Passover
Passover called Pesach, is a major, biblically derived Jewish holiday. Jews celebrate Passover as a commemoration of their liberation by God from slavery in ancient Egypt and their freedom as a nation under the leadership of Moses, it commemorates the story of the Exodus as described in the Hebrew Bible in the Book of Exodus, in which the Israelites were freed from slavery in Egypt. According to standard biblical chronology, this event would have taken place at about 1300 BCE. Passover is a spring festival which during the existence of the Temple in Jerusalem was connected to the offering of the "first-fruits of the barley", barley being the first grain to ripen and to be harvested in the Land of Israel. Passover commences on the 15th of the Hebrew month of Nisan and lasts for either seven days or eight days for Orthodox and most Conservative Jews. In Judaism, a day commences at dusk and lasts until the following dusk, thus the first day of Passover begins after dusk of the 14th of Nisan and ends at dusk of the 15th day of the month of Nisan.
The rituals unique to the Passover celebrations commence with the Passover Seder when the 15th of Nisan has begun. In the Northern Hemisphere Passover takes place in spring as the Torah prescribes it: "in the month of spring", it is one of the most celebrated Jewish holidays. In the narrative of the Exodus, the Bible tells that God helped the Children of Israel escape from their slavery in Egypt by inflicting ten plagues upon the ancient Egyptians before the Pharaoh would release his Israelite slaves; the Israelites were instructed to mark the doorposts of their homes with the blood of a slaughtered spring lamb and, upon seeing this, the spirit of the Lord knew to pass over the first-born in these homes, hence the English name of the holiday. When the Pharaoh freed the Israelites, it is said that they left in such a hurry that they could not wait for bread dough to rise. In commemoration, for the duration of Passover no leavened bread is eaten, for which reason Passover is called the feast of unleavened bread in the Torah.
Thus matzo is eaten during Passover and it is a tradition of the holiday. Together with Shavuot and Sukkot, Passover is one of the Three Pilgrimage Festivals during which the entire population of the kingdom of Judah made a pilgrimage to the Temple in Jerusalem. Samaritans still make this pilgrimage to Mount Gerizim; the Passover begins on the 15th day of the month of Nisan, which falls in March or April of the Gregorian calendar. Passover is a spring festival, so the 15th day of Nisan begins on the night of a full moon after the northern vernal equinox. However, due to leap months falling after the vernal equinox, Passover sometimes starts on the second full moon after vernal equinox, as in 2016. To ensure that Passover did not start before spring, the tradition in ancient Israel held that the first day of Nisan would not start until the barley was ripe, being the test for the onset of spring. If the barley was not ripe, or various other phenomena indicated that spring was not yet imminent, an intercalary month would be added.
However, since at least the 4th century, the date has been fixed mathematically. In Israel, Passover is the seven-day holiday of the Feast of Unleavened Bread, with the first and last days celebrated as legal holidays and as holy days involving holiday meals, special prayer services, abstention from work. Diaspora Jews celebrated the festival for eight days. Reform and Reconstructionist Jews and Israeli Jews, wherever they are celebrate the holiday over seven days; the reason for this extra day is due to enactment of the ancient Jewish sages. It is thought by many scholars that Jews outside of Israel could not be certain if their local calendars conformed to practice of the Temple at Jerusalem, so they added an extra day, but as this practice attaches only to certain sacred days, others posit the extra day may have been added to accommodate people who had to travel long distances to participate in communal worship and ritual practices. Karaites and Samaritans use different versions of the Jewish calendar, which are out of sync with the modern Jewish calendar by one or two days.
