Fire
Fire is the name given to the set of incandescent particles or molecules of combustible matter (see also combustion), capable of emitting heat and light, product of an accelerated oxidation chemical reaction. The flames are the parts of the fire that emit light, while the smoke is the physical set of the same that no longer emit it. Flames consist primarily of carbon dioxide, water vapor, oxygen, and nitrogen. If hot enough, the gases can ionize and become plasma. It is also known as lumbre or candela (in Cuba, Puerto Rico and Venezuela).
Physicochemical behavior
This strong chemical reaction of oxidation is an exothermic process, which means that, at the same time, it gives off energy in the form of heat to the air around it. The air around the hot molecules or particles decreases in density and tends to float on top of the cooler air (convection). In the particular case of a solid-state fire, hot air travels upward at such a speed that it pushes heavy fuel particles in the same direction (still hot and shiny), which drop in temperature like the surrounding air, leaving of shining and becoming generally coal-black; As the air cools, it begins to slow down to such an extent that it can no longer push the particles up and, if they weigh more than the air, they begin to levitate without rising, and then fall back to the ground.[citation required]
Evolution of the scientific conception of fire
In classical antiquity, fire was one of the four classical elements, along with water, air and earth. The four elements represented the four known forms of matter and were used to explain different behaviors of nature. In Western culture, the origin of the theory of the four elements can be found in the pre-Socratic philosophers of classical Greece, and since then it has been the subject of numerous works of artistic and philosophical expression, lasting through the Middle Ages and the Renaissance and influencing deep into European culture and thought. In parallel, Hinduism and Buddhism had developed very similar concepts.
In most of these schools of thought, a fifth element is usually added to the traditional four, alternately called idea, void, ether, or quintessence (literally "the quintessence").
The concept of the classical elements continued in force in Europe during the Middle Ages, due to the preeminence of the Aristotelian cosmological vision and the approval of the Catholic Church of the concept of the ether that supported the conception of earthly life as an imperfect state and paradise as something eternal.
The use of the four elements in science was abandoned in the 16th and 17th centuries, when new discoveries about the states of matter surpassed the classical conception.
In the 17th century, Johann Joachim Becher proposed a particular version of the four-element theory: the fundamental role it was reserved for earth and water, while fire and air were considered as simple agents of transformations. All bodies, both animal and vegetable and mineral, were formed, according to Becher, by mixtures of water and earth. He also defended that the true elements of the bodies should be investigated through analysis, and, coherently, he proposed a classification based on an increasing order of composition. Becher maintained that the immediate components of ore bodies were three different types of earth, each carrying a property: glassy appearance, combustible character, and fluidity or volatility. The earth, which he called terra pinguis , was considered to carry the principle of flammability. Its name could be translated as fatty earth or oily earth, which in alchemy is known by the name of sulfur, although Becher also used other expressions to designate it; among them, phlogisto sulphur (this noun derived from the Greek phlogistos, which means 'flammable'). Finally, it was the word phlogiston that ended up prevailing, thanks above all to the work of the most effective defender of his ideas, Georg Ernst Stahl.
Lavoisier's theory of combustion
The phlogiston theory was maintained until the 1780s, when Antoine Laurent Lavoisier, considered the father of modern chemistry, designed an experiment to test it. Lavoisier placed a small amount of mercury on a solid floating on water, closed it under a glass bell jar, and caused the mercury to burn. According to the phlogiston theory, the floating body should be less submerged after combustion, since the remaining amount of substance together with the ash should weigh less than the initial one and the volume of air inside the bell should increase as a result of assimilation. of the phlogiston, and with it the closed liquid level should be lower than at the beginning. The result of the experiment contradicted the expected results according to this theory. Lavoisier correctly interpreted the combustion, eliminating the phlogiston in his explanation. Burning substances combine with oxygen in the air, thereby gaining weight. The air that is in contact with the burning substance loses oxygen and, therefore, also volume.
With Lavoisier, chemists progressively abandoned the phlogiston theory and joined the oxygen-based combustion theory.
Mythology about fire
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Since humans began to master fire, a major problem arose: lighting it. Hence religions became the keepers of the fire: keeping a permanent fire was important in case domestic fires went out, and hence all religions, even now, keep a fire burning in the sanctuary.
The cult of fire followed the one that was tributed to the Sun and almost all the towns worshiped it as the most noble of elements and as a living image of the star of the day. The Chaldeans regarded him as a supreme deity. However, in Persia is where his cult spread almost exclusively. There were fences on all sides, closed with walls and without a roof, inside which the fire was lit assiduously, where the devout people came at certain hours to pray to him. The great lords ruined themselves [citation needed] by throwing precious essences and fragrant flowers into it, a privilege they regarded as one of the best rights of the nobility. These discovered temples were known to the Greeks as Pyreia (Πυραία) or Pyrateia (Πυραταία). Modern travelers also speak of them as the most ancient monuments of the cult of fire. When a king of Persia was dying, the fire was put out in the main cities of the kingdom and was not rekindled until after the coronation of his successor. These peoples imagined that the fire had been brought from heaven and placed on the altar of the first temple that Zoroaster had ordered to be built in the city of Xis, in Media. It was forbidden to throw anything that was not pure into it, superstition reaching such a point that no one dared to look at it closely. In short, to make it more imposing, the priests kept it secretly and made the people believe that it was unalterable and fed on itself. Hyde has believed that this cult had the sole purpose of representing the Supreme Being.
