle of burning... a weighty piece of diamond in a sealed cauldron. How can one resist curiosity? After all, we are not talking about anything, but about a diamond!
It is quite understandable that, following the sensational message, the scientist’s ardent opponents, who had previously not wanted to delve into his experiments with all sorts of sulfur, phosphorus and coal, poured into the laboratory along with ordinary people. The room was polished to a shine and shone no less than a precious stone sentenced to public burning. It must be said that Lavoisier’s laboratory at that time belonged to one of the best in the world and was fully consistent with an expensive experiment in which the owner’s ideological opponents were now simply eager to take part.
The diamond did not disappoint: it burned without a visible trace, according to the same laws that applied to other despicable substances. Nothing significantly new has happened from a scientific point of view. But the “oxygen” theory, the mechanism of formation of “bound air” (carbon dioxide) have finally reached the consciousness of even the most inveterate skeptics. They realized that the diamond had not disappeared without a trace, but that under the influence of fire and oxygen it had undergone qualitative changes and turned into something else. After all, at the end of the experiment, the flask weighed exactly as much as at the beginning. So, with the false disappearance of the diamond before everyone’s eyes, the word “phlogiston” disappeared forever from the scientific lexicon, denoting a hypothetical component of the substance that is supposedly lost during its combustion.
But a holy place is never empty. One went, another came. The phlogiston theory was supplanted by a new fundamental law of nature - the law of conservation of matter. Lavoisier was recognized by historians of science as the discoverer of this law. Diamond helped convince humanity of its existence. At the same time, these same historians have created such clouds of fog around the sensational event that it still seems quite difficult to understand the reliability of the facts. The priority of an important discovery has been disputed for many years now, without any reason, by “patriotic” circles in various countries: Russia, Italy, England...
What arguments support the claims? The most ridiculous ones. In Russia, for example, the law of conservation of matter is attributed to Mikhail Vasilyevich Lomonosov, who did not actually discover it. Moreover, as evidence, the scribblers of chemical science shamelessly use excerpts from his personal correspondence, where the scientist, sharing with colleagues his reasoning about the properties of matter, allegedly personally testifies in favor of this point of view.
Italian historiographers explain their claims to the priority of a world discovery in chemical science by the fact that... Lavoisier was not the first to have the idea to use diamond in experiments. It turns out that back in 1649, prominent European scientists became acquainted with letters reporting similar experiments. They were provided by the Florentine Academy of Sciences, and from their contents it followed that local alchemists had already exposed diamonds and rubies to strong fire, placing them in hermetically sealed vessels. At the same time, the diamonds disappeared, but the rubies were preserved in their original form, from which the conclusion was drawn about the diamond as “a truly magical stone, the nature of which defies explanation.” So what? We are all, in one way or another, following in the footsteps of our predecessors. And the fact that the alchemists of the Italian Middle Ages did not recognize the nature of diamond only suggests that many other things were inaccessible to their consciousness, including the question of where the mass of a substance goes when it is heated in a vessel that excludes access to air.
The authorial ambitions of the British also look very shaky, as they generally deny Lavoisier’s involvement in the sensational experiment. In their opinion, the great French aristocrat was unfairly credited with credit that actually belonged to their compatriot Smithson Tennant, who is known to mankind as the discoverer of the two most expensive metals in the world - osmium and iridium. It was he, as the British claim, who performed such demonstration stunts. In particular, he burned diamond in a golden vessel (previously graphite and charcoal). And it was he who came up with the important conclusion for the development of chemistry that all these substances are of the same nature and, upon combustion, form carbon dioxide in strict accordance with the weight of the substances being burned.
But no matter how hard some historians of science try, either in Russia or in England, to belittle Lavoisier’s outstanding achievements and assign him a secondary role in unique research, they still fail. The brilliant Frenchman continues to remain in the eyes of the world community as a man of a comprehensive and original mind. Suffice it to recall his famous experiment with distilled water, which once and for all shook the prevailing view among many scientists at that time about the ability of water to turn into a solid substance when heated.
This incorrect view was formed on the basis of the following observations. When the water was evaporated “to dryness,” a solid residue was invariably found at the bottom of the vessel, which for simplicity was called “earth.” This is where there was talk about turning water into land.
In 1770, Lavoisier put this conventional wisdom to the test. To begin with, he did everything to get the purest water possible. This could be achieved then only in one way - distillation. Taking the best rainwater in nature, the scientist distilled it eight times. Then he filled a pre-weighed glass container with water purified from impurities, sealed it hermetically and recorded the weight again. Then, for three months, he heated this vessel on a burner, bringing its contents almost to a boil. As a result, there really was “ground” at the bottom of the container.