In 2009, for example, Nisan 15 on the Jewish calendar used by Rabbinic Judaism corresponds to April 9. On the calendars used by Karaites and Samaritans, Abib or Aviv 15 corresponds to April 11 in 2009; the Karaite and Samaritan Passovers are each one day long, followed by the six-day Festival of Unleavened Bread – for a total of seven days. The origins of the Passover festival antedate the Exodus; the Passover ritual, prior to Deuteronomy, is thought to have its origins in an apotropaic rite, unrelated to the Exodus, to ensure the protection of a family home, a rite conducted wholly within a clan. Hyssop was employed to daub the blood of a slaughtered sheep on the lintels and door posts to ensure that demonic forces could not enter the home. A further hypothesis maintains that, once the Priestly Code was promulgated, the exodus narrative took on a central fu
Bread
Bread is a staple food prepared from a dough of flour and water by baking. Throughout recorded history it has been a prominent food in large parts of the world and is one of the oldest man-made foods, having been of significant importance since the dawn of agriculture. Bread may be leavened by processes such as reliance on occurring sourdough microbes, industrially produced yeast, or high-pressure aeration. Commercial bread contains additives to improve flavor, color, shelf life and ease of manufacturing. Bread plays essential roles in secular culture; the Old English word for bread was hlaf. Old High German hleib and modern German Laib derive from this Proto-Germanic word, borrowed into Slavic and Finnic languages as well; the Middle and Modern English word bread appears in Germanic languages, such as West Frisian brea, Dutch brood, German Brot, Swedish bröd, Norwegian and Danish brød. Bread is one of the oldest prepared foods. Evidence from 30,000 years ago in Europe revealed starch residue on rocks used for pounding plants.
It is possible that during this time, starch extract from the roots of plants, such as cattails and ferns, was spread on a flat rock, placed over a fire and cooked into a primitive form of flatbread. The world's oldest evidence of bread-making has been found in a 14,500 year old Natufian site in Jordan's northeastern desert. Around 10,000 BC, with the dawn of the Neolithic age and the spread of agriculture, grains became the mainstay of making bread. Yeast spores are ubiquitous, including on the surface of cereal grains, so any dough left to rest leavens naturally. There were multiple sources of leavening available for early bread. Airborne yeasts could be harnessed by leaving uncooked dough exposed to air for some time before cooking. Pliny the Elder reported that the Gauls and Iberians used the foam skimmed from beer called barm to produce "a lighter kind of bread than other peoples" such as barm cake. Parts of the ancient world that drank wine instead of beer used a paste composed of grape juice and flour, allowed to begin fermenting, or wheat bran steeped in wine, as a source for yeast.
The most common source of leavening was to retain a piece of dough from the previous day to use as a form of sourdough starter, as Pliny reported. The Chorleywood bread process was developed in 1961; the process, whose high-energy mixing allows for the use of lower protein grain, is now used around the world in large factories. As a result, bread can be produced quickly and at low costs to the manufacturer and the consumer. However, there has been some criticism of the effect on nutritional value. Bread is the staple food of the Middle East, Central Asia, North Africa, in European-derived cultures such as those in the Americas and Southern Africa, in contrast to parts of South and East Asia where rice or noodle is the staple. Bread is made from a wheat-flour dough, cultured with yeast, allowed to rise, baked in an oven; the addition of yeast to the bread explains the air pockets found in bread. Owing to its high levels of gluten, common or bread wheat is the most common grain used for the preparation of bread, which makes the largest single contribution to the world's food supply of any food.
Bread is made from the flour of other wheat species. Non-wheat cereals including rye, maize, sorghum and rice have been used to make bread, with the exception of rye in combination with wheat flour as they have less gluten. Gluten-free breads have been created for people affected by gluten-related disorders such as coeliac disease and non-coeliac gluten sensitivity, who may benefit from a gluten-free diet. Gluten-free bread is made with ground flours from a variety of materials such as almonds, sorghum, corn, or legumes such as beans, tubers such as cassava, but since these flours lack gluten they may not hold their shape as they rise and their crumb may be dense with little aeration. Additives such as xanthan gum, guar gum, hydroxypropyl methylcellulose, corn starch, or eggs are used to compensate for the lack of gluten. In wheat, phenolic compounds are found in hulls in the form of insoluble bound ferulic acid, where it is relevant to wheat resistance to fungal diseases. Rye bread contains ferulic acid dehydrodimers.
