1.
Lake George (New York)
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It lies within the upper region of the Great Appalachian Valley and drains all the way northward into Lake Champlain and the St. Lawrence River drainage basin. The lake extends about 32.2 mi on an axis, is quite deep. Ultimately the waters flowing via the 106-mile-long Richelieu River drain into the St. Lawrence River downstream and northeast of Montreal, Lake George is located in the southeastern Adirondack State Park. It is part of the St. Lawrence watershed, notable landforms include Anthonys Nose, Deers Leap, Rogers Rock, the Indian Kettles, Divers Rock, and Double-Divers. Some of the include the Tongue Mountain Range, Sugarloaf Mountain, Elephant Mountain, Prospect Mountain, Shelving Rock, Sleeping Beauty Mountain, Pilot Knob. Some of the more famous bays are Silver Bay, Kattskill Bay, Northwest Bay, Basin Bay, the lake is distinguished by The Narrows, an island-filled narrow section that is bordered on the west by the Tongue Mountain Range and the east by Black Mountain. In all, Lake George is home to over 170 islands,148 them state-owned and they range from the car-sized Skippers Jib to larger Vicars and Long Islands. Camping permits are attainable for the portion of islands. The lakes deepest point is 196 feet, found between Dome Island and Buck Mountain in the quarter of the lake. The northern end of the lake that is located near Ticonderoga is considered the end of the Champlain Valley that includes Lake Champlain, as well as the cities of Plattsburgh. There are six known species in Lake George, according to the Lake George Association. The Asian clam first found in 2010 is the biggest threat, other invasive species are the spiny water flea, zebra mussel, Chinese mystery snail and curly-leaf pondweed. The lake was named the Andia-ta-roc-te by local Native Americans. James Fenimore Cooper in his narrative Last of the Mohicans called it the Horican, after a tribe which may have lived there, because he felt the original name was too hard to pronounce. The first European visitor to the area, Samuel de Champlain, noted the lake in his journal on July 3,1609, but did not name it. In 1646, the French Canadian Jesuit missionary Isaac Jogues, the first European to view the lake, named it Lac du Saint-Sacrement, on August 28,1755, William Johnson led British colonial forces to occupy the area in the French and Indian War. He renamed the lake as Lake George for King George II, on September 8,1755 the Battle of Lake George was fought between the forces of Britain and France resulting in a strategic victory for the British and their Iroquois allies. After the battle, Johnson ordered the construction of a fortification at the southern end of the lake
2.
Nitrogen
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Nitrogen is a chemical element with symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772, although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is generally accorded the credit because his work was published first. Nitrogen is the lightest member of group 15 of the periodic table, the name comes from the Greek πνίγειν to choke, directly referencing nitrogens asphyxiating properties. It is an element in the universe, estimated at about seventh in total abundance in the Milky Way. At standard temperature and pressure, two atoms of the element bind to form dinitrogen, a colourless and odorless diatomic gas with the formula N2, dinitrogen forms about 78% of Earths atmosphere, making it the most abundant uncombined element. Nitrogen occurs in all organisms, primarily in amino acids, in the nucleic acids, the human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes movement of the element from the air, into the biosphere and organic compounds, many industrially important compounds, such as ammonia, nitric acid, organic nitrates, and cyanides, contain nitrogen. The extremely strong bond in elemental nitrogen, the second strongest bond in any diatomic molecule. Synthetically produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems. Apart from its use in fertilisers and energy-stores, nitrogen is a constituent of organic compounds as diverse as Kevlar used in high-strength fabric, Nitrogen is a constituent of every major pharmacological drug class, including antibiotics. Many notable nitrogen-containing drugs, such as the caffeine and morphine or the synthetic amphetamines. Nitrogen compounds have a long history, ammonium chloride having been known to Herodotus. They were well known by the Middle Ages, alchemists knew nitric acid as aqua fortis, as well as other nitrogen compounds such as ammonium salts and nitrate salts. The mixture of nitric and hydrochloric acids was known as aqua regia, celebrated for its ability to dissolve gold, the discovery of nitrogen is attributed to the Scottish physician Daniel Rutherford in 1772, who called it noxious air. Though he did not recognise it as a different chemical substance, he clearly distinguished it from Joseph Blacks fixed air. The fact that there was a component of air that does not support combustion was clear to Rutherford, Nitrogen was also studied at about the same time by Carl Wilhelm Scheele, Henry Cavendish, and Joseph Priestley, who referred to it as burnt air or phlogisticated air. Nitrogen gas was inert enough that Antoine Lavoisier referred to it as air or azote, from the Greek word άζωτικός. In an atmosphere of nitrogen, animals died and flames were extinguished
3.