But from where? To answer this question, Lavoisier again weighed the dry vessel, the mass of which had decreased. Having established that the weight of the vessel had changed as much as “earth” had appeared in it, the experimenter realized that the solid residue that had confused his colleagues was simply leaching out of the glass, and there could be no question of any miraculous transformations of water into earth. This is where a curious chemical process occurs. And under the influence of high temperatures it proceeds much faster.
Yuri Frolov.
The history of natural science is full of experiments that deserve to be called strange. The ten described below were chosen entirely according to the taste of the author, with whom you may disagree. Some of the experiments included in this collection ended in nothing. Others led to the emergence of new branches of science. There are experiments that began many years ago, but have not yet been completed.
This is what the stop looks like in our time, past which a platform with trumpeters drove, testing the Doppler principle.
Donald Kellogg and Gua.
With this drawing you can test your color vision. People with normal vision see the number 74 in the circle, colorblind people see the number 21.
What was seen through a telescope during an experiment to test the sphericity of the Earth. Drawing by A. Wallace.
Another five years will pass, and the ninth drop of viscous resin since 1938 will fall into the glass.
Biosphere 2 is a giant sealed complex of buildings made of concrete, steel pipes and 5,600 glass panels.
NEWTON JUMPING
As a child, Isaac Newton (1643-1727) grew up as a rather frail and sickly boy. In outdoor games, he usually lagged behind his peers.
On September 3, 1658, Oliver Cromwell, an English revolutionary who briefly became the sovereign ruler of the country, died. On this day, an unusually strong wind swept over England. The people said: it was the devil himself who flew for the soul of the usurper! But in the town of Grantham, where Newton lived at that time, the children started a long jump competition. Noticing that it was better to jump with the wind than against it, Isaac galloped ahead of all his rivals.
Later, he began experiments: he wrote down how many feet he could jump in the wind, how many feet he could jump against the wind, and how far he could jump on a windless day. This gave him an idea of the strength of the wind, expressed in feet. Having already become a famous scientist, he said that he considered these jumps to be his first experiments.
Newton is known as a great physicist, but his first experiment can be attributed more to meteorology.
CONCERT ON RAILS
There was also the opposite case: a meteorologist conducted an experiment that proved the validity of one physical hypothesis.
The Austrian physicist Christian Doppler in 1842 put forward and theoretically substantiated the assumption that the frequency of light and sound vibrations should change for the observer depending on whether the source of light or sound is moving from the observer or towards him.
In 1845, Dutch meteorologist Christopher Bays-Ballot decided to test Doppler's hypothesis. He hired a locomotive with a flatbed, placed two trumpeters on the platform and asked them to hold the note G (two trumpeters were needed so that one of them could take air while the other played the note, and thus the sound would not be interrupted). On the platform of a stop between Utrecht and Amsterdam, the meteorologist placed several musicians without instruments, but with an absolute ear for music. After which the locomotive began to drag the platform with the trumpeters at different speeds past the platform with the listeners, and they noted which note they heard. Then the observers were forced to ride, and the trumpeters played while standing on the platform. The experiments lasted two days, as a result it became clear that Doppler was right.
By the way, later Beis-Ballot founded the Dutch weather service, formulated the law of his name (if in the Northern Hemisphere you stand with your back to the wind, then the low pressure area will be on your left) and became a foreign corresponding member of the St. Petersburg Academy of Sciences.
SCIENCE BORN WITH A CUP OF TEA
One of the founders of biometrics (mathematical statistics for processing the results of biological experiments), the English botanist Robert Fisher worked in 1910-1914 at an agrobiological station near London.
The team of employees consisted of only men, but one day they hired a woman, an algae specialist. For her sake, it was decided to establish fife-o-clocks in the common room. At the very first tea party, a dispute arose on an eternal topic for England: what is more correct - adding milk to tea or pouring tea into a cup that already contains milk? Some skeptics began to say that with the same proportion there would be no difference in the taste of the drink, but Muriel Bristol, a new employee, claimed that she could easily distinguish the “wrong” tea (English aristocrats consider it correct to add milk to tea, and not vice versa).
In the next room, with the assistance of the staff chemist, several cups of tea were prepared in various ways, and Lady Muriel showed the subtlety of her taste. And Fischer wondered: how many times must the experiment be repeated for the result to be considered reliable? After all, if there were only two cups, it would be entirely possible to guess the cooking method purely by chance. If three or four, chance could also play a role...