Three natural phenolic glucosides, secoisolariciresinol diglucoside, p-coumaric acid glucoside and ferulic acid glucoside, can be found in commercial breads containing flaxseed. Glutenin and gliadin are functional proteins found in wheat bread that contribute to the structure of bread. Glutenin forms interconnected gluten networks within bread through interchain disulfide bonds. Gliadin binds weakly to the gluten network established by glutenin via intrachain disulfide bonds. Structurally, bread can be defined as an elastic-plastic foam; the glutenin protein contributes to its elastic nature, as it is able to regain its initial shape after deformation. The gliadin protein contributes to its plastic nature, because it demonstrates non-reversible structural change after a certain amount of applied force; because air pockets within this gluten network result from carbon dioxide production during leavening, bread can be defined as a foam, or a
Nitrous oxide
Nitrous oxide known as laughing gas or nitrous, is a chemical compound, an oxide of nitrogen with the formula N2O. At room temperature, it is a colourless non-flammable gas, with taste. At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen, it is soluble in water. Nitrous oxide has significant medical uses in surgery and dentistry, for its anaesthetic and pain reducing effects, its name "laughing gas", coined by Humphry Davy, is due to the euphoric effects upon inhaling it, a property that has led to its recreational use as a dissociative anaesthetic. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system, it is used as an oxidiser in rocket propellants, in motor racing to increase the power output of engines. Nitrous oxide occurs in small amounts in the atmosphere, but has been found to be a major scavenger of stratospheric ozone, with an impact comparable to that of CFCs, it is estimated that 30% of the N2O in the atmosphere is the result of human activity, chiefly agriculture.
Nitrous oxide may be used as an oxidiser in a rocket motor. This is advantageous over other oxidisers in that it is much less toxic, due to its stability at room temperature is easier to store and safe to carry on a flight; as a secondary benefit, it may be decomposed to form breathing air. Its high density and low storage pressure enable it to be competitive with stored high-pressure gas systems. In a 1914 patent, American rocket pioneer Robert Goddard suggested nitrous oxide and gasoline as possible propellants for a liquid-fuelled rocket. Nitrous oxide has been the oxidiser of choice in several hybrid rocket designs; the combination of nitrous oxide with hydroxyl-terminated polybutadiene fuel has been used by SpaceShipOne and others. It is notably used in amateur and high power rocketry with various plastics as the fuel. Nitrous oxide may be used in a monopropellant rocket. In the presence of a heated catalyst, N2O will decompose exothermically into nitrogen and oxygen, at a temperature of 1,070 °F.
Because of the large heat release, the catalytic action becomes secondary, as thermal autodecomposition becomes dominant. In a vacuum thruster, this may provide a monopropellant specific impulse of as much as 180 s. While noticeably less than the Isp available from hydrazine thrusters, the decreased toxicity makes nitrous oxide an option worth investigating. Nitrous oxide is said to deflagrate at 600 °C at a pressure of 309 psi. At 600 psi, for example, the required ignition energy is only 6 joules, whereas N2O at 130 psi a 2,500-joule ignition energy input is insufficient. In vehicle racing, nitrous oxide allows the engine to burn more fuel by providing more oxygen than air alone, resulting in a more powerful combustion; the gas is not flammable at a low pressure/temperature, but it delivers more oxygen than atmospheric air by breaking down at elevated temperatures. Therefore, it is mixed with another fuel, easier to deflagrate. Nitrous oxide is a strong oxidant equivalent to hydrogen peroxide, much stronger than oxygen gas.
