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Phlogiston Theory
The phlogiston theory is a superseded scientific theory that postulated the existence of a fire-like element called phlogiston () contained within combustible bodies and released during combustion. The name comes from the Ancient Greek (''burning up''), from (''flame''). The idea was first proposed in 1667 by Johann Joachim Becher and later put together more formally by Georg Ernst Stahl. Phlogiston theory attempted to explain chemical processes such as combustion and rusting, now collectively known as oxidation. It was challenged by the concomitant weight increase, and was abandoned before the end of the 18th century following experiments by Antoine Lavoisier and others. Phlogiston theory led to experiments which ultimately concluded with the discovery of oxygen. Theory Phlogiston theory states that ''phlogisticated'' substances contain phlogiston and that they ''dephlogisticate'' when burned, releasing stored phlogiston which is absorbed by the air. Growing plants then absor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Classical Elements
Classical elements typically refer to earth, water, air, fire, and (later) aether which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Ancient cultures in Greece, Tibet, and India had similar lists which sometimes referred, in local languages, to "air" as "wind" and the fifth element as "void". These different cultures and even individual philosophers had widely varying explanations concerning their attributes and how they related to observable phenomena as well as cosmology. Sometimes these theories overlapped with mythology and were personified in deities. Some of these interpretations included atomism (the idea of very small, indivisible portions of matter), but other interpretations considered the elements to be divisible into infinitely small pieces without changing their nature. While the classification of the material world in ancient Indian, Hellenistic Egypt, and ancient Greece into Air, Earth, Fire and Water was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giovanni Antonio Giobert
Giovanni Antonio Giobert also known as Jean-Antoine Giobert (27 October 1761 in Mongardino - 14 September 1834 in Millefiori) was an Italian chemist and mineralogist who studied magnetism, galvanism, and agricultural chemistry. He introduced Antoine Lavoisier's theories to Italy, and built a phosphorus-based eudiometer sufficiently sensitive to measure atmospheric carbon dioxide and oxygen. He identified the correct composition of the mineral Gioberite, a form of magnesite (MgCO3) found in the Piedmont area. He was made a knight (Cavaliere) for his work on the chemistry of indigo dyes. Early life Giovanni Antonio Giobert was born on 27 October 1761 in Mongardino near Asti, to Spirito and Anna Gugalin. He was educated by Abbot G. B. Lovizzolo, studying the physical sciences and chemistry, and was apprenticed in pharmacies in Asti and Turin. Science In his early twenties, Giobert focused his studies on the application of chemistry in agriculture and industry. He became a member of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guillaume-François Rouelle
Guillaume François Rouelle (, 15 September 1703 – 3 August 1770) was a French chemist and apothecary. In 1754 he introduced the concept of a base into chemistry as a substance which reacts with an acid to form a salt). He is known as ''l'Aîné'' (the elder) to distinguish him from his younger brother, Hilaire Rouelle, who was also a chemist and known as the discoverer of urea. He started a public course in his laboratory in 1738 where he taught many students among whom were Denis Diderot, Antoine-Laurent de Lavoisier, Joseph Proust and Antoine-Augustin Parmentier. He was elected a foreign member of the Royal Swedish Academy of Sciences in 1749. Why bases for neutral salts were called bases The modern meaning of the word "base" and its general introduction into the chemical vocabulary are usually attributed to the French chemist, Guillaume-François Rouelle (1703–1770), who used the term "Base" in a memoir on salts written in 1754 (see The Origin of the Term "Base" by Wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johann Juncker
Johann Juncker (23 December 1679 in Londorf, Hesse – 25 October 1759 in Halle) was a German physician and chemist. Juncker was a leader in the Pietist reform movement as it applied to medicine. He directed the Francke Foundations and initiated approaches to medical practice, charitable treatment, and education at the University of Halle that influenced others internationally. He was a staunch proponent of Georg Ernst Stahl and helped to more clearly present Stahl's phlogiston theory of combustion. Early life and education Johann Juncker was born on 23 December 1679 to Johann Ludwig Juncker, a well-to-do tenant farmer in Londorf, near Giessen. Juncker went to school in Allendorf and Obernhof, before attending the Pädagogium in Giessen for four years. The head of the institution at that time, J. H. May, was a Pietist. A dissident evangelical reform movement, Pietism emphasized the practical application of theology and active charitable work. Juncker attended the University ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcination
Calcination refers to thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), generally for the purpose of removing impurities or volatile substances and/or to incur thermal decomposition. The root of the word calcination refers to its most prominent use, which is to remove carbon from limestone (calcium carbonate) through combustion to yield calcium oxide (quicklime). This calcination reaction is CaCO3(s) → CaO(s) + CO2(g). Calcium oxide is a crucial ingredient in modern cement, and is also used as a chemical flux in smelting. Industrial calcination generally emits carbon dioxide (), making it a major contributor to climate change. A calciner is a steel cylinder that rotates inside a heated furnace and performs indirect high-temperature processing (550–1150 °C, or 1000–2100 °F) within a controlled ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tacit Knowledge