From these reflections was born the classic book Statistical Methods for Scientific Workers, published in 1925. Fisher's methods are still used by biologists and doctors.
Note that Muriel Bristol, according to the recollections of one of the tea party participants, correctly identified all the cups.
By the way, the reason why in English high society it is customary to add milk to tea, and not vice versa, is associated with a physical phenomenon. The nobility always drank tea from porcelain, which can burst if you first pour cold milk into the cup and then add hot tea. Ordinary Englishmen drank tea from earthenware or tin mugs without fear for their integrity.
HOME MOWGLI
In 1931, an unusual experiment was carried out by a family of American biologists - Winthrop and Luella Kellogg. After reading an article about the sad fate of children growing up among animals - wolves or monkeys, biologists began to think: what if we do the opposite - try to raise a monkey baby in a human family? Will he get closer to the person? At first, the scientists wanted to move with their little son Donald to Sumatra, where it would be easy to find a companion for Donald among the orangutans, but there was not enough money for this. However, the Yale Center for the Study of Great Apes lent them a small female chimpanzee named Gua. She was seven months old and Donald was 10.
The Kellogg couple knew that almost 20 years before their experiment, Russian researcher Nadezhda Ladygina had already tried to raise a one-year-old chimpanzee the way children are raised, and for three years she had not achieved success in “humanizing” it. But Ladygina conducted the experiment without the participation of children, and the Kellogs hoped that co-parenting with their son would yield different results. In addition, it could not be ruled out that the age of one is already too late for “re-education.”
Gua was accepted into the family and began to be raised equally with Donald. They liked each other and soon became inseparable. The experimenters wrote down every detail: Donald likes the smell of perfume, Gua doesn't like it. We conducted experiments: who can quickly guess how to use a stick to get a cookie suspended from the ceiling in the middle of the room on a thread? And if you blindfold a boy and a monkey and call them by name, who will be better at determining the direction where the sound is coming from? Gua won both tests. But when Donald was given a pencil and paper, he himself began to scribble something on the sheet, and the monkey had to be taught what to do with a pencil.
Attempts to bring the monkey closer to humans under the influence of education turned out to be rather unsuccessful. Although Gua often moved on two legs and learned to eat with a spoon, even began to understand human speech a little, she became confused when familiar people appeared in different clothes, she could not be taught to pronounce at least one word - “dad” and she, in contrast from Donald, I couldn’t master a simple game like our “ladushki”.
However, the experiment had to be interrupted when it turned out that by the age of 19 months, Donald did not shine with eloquence - he had mastered only three words. And what’s worse, he began to express his desire to eat with a typical monkey sound like barking. The parents were afraid that the boy would gradually drop to all fours and would never master the human language. And Gua was sent back to the nursery.
DALTON'S EYES
We will talk about an experiment conducted at the request of the experimenter after his death.
The English scientist John Dalton (1766-1844) is remembered mainly for his discoveries in the field of physics and chemistry, as well as for the first description of a congenital defect of vision - color blindness, in which color recognition is impaired.
Dalton himself noticed that he suffered from this deficiency only after he became interested in botany in 1790 and found it difficult to understand botanical monographs and keys. When the text referred to white or yellow flowers, he had no difficulty, but if the flowers were described as purple, pink or dark red, they all seemed indistinguishable from blue to Dalton. Often, when identifying a plant from a description in a book, a scientist had to ask someone: is this a blue or pink flower? People around him thought he was joking. Dalton was understood only by his brother, who had the same hereditary defect.
Dalton himself, comparing his color perception with the vision of colors by friends and acquaintances, decided that there was some kind of blue filter in his eyes. And he bequeathed to his laboratory assistant after his death to remove his eyes and check whether the so-called vitreous body, the gelatinous mass that fills the eyeball, was colored bluish?
The laboratory assistant carried out the scientist’s wishes and did not find anything special in his eyes. He suggested that Dalton may have had something wrong with his optic nerves.
Dalton's eyes were preserved in a jar of alcohol at the Manchester Literary and Philosophical Society, and already in our time, in 1995, geneticists isolated and studied DNA from the retina. As one would expect, genes for color blindness were found in her.