Nitrous oxide is stored as a compressed liquid. Sometimes nitrous oxide is injected into the intake manifold, whereas other systems directly inject, right before the cylinder to increase power; the technique was used during World War II by Luftwaffe aircraft with the GM-1 system to boost the power output of aircraft engines. Meant to provide the Luftwaffe standard aircraft with superior high-altitude performance, technological considerations limited its use to high altitudes. Accordingly, it was only used by specialised planes such as high-altitude reconnaissance aircraft, high-speed bombers and high-altitude interceptor aircraft, it sometimes could be found on Luftwaffe aircraft fitted with another engine-boost system, MW 50, a form of water injection for aviation engines that used methanol for its boost capabilities. One of the major problems of using nitrous oxide in a reciprocating engine is that it can produce enough power to damage or destroy the engine. Large power increases are possible, if the mechanical structure of the engine is not properly reinforced, the engine may be damaged, or destroyed, during this kind of operation.
It is important with nitrous oxide augmentation of petrol engines to maintain proper operating temperatures and fuel levels to prevent "pre-ignition", or "detonation". Most problems that are associated with nitrous oxide do not come from mechanical failure due to the power increases. Since nitrous oxide allows a much denser charge into the cylinder, it increases cylinder pressures; the increased pressure and temperature can cause problems such as melting valves. It may crack or warp the piston or head and cause pre-ignition due to uneven heating. Automotive-grade liquid nitrous oxide differs from medical-grade nitrous oxide. A small amount of sulfur dioxide is added to prevent substance abuse. Multiple washes through a base can remove this, decreasing the corrosive properties observed when SO2 is further oxidised during combustion into sulfuric
Ginger beer
Traditional ginger beer is a sweetened and carbonated non-alcoholic beverage. It is produced by the natural fermentation of prepared ginger spice and sugar, its origins date from the colonial spice trade with the Orient and the sugar producing islands of the Caribbean. It was popular in its colonies from the 18th century. Other spices were variously added and any alcohol content was limited to 2% by excise tax laws in 1855. Few brewers have maintained an alcoholic product. Current ginger beers are manufactured rather than brewed with flavor and color additives. Ginger ales are not brewed. Ginger beer is still produced at home using a symbiotic colony of yeast and a Lactobacillus known as a "ginger beer plant". Ginger beer has experienced a marked increase in popularity in recent years accompanying the popularity of cocktails based on it, such as the Moscow Mule and the Dark'n' Stormy; as early as 500 BC, ginger was used as a medicine and for flavouring food in Ancient China and India. In the western hemisphere, ginger was used to spice up drinks.
During the Victorian era, it was used to brew an alcoholic beverage termed "ginger beer". Brewed ginger beer originated in Yorkshire in England in the mid-18th century and became popular throughout Britain, the United States, South Africa and Canada, reaching a peak of popularity in the early 20th century. Brewed ginger beer was brought to the United States of the Ionian Islands by the British Army in the 19th century, is still made as a local specialty known as tsitsibíra by villagers in rural Corfu. Brewed ginger beer is sold worldwide. Crabbie's is a popular brand in the UK, it is labelled "alcoholic ginger beer" to distinguish it from the more established commercial ginger beers, which are not brewed, but carbonated with pressurized carbon dioxide. Hollows & Fentimans claims its ginger beer to be gluten-free. Crabbie's ginger beer is free from gluten in the UK, but not the US; the ginger beer plant known as "bees wine", "Palestinian bees", "Californian bees", "balm of Gilead", is not what is considered a plant but a composite organism comprising the yeast Saccharomyces florentinus and the bacterium Lactobacillus hilgardii, which form a symbiotic culture of bacteria and yeast.
It forms a gelatinous substance that allows it to be transferred from one fermenting substrate to the next, much like kefir grains and tibicos. The GBP was first described by Harry Marshall Ward in 1892, from samples he received in 1887. Original ginger beer is brewed by leaving water, ginger, optional ingredients such as lemon juice and cream of tartar, GBP to ferment for several days, converting some of the sugar into alcohol. GBP may be obtained from several commercial sources; until about 2008 laboratory-grade GBP was available, only from the yeast bank Deutsche Sammlung von Mikroorganismen und Zellkulturen in Germany, but the item is no longer listed. The National Collection of Yeast Cultures had an old sample of "Bees wine" as of 2008, but current staff have not used it, NCYC are unable to supply it for safety reasons, as the exact composition of the sample is unknown. In the UK, the origins of the original ginger beer plant is unknown; when a batch of ginger beer was made using some ginger beer plant, the jelly-like residue was bottled and became the new GBP.
