Magia Naturalis is a work of popular science by Giambattista della Porta first published in Naples in 1558. Its popularity ensured it was republished in five Latin editions within ten years, with translations into Italian, French and English printed. Natural Magic was revised and expanded throughout the author's lifetime. Natural Magic is an example of pre-Baconian science, its sources include the ancient learning of Pliny the Elder and Theophrastus as well as numerous scientific observations made by Della Porta. Natural Magic was translated and published in English in 1658. Natural magic White magic Natural Magic online Natural Magick From the Collections at the Library of Congress
Manganese is a chemical element with symbol Mn and atomic number 25. It is not found as a free element in nature. Manganese is a metal with important industrial metal alloy uses in stainless steels. Manganese is named for pyrolusite and other black minerals from the region of Magnesia in Greece, which gave its name to magnesium and the iron ore magnetite. By the mid-18th century, Swedish-German chemist Carl Wilhelm Scheele had used pyrolusite to produce chlorine. Scheele and others were aware that pyrolusite contained a new element, but they were unable to isolate it. Johan Gottlieb Gahn was the first to isolate an impure sample of manganese metal in 1774, which he did by reducing the dioxide with carbon. Manganese phosphating is used for corrosion prevention on steel. Ionized manganese is used industrially as pigments of various colors, which depend on the oxidation state of the ions; the permanganates of alkali and alkaline earth metals are powerful oxidizers. Manganese dioxide is used as the cathode material in alkaline batteries.
In biology, manganese ions function as cofactors for a large variety of enzymes with many functions. Manganese enzymes are essential in detoxification of superoxide free radicals in organisms that must deal with elemental oxygen. Manganese functions in the oxygen-evolving complex of photosynthetic plants. While the element is a required trace mineral for all known living organisms, it acts as a neurotoxin in larger amounts. Through inhalation, it can cause manganism, a condition in mammals leading to neurological damage, sometimes irreversible. Manganese is a silvery-gray metal, it is hard and brittle, difficult to fuse, but easy to oxidize. Manganese metal and its common ions are paramagnetic. Manganese tarnishes in air and oxidizes like iron in water containing dissolved oxygen. Occurring manganese is composed of one stable isotope, 55Mn. Eighteen radioisotopes have been isolated and described, ranging in atomic weight from 46 u to 65 u; the most stable are 53Mn with a half-life of 3.7 million years, 54Mn with a half-life of 312.3 days, 52Mn with a half-life of 5.591 days.
All of the remaining radioactive isotopes have half-lives of less than three hours, the majority of less than one minute. The primary decay mode before the most abundant stable isotope, 55Mn, is electron capture and the primary mode after is beta decay. Manganese has three meta states. Manganese is part of the iron group of elements, which are thought to be synthesized in large stars shortly before the supernova explosion. 53Mn decays to 53Cr with a half-life of 3.7 million years. Because of its short half-life, 53Mn is rare, produced by cosmic rays impact on iron. Manganese isotopic contents are combined with chromium isotopic contents and have found application in isotope geology and radiometric dating. Mn–Cr isotopic ratios reinforce the evidence from 26Al and 107Pd for the early history of the solar system. Variations in 53Cr/52Cr and Mn/Cr ratios from several meteorites suggest an initial 53Mn/55Mn ratio, which indicates that Mn–Cr isotopic composition must result from in situ decay of 53Mn in differentiated planetary bodies.
Hence, 53Mn provides additional evidence for nucleosynthetic processes before coalescence of the solar system. The most common oxidation states of manganese are +2, +3, +4, +6, +7, though all oxidation states from −3 to +7 have been observed. Mn2+ competes with Mg2+ in biological systems. Manganese compounds where manganese is in oxidation state +7, which are restricted to the unstable oxide Mn2O7, compounds of the intensely purple permanganate anion MnO4−, a few oxyhalides, are powerful oxidizing agents. Compounds with oxidation states +5 and +6 are strong oxidizing agents and are vulnerable to disproportionation; the most stable oxidation state for manganese is +2, which has a pale pink color, many manganese compounds are known, such as manganese sulfate and manganese chloride. This oxidation state is seen in the mineral rhodochrosite. Manganese most exists with a high spin, S = 5/2 ground state because of the high pairing energy for manganese. However, there are a few examples of S = 1/2 manganese.
