In 1775, the same year that Lavoisier read out his theory of oxidation by combustion at the French Academy of Sciences, across the Channel, the British inventor Watt began mass-producing and selling steam engines in a factory he co-owned with Boylston. The steam engine converted fire into power, and a power revolution took place, adding endless power to man.
As the birthplace of the steam engine and the Industrial Revolution in Britain, science and technology flourished during this period. Counting all the greats, the following is about the British chemists David, Faraday and Dalton, who established the atomic theory.
Humphrey Davy was born on December 17, 1778, in Penzance, England. His father was a woodcarver and his mother was a hard worker, but they were not well off. His parents raised Davy and his four siblings with great difficulty and wanted Humphrey and his brother to have a good education.
David was an active and emotional child who loved to tell stories and recite poetry, often making up silly poems to make fun of his friends and teachers. His best work was translating classical literature into contemporary English. Even his favorite subject was not as good as David's love of fishing and hiking. Sometimes he was so happy with his fun that he forgot to attend class. Fortunately, his tenacious mother took his studies seriously and was patient, enabling him to finish school better.
In this free and enjoyable childhood life, David had enough time to think and imagine, forming his enthusiastic, positive, independent, not blindly follow, and rich in creative personality. His school was one of the better secondary schools in Cornwall at the end of the 18th century, where David learned many things, such as theology, geometry, foreign languages and other subjects. He also read a great deal of philosophy, such as Kant's books on Preterism.
Eldest brother after family changes
After the age of 15, David began to drop out of school due to his father's illness and the family's poverty, and in 1794, his father died after a long illness. Not yet 16, David suddenly felt the responsibility of being the eldest brother, and in 1795, he changed his boyish ways and apprenticed himself to Porras, a surgeon and physiologist in Penzance. There, David came into contact with many knowledgeable people and was so inspired that he set up a vast program of self-education, including seven foreign languages alone. He also began his first experimental training in chemistry with readily available medicines and instruments, and in 1797 David's knowledge of chemistry was greatly enriched by his reading of Nicholson's Zinc Dictionary of Chemistry and Lavoisier's masterpiece Outline of Chemistry. During this period he became acquainted with Gregory Watt, son of James Watt, the inventor of the steam engine, and Giddy, who later succeeded Davy as president of the Royal Academy. Giddy allowed David to make use of his books, and also introduced David to the very complete library owned by the Bolles family in Clifton, which gave David the opportunity to engage in a wide range of subjects, laying a solid foundation for his later inventions.
In Clifton, the British physicist Beddoes founded the Gas Research Institute to study the physiological effects of gases on the human body, in the hope of finding some gases that have medical properties, as well as figuring out which gases are harmful to the human body. The institute needed a good chemist, and Beddoes hired David. The first gas David studied was nitrous oxide. According to Mitchell, an American chemist, nitrous oxide was harmful to the human body and could be fatal to anyone who inhaled it. David was not blind to Mitchell, he repeatedly conducted tests and found that nitrous oxide was not harmful to the human body, and when a person inhaled the gas, it produced an intoxicating sensation, so David suggested that nitrous oxide could be used in surgery. Davy's treatise on the effects of nitrous oxide on the human body, published in 1800, provided a comprehensive evaluation of the anesthetic effects of nitrous oxide, and concluded that it was the best anesthetic since recorded history. Since then, dentists and surgeons have been using nitrous oxide as an anesthetic; circus clowns also inhale a little bit of nitrous oxide before going on stage because it has a strange effect on the facial nerves of people, causing them to produce a different kind of maniacal laughter. Nitrous oxide became known as "laughing gas" and spread. David also studied the physiological effects of various gases, including nitrogen dioxide and carbon monoxide, on the human body. Obviously, the study of these two gases is very dangerous, but David insisted on doing it, and encouraged his brother, John David, to do the same risky experiments.