Trophic level
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The trophic level of an organism is the position it occupies in a food chain. The word trophic derives from the Greek τροφή referring to food or feeding, a food chain represents a succession of organisms that eat another organism and are, in turn, eaten themselves. The number of steps an organism is from the start of the chain is a measure of its trophic level. Food chains start at trophic level 1 with primary producers such as plants, move to herbivores at level 2, predators at level 3, the path along the chain can form either a one-way flow or a food web. Ecological communities with higher biodiversity form more complex trophic paths, the three basic ways in which organisms get food are as producers, consumers and decomposers. Producers are typically plants or algae, Plants and algae do not usually eat other organisms, but pull nutrients from the soil or the ocean and manufacture their own food using photosynthesis. For this reason, they are called primary producers, in this way, it is energy from the sun that usually powers the base of the food chain. An exception occurs in deep-sea hydrothermal ecosystems, where there is no sunlight, here primary producers manufacture food through a process called chemosynthesis. Consumers are species that cannot manufacture their own food and need to other organisms. Animals that eat primary producers are called herbivores, animals that eat other animals are called carnivores, and animals that eat both plant and other animals are called omnivores. Decomposers break down plant and animal material and wastes and release it again as energy. Decomposers, such as bacteria and fungi, feed on waste and dead matter, Trophic levels can be represented by numbers, starting at level 1 with plants. Further trophic levels are numbered according to how far the organism is along the food chain. Level 1, Plants and algae make their own food and are called primary producers, level 2, Herbivores eat plants and are called primary consumers. Level 3, Carnivores that eat herbivores are called secondary consumers, level 4, Carnivores that eat other carnivores are called tertiary consumers. Level 5, Apex predators that have no predators are at the top of the food chain. In real world ecosystems, there is more than one chain for most organisms. A diagram that sets out the network of intersecting and overlapping food chains for an ecosystem is called its food web
4.
United States Environmental Protection Agency
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The EPA was proposed by President Richard Nixon and began operation on December 2,1970, after Nixon signed an executive order. The order establishing the EPA was ratified by committee hearings in the House, the agency is led by its Administrator, who is appointed by the president and approved by Congress. The current administrator is Scott Pruitt, the EPA is not a Cabinet department, but the administrator is normally given cabinet rank. The EPA has its headquarters in Washington, D. C. regional offices for each of the ten regions. The agency conducts environmental assessment, research, and education and it has the responsibility of maintaining and enforcing national standards under a variety of environmental laws, in consultation with state, tribal, and local governments. It delegates some permitting, monitoring, and enforcement responsibility to U. S. states, EPA enforcement powers include fines, sanctions, and other measures. The agency also works with industries and all levels of government in a variety of voluntary pollution prevention programs. In 2016, the agency had 15,376 full-time employees, more than half of EPAs employees are engineers, scientists, and environmental protection specialists, other employees include legal, public affairs, financial, and information technologists. Beginning in the late 1950s and through the 1960s, Congress reacted to increasing concern about the impact that human activity could have on the environment. Senator James E. Murray introduced a bill, the Resources and Conservation Act of 1959, the 1962 publication of Silent Spring by Rachel Carson alerted the public about the detrimental effects on the environment of the indiscriminate use of pesticides. In the years following, similar bills were introduced and hearings were held to discuss the state of the environment, in the colloquium, some members of Congress expressed a continuing concern over federal agency actions affecting the environment. The National Environmental Policy Act of 1969 was modeled on RCA, President Nixon signed NEPA into law on January 1,1970. The law created the Council on Environmental Quality in the Executive Office of the President, NEPA required that a detailed statement of environmental impacts be prepared for all major federal actions significantly affecting the environment. The detailed statement would ultimately be referred to as an impact statement. On July 9,1970, Nixon proposed a reorganization that consolidated many environmental responsibilities of the federal government under one agency. After conducting hearings during that summer, the House and Senate approved the proposal, the agency’s first administrator, William Ruckelshaus, took the oath of office on December 4,1970. In May 2013, Congress renamed the EPA headquarters as the William Jefferson Clinton Federal Building, the EPA is led by an Administrator of the Environmental Protection Agency. As of 2017 Scott Pruitt is the 14th administrator, each EPA regional office is responsible within its states for implementing the Agencys programs, except those programs that have been specifically delegated to states
5.