There are no spin-allowed d–d transitions in manganese, explaining why manganese compounds are pale to colorless. The +3 oxidation state is known in compounds like manganese acetate, but these are quite powerful oxidizing agents and prone to disproportionation in solution, forming manganese and manganese. Solid compounds of manganese are characterized by its strong purple-red color and a preference for distorted octahedral coordination resulting from the Jahn-Teller effect; the oxidation state +5 can be produced by dissolving manganese dioxide in molten sodium nitrite. Manganate salts can be produced by dissolving Mn compounds, such as manganese dioxide, in molten alkali while exposed to air. Permanganate compounds are purple, can give glass a violet color. Potassium permanganate, sodium permanganate, barium permanganate are all potent oxidizers. Potassium permanganate called Condy's crystals, is a used laboratory reagent because of its oxidizing properties. Solutions of potassium permanganate were among the first stains and fixatives to be used in the preparation of biological cells and tissues for electron microscopy
Critical point (thermodynamics)
In thermodynamics, a critical point is the end point of a phase equilibrium curve. The most prominent example is the liquid-vapor critical point, the end point of the pressure-temperature curve that designates conditions under which a liquid and its vapor can coexist. At higher temperatures, the gas cannot be liquefied by pressure alone. At the critical point, defined by a critical temperature Tc and a critical pressure pc, phase boundaries vanish. Other examples include the liquid–liquid critical points in mixtures. For simplicity and clarity, the generic notion of critical point is best introduced by discussing a specific example, the liquid-vapor critical point; this was the first critical point to be discovered, it is still the best known and most studied one. The figure to the right shows the schematic PT diagram of a pure substance; the known phases solid and vapor are separated by phase boundaries, i.e. pressure-temperature combinations where two phases can coexist. At the triple point, all three phases can coexist.
However, the liquid-vapor boundary terminates in an endpoint at some critical temperature Tc and critical pressure pc. This is the critical point. In water, the critical point occurs at 22.064 MPa. In the vicinity of the critical point, the physical properties of the liquid and the vapor change with both phases becoming more similar. For instance, liquid water under normal conditions is nearly incompressible, has a low thermal expansion coefficient, has a high dielectric constant, is an excellent solvent for electrolytes. Near the critical point, all these properties change into the exact opposite: water becomes compressible, expandable, a poor dielectric, a bad solvent for electrolytes, prefers to mix with nonpolar gases and organic molecules. At the critical point, only one phase exists; the heat of vaporization is zero. There is a stationary inflection point in the constant-temperature line on a PV diagram; this means that at the critical point: T = 0 T = 0 Above the critical point there exists a state of matter, continuously connected with both the liquid and the gaseous state.
It is called supercritical fluid. The common textbook knowledge that all distinction between liquid and vapor disappears beyond the critical point has been challenged by Fisher and Widom who identified a p,T-line that separates states with different asymptotic statistical properties; the existence of a critical point was first discovered by Charles Cagniard de la Tour in 1822 and named by Dmitri Mendeleev in 1860 and Thomas Andrews in 1869. Cagniard showed that CO2 could be liquefied at 31 °C at a pressure of 73 atm, but not at a higher temperature under pressures as high as 3,000 atm. Solving the above condition T = 0 for the van der Waals equation, one can compute the critical point as T c = 8 a 27 R b, V c = 3 n b, p c = a 27 b 2. However, the van der Waals equation, based on a mean field theory, does not hold near the critical point. In particular, it predicts wrong scaling laws. To analyse properties of fluids near the critical point, reduced state variables are sometimes defined relative to the critical properties T r = T T c, p r = p p c, V r = V R T c / p c.