Davey showed great ability in quantitative experimental research in his gas studies, and his experimental technique of volumetric analysis was very skillful. His research work was characterized by a willingness to expend intense labor, but to obtain experimental results with astonishing rapidity, and he showed special inventiveness in adapting existing apparatus to the study of new subjects. He was not interested in repeating and proving the discoveries of others, but showed great perseverance in innovation.
David's treatise on the respiration of nitrous oxide made him greatly famous, and from then on his career in chemistry got off to a good start.
After the announcement of Voltar's invention of the electric pile, Nicholson and Carisle reported their use of the Voltar pile to break down water into hydrogen and oxygen. Upon learning of these new discoveries, Davy immediately devoted himself to this field of research and published papers, such as "Chemistry and Processes" in Nicholson's Journal of Natural Philosophy in 1800. In his research, Davy not only utilized the Voltaren electric pile, an advanced experimental tool of the time, but also always kept a clear head and explored whether there were any practical and theoretical shortcomings of his predecessors. Vodafone had always believed that the electric current in the electrostat was produced only by the contact of two different metals, but Davy was the first chemist to recognize the inadequacy of this "contact theory", and believed that the electric current was not produced only by contact, but was actually produced by chemical reactions in the electrostat. He also pointed out that in an electrolytic cell, the action of the electric current causes a compound to decompose into its components. Davy's views were generally appreciated and supported in France and Germany.
David also found that the electrostack would not function well without the presence of oxygen in the water between the metal sheets, leading to the conclusion that the redox reaction between the metals zinc and copper (or silver) was responsible for the electric current produced by the zinc-copper (or silver) electrostack. It was further deduced that the electrostack would work better if nitric acid was used in it instead of the water or table salt solution in it, because nitric acid is more oxidizing than oxygen. Davy also used an electrostack in which the electrodes were placed in two separate containers so that the solutions in these containers were connected to each other by moistened asbestos rope.
The above findings were published in 1801, and it is here that we can once again see Davy's innovative spirit.
At the Royal Academy
In this year, Davy was elected to the Royal Academy as a lecturer at the college. He was delighted to write to his mother, "You have probably heard of the Royal Academy, founded by the Earl of Longford and other noblemen? It is a very splendid building, only it has not yet been organized with men of talent to make it prominent, and the Earl of Longford has suggested that I should work there." It was indeed as David had said, and it was only since the Royal Academy had absorbed such fresh blood as David's (who later found an assistant, Faraday, and elected him to the Royal Academy) that it became one of the most famous scientific institutions in the world. The aims of the Royal Academy were to disseminate knowledge, to provide technical training for the majority of the population, to encourage the invention and improvement of new and useful machines, and to hold regular lectures to publicize the results. During the tenure of David's office such lectures were given more frequently, and as he was himself an excellent orator, he succeeded in attracting a large number of undergraduates, scientists, and scientific enthusiasts, among whom there was no lack of idle ladies and gentlemen to attach themselves. Thus, in a short time David became a London celebrity, and science became more fashionable in the city. The Royal Academy became the center of scientific research in England and an important place for lectures on science.
When David first came to the Royal Academy, his lectures were on technical subjects, and in 1805 he was awarded the Copley paddle for a paper on tanning, and in 1802 he gave lectures on agricultural chemistry to the agricultural department, which continued until 1812, the first attempt to apply chemistry to agriculture, and which had been used until the publication of Lepage's work on agricultural chemistry. Until the publication of Lippincott's work on agricultural chemistry, David's lectures had been regarded as pioneering work in agricultural chemistry.