Biomass (ecology)
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Biomass, is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass and it can include microorganisms, plants or animals. The mass can be expressed as the mass per unit area. How biomass is measured depends on why it is being measured, sometimes, the biomass is regarded as the natural mass of organisms in situ, just as they are. For example, in a fishery, the salmon biomass might be regarded as the total wet weight the salmon would have if they were taken out of the water. In other contexts, biomass can be measured in terms of the organic mass, so perhaps only 30% of the actual weight might count. For other purposes, only biological tissues count, and teeth, bones, in some applications, biomass is measured as the mass of organically bound carbon that is present. Apart from bacteria, the total biomass on Earth is about 560 billion tonnes C. The total live biomass of bacteria may be as much as that of plants, the total amount of DNA base pairs on Earth, as a possible approximation of global biodiversity, is estimated at 5.0 x 1037, and weighs 50 billion tonnes. In comparison, the mass of the biosphere has been estimated to be as much as 4 TtC. An ecological pyramid is a representation that shows, for a given ecosystem. A biomass pyramid shows the amount of biomass at each trophic level, a productivity pyramid shows the production or turn-over in biomass at each trophic level. An ecological pyramid provides a snapshot in time of an ecological community, the bottom of the pyramid represents the primary producers. The primary producers take energy from the environment in the form of sunlight or inorganic chemicals and this mechanism is called primary production. The pyramid then proceeds through the trophic levels to the apex predators at the top. When energy is transferred from one level to the next. The remaining ninety percent goes to metabolic processes or is dissipated as heat and this energy loss means that productivity pyramids are never inverted, and generally limits food chains to about six levels. However, in oceans, biomass pyramids can be wholly or partially inverted, terrestrial biomass generally decreases markedly at each higher trophic level
6.
Aquatic plant
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Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or macrophytes and these plants require special adaptations for living submerged in water, or at the waters surface. The most common adaptation is aerenchyma, but floating leaves and finely dissected leaves are also common, aquatic plants can only grow in water or in soil that is permanently saturated with water. They are therefore a component of wetlands. The principal factor controlling the distribution of plants is the depth. However, other factors may also control their distribution, abundance, and growth form, including nutrients, disturbance from waves, grazing, aquatic vascular plants have originated on multiple occasions in different plant families, they can be ferns or angiosperms. Seaweeds are not vascular plants, rather they are marine algae. A few aquatic plants are able to survive in brackish, saline, examples are found in genera such as Thalassia and Zostera. Although most aquatic plants can reproduce by flowering and setting seed, many also have extensive asexual reproduction by means of rhizomes, turions, one of the largest aquatic plants in the world is the Amazon water lily, one of the smallest is the minute duckweed. Many small aquatic animals use plants like duckweed for a home, or for protection from predators, some other familiar examples of aquatic plants might include floating heart, water lily, lotus, and water hyacinth. Some aquatic plants are used by humans as a food source, examples include wild rice, water caltrop, Chinese water chestnut, Indian lotus, water spinach, and watercress. The many possible classifications of plants are based upon morphology. org http
7.