The principle of corresponding states indicates that substances at equal reduced pressures and temperatures have equal reduced volumes. This relationship is true for many substances, but becomes inaccurate for large values of pr. For some gases, there is an additional correction factor, called Newton's correction, added to the critical temperature and critical pressure calculated in this manner; these vary with the pressure range of interest. The liquid–liquid critical point of a solution, which occurs at the critical solution temperature, occurs at the limit of the two-phase region of the phase diagram. In other words, it is the point at which an infinitesimal change in some thermodynamic variable will lead to separation of the mixture into two distinct liquid phases, as shown in the polymer–solvent phase diagram to the right. Two types of liquid–liquid critical points are the upper critical solution temperature, t
Martensite is named after the German metallurgist Adolf Martens. The term most refers to a hard form of steel crystalline structure, but can refer to any crystal structure, formed by diffusionless transformation. Martensite includes a class of hard minerals. Martensite is formed in carbon steels by the rapid cooling of the austenite form of iron at such a high rate that carbon atoms do not have time to diffuse out of the crystal structure in large enough quantities to form cementite. Austenite is γ-Fe, a solid solution of iron and alloying elements; as a result of the quenching, the face-centered cubic austenite transforms to a strained body-centered tetragonal form called martensite, supersaturated with carbon. The shear deformations that result produce a large number of dislocations, a primary strengthening mechanism of steels; the highest hardness of a pearlitic steel is 400 Brinell. The martensitic reaction begins during cooling when the austenite reaches the martensite start temperature and the parent austenite becomes mechanically unstable.
As the sample is quenched, an large percentage of the austenite transforms to martensite until the lower transformation temperature Mf is reached, at which time the transformation is completed. For a eutectoid steel, between 6 and 10% of austenite, called retained austenite, will remain; the percentage of retained austenite increases from insignificant for less than 0.6% C steel, to 13% retained austenite at 0.95% C and 30–47% retained austenite for a 1.4% carbon steels. A rapid quench is essential to create martensite. For a eutectoid carbon steel of thin section, if the quench starting at 750 °C and ending at 450 °C takes place in 0.7 seconds no pearlite will form and the steel will be martensitic with small amounts of retained austenite. For steel 0-0.6% carbon the martensite has the appearance of lath, is called lath martensite. For steel greater than 1 % carbon. Between those two percentages, the physical appearance of the grains is a mix of the two; the strength of the martensite is reduced.
If the cooling rate is slower than the critical cooling rate, some amount of pearlite will form, starting at the grain boundaries where it will grow into the grains until the Ms temperature is reached the remaining austenite transforms into martensite at about half the speed of sound in steel. In certain alloy steels, martensite can be formed by the working and hence deformation of the steel at temperature, while it is in its austenitic form, by quenching to below Ms and working by plastic deformations to reductions of cross section area between 20% to 40% of the original; the process produces dislocation densities up to 1013/cm2. The great number of dislocations, combined with precipitates that originate and pin the dislocations in place, produces a hard steel; this property is used in toughened ceramics like yttria-stabilized zirconia and in special steels like TRIP steels. Thus, martensite can be stress induced. One of the differences between the two phases is that martensite has a body-centered tetragonal crystal structure, whereas austenite has a face-centered cubic structure.
The growth of martensite phase requires little thermal activation energy because the process is a diffusionless transformation, which results in the subtle but rapid rearrangement of atomic positions, has been known to occur at cryogenic temperatures. Martensite has a lower density than austenite, so that the martensitic transformation results in a relative change of volume. Of greater importance than the volume change is the shear strain, which has a magnitude of about 0.26 and which determines the shape of the plates of martensite. Martensite is not shown in the equilibrium phase diagram of the iron-carbon system because it is not an equilibrium phase. Equilibrium phases form by slow cooling rates that allow sufficient time for diffusion, whereas martensite is formed by high cooling rates. Since chemical processes accelerate at higher temperature, martensite is destroyed by the application of heat; this process is called tempering. In some alloys, the effect is reduced by adding elements such as tungsten that interfere with cementite nucleation, more than not, the nucleation is allowed to proceed to relieve stresses.