In 1806 Davy gave the Becklin Lectures on the electrolysis of water, using the results of electrochemical research. He pointed out that in the electrolysis of pure water, the products were only hydrogen and oxygen produced in theoretical proportions, which was consistent with the experimental results obtained by the Swedish master chemist, Bezelius. But other chemists who studied the electrolysis of water pointed out that acids and bases appeared around the electrodes during electrolysis, and that the theoretical proportions of hydrogen and oxygen were not produced during electrolysis. Davy answered these doubts with his own precise experiments, stating that pure water, redistilled in a silver apparatus, placed in a gold or onyx vessel, and electrolyzed in an atmosphere of hydrogen (which avoids the reaction of the new ecological hydrogen and oxygen with the nitrogen in the air), produces only hydrogen and oxygen, and that the reason for the production of acids and alkalis around the electrodes during electrolysis of water is that the water is not of a sufficiently pure nature (it contains salt). is not sufficient (it contains salt). Within six years of the publication of Nicholson's and Carisle's experiments on the electrolysis of water, no chemist had noticed the above problem, and it was Davy who explained the difficulty. He also proposed the use of electrolysis as a method of chemical analysis and discussed the transport of substances in solution during electrolysis. He found that if two cups were filled with electrodes and a conducting solution, and a third with a neutral salt solution, and a turmeric or litmus indicator was added to each cup, and the solutions in the three cups were connected by an asbestos string, the indicator would change color near the electrodes during electrolysis. If barium chloride solution is added to the two cups containing the electrodes, the cup containing sulfuric acid is placed in the middle of them, and the solutions in the three cups are connected by asbestos string, a precipitate of barium sulfate will be produced in the middle cup during electrolysis, proving that the substance is transported during electrolysis.
David was a strong supporter of Betserius' theory of electrochemical duality. They divided the chemical elements into positively and negatively charged ones, and only elements with different electrical properties could be chemically combined to form neutral substances, which in turn could be polarized and decomposed by the electric current. Each element has a positive or negative, strong or weak electrical property, which determines the chemical affinity between them - strong positive and strong negative elements have a strong chemical affinity, so it is very easy to chemically combine to form stable compounds. Electrochemical dichotomy ran through the chemical theories of the time, playing a fundamental role in organizing and classifying them. The sensational effect of David's discovery of many new elements by electrolysis prompted Betzelius to systematically formulate electrochemical dualism.
Discovery of many new elements by electrolysis
David described the process of separating out the metals potassium and sodium in his Becklin Lectures in 1807. The previous year he had begun to use the new method of electrolysis to study the chemical elements. Lavoisier had argued that chemists were not concerned with the elements, but with objects that were not currently capable of being decomposed. At the time, alkali, soda, and potash (potassium carbonate extracted from wood ash) had been treated as objects that could not be decomposed, but Lavoisier refused to include them in the list of objects that could not be decomposed. Inspired by Lavoisier's article, Davy then wanted to dissociate these chemical elements from potassium carbonate, sodium carbonate and alkali by electrolysis. He made the bold prediction, "If chemical combinations have the kind of properties which I have ventured to envisage, however strong the natural electric power (the power of combination) of the elements in an object may be, it cannot be without limit , and as the power of our artificial instruments seems to be capable of unlimited increase, it is to be hoped that the new method (referring to electrolysis) will lead us to the discovery of the true elements of the object. "
David made the largest voltaic pile of its time out of 250 pairs of metal plates in order to produce a strong current and a very high voltage. At first, he electrolyzed a saturated solution of caustic potash, but it did not separate the potassium metal, only broke down the water. Davy decided to change this by electrolyzing pure caustic potash, but the dried caustic potash did not conduct electricity. He then burned the caustic potash until it melted, and when the current was turned on, a brightly burning lavender flame soon appeared around the cathode's platinum wire. David still found nothing.
After he calmed down and thought about it, he decided that the caustic potash had indeed decomposed, but the decomposition products burned off again immediately at the high temperature. He felt a wave of relief and exhilaration. There were other people's dinners and dances in the evening, and David had no time to change, so he threw on a new coat and ran off like the wind. In spite of the great strain of the experiment, he never delayed the banquet. His excellent eloquence, his ability to write poetry instantly, was on full display at the parties. The praise of others delighted him. In socializing he fully enjoyed the passions of life.
While the city of London was abuzz with tales of David's decomposition of caustic potash, David grew anxious. With the Becklin Lecture only a month or so away, how to get the decomposition product for all to see? The founder of the Royal Academy, the Earl of Longford, had moved to France in 1803 to marry Marie, Lavoisier's widow, and the Becklin Lectures, which were paid for, were the mainstay of the Royal Academy, so there was no room for error. David threw himself into his experiments with greater vigor.