Some of this GBP was kept for making the next batch of ginger beer, some was given to friends and family, so the'plant' was passed on through generations. Following Ward's research and experiments, he created his own ginger beer from a new'plant' that he had made, he proposed, but did not prove, that the'plant' was created by contaminants found on the raw materials, with the yeast coming from the raw brown sugar and the bacteria coming from the ginger root. A form of Ginger beer plant can be made by fermenting a mixture of water, brewer's or baker's yeast and sugar. More ginger may be added; when finished, this concentrated mix is strained, diluted with water and lemon juice, bottled. Non-alcoholic ginger beer is a type of carbonated soft drink flavoured with ginger. An example is Stoney, a product of The Coca-Cola Company sold in southern and eastern Africa; the ginger beer soft drink may be mixed with beer to make one type of shandy, or with dark rum to make a drink from Bermuda, called a Dark'N' Stormy.
It is the main ingredient in the Moscow Mule cocktail. Ginger ale Crabbie's Root beer Barritt's Ginger Beer Sockerdricka Caribbean cuisine Ginger wine Canton Socată List of soft drink flavors Donoghue v. Stevenson, legal case involving ginger beer Of the Street Sale of Ginger-Beer, Lemonade,&C. from London Labour and the London Poor, Volume 1, Henry Mayhew, 1851. Http://www.scienceinschool.org/sites/default/files/issuePdf/issue8.pdf
Steam
Steam is water in the gas phase, formed when water boils or evaporates. Steam is invisible. At lower pressures, such as in the upper atmosphere or at the top of high mountains, water boils at a lower temperature than the nominal 100 °C at standard pressure. If heated further it becomes superheated steam; the enthalpy of vaporization is the energy required to turn water into the gaseous form when it increases in volume by 1,700 times at standard temperature and pressure. Piston type steam engines played a central role to the Industrial Revolution and modern steam turbines are used to generate more than 80% of the world's electricity. If liquid water comes in contact with a hot surface or depressurizes below its vapor pressure, it can create a steam explosion. Steam is traditionally created by heating a boiler via burning coal and other fuels, but it is possible to create steam with solar energy. Water vapor that includes water droplets is described as wet steam; as wet steam is heated further, the droplets evaporate, at a high enough temperature all of the water evaporates and the system is in vapor–liquid equilibrium.
Superheated steam is steam at a temperature higher than its boiling point for the pressure, which only occurs where all liquid water has evaporated or has been removed from the system. Steam tables contain thermodynamic data for water/steam and are used by engineers and scientists in design and operation of equipment where thermodynamic cycles involving steam are used. Additionally, thermodynamic phase diagrams for water/steam, such as a temperature-entropy diagram or a Mollier diagram shown in this article, may be useful. Steam charts are used for analysing thermodynamic cycles. In agriculture, steam is used for soil sterilization to avoid the use of harmful chemical agents and increase soil health. Steam's capacity to transfer heat is used in the home: for cooking vegetables, steam cleaning of fabric and flooring, for heating buildings. In each case, water is heated in a boiler, the steam carries the energy to a target object. Steam is used in ironing clothes to add enough humidity with the heat to take wrinkles out and put intentional creases into the clothing.
As of 2000 around 90% of all electricity was generated using steam as the working fluid, nearly all by steam turbines. In electric generation, steam is condensed at the end of its expansion cycle, returned to the boiler for re-use. However, in cogeneration, steam is piped into buildings through a district heating system to provide heat energy after its use in the electric generation cycle; the world's biggest steam generation system is the New York City steam system, which pumps steam into 100,000 buildings in Manhattan from seven cogeneration plants. In other industrial applications steam is used for energy storage, introduced and extracted by heat transfer through pipes. Steam is a capacious reservoir for thermal energy because of water's high heat of vaporization. Fireless steam locomotives were steam locomotives that operated from a supply of steam stored on board in a large tank resembling a conventional locomotive's boiler; this tank was filled by process steam, as is available in many sorts of large factory, such as paper mills.