Since quenching can be difficult to control, many steels are quenched to produce an overabundance of martensite tempered to reduce its concentration until the preferred structure for the intended application is achieved. The needle-like microstructure of martensite leads to brittle behavior of the material. Too much martensite leaves steel brittle. Eutectic Eutectoid Ferrite Maraging steel Spring steel Tool steel Comprehensive resources on martensite, from the University of Cambridge Metallurgy for the Non-Metallurgist from the American Society for Metals PTCLab---Capable of calculating martensite crystallography with single shear or double shear theory
Steel is an alloy of iron and carbon, sometimes other elements. Because of its high tensile strength and low cost, it is a major component used in buildings, tools, automobiles, machines and weapons. Iron is the base metal of steel. Iron is able to take on two crystalline forms, body centered cubic and face centered cubic, depending on its temperature. In the body-centered cubic arrangement, there is an iron atom in the center and eight atoms at the vertices of each cubic unit cell, it is the interaction of the allotropes of iron with the alloying elements carbon, that gives steel and cast iron their range of unique properties. In pure iron, the crystal structure has little resistance to the iron atoms slipping past one another, so pure iron is quite ductile, or soft and formed. In steel, small amounts of carbon, other elements, inclusions within the iron act as hardening agents that prevent the movement of dislocations that are common in the crystal lattices of iron atoms; the carbon in typical steel alloys may contribute up to 2.14% of its weight.
Varying the amount of carbon and many other alloying elements, as well as controlling their chemical and physical makeup in the final steel, slows the movement of those dislocations that make pure iron ductile, thus controls and enhances its qualities. These qualities include such things as the hardness, quenching behavior, need for annealing, tempering behavior, yield strength, tensile strength of the resulting steel; the increase in steel's strength compared to pure iron is possible only by reducing iron's ductility. Steel was produced in bloomery furnaces for thousands of years, but its large-scale, industrial use began only after more efficient production methods were devised in the 17th century, with the production of blister steel and crucible steel. With the invention of the Bessemer process in the mid-19th century, a new era of mass-produced steel began; this was followed by the Siemens–Martin process and the Gilchrist–Thomas process that refined the quality of steel. With their introductions, mild steel replaced wrought iron.
Further refinements in the process, such as basic oxygen steelmaking replaced earlier methods by further lowering the cost of production and increasing the quality of the final product. Today, steel is one of the most common manmade materials in the world, with more than 1.6 billion tons produced annually. Modern steel is identified by various grades defined by assorted standards organizations; the noun steel originates from the Proto-Germanic adjective stahliją or stakhlijan, related to stahlaz or stahliją. The carbon content of steel is between 0.002% and 2.14% by weight for plain iron–carbon alloys. These values vary depending on alloying elements such as manganese, nickel, so on. Steel is an iron-carbon alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction. Too little carbon content leaves iron quite soft and weak. Carbon contents higher than those of steel make a brittle alloy called pig iron. While iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel.
Common alloying elements include: manganese, chromium, boron, vanadium, tungsten and niobium. Additional elements, most considered undesirable, are important in steel: phosphorus, sulfur and traces of oxygen and copper. Plain carbon-iron alloys with a higher than 2.1% carbon content are known as cast iron. With modern steelmaking techniques such as powder metal forming, it is possible to make high-carbon steels, but such are not common. Cast iron is not malleable when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties. Certain compositions of cast iron, while retaining the economies of melting and casting, can be heat treated after casting to make malleable iron or ductile iron objects. Steel is distinguishable from wrought iron, which may contain a small amount of carbon but large amounts of slag. Iron is found in the Earth's crust in the form of an ore an iron oxide, such as magnetite or hematite. Iron is extracted from iron ore by removing the oxygen through its combination with a preferred chemical partner such as carbon, lost to the atmosphere as carbon dioxide.
This process, known as smelting, was first applied to metals with lower melting points, such as tin, which melts at about 250 °C, copper, which melts at about 1,100 °C, the combination, which has a melting point lower than 1,083 °C. In comparison, cast iron melts at about 1,375 °C. Small quantities of iron were smelted in ancient times, in the solid state, by heating the ore in a charcoal fire and welding the clumps together with a hammer and in the process squeezing out the impurities. With care, the carbon content could be controlled by moving it around in the fire. Unlike copper and tin, liquid or solid iron dissolves carbon quite readily. All of these temperatures could be reached with ancient methods used since the Bronze Age. Since the oxidation rate of iron increases beyond 800 °C, it is important that smelting take place in a low-oxygen environment. Smelting, using carbon to reduce iro
Giambattista della Porta
Giambattista della Porta known as Giovanni Battista Della Porta, was an Italian scholar and playwright who lived in Naples at the time of the Scientific Revolution and Reformation. Giambattista della Porta spent the majority of his life on scientific endeavors, he benefited from an informal education of visits from renowned scholars. His most famous work, first published in 1558, is entitled Magiae Naturalis. In this book he covered a variety of the subjects he had investigated, including occult philosophy, alchemy, mathematics and natural philosophy, he was referred to as "professor of secrets". Giambattista della Porta was born at Vico Equense, near Naples, to the nobleman Nardo Antonio della Porta, he was the third of four sons and the second to survive childhood, having an older brother Gian Vincenzo and a younger brother Gian Ferrante. Della Porta had a privileged childhood including his education, his father had a thirst for a trait he would pass onto all of his children. He surrounded himself with distinguished people and entertained the likes of philosophers, mathematicians and musicians.