It is impossible not to mention two more extremely strange experiments with the human visual organs. Isaac Newton cut a thin curved probe from ivory, launched it into his eye and pressed it on the back of the eyeball. At the same time, colored flashes and circles appeared in the eye, from which the great physicist concluded that we see the world around us because light puts pressure on the retina. In 1928, one of the pioneers of television, English inventor John Baird, tried to use the human eye as a transmitting camera, but naturally failed.
IS THE EARTH A BALL?
A rare example of an experiment in geography, which is not actually an experimental science.
The outstanding English evolutionary biologist, Darwin's comrade-in-arms, Alfred Russell Wallace, was an active fighter against pseudoscience and all kinds of superstitions (see Science and Life No. 5, 1997).
In January 1870, Wallace read an advertisement in a scientific journal, the submitter of which offered a bet for £500 to anyone who would undertake to clearly prove the sphericity of the Earth and “demonstrate in a manner understandable to every reasonable person a convex railway, river, canal or lake.” The dispute was proposed by a certain John Hamden, the author of a book proving that the Earth is in fact a flat disk.
Wallace decided to take on the challenge and chose a six-mile straight section of canal to demonstrate the roundness of the Earth. There were two bridges at the beginning and end of the section. On one of them, Wallace mounted a strictly horizontal 50x telescope with sighting threads in the eyepiece. In the middle of the canal, at a distance of three miles from each bridge, he placed a tall sign with a black circle on it. On the other bridge I hung a board with a horizontal black stripe. The height above the water of the telescope, the black circle and the black stripe was exactly the same.
If the Earth (and the water in the channel) is flat, the black stripe and black circle should coincide in the telescope eyepiece. If the surface of the water is convex, repeating the convexity of the Earth, then the black circle should be above the stripe. And so it happened (see picture). Moreover, the size of the discrepancy coincided well with the calculated one, derived from the known radius of our planet.
However, Hamden refused to even look through the telescope, sending his secretary to do this. And the secretary assured the audience that both marks were at the same level. If some discrepancy is observed, it is due to aberrations of the telescope lenses.
A multi-year lawsuit followed, as a result of which Hamden was still forced to pay 500 pounds, but Wallace spent significantly more on legal costs.
THE TWO LONGEST EXPERIMENTS
Perhaps the most started 130 years ago (see “Science and Life” No. 7, 2001) and has not yet been completed. American botanist W. J. Beale buried 20 bottles of common weed seeds in the ground in 1879. Since then, periodically (first every five, then ten, and even later - every twenty years) scientists dig up one bottle and test the seeds for germination. Some particularly persistent weeds still germinate. The next bottle should be available in spring 2020.
The longest physics experiment began at the University of the Australian city of Brisbane, Professor Thomas Parnell. In 1927, he placed a piece of solid resin - var, which, according to its molecular properties, is a liquid, although very viscous, in a glass funnel mounted on a tripod. Parnell then heated the funnel until the varnish melted slightly and flowed into the spout of the funnel. In 1938, the first drop of resin fell into a laboratory beaker placed by Parnell. The second one fell in 1947. In the fall of 1948, the professor died, and his students continued observing the crater. Since then, drops have fallen in 1954, 1962, 1970, 1979, 1988 and 2000. The frequency of droplets has slowed down in recent decades due to the fact that air conditioning was installed in the laboratory and it became colder. It is curious that not once did the drop fall in the presence of any of the observers. And even when in 2000 a webcam was installed in front of the funnel to transmit images to the Internet, at the moment of the eighth and today last drop the camera failed!
The experiment is still far from complete, but it is already clear that var is a hundred million times more viscous than water.
BIOSPHERE-2
This is the largest experiment included in our arbitrary list. It was decided to make a working model of the earth's biosphere.
In 1985, more than two hundred American scientists and engineers teamed up to build a huge glass building in the Sonoran Desert (Arizona) containing samples of the earth's flora and fauna. They planned to hermetically seal the building from any influx of foreign substances and energy (except for the energy of sunlight) and settle a team of eight volunteers, who were immediately nicknamed “bionauts,” here for two years. The experiment was supposed to contribute to the study of connections in the natural biosphere and test the possibility of long-term existence of people in a closed system, for example, during long-distance space flights. Plants had to supply oxygen; water, it was hoped, would be provided by the natural cycle and processes of biological self-purification, food by plants and animals.