Fish kill
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The term fish kill, known also as fish die-off, refers to a localized die-off of fish populations which may also be associated with more generalized mortality of aquatic life. The most common cause is reduced oxygen in the water, which in turn may be due to such as drought, algae bloom, overpopulation. Infectious diseases and parasites can also lead to fish kill, toxicity is a real but far less common cause of fish kill. Fish kills are often the first visible signs of stress and are usually investigated as a matter of urgency by environmental agencies to determine the cause of the kill. Pollution events may affect fish species and fish age classes in different ways, if it is a cold-related fish kill, juvenile fish or species that are not cold-tolerant may be selectively affected. If toxicity is the cause, species are more generally affected, a reduction in dissolved oxygen may affect larger specimens more than smaller fish as these may be able to access oxygen richer water at the surface, at least for a short time. Fish kills may result from a variety of causes, of known causes, fish kills are most frequently caused by pollution from agricultural runoff or biotoxins. Ecological hypoxia is one of the most common causes of fish kills. The hypoxic event may be brought on by such as algae blooms, droughts, high temperatures. Because of the difficulty and lack of standard protocol to investigate fish kills, oxygen enters the water through diffusion. The amount of oxygen that can be dissolved in water depends on the atmospheric pressure, the water temperature and whether the water is salty. For example, at 20 °C and one atmosphere of pressure, the amount of oxygen that can be dissolved in the water decreases by about 1 mg/l for each 10 °C increase in water temperature above 20 °C. Many cold water fish live in clean cold waters become stressed when oxygen concentrations fall below 8 mg/l while warm water fish generally need at least 5 ppm of dissolved oxygen. Fish can endure periods of reduced oxygen. Depleted oxygen levels are the most common cause of fish kills, associated with these photosynthetic rhythms there is a matching pH rhythm as bicarbonate ion is metabolised by plant cells. This can lead to pH stress even when oxygen levels are high and these are naturally occurring in many bodies of water, and fish that are stressed for other reasons, such as spawning or suboptimal water quality, are more susceptible. For example, since 2004 fish kills have been observed in the Shenandoah River basin in the spring, so far, investigators suspect certain bacteria, along with environmental and contaminant factors that may cause immune suppression. In fish farming, where populations are optimized for the resources, parasites or disease can spread quickly
8.
Tatra Mountains
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The Tatra Mountains, Tatras or Tatra, are a mountain range that form a natural border between Slovakia and Poland. They are the highest mountain range in the Carpathian Mountains, the Tatras should be distinguished from the Low Tatras which are located south of the Tatra Mountains in Slovakia. The Tatra Mountains occupy an area of 785 square kilometres, of which about 610 square kilometres lie within Slovakia, the highest peak, called Gerlach, at 2,655 m is located north of Poprad. The highest point in Poland, Rysy, at 2,499 m is located south of Zakopane. The Tatras length, measured from the foothills of the Kobyli Wierch to the southwestern foot of Ostry Wierch Kwaczański, in a straight line is 57 km. The range is only 19 km wide, the Tatras main ridge leads from Huciańska Pass in the west to Zdziarska Pass to the east. In 1992 the Polish and Slovak parks were designated a transboundary biosphere reserve by UNESCO in the World Network of Biosphere Reserves under its Man. It is the highest mountain range within Carpathians, by the end of the First Polish Republic and the Polish border between the Kingdom of Hungary in the Tatras was not strictly defined. The Tatras became an unoccupied borderland, two years later, the First Partition of Poland allocated the lands to Austria. In 1824, Zakopane good and Fish Creek Valley with Morskie Oko purchased from the authorities of the Austrian Hungarian Emanuel Homolacs. In 1867 formed the Austria-Hungary and the Tatra Mountains have become imaginary border between the two states of the monarchy, but the border still has not been exactly determined. In 1889, Count Władysław Zamoyski purchased at auction a good Zakopane, due to numerous disputes over lands belonging in the late nineteenth century, attempts were made to the delimitation of the border. They did not bring effect in 1897, and the case went to a court that on September 13,1902 determined the exact course of the Austria-Hungary border in the disputed area. The Tatras lie in the zone of Central Europe. They are an important barrier to the movements of air masses and their mountainous topography causes one of the most diverse climates in that region. Winds The average wind speed on the summits is 6 m/s. southerly winds on the northern side westerly winds at the base of Tatra foehn winds most often occur between October and May and they are warm and dry and can cause extensive damage. On 19 November 2004, large parts of the forests in the southern Slovak part of the High Tatras were damaged by a wind storm. Three million cubic metres of trees were uprooted, two died and several villages were totally cut off
9.
