La France (airship)
The La France was a French Army non-rigid airship launched by Charles Renard and Arthur Constantin Krebs on August 9, 1884. Collaborating with Charles Renard, Arthur Constantin Krebs piloted the first controlled free-flight with the La France; the 170-foot long, 66,000 cubic feet airship, electric-powered with a 435 kg zinc-chlorine flow battery completed a flight that covered 8 km in 23 minutes. It was the first full round trip flight with a landing on the starting point. On its seven flights in 1884 and 1885 the La France dirigible returned five times to its starting point; the airship hangar was built as Hangar “Y” at Chalais Meudon near Paris in 1879 where the La France” was constructed. Hangar “Y” is one of the few remaining airship hangars in Europe. Timeline of hydrogen technologies "LE BALLON DIRIGEABLE "LA FRANCE" / Plans, croquis et photos / N° 1 – Plans du dirigeable". Archived from the original on May 28, 2007. "LE BALLON DIRIGEABLE "