Tacit knowledge or implicit knowledge—as opposed to formal, codified or explicit knowledge—is knowledge that is difficult to express or extract, and thus more difficult to transfer to others by means of writing it down or verbalizing it. This can include personal wisdom, experience, insight, and intuition. For example, knowing that London is in the United Kingdom is a piece of ''explicit'' knowledge; it can be written down, transmitted, and understood by a recipient. In contrast, the ability to speak a language, ride a bicycle, knead dough, play a musical instrument, or design and use complex equipment requires all sorts of knowledge which is not always known ''explicitly'', even by expert practitioners, and which is difficult or impossible to explicitly transfer to other people. Overview Origin The term tacit knowing is attributed to Michael Polanyi's ''Personal Knowledge'' (1958). In his later work, ''The Tacit Dimension'' (1966), Polanyi made the assertion that "we can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Popular Science
''Popular Science'' (also known as ''PopSci'') is an American digital magazine carrying popular science content, which refers to articles for the general reader on science and technology subjects. ''Popular Science'' has won over 58 awards, including the American Society of Magazine Editors awards for its journalistic excellence in 2003 (for General Excellence), 2004 (for Best Magazine Section), and 2019 (for Single-Topic Issue). With roots beginning in 1872, ''Popular Science'' has been translated into over 30 languages and is distributed to at least 45 countries. Early history ''The Popular Science Monthly'', as the publication was originally called, was founded in May 1872 by Edward L. Youmans to disseminate scientific knowledge to the educated layman. Youmans had previously worked as an editor for the weekly ''Appleton's Journal'' and persuaded them to publish his new journal. Early issues were mostly reprints of English periodicals. The journal became an outlet for writings ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johann Heinrich Pott
Johann Heinrich Pott (6 October 1692 – 29 March 1777) was a Prussian physician and chemist. He is considered a pioneer of pyrochemistry. He examined the elements bismuth and manganese apart from attempting improvements to glass and porcelain production. Biography Pott was born in Halberstadt, son of the royal councillor Johann Andreas Pott (1662–1729) and Dorothea Sophia daughter of Andreas Machenau. He studied at the cathedral school in Halberstadt and Francke's pedagogium before studying theology at the University of Halle. He then shifted to study medicine and chemistry under Georg Ernst Stahl. In 1713 he studied assaying at Mansfield under mining master Lages. He spent two years along with two of his brothers as travelling evangelists for the Community of True Inspiration but he left the sect in 1715 and returned to study chemistry at Halle, receiving a doctorate in 1716 on sulfur under Friedrich Hoffmann. He worked as a physician in Halberstadt before moving to Berlin in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liver Of Sulphur
Liver of sulfur is a loosely defined mixture of potassium sulfide, potassium polysulfide, potassium thiosulfate, and likely potassium bisulfide. Synonyms include hepar sulfuris, sulfur, sulfurated potash and sulfurated potassa. There are two distinct varieties: "potassic liver of sulfur" and "ammoniacal liver of sulfur". Overview Liver of sulfur is mainly used in metalworking to form a brown or black patina on copper and silver as well as many (though not all) copper alloys and silver alloys (brass, for example— a copper alloy— does not react with sulfur compounds). It is sold as a yellow brittle solid (a "lump" which must be mixed with water before use) as well as a pre-mixed liquid and a gel form. The solid is believed to have the longest shelf life, though all liver of sulfur tends to decompose with time. Modern gel forms contain stabilizers that allow the reactivity to last much longer. Liver of sulfur that is kept dry, sealed from air, out of the light, and in a fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulphate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many are prepared from that acid. Spelling "Sulfate" is the spelling recommended by IUPAC, but "sulphate" was traditionally used in British English. Structure The sulfate anion consists of a central sulfur atom surrounded by four equivalent oxygen atoms in a tetrahedral arrangement. The symmetry is the same as that of methane. The sulfur atom is in the +6 oxidation state while the four oxygen atoms are each in the −2 state. The sulfate ion carries an overall charge of −2 and it is the conjugate base of the bisulfate (or hydrogensulfate) ion, , which is in turn the conjugate base of , sulfuric acid. Organic sulfate esters, such as dimethyl sulfate, are covalent compounds and esters of sulfuric acid. The tetrahedral molecular geometry of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soot
Soot ( ) is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons. It is more properly restricted to the product of the gas-phase combustion process but is commonly extended to include the residual pyrolysed fuel particles such as coal, cenospheres, charred wood, and petroleum coke that may become airborne during pyrolysis and that are more properly identified as cokes or char. Soot causes various types of cancer and lung disease. Sources Soot as an airborne contaminant in the environment has many different sources, all of which are results of some form of pyrolysis. They include soot from coal burning, internal-combustion engines, power-plant boilers, hog-fuel boilers, ship boilers, central steam-heat boilers, waste incineration, local field burning, house fires, forest fires, fireplaces, and furnaces. These exterior sources also contribute to the indoor environment sources such as smoking of plant matter, cooking, oil lamps, candles, qu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