The atmosphere of the house resembled an academy for his sons. The members of the learned circle of friends stimulated the boys and mentoring them, under strict guidance of their father, it is possible that his father's interest and influence in providing a well-rounded education helped to turn della Porta into the Renaissance man that he was to become. In addition to having talents for the sciences and mathematics, all the brothers were extremely interested in the arts, music in particular. Despite their interest none of them possessed any sort of talent for it, but they did not allow that to stifle their progress in learning of theory, they were all accepted into the Scuola di Pitagora, a exclusive academy of musicians. The pure impressiveness of their intellect was enough to allow three tone-deaf mathematicians into a school for the musically gifted; the status of the family as a symbol of knowledge and intellectual growth helped in their acceptance as well. More aware of their social position than the idea that his sons could have professions in science, Nardo Antonio was raising the boys more as gentlemen.
Therefore, the boys struggled with singing, as, considered a courtly accomplishment of gentlemen. They were taught to dance, ride, to take part and perform well in tournaments and games, dress well so they could look good doing all these noble activities; the training gave della Porta, at least earlier in his life, a taste for the finer aspects of his privileged living, where he surrounded himself in noble company and lavish things. This kind of lifestyle, the façade and showmanship involved in presenting one's self carried with Giambattista throughout his life. In 1563, della Porta published a work about cryptography. In it he described the first known digraphic substitution cipher. Charles J. Mendelsohn commented: He was, in my opinion, the outstanding cryptographer of the Renaissance; some unknown who worked in a hidden room behind closed doors may have surpassed him in general grasp of the subject, but among those whose work can be studied he towers like a giant. Della Porta invented a method.
During the Spanish Inquisition, some of his friends were imprisoned. At the gate of the prison, everything was checked except for eggs. Della Porta wrote messages on the egg shell using a mixture made of alum; the ink penetrated the egg shell, semi-porous. When the egg shell was dry, he boiled the egg in hot water and the ink on the outside of the egg was washed away; when the recipient in prison peeled off the shell, the message was revealed once again on the egg white. In 1586 della Porta published a work on physiognomy, De humana physiognomonia libri IIII; this influenced the Swiss eighteenth-century pastor Johann Kaspar Lavater as well as the 19th century criminologist Cesare Lombroso. Della Porta wrote extensively on a wide spectrum of subjects throughout his life – for instance, an agricultural encyclopedia entitled "Villa" as well as works on meteorology and astronomy. In 1589, on the eve of the early modern Scientific Revolution, della Porta became the first person to attack in print, on experimental grounds, the ancient assertion that garlic could disempower magnets.
This was an early example of the authority of early authors being replaced by experiment as the backing for a scientific assertion. Della Porta's conclusion was confirmed experimentally among others. In life, della Porta collected rare specimens and grew exotic plants, his work Phytognomonica lists plants according to their geographical location. In Phytognomonica the first observation of fungal spores is recorded, making him a pioneer of mycology, his private museum was visited by travelers and was one of the earliest examples of natural history museums. It inspired the Jesuit Athanasius Kircher to begin a similar more renowned, collection in Rome. Della Porta was the founder of a scientific society called the Academia Secretorum Naturae; this group was more known as the Otiosi. Founded sometime before 1580, the Otiosi were one of the first scientific societies in Europe and their aim was to study the "secrets of nature." Any person applying for membership had to demonstrate they had made a new discovery in the natural sciences.
The Academia Secretorum Naturae was compelled to disband when its members were suspected of dealing with the Occ