The locomotive's propulsion used connecting rods, as for a typical steam locomotive. These locomotives were used in places where there was a risk of fire from a boiler's firebox, but were used in factories that had a plentiful supply of steam to spare. Owing to its low molecular mass, steam is an effective lifting gas, providing 60% as much lift as helium and twice as much as hot air, it is not flammable, unlike hydrogen, is cheap and abundant, unlike helium. The required heat, leads to condensation problems and requires an insulated envelope; these factors have limited its use thus far to demonstration projects. Steam engines and steam turbines use the expansion of steam to drive a piston or turbine to perform mechanical work; the ability to return condensed steam as water-liquid to the boiler at high pressure with little expenditure of pumping power is important. Condensation of steam to water occurs at the low-pressure end of a steam turbine, since this maximizes the energy efficiency, but such wet-steam conditions must be limited to avoid excessive turbine blade erosion.
Engineers use an idealised thermodynamic cycle, the Rankine cycle, to model the behavior of steam engines. Steam turbines are used in the production of electricity. An autoclave, which uses steam under pressure, is used in microbiology laboratories and similar environments for sterilization. Steam dry steam, may be used for antimicrobial cleaning to the levels of sterilization. Steam is a non-toxic antimicrobial agent. Steam is used in piping for utility lines, it is used in jacketing and tracing of piping to maintain the uniform temperature in pipelines and vessels. Steam is used in the process of wood killing insects and increasing plasticity. Steam is used to accentuate drying in prefabricates. Care should be taken since concrete produces heat during hydration and additional heat from the steam could be detrimental to hardening reaction processes of the concrete. Used in cleaning of fibers and other materials, sometimes in preparation for painting. Steam is useful in melting hardened grease and oil resid
Unleavened bread
Unleavened bread is any of a wide variety of breads which are not prepared with raising agents such as yeast. Unleavened breads are flat breads. Unleavened breads, such as the tortilla and roti, are staple foods in Central America and South Asia, respectively. Unleavened breads have symbolic importance in Christianity. Jews consume unleavened breads such as matzo during Passover - various traditions explain this usage. Unleavened bread features in some Western Christian liturgies during the Eucharist, a rite derived from the Last Supper when Jesus broke bread believed to have been matzo, with his disciples during a Passover Seder. Canon Law of the Latin Rite of the Roman Catholic Church mandates the use of unleavened bread for the Host, unleavened wafers for the communion of the faithful; the more liturgical Protestant churches tend to follow the Latin Catholic practice, whereas others use either unleavened bread or wafers or ordinary bread, depending on the traditions of their particular denomination or local usage.
On the other hand, most Eastern Churches explicitly forbid the use of unleavened bread for the Eucharist. Eastern Christians associate unleavened bread with the Old Testament and allow only for bread with yeast, as a symbol of the New Covenant in Christ's blood. Indeed, this usage figures as one of the three points of contention that traditionally accounted as causes of the Great Schism of 1054 between Eastern and Western churches. Matzo – Jewish flat bread Tortilla – Mesoamerican/Mexican flat bread Roti – South Asian flat breads including Chapati and variants. Kitcha or Qitta - Ethiopian type of flat bread used in the traditional fit-fit or chechebsa dish. Tortilla de rescoldo - Chilean unleavened bread made of wheat flour, traditionally baked in the coals of a campfire. Bannock - Unleavened bread originating in the British isles. Passover Parkin
Potash
Potash is some of various mined and manufactured salts that contain potassium in water-soluble form. The name derives from pot ash, which refers to plant ashes soaked in water in a pot, the primary means of manufacturing the product before the industrial era; the word potassium is derived from potash. Potash is produced worldwide at amounts exceeding 90 million tonnes per year for use in manufacturing. Various types of fertilizer-potash constitute the single largest industrial use of the element potassium in the world. Potassium was first derived in 1807 by electrolysis of caustic potash. Potash refers to potassium compounds and potassium-bearing materials, the most common being potassium chloride; the term potash comes from the Middle Dutch word potaschen. The old method of making potassium carbonate was by collecting or producing wood ash, leaching the ashes and evaporating the resulting solution in large iron pots, leaving a white residue called pot ash. 10% by weight of common wood ash can be recovered as pot ash.