Poland
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Poland, officially the Republic of Poland, is a country in Central Europe, situated between the Baltic Sea in the north and two mountain ranges in the south. Bordered by Germany to the west, the Czech Republic and Slovakia to the south, Ukraine and Belarus to the east, the total area of Poland is 312,679 square kilometres, making it the 69th largest country in the world and the 9th largest in Europe. With a population of over 38.5 million people, Poland is the 34th most populous country in the world, the 8th most populous country in Europe, Poland is a unitary state divided into 16 administrative subdivisions, and its capital and largest city is Warsaw. Other metropolises include Kraków, Wrocław, Poznań, Gdańsk and Szczecin, the establishment of a Polish state can be traced back to 966, when Mieszko I, ruler of a territory roughly coextensive with that of present-day Poland, converted to Christianity. The Kingdom of Poland was founded in 1025, and in 1569 it cemented a political association with the Grand Duchy of Lithuania by signing the Union of Lublin. This union formed the Polish–Lithuanian Commonwealth, one of the largest and most populous countries of 16th and 17th century Europe, Poland regained its independence in 1918 at the end of World War I, reconstituting much of its historical territory as the Second Polish Republic. In September 1939, World War II started with the invasion of Poland by Nazi Germany, followed thereafter by invasion by the Soviet Union. More than six million Polish citizens died in the war, after the war, Polands borders were shifted westwards under the terms of the Potsdam Conference. With the backing of the Soviet Union, a communist puppet government was formed, and after a referendum in 1946. During the Revolutions of 1989 Polands Communist government was overthrown and Poland adopted a new constitution establishing itself as a democracy, informally called the Third Polish Republic. Since the early 1990s, when the transition to a primarily market-based economy began, Poland has achieved a high ranking on the Human Development Index. Poland is a country, which was categorised by the World Bank as having a high-income economy. Furthermore, it is visited by approximately 16 million tourists every year, Poland is the eighth largest economy in the European Union and was the 6th fastest growing economy on the continent between 2010 and 2015. According to the Global Peace Index for 2014, Poland is ranked 19th in the list of the safest countries in the world to live in. The origin of the name Poland derives from a West Slavic tribe of Polans that inhabited the Warta River basin of the historic Greater Poland region in the 8th century, the origin of the name Polanie itself derives from the western Slavic word pole. In some foreign languages such as Hungarian, Lithuanian, Persian and Turkish the exonym for Poland is Lechites, historians have postulated that throughout Late Antiquity, many distinct ethnic groups populated the regions of what is now Poland. The most famous archaeological find from the prehistory and protohistory of Poland is the Biskupin fortified settlement, dating from the Lusatian culture of the early Iron Age, the Slavic groups who would form Poland migrated to these areas in the second half of the 5th century AD. With the Baptism of Poland the Polish rulers accepted Christianity and the authority of the Roman Church
10.