Whatever it was, this custom carried over to Greece. The sacred fire still burned in the temples of Apollo in Athens and Delphi, in that of Ceres in Mautíuaa, in that of Minerva, in that of Jupiter Ammon, and in the Prytanea of all the Greek cities, where lamps burned continuously, taking special care that they did not turn off The Romans, imitators of the Greeks, adopted this cult and Numa founded a college of vestals, whose functions consisted of conserving the sacred fire. This religion subsisted among the Guebros or Parsos, as well as in many American towns, among others, in Virginia. When these peoples returned from a military expedition or had happily escaped imminent danger, they would light a great fire and testify to their joy by dancing around it with a gourd or bell in their hands, as if giving thanks to this element for having saved their lives.
They never started their meals without first throwing the first bite into the fire as an offering and every evening they lit them up singing and dancing around them.
Fire is also one of the main divinities of the Tartars. They do not allow any foreigner to approach their territory without first having been purified by passing between two bonfires. They carefully avoid putting a knife into the fire or even touching it with this instrument. It would be a greater crime to splinter wood with an ax near the flames. Before drinking, they have the custom of turning towards noon, which is the side that, according to them, corresponds to the fire, in honor of which they also build their cabins with the door facing that part. A cabin was expressly built in the place where the emperor of Monomotapa was camped, in which a fire was lit that was preserved with religious care.
The ancient Africans paid divine honors to this element and kept an eternal fire in their temples.
The Yakouts, a population of Siberia, believe that a being exists in fire, to whom they attribute the power to dispense good and evil and offer perpetual sacrifices. The neighboring Indians on the shores of Columbia regarded fire as a powerful and terrible being. They constantly offered him sacrifices and they also supposed him to be the arbiter of good and evil. They sought his support because only he could intercede with their winged protector and provide them with everything they wanted as male children, that is, abundant fishing and hunting, in a word, everything that in their view constituted wealth and well-being.
The Chinese living in the far reaches of Siberia acknowledge a god of fire. During the residence of M. Pailas in Maiinatschiu, the town was set on fire; the flames devoured many houses and yet no inhabitant tried to stop it. Everyone stood around the fire in sluggish consternation; some only occasionally threw drops of water into it to appease the god, who they said had chosen his rooms for a sacrifice. If the Russians hadn't put out the fire, the entire city would have been reduced to ashes.
Symbolic meaning and iconology
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This element had altars, priests and sacrifices in many communities on the planet. The Romans represented him under the figure of Vulcan in the midst of the Cyclops. A vestal near an altar on which the sacred fire burns or a woman holding a vase full of it with a salamander at her feet are also symbols by which the ancients represented fire. Cesare Ripa and Gravelot have added to these emblems the presence of the Sun, the principle of heat and light, and the phoenix, which dies and is reborn in this element, a symbolic expression that, in the opinion of philosophers, believed that the world would be consumed. someday by the flames to be reborn brighter and more perfect.
Freemasonry also includes fire among its symbols: it is one of the four elements that, as in ancient cultures, are a permanent presence in the language and work of the lodges. Freemasonry takes the ancient symbolic meaning of fire and recognizes its double nature: creation and illumination, on the one hand, and destruction and purification, on the other.
Fossil Record
The fossil record of fires first appears with the establishment of a terrestrial flora in the Middle Ordovician period, 470 million years ago, allowing oxygen to accumulate in the atmosphere like never before, as new hordes from land plants pumped it out as a waste product. When this concentration rose above 13%, it allowed for the possibility of a wildfire. Wildfires were first recorded in the late Silurian fossil record, 420 million years ago, by charred plant fossils. Apart from a disputed breccia in the Late Devonian, charcoal has been around since then. The level of atmospheric oxygen is closely related to the prevalence of charcoal: clearly, oxygen is the key factor in the abundance of wildfires. Fire also became more abundant when grasses radiated and became the dominant component of many ecosystems, around 6 to 7 million years ago; this kindling provided tinder that allowed the fire to spread more quickly. These widespread fires may have started a positive feedback process, whereby they produced a warmer, drier climate more conducive to fires.
Human Control
The ability to control fire was a drastic change in the habits of early humans. Making fire to generate heat and light made it possible for people to cook food, simultaneously increasing the variety and availability of nutrients and reducing disease by killing organisms in food. The heat produced would also help people stay warm in cold weather, allowing them to live in cooler climates. The fire also kept nocturnal predators at bay. Evidence of cooked food dates back 1 million years, although fire was probably not used in a controlled way until 400,000 years ago. There is some evidence that fire may have been used in a controlled way about 1 million years ago. Evidence generalizes to around 50 to 100 thousand years ago, suggesting regular use from this time; Interestingly, resistance to air pollution began to evolve in human populations at a similar time. The use of fire became progressively more sophisticated, and it was used to create charcoal and control wildlife for "tens of thousands" of years.