The internal area of the building (1.3 hectares) was divided into three main parts. The first contains examples of five characteristic ecosystems of the Earth: a patch of rainforest, an “ocean” (a basin of salt water), a desert, a savanna (with a “river” flowing through it), and a swamp. In all these parts, representatives of flora and fauna selected by botanists and zoologists were settled. The second part of the building was dedicated to life support systems: a quarter of a hectare for growing edible plants (139 species, counting tropical fruits from the “forest”), fish pools (they took tilapia as an unpretentious, fast-growing and tasty species) and a compartment for biological wastewater treatment. Finally, there were living quarters for the “bionauts” (each 33 square meters with a common dining room and living room). Solar panels provided electricity for computers and night lighting.
At the end of September 1991, eight people were “walled up” in a glass greenhouse. And soon problems began. The weather turned out to be unusually cloudy, photosynthesis was weaker than normal. In addition, bacteria that consume oxygen multiplied in the soil, and over 16 months its content in the air decreased from normal 21% to 14%. We had to add oxygen from outside, from cylinders. The yields of edible plants turned out to be lower than expected, the population of “Biosphere-2” was constantly hungry (although already in November they had to open the grocery store; over two years of experience, the average weight loss was 13%). Inhabited insect pollinators disappeared (in general, from 15 to 30% of species became extinct), but cockroaches, which no one inhabited, multiplied. The “Bionauts” were still, at the very least, able to stay in captivity for the planned two years, but overall the experiment was unsuccessful. However, it once again showed how delicate and vulnerable the mechanisms of the biosphere that ensure our life are.
The giant structure is now used for individual experiments with animals and plants.
BURNING DIAMOND
Nowadays, no one is surprised by experiments that are expensive and require huge experimental facilities. However, 250 years ago this was a novelty, so crowds of people gathered to watch the amazing experiments of the great French chemist Antoine Laurent Lavoisier (especially since the experiments took place in the fresh air, in a garden near the Louvre).
Lavoisier studied the behavior of various substances at high temperatures, for which he built a giant installation with two lenses that concentrated sunlight. Making a collecting lens with a diameter of 130 centimeters is still a non-trivial task now, but in 1772 it was simply impossible. But opticians found a way out: they made two round concave glasses, soldered them and poured 130 liters of alcohol into the space between them. The thickness of such a lens in the center was 16 centimeters. The second lens, which helped to collect the rays even more strongly, was two times smaller, and was made in the usual way - by grinding a glass casting. This optics was installed on (its drawing can be seen in “Science and Life” 8, 2009). A well-thought-out system of levers, screws and wheels made it possible to point the lenses at the Sun. The participants in the experiment were wearing smoked glasses.
Lavoisier placed various minerals and metals at the focus of the system: sandstone, quartz, zinc, tin, coal, diamond, platinum and gold. He noted that in a hermetically sealed glass vessel with a vacuum, a diamond becomes charred when heated, and burns in air, completely disappearing. The experiments cost thousands of gold livres.
LAVOISIER
In the history of chemistry, there are few names with which so many important chemical events were associated as with the name of Antoine Laurent Lavoisier.
He himself made relatively few discoveries, but had a very rare gift for combining new facts, the discoveries of others and his own experiences into one whole. He was one of the most outstanding natural scientists, whose work had a tremendous influence on the development of not only chemistry, but also other natural sciences, introducing quantitative methods of research and accuracy into them. The beautiful language in which Lavoisier expresses his thoughts, simple and figurative, where every word evokes in the reader exactly the idea that the author wants to give, has become a prototype of what every scientist should strive for.
After graduating from college, Lavoisier entered a higher law school, where he received a bachelor's degree in law, and a year later - a licentiate of rights. But at the same time, he did not stop studying the natural sciences, to which he became very fond of in college, continuing to study them under the guidance of the most outstanding scientists of his time - astronomer Nicolas Louis Lacaille, botanist Bernard Jussieux, geologist and mineralogist Jean Etienne Guettard, whose assistant he became. The young lawyer was especially attracted to the lectures on chemistry by Professor Guillaume François Ruel. Beautifully presented and accompanied by numerous experiments, these lectures always attracted a full audience. From the recordings of these lectures, which have come down to us in several copies, it is clear that Ruel sought to give his listeners a complete understanding of the state of chemistry at that time. Like other chemists of that era, he was a supporter of the phlogiston theory and, based on it, explained chemical phenomena. In the end, Lavoisier completely abandoned jurisprudence and devoted himself entirely to natural science. Exceptional efficiency and systematicity made these studies very productive; he always tried to get to the essence of things and find explanations for phenomena.
Along with this, Lavoisier was keenly interested in technical and socio-economic issues. His first scientific research on the composition of gypsum was at the same time the first communication he made in 1765 at the Paris Academy of Sciences. In the same year, Lavoisier took part in a competition announced by the academy to find the best way to illuminate streets in Paris. Lavoisier received a gold medal for his report.