Algae
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Algae is an informal term for a large, diverse group of photosynthetic organisms which are not necessarily closely related, and is thus polyphyletic. Included organisms range from unicellular genera, such as Chlorella and the diatoms, to forms, such as the giant kelp. Most are aquatic and autotrophic and lack many of the cell and tissue types, such as stomata, xylem, and phloem. No definition of algae is generally accepted, one definition is that algae have chlorophyll as their primary photosynthetic pigment and lack a sterile covering of cells around their reproductive cells. Some authors exclude all prokaryotes thus do not consider cyanobacteria as algae, Algae constitute a polyphyletic group since they do not include a common ancestor, and although their plastids seem to have a single origin, from cyanobacteria, they were acquired in different ways. Green algae are examples of algae that have primary chloroplasts derived from endosymbiotic cyanobacteria, diatoms and brown algae are examples of algae with secondary chloroplasts derived from an endosymbiotic red alga. Algae exhibit a range of reproductive strategies, from simple asexual cell division to complex forms of sexual reproduction. Algae lack the various structures that characterize land plants, such as the phyllids of bryophytes, rhizoids in nonvascular plants, and the roots, leaves, and other organs found in tracheophytes. Most are phototrophic, although some are mixotrophic, deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy, myzotrophy, or phagotrophy. Some other heterotrophic organisms, such as the apicomplexans, are derived from cells whose ancestors possessed plastids. Fossilized filamentous algae from the Vindhya basin have been dated back to 1.6 to 1.7 billion years ago, the singular alga is the Latin word for seaweed and retains that meaning in English. Although some speculate that it is related to Latin algēre, be cold, a more likely source is alliga, binding, entwining. The Ancient Greek word for seaweed was φῦκος, which could mean either the seaweed or a red dye derived from it, the Latinization, fūcus, meant primarily the cosmetic rouge. It could be any color, black, red, green, accordingly, the modern study of marine and freshwater algae is called either phycology or algology, depending on whether the Greek or Latin root is used. The name Fucus appears in a number of taxa, most algae contain chloroplasts that are similar in structure to cyanobacteria. Chloroplasts contain circular DNA like that in cyanobacteria and presumably represent reduced endosymbiotic cyanobacteria, however, the exact origin of the chloroplasts is different among separate lineages of algae, reflecting their acquisition during different endosymbiotic events. The table below describes the composition of the three groups of algae. Their lineage relationships are shown in the figure in the upper right, many of these groups contain some members that are no longer photosynthetic
11.
Drinking water
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Drinking water, also known as potable water or improved drinking water, is water that is safe to drink or to use for food preparation, without risk of health problems. Globally, in 2015, 91% of people had access to suitable for drinking. Nearly 4.2 billion had access to tap water while another 2.4 billion had access to wells or public taps,1.8 billion people still use an unsafe drinking water source which may be contaminated by feces. This can result in infectious diarrhea such as cholera and typhoid among others, the amount of drinking water required is variable. It depends on activity, age, health issues. It is estimated that the average American drinks about one litre of water a day with 95% drinking less than three litres per day, for those working in a hot climate, up to 16 liters a day may be required. Water makes up about 60% of weight in men and 55% of weight in women, infants are about 70% to 80% water while the elderly are around 45%. Typically in developed countries, tap water meets drinking water quality standards, other typical uses include washing, toilets, and irrigation. Greywater may also be used for toilets or irrigation and its use for irrigation however may be associated with risks. Water may also be due to levels of toxins or suspended solids. Reduction of waterborne diseases and development of water resources is a major public health goal in developing countries. Bottled water is sold for consumption in most parts of the world. The word potable came into English from the Late Latin potabilis, the amount of drinking water required is variable. It depends on activity, age, health, and environmental conditions. It is estimated that the average American drinks about one litre of water a day with 95% drinking less than three litres per day, for those working in a hot climate, up to 16 litres per day may be required. Some health authorities have suggested that at least eight glasses of eight fl oz each are required by an adult per day, the British Dietetic Association recommends 1.8 litres. However, various reviews of the evidence performed in 2002 and 2008 could not find any scientific evidence recommending eight glasses of water per day. An individuals thirst provides a guide for how much water they require rather than a specific
12.
Oxygen
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Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog. At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