Potash became the term applied to occurring potassium salts and the commercial product derived from them. The following table lists a number of potassium compounds which use the word potash in their traditional names: All commercial potash deposits come from evaporite deposits and are buried deep below the earth's surface. Potash ores are rich in potassium chloride, sodium chloride and other salts and clays, are obtained by conventional shaft mining with the extracted ore ground into a powder. Other methods include dissolution evaporation methods from brines. In the evaporation method, hot water is injected into the potash, dissolved and pumped to the surface where it is concentrated by solar induced evaporation. Amine reagents are added to either the mined or evaporated solutions; the amine coats the KCl but not NaCl. Air bubbles cling to the amine + KCl and float it to the surface while the NaCl and clay sink to the bottom; the surface is skimmed for the amine + KCl, dried and packaged for use as a K rich fertilizer—KCl dissolves in water and is available for plant nutrition.
Potash deposits can be found all over the world. At present, deposits are being mined in Canada, China, Israel, Chile, the United States, Spain, the United Kingdom and Brazil, with the most significant deposits present in Saskatchewan, Canada. Excessive respiratory disease has been a concern for potash miners throughout history due to environmental hazards, such as radon and asbestos. Potash miners are liable to develop silicosis. Based on a study done between 1977 and 1987 cardiovascular disease among potash workers, the overall mortality rates were low, but a noticeable difference in above ground workers was documented. Potash has been used in bleaching textiles, making glass, making soap, since about AD 500. Potash was principally obtained by leaching the ashes of sea plants. Beginning in the 14th century potash was mined in Ethiopia. One of the world's largest deposits, 140 to 150 million tons, is located in the Tigray's Dallol area. Potash was one of the most important industrial chemicals.
It was refined from the ashes of broadleaved trees and produced in the forested areas of Europe and North America. The first U. S. patent of any kind was issued in 1790 to Samuel Hopkins for an improvement "in the making of Pot ash and Pearl ash by a new Apparatus and Process". Pearl ash was a purer quality made by calcination of potash in kiln. Potash pits were once used in England to produce potash, used in making soap for the preparation of wool for yarn production; as early as 1767, potash from wood ashes was exported from Canada, exports of potash and pearl ash reached 43,958 barrels in 1865. There were 519 asheries in operation in 1871; the industry declined in the late 19th century when large-scale production of potash from mineral salts was established in Germany. In 1943, potash was discovered in Canada, in the process of drilling for oil. Active exploration began in 1951. In 1958, the Potash Company of America became the first potash producer in Canada with the commissioning of an underground potash mine at Patience Lake.
The underground mine was flooded in 1987 and was reactivated for commercial production as a solution mine in 1989. In the late 18th and early 19th centuries, potash production provided settlers in North America a way to obtain badly needed cash and credit as they cleared wooded land for crops. To make full use of their land, settlers needed to dispose of excess wood; the easiest way to accomplish this was to burn any wood not needed for construction. Ashes from hardwood trees could be used to make lye, which could either be used to make soap or boiled down to produce valuable potash. Hardwood could generate ashes at the rate of 60 to 100 bushels per acre. In 1790, ashes could be sold for $3.25 to $6.25 per acre in rural New York State – nearly the same rate as hiring a laborer to clear the same area. Potash making became a major industry in British North America. Great Britain was always the most important market; the American potash industry followed the woodsman's ax across the country. After about 1820, New York replaced New England as the most important source.
Potash production was always