On October 6, 1807, it was foggy in London. Davy took out a piece of caustic potash and put it in the air to observe it, and a moment later it adsorbed some moisture on its surface. "Doesn't that give it the ability to conduct electricity?" David thought, and immediately greeted his assistant to prepare the experiment. They put the surface of the wet caustic potash on a small platinum disk, and the platinum disk with a wire connected to the cathode of the battery; a platinum wire connected to the anode of the battery is inserted into the caustic potash, the whole device is exposed to the air. After the electricity was applied, the caustic potash began to melt, and the surface boiled, and Davy noticed that a strong light occurred on the cathode, and particles of mercury with a metallic luster were produced near the cathode; some of these particles burned immediately after their formation, and produced a mauve flame, and even exploded; others were oxidized, and a white film formed on the surface. David reversed the current in the electrolytic cell, and still found silver-white particles on the cathode, which also burned and exploded. David was so ecstatic at this amazing discovery that he actually jumped up and down in the room and wrote in his lab notebook, "Important experiment proving the decomposition of potash." He flung his pen away, and a large blob of ink ran down the book.
Later Davy electrolyzed moist caustic potash in an airtight crucible and finally got this silvery-white metal. David plunged it into the water and at first it spun rapidly on the surface with a hissing sound, then burned to release a lavender flame. He confirmed that he had discovered a new metallic element. Since this metal is made from potash (potash), so it will be named Potassium (Chinese translation for potassium). He later produced the metals sodium, magnesium, calcium, strontium and barium by electrolysis, as well as the non-metallic elements boron and silicon, making him the most prolific discoverer of new elements in the history of chemistry.
David in the electrolysis of lime and heavy clay (BaO) suffered a number of failures, because the melting point of lime and heavy clay up to 2,580 ℃ and 1,923 ℃, respectively, such high temperatures of calcium, barium, as soon as the appearance of the immediate combustion. 1808, May, David received a letter from Betserius, which mentioned that he and the king's royal physician in Sweden had been mixed with the electrolysis of lime and mercury, and successfully decomposed lime; they also received a letter from the King of Sweden's royal physician, which mentioned that he and the King of Sweden had been mixed with the electrolysis of mercury, and successfully decomposed the lime; they also had the electrolysis of lime. decomposed lime; they had also made barium amalgam by electrolyzing heavy clay in this way. Inspired by Betserius, David made large quantities of calcium amalgam by mixing moist lime and mercuric oxide in the ratio of 3:1 and electrolyzing it in a platinum dish. He carefully vaporized the mercury, thus obtaining pure calcium metal for the first time in the history of chemistry.
"Oxidized hydrochloric acid" is not a compound
In his study of the alkali and alkaline-earth metals, Davy encountered another difficulty; he found that alkalis were oxides, but he was puzzled by the suggestion that an acid could be said to contain oxygen. He had long been aware of Lavoisier's theory of the oxygen content of acids, and Lavoisier believed that oxygen was the origin of acidity and that all acids contained oxygen. Was the great chemist Lavoisier wrong, or was Davy incorrect about acids?
David was studying the chemistry of tellurium when he discovered that hydrogen telluride was an acid, but that it did not contain oxygen, leading him to wonder if oxygen was present in all acids. Looking for more evidence, Davy began to study hydrochloric acid. According to Lavoisier, a new yellowish-green gas produced by Scheele in 1774 by the action of hydrochloric acid with manganese dioxide was oxidized hydrochloric acid, which is made up of oxygen and another unknown group, and oxidized hydrochloric acid, which is made up of this group combined with more oxidation. But David could not wrest the oxygen from the oxidized hydrochloric acid by all means. He says: "Even when charcoal is burned to a white heat by a voltaic pile, it does not make any change in the oxidized hydrochloric acid gas, and I have repeated this experiment so many times, with the same result, that I doubt whether there is any oxygen in these substances."
The French physicists and chemists Guy Lussac and Thénard performed the same experiment and concluded that there was no oxygen in the oxidized hydrochloric acid, and that, on the contrary, the oxidized hydrochloric acid might have an elemental nature. But again they were convinced that the great chemist Lavoisier was without error, so that although they had opened the way to the discovery of chlorine as a chemical element, the result was still nothing creative. Only Davy declared that all the reactions which take place in oxidized hydrochloric acid do not produce oxygen so long as water is not present, and he thought it best to regard oxidized hydrochloric acid as a substance which cannot be decomposed . He thought the facts showed that the opinion held by Lavoisier and the French school of chemistry, beautiful and satisfactory on the face of it, was nothing more than a theory based on assumptions when examined in the light of the knowledge now available. So David confirmed with irrefutable facts that the so-called "oxidized hydrochloric acid" was in no way a compound, but a chemical element, which he named Chlorine, meaning yellowish-green. He believed that chlorine, like oxygen, could be ignited, that oxygen was not necessary for oxidation reactions, and that all exothermic reactions were oxidative. These ideas of Davy brilliantly developed Lavoisier's oxidizing theory of combustion.
"The Greatest Discovery"
While we marvel at Davy's daring to break with authority, his respect for facts, and his innovative spirit, and while the audience at the Becklin Lecture was impressed and booed by Davy's continuing discoveries, Davy's health was in overdrive. The frenzy of work had left him very debilitated. Just before the Becklin Lecture, he was invited to visit a prison to study the epidemic of typhoid fever and became infected himself. After the Becklin Lecture he could not hold out any longer, and it was only after several attempts at resuscitation that he gradually recovered in the hospital. During this period there was a steady stream of visitors, and the hospital had to put up a notice board at the front door announcing David's condition for the day every day.
David was discharged from the hospital and stayed at home. One day he received a letter and a 368-page, finely bound book with a cover that read: David's Lectures. The book was handwritten, with many beautiful illustrations. The letter reads: "I am a printer's bookbinding apprentice, love of science, listened to your four lectures. I am now presenting my notes as a Christmas gift. I would be grateful if you could help me to change my present situation. --Faraday"
David was overwhelmed with emotion, and remembering his own life, he immediately wrote to Faraday, asking him to meet him in a month.
Faraday was born on September 22, 1791, to a family of blacksmiths in London. He received no formal education beyond lessons in reading, writing and arithmetic. Beginning at age thirteen, he was apprenticed to a bookbinder. Faraday read almost all the scientific books sent to this store for binding, including the electricity section of the Encyclopedia Britannica. One book that had a particularly profound effect on him was Conservation in Chemistry by Mrs. Masset (the wife of a physicist), and he began to experiment in chemistry with some cheap apparatus and medicines that he bought with the pocket money he had saved. With the financial support of one of his not-so-wealthy brothers, Faraday listened to David's Becklin Lectures, and felt so inspired that he carefully organized his lecture notes, took out his bookbinding skills, and a finely bound copy of David's Lectures appeared in front of David's eyes.
Soon, David arranged for Faraday to work as an assistant in his laboratory. Although there was a lot of cleaning and scrubbing of instruments and other chores, Faraday was delighted to be able to listen to Davy and his assistants talk about science and the process of their experiments. David soon recognized Faraday's talent and gradually let him participate more in experiments and even work independently.
At the time, steam engines were widely used, coal mining was in short supply, and gas explosions in mines were frequent. For example, thousands of miners were killed in a gas explosion at the Newcastle upon Tyne colliery in England. David responded to the call of the "Association for the Prevention of Coal Mining Disasters" to develop a safety lamp. In Faraday's assistance, David will be added to the outside of the miner's lamp, a wire mesh made of the outer cover, the wire mesh conducts away the heat of the flame of the miner's lamp, so that the combustible gases do not reach the ignition point, the gas will not explode. This safety lamp has been used for more than a hundred years, saving the lives of millions of miners around the world.
In the fall of 1813, David took Faraday to Europe for a year and a half of travel and academic visits. Faraday as an assistant and valet to do a lot of services for Mr. and Mrs. David, but he had the opportunity to get acquainted with many famous scientists, such as Ampere, Chevreuse, Guy Lussac and Volt, listen to their lectures and conversations, to understand their scientific research activities, and broaden the scientific horizons. As the British chemist Wollaston, who was familiar with Faraday, said, "Faraday's university was Europe, and his teachers were the masters he served -- David, and the distinguished scientists whom Faraday was able to meet because of David's fame."
During his years with Davy, Faraday published papers in almost every field of chemistry. He succeeded in obtaining liquid chlorine; was an early smelter of stainless steel; studied the reaction of silver compounds with ammonia; isolated a variety of organic substances, the most important of which was benzene; and discovered the law of electrolytic equivalence. Faraday's greatest contribution, of course, was in electromagnetism in physics, where he discovered by experiment all the principles of the dynamo and the electric motor, which greatly contributed to the progress of society. He can thus be ranked with Galileo, Newton, Maxwell and Einstein.
In 1816 Faraday began a series of lectures at the Royal Academy, which were a brilliant success, and in 1825 he succeeded David as director of the laboratory. As Faraday's reputation grew, it was often said that "Davy's greatest discovery was the discovery of Faraday." Such jokes made David jealous of Faraday, and in 1824, David opposed Faraday's election as a member of the Royal Society (not the Royal Academy), and he was the only one of 25 to vote against it. Although Faraday was successfully elected, the incident made people feel very sorry and sad.
Sir Humphrey Davy
While in France in 1813, Davy and Faraday asked Napoleon to set up a system of scientific awards. For Davy's significant contribution, he was awarded three thousand francs. At the time there was fighting between Britain and France, but Davy believed that science had no borders, so he and his assistant Faraday kept visiting France. During this time David was also elected to the French Academy of Sciences.
In 1820 David learned of the illness of Sir David Banks, who had been president of the Royal Society before David was born, and immediately returned to London. After the death of Banks, it became clear that there were only two candidates for the presidency of the Royal Society, one of whom was David; the other was Wollaston. Davy was convinced that he would win the election, while Wollaston announced his withdrawal on the eve of the election, and Davy was elected President of the Royal Society in 1820, a position he held from 1820 to 1827. From then on, the Royal Society became more vibrant and attracted a large number of scientists, and Davie wanted all of these colleagues to do their best and to receive maximum support from the British government. He also suggested that the Museum of Great Britain follow the example of the Museum of Natural History in Paris, not only for all to see, but also as a center for research.
The Royal Society asked for information on the causes of corrosion of copper hulls of ships, David began to study the subject again, and found that if a more electropositive sheet of metal (called a protective layer) was fixed on the copper, the copper would not be corroded by seawater anymore. But in the test process, sea creatures, plants tightly adhering to the protective layer, so that the ship traveling by serious resistance, so this research has never been successful.
In 1826, due to family reasons, David ended the last Becklin Lecture, and thereafter withdrew from the field of scientific research due to declining health, and began to travel to Europe to cure his illness. 1826 David received the highest honor, and was named Sir Humphrey Davy.
Talk of Davy's illness is often associated with his enthusiastic, almost frenzied style, and those bold behaviors in his chemical experiments, as his younger brother, John Davy, said in describing his brother, "Humphrey was quite famous for his boldness in his experiments. He almost forgot the dangers in making his experiments, and such adventurous actions took place every day." Davy once injured his eye in an experiment in the preparation of nitrogen trichloride. Such years of poisoning and frantic work left Davy in unusually weakened health, and although he traveled to Europe to visit famous doctors, it was to no avail, and he died prematurely in Geneva, Switzerland, on May 29, 1829, having lived to be only 51 years old.
After David's death, his brother compiled a complete work on his behalf, titled The Complete Works of Sir Humphrey Davy, **** nine volumes, which became an important document in the history of chemistry.