Fire has also been used for centuries as a method of torture and execution, as evidenced by death by burning and torture devices such as the iron boot that can be filled with water, oil, or even lead and then heated over a fire for the user's agony.
By the Neolithic revolution, during the introduction of grain-based agriculture, people around the world used fire as a tool in landscape management. These fires were typically controlled burns or "cold fires," as opposed to "hot fires" uncontrolled, which damage the soil. Hot fires destroy plants and animals and endanger communities. This is especially a problem in today's forests, where traditional burning is avoided to stimulate the growth of timber crops. Cold fires are usually held in the spring and fall. They remove brush, burning biomass that could start a hot fire if it gets too dense. They provide a greater variety of environments, which encourages the diversity of animals and plants. For humans, they make dense, impassable forests passable. Another human use of fire in regards to landscape management is its use to clear land for agriculture. Slash-and-burn agriculture remains common in much of tropical Africa, Asia, and South America. "For small farmers, it is a convenient way to clear overgrown areas and release nutrients from standing vegetation back into the soil," said Miguel Pinedo-Vásquez, an ecologist at the Center for Environmental Research and Conservation at the Earth Institute. However, this useful strategy is also problematic. Population growth, forest fragmentation and a warming climate are making the earth's surface more prone to ever larger fires. These damage ecosystems and human infrastructure, cause health problems, and send up spirals of carbon and soot that can further encourage warming of the atmosphere and thus feed back into more fires. Currently, globally, up to 5 million square kilometers burn in any given year, an area more than half the size of the United States.
There are numerous modern applications of fire. In its broadest sense, almost every human being on earth uses fire in a controlled environment every day. Users of internal combustion vehicles use fire every time they drive. Thermal power plants provide electricity to a large percentage of humanity.
The use of fire in warfare has a long history. Fire was the basis for all early thermal weapons. Homer detailed the use of fire by Greek soldiers who hid in a wooden horse to burn down Troy during the Trojan War. Later, the Byzantine fleet used Greek fire to attack ships and men. In World War I the first modern flamethrowers were used by infantry and were successfully mounted on armored vehicles in World War II. In this last war, both the Axis and the Allies used incendiary bombs, in cities such as Tokyo, Rotterdam, London, Hamburg and particularly Dresden; in the latter two cases, firestorms were deliberately created, in which a ring of fire surrounding each city was drawn inward by an updraft caused by a central group of fires. The United States Army Air Force also used incendiaries extensively against Japanese targets in the last months of the war, devastating entire cities built primarily of wooden and paper houses. The use of napalm was employed in July 1944, towards the end of World War II, although its use did not come to public attention until the Vietnam War. Molotov cocktails were also used.
Dangers
Fire carries a number of dangers, the first and most obvious being burns. Also others such as smoke inhalation poisoning.
In the psychology section there is pyromania, which is defined as a disease in which a person feels the need to burn something and the bigger the fire the better (for him). This has caused intentional forest fires.
Fires
A fire is an uncontrolled occurrence of fire that can burn something that is not intended to burn. It can affect structures and living beings. Exposure to fire can cause death, generally from smoke inhalation or fainting caused by poisoning and subsequent severe burns.
For a fire to start, it is necessary that these three factors occur together: fuel, oxidizer and heat or activation energy.
Fires in buildings can start with failures in electrical or combustion installations, such as boilers, fuel leaks, accidents in the kitchen, children playing with lighters or matches, or accidents involving other sources of fire, such as candles and cigarettes. Fire can quickly spread to other structures, especially those where basic safety standards are not followed. For this reason, many municipalities offer fire services to extinguish possible fires quickly.
Forest fires
A forest fire is a type of fire characterized by occurring and developing mainly in natural areas with abundant vegetation.
Although the immediate causes that give rise to forest fires can be very varied, the same assumptions are given in all of them, that is, the existence of large masses of vegetation in concurrence with more or less prolonged periods of drought.
Solar heat causes dehydration in plants, which recover lost water from the substrate. However, when soil moisture drops below 30%, the plants are unable to obtain water from the soil, so they gradually dry out. This process causes the emission into the atmosphere of ethylene, a chemical compound present in the vegetation and highly combustible. A double phenomenon then takes place: both the plants and the air that surrounds them become easily flammable, thereby increasing the risk of fire. And if periods of high temperatures and strong or moderate winds are added to these conditions, the possibility of a simple spark causing a fire becomes significant.
Fire behavior in confined structures
Within enclosed or confined structures there are certain special fire phenomena. Firefighters have to train thoroughly and know these phenomena to avoid dying as a result of any of them. Some of these phenomena are:
- Formation of the ceiling layer
- Backdraft
- Generalized sudden combustion
- Dancing Angels
- Flameover
- Overflow by boiling (Boiling over English)
- BLEVE -- organic
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