Ethylene first appeared because methane (CH4), ethylene (C2H4) and acetylene (C2H2) are the three simplest hydrocarbons, all of which are chain hydrocarbons, because they all have chain structures, which are different from cyclic hydrocarbons with cyclic structures. Party A, Party B, Party C, Party D, Party E, Party B, Party G, Party B, Party A, Party B, Party B, Party B and Party B are called heavenly stems, also known as ten stems. They and earthly branches have been used to express the order of year, month, day and time since ancient times and have been used repeatedly. Chemists in China use them to represent the number of carbon atoms in chain hydrocarbons. Alkanes, alkenes and alkynes are used to indicate the saturation of hydrogen atoms: alkanes mean "integrity", carbon is tetravalent, 1 carbon atom is combined with 4 hydrogen atoms; Olefin means "rare"; Acetylene means "lack". All three use "fire" to indicate that they can burn. Methane is the product of plant decay, which exists in swamps, coal seams and sludge of natural gas. It is also called biogas and coal pit gas. There is a saying in Zhouyi that "there is fire in the river", that is to say, the biogas produced in the swamp is burning. As early as 250 BC, Li Bing, the guardian of Shu County in Qin Dynasty in China, dug a salt well in Sichuan, and boiled the well salt with biogas in the fire well. Later generations recorded the use of biogas. In ancient China, people only extracted and utilized it, but did not analyze and study it. Italian physicist Volt described his methane discovery in a letter to a friend in 1776. He collected a gas in the mud of Lake Como in northern Italy. At that time, he stirred the mud with a wooden stick, let the emitted gas turn upside down in a bottle full of water, let the water go, and then lit the gas. Results The flame was bluish blue and burned slowly, and it was mixed with air with twice the volume of 10 ~ 12. The result was different from that of combustible air (hydrogen) found at that time. 1790, British doctor Austin published a research report on burning methane and hydrogen. He called methane heavy combustible air and hydrogen light combustible air. The difference is that heavy combustible air produces fixed air (carbon dioxide) and water, while light combustible air only produces water, so he determined that methane is a compound of carbon and hydrogen. 1804, British chemist Dalton also collected methane from the swamp. In the same year, he carried out the experiment of mixed combustion and explosion of methane and oxygen, and determined that its atomic weight was 6. 3。 At that time, he didn't have the concept of molecules, and thought that the molecules of compounds were composed of compound atoms, so he took the atomic weight of hydrogen equal to 1 as the standard to determine the atomic weight. He didn't measure the atomic ratio of carbon to hydrogen in methane, but realized that it contained a lot of carbon and called it "carbon-filled hydrogen". 16 ~17th century, coal mines all over Europe often exploded due to lamp flame when they were in into the pit. 18 12. The Gateshead coal mine on the river Tyne in the British port city exploded, killing 392 people. Some people think this is because there is a kind of coal pit gas in the coal pit. British chemist Thomson determined that coal mine gas is "hydrogen full of carbon". David, a British chemist, conducted a study to prevent explosion accidents. David made a safety lamp and sealed the flame in a cover made of barbed wire, so that the heat generated by the lamp was absorbed by the barbed wire, and the temperature of explosive gas outside the barbed wire would not rise to the ignition point. 1839, French chemist Pessotz said in his report that methane was produced by the action of sodium acetate and sodium hydroxide. He analyzed the chemical composition of methane, called it carbon tetrahydride, and gave its chemical formula CH4. This method of producing methane with Pessotz is still used in chemistry laboratory. 1856, French chemist Berthelot mixed carbon disulfide with hydrogen sulfide or water vapor by burning red copper to get methane. Dutch chemists first made and discovered ethylene. Dutch naturalist Ingen? In the report published in 1779, Holtz said that in March 1779 and October 165438 10, he saw Dutch chemist Kas batson and others mix alcohol with sulfuric acid (sulfuric acid) and a gas released by heating with ordinary air or oxygen, which exploded violently. They determined that this gas is heavier than ordinary air and is a mixture of hydrogen and oxygen. At the end of 18, Dutch chemist Diman and others not only discovered the method of dehydration of ethanol with sulfuric acid, which is still used in chemical laboratories, but also discovered the method of obtaining ethylene by introducing ethanol vapor into clay or alumina catalyst. They determined that the chemical composition of ethylene is carbon and hydrogen, and found that it reacts with chlorine to form an oily liquid (vinyl chloride), so it is called "hydrocarbon-forming hydrogen". This substance is called "hydrocarbon generation" when it arrives in France. Acetylene, commonly known as calcium carbide gas, was discovered as early as 1836. This year, David, a British chemistry professor, put the residue (potassium carbide) into water during the process of heating carbon and potassium carbonate to prepare metal potassium, which produced gas and exploded. Therefore, it is determined that its chemical composition is C2H (calculated by the atomic weight of carbon equal to 6), which is called "new hydrogen carbide" to distinguish it from the hydrocarbon (benzene) obtained from whale body by chemist Faraday in 1825. 1862, French chemist Berthollet passed hydrogen through an arc between two carbon electrodes, so that hydrogen and carbon directly synthesized acetylene, and its chemical formula was determined as C4H2. In the 1990s, the French chemist Muwasan invented the electric stove. Calcium carbide (calcium carbide) is made by the reaction of calcium oxide and coke in an electric furnace, and acetylene is made by the reaction of calcium carbide and water, which became the method of making acetylene in industry later. 1On May 4th, 892, Wilson, the owner of American aluminum smelter, put the mixture of lime and coal tar into the electric furnace, hoping to use the carbon in coal tar to reduce the calcium in lime, and the result was a dark black brittle substance. He dumped these wastes into water and produced a lot of gas; He lit the gas, which produced a lot of black smoke and a bright flame. He once studied chemistry and realized that this gas is not hydrogen, but a carbon-containing compound gas, otherwise it would not produce black smoke. He sent the samples to Willeb, a chemistry professor at the University of North Carolina, for analysis and identification. Results It was determined that the black brittle substance was calcium carbide and the gas produced was acetylene. At the beginning of 1895, Le Chatterley, a French chemist and metallurgical engineer, submitted a paper to the French Academy of Sciences, pointing out that acetylene is dangerous in compression and will explode. 1897, French chemist Claude discovered that acetylene can be easily absorbed and dissolved by acetone and can be safely used in steel cylinders. Later, in 190 1 year, the French Fauci brothers completed the torch design. Therefore, oxyacetylene flame is widely used in metal cutting and welding, which makes the processing of many parts in industrial production have simpler methods besides arc cutting and welding.