Naturally, a proposal was soon made to elect Lavoisier, as an educated, intelligent, energetic and very useful person for science, as a member of the Academy of Sciences. The election took place in 1768. Lavoisier first attended a meeting of the academy, where he was elected a member of several commissions. His activities in these commissions were marked by the same methodicality that characterizes all his work.
Wanting to improve his financial situation, Lavoisier in the same year committed an act that had fatal consequences for him: he became one of the tax farmers for internal taxes, a “general farmer,” having first very thoroughly studied everything related to the “General Farmer”*. Farmers took taxes from the state, that is, they contributed a certain amount of money to the treasury annually, and they themselves collected taxes from the people; the difference was in their favor. He was entrusted with the supervision of tobacco production, supervision of customs operations and other matters related to indirect taxes. Lavoisier took up this matter with his characteristic energy and in 1769–1770. traveled a lot around France in the interests of farming.
He also used these trips to study drinking and other natural waters.
Studying them, Lavoisier noticed that even a hundredfold distillation does not completely rid the water of impurities dissolved in it. Assuming that the source of the latter were the vessels used for distillation, he heated water in a glass vessel to 90 °C for 100 days. Then, by precise weighing, he determined the weight loss of the vessel and the weight of the contaminants released from the water: both weights turned out to be identical.
So Lavoisier refuted the age-old opinion that water can turn into “earth”.
The corresponding experiments, begun in October 1772, were carried out strictly quantitatively: the substances taken and obtained were carefully weighed. One of the first results of the experiments was that they discovered an increase in weight when burning sulfur, phosphorus, and coal.
Then the phenomena of burning metals were also carefully studied.
Let us present here some data on experiments that are now rarely mentioned, but at one time aroused great interest among contemporaries - experiments on burning diamonds.
It has long been observed that when heated strongly enough in air, diamonds disappear without a trace. Lavoisier proved experimentally that air plays a decisive role in this phenomenon; a diamond to which air does not have access does not change at the same temperature.
A diamond burned under a glass bell by the sun's rays collected at the focus of a burning glass produced, as Lavoisier had predicted, a colorless gas that formed a white precipitate with limewater, which boiled when acid was poured over it - it was carbon dioxide. To confirm this, a piece of charcoal was burned under the same conditions. As a result, as when burning a diamond, carbon dioxide was produced. From this Lavoisier concluded that diamond is a modification of coal: both substances produce carbon dioxide when burned.
The scientist’s experiments and the most important conclusions from them were described by him in 1774. A masterful presentation provides convincing evidence of the opinion that air consists of two gases, one of which combines with substances during combustion and burning. One has to wonder how, after this, the theory of phlogiston could still retain its rabid adherents. Further conclusions from these experiments are given in an article of 1775, in which Lavoisier specifically considered the nature of the gases formed during combustion, especially carbon dioxide. Avoisier moved to the Arsenal, where he set up a laboratory for himself, in which he worked for almost his entire life. This laboratory became the center of meetings of scientists: both French and foreign, who took an active part not only in discussions, but also in the experiments themselves. Usually here, before presenting a report to the Academy of Sciences, Lavoisier carried out the necessary experiments in front of friends and acquaintances and, together with them, discussed their results in the light of his oxygen theory. Having irrefutably proven the validity of this theory, he transferred the center of his scientific activity to another area related to the previous one: he began a comprehensive study of the chemical side of respiration and the changes that occur with the air.
He proved the presence in the exhaled air of the same carbon dioxide that is formed during combustion. The fact that an aqueous solution of this gas has acidic properties, like solutions of the combustion products of sulfur and phosphorus, gave Lavoisier reason to believe that all oxygen compounds are acids, which he expressed in the name “oxygen,” i.e., an acid former. It is interesting to note that the name “carbonic acid”, then given to carbon dioxide, is still used by many, although more than a hundred years ago it was proven that carbon dioxide and carbon dioxide are two different substances.
In 1785, Lavoisier was appointed director of the Academy of Sciences and immediately began to transform it. From that time on, he was even more closely connected with the academy than before. The pace of Lavoisier's chemical work slowed down at this time, but nevertheless, a number of important works interesting for practical applications of chemistry came out of his pen. Of these applications, we will only mention the activities in the aeronautics committee, then just emerging: the first balloon filled with hydrogen took off in 1783.
By 1790, a large study on the nature of heat was completed, carried out by the scientist together with academician Pierre Simon Laplace. In this work they showed how to measure the amount of heat, determine the heat capacity of bodies;
It is necessary to say more about Lavoisier’s work on the decomposition of water, carried out in 1783 by passing water vapor over hot iron, and on its synthesis. These works finally proved the complex composition of water and the nature of hydrogen, its source. In connection with his results, Lavoisier began to more vigorously oppose the theory of phlogiston, a theory that, of course, could only exist in the chemistry of that period, which did not use quantitative determinations.
|
Laboratory instruments and apparatus
|
IN Lavoisier published this new chemistry in its final form in 1787-1789. The first of these dates is the time of compilation of new names of substances, names indicating the composition of bodies from the chemical elements that form them according to chemical analysis. This first scientific chemical nomenclature was intended to distinguish the new chemistry from the old - phlogistic. The same nomenclature is given in the “Elementary Course of Chemistry” (1789).
The first part of this remarkable work is devoted to a description of quantitative experiments in the formation and decomposition of gases, the combustion of simple substances, and the formation of acids and salts. Having studied the phenomenon of fermentation, Lavoisier emphasized the peculiarity of chemical interaction in the following words: “Nothing is created either in artificial processes or in natural ones, and it can be stated that in every operation there is the same amount of matter before and after, that the quality and quantity of the principles remain the same the most, there were only displacements and regroupings. The entire art of doing experiments in chemistry is based on this proposition. It is necessary to assume in all cases real (complete) equality between the principles of the body under study and the one obtained from it by analysis. This chemical equality is a mathematical expression of the equality of body weight before and after interaction.”
The second part of the course is devoted to simple, non-decomposable substances that make up chemical elements. Lavoisier counted 33 of these (including light and heat, and he indicated that improvements in analytical methods could lead to the decomposition of some elements). Next come the mutual connections they form.
Finally, the third part of the course, devoted to instruments and operations in chemistry, is illustrated with numerous engravings made by Lavoisier’s wife.
Lavoisier participated in the completion of the development of the system of weights and measures undertaken by the Academy of Sciences.
This work was continued in the National Assembly, which decided to introduce a decimal system of weights and measures based on the length of the earth's meridian. For this purpose, a number of committees and commissions were formed, headed by A.L. Lavoisier, J.A.N. Condorcet, P.S. Laplace. They completed the work assigned to them, the result of which was the metric system, which is now used everywhere. This is one of the scientist’s latest scientific works.
“General tax farming” and tax farmers have long been the subject of just hatred of the people. The National Assembly in March 1791 abolished the farm-out and proposed to liquidate it by January 1, 1794. From that time on, Lavoisier left work in this institution. The movement against tax farmers continued to develop, and in 1793 the Convention decided to arrest tax farmers and speed up the liquidation of tax farming. Along with others, Lavoisier was arrested on November 24.
After the trial of the case at the tribunal on May 8, 1794, all tax farmers were sentenced to death, and on the same day Lavoisier was guillotined along with others.
* Society for collecting taxes from the population.
Eighteenth century, France, Paris. Antoine Laurent Lavoisier, one of the future creators of chemical science, after many years of experiments with various substances in the quiet of his laboratory, is convinced again and again that he has made a genuine revolution in science. His essentially simple chemical experiments on the combustion of substances in hermetically sealed volumes completely refuted the generally accepted theory of phlogiston at that time. But strong, strictly quantitative evidence in favor of the new “oxygen” theory of combustion is not accepted in the scientific world. The visual and convenient phlogiston model has become very firmly ingrained in our heads.
What to do? Having spent two or three years in fruitless efforts to defend his idea, Lavoisier comes to the conclusion that his scientific environment has not yet matured to purely theoretical arguments and that he should take a completely different path. In 1772, the great chemist decided to undertake an unusual experiment for this purpose. He invites everyone to take part in the spectacle of burning... a weighty piece of diamond in a sealed cauldron. How can one resist curiosity? After all, we are not talking about anything, but about a diamond!
It is quite understandable that, following the sensational message, the scientist’s ardent opponents, who had previously not wanted to delve into his experiments with all sorts of sulfur, phosphorus and coal, poured into the laboratory along with ordinary people. The room was polished to a shine and shone no less than a precious stone sentenced to public burning. It must be said that Lavoisier’s laboratory at that time belonged to one of the best in the world and was fully consistent with an expensive experiment in which the owner’s ideological opponents were now simply eager to take part.
The diamond did not disappoint: it burned without a visible trace, according to the same laws that applied to other despicable substances. Nothing significantly new has happened from a scientific point of view. But the “oxygen” theory, the mechanism of formation of “bound air” (carbon dioxide) have finally reached the consciousness of even the most inveterate skeptics. They realized that the diamond had not disappeared without a trace, but that under the influence of fire and oxygen it had undergone qualitative changes and turned into something else. After all, at the end of the experiment, the flask weighed exactly as much as at the beginning. So, with the false disappearance of the diamond before everyone’s eyes, the word “phlogiston” disappeared forever from the scientific lexicon, denoting a hypothetical component of the substance that is supposedly lost during its combustion.
But a holy place is never empty. One went, another came. The phlogiston theory was supplanted by a new fundamental law of nature - the law of conservation of matter. Lavoisier was recognized by historians of science as the discoverer of this law. Diamond helped convince humanity of its existence. At the same time, these same historians have created such clouds of fog around the sensational event that it still seems quite difficult to understand the reliability of the facts. The priority of an important discovery has been disputed for many years now, without any reason, by “patriotic” circles in various countries: Russia, Italy, England...
What arguments support the claims? The most ridiculous ones. In Russia, for example, the law of conservation of matter is attributed to Mikhail Vasilyevich Lomonosov, who did not actually discover it. Moreover, as evidence, the scribblers of chemical science shamelessly use excerpts from his personal correspondence, where the scientist, sharing with colleagues his reasoning about the properties of matter, allegedly personally testifies in favor of this point of view.
Italian historiographers explain their claims to the priority of a world discovery in chemical science by the fact that... Lavoisier was not the first to have the idea to use diamond in experiments. It turns out that back in 1649, prominent European scientists became acquainted with letters reporting similar experiments. They were provided by the Florentine Academy of Sciences, and from their contents it followed that local alchemists had already exposed diamonds and rubies to strong fire, placing them in hermetically sealed vessels. At the same time, the diamonds disappeared, but the rubies were preserved in their original form, from which the conclusion was drawn about the diamond as “a truly magical stone, the nature of which defies explanation.” So what? We are all, in one way or another, following in the footsteps of our predecessors. And the fact that the alchemists of the Italian Middle Ages did not recognize the nature of diamond only suggests that many other things were inaccessible to their consciousness, including the question of where the mass of a substance goes when it is heated in a vessel that excludes access to air.
The authorial ambitions of the British also look very shaky, as they generally deny Lavoisier’s involvement in the sensational experiment. In their opinion, the great French aristocrat was unfairly credited with credit that actually belonged to their compatriot Smithson Tennant, who is known to mankind as the discoverer of the two most expensive metals in the world - osmium and iridium. It was he, as the British claim, who performed such demonstration stunts. In particular, he burned diamond in a golden vessel (previously graphite and charcoal). And it was he who came up with the important conclusion for the development of chemistry that all these substances are of the same nature and, upon combustion, form carbon dioxide in strict accordance with the weight of the substances being burned.
But no matter how hard some historians of science try, either in Russia or in England, to belittle Lavoisier’s outstanding achievements and assign him a secondary role in unique research, they still fail. The brilliant Frenchman continues to remain in the eyes of the world community as a man of a comprehensive and original mind. Suffice it to recall his famous experiment with distilled water, which once and for all shook the prevailing view among many scientists at that time about the ability of water to turn into a solid substance when heated.
This incorrect view was formed on the basis of the following observations. When the water was evaporated “to dryness,” a solid residue was invariably found at the bottom of the vessel, which for simplicity was called “earth.” This is where there was talk about turning water into land.
In 1770, Lavoisier put this conventional wisdom to the test. To begin with, he did everything to get the purest water possible. This could be achieved then only in one way - distillation. Taking the best rainwater in nature, the scientist distilled it eight times. Then he filled a pre-weighed glass container with water purified from impurities, sealed it hermetically and recorded the weight again. Then, for three months, he heated this vessel on a burner, bringing its contents almost to a boil. As a result, there really was “ground” at the bottom of the container.
But from where? To answer this question, Lavoisier again weighed the dry vessel, the mass of which had decreased. Having established that the weight of the vessel had changed as much as “earth” had appeared in it, the experimenter realized that the solid residue that had confused his colleagues was simply leaching out of the glass, and there could be no question of any miraculous transformations of water into earth. This is where a curious chemical process occurs. And under the influence of high temperatures it proceeds much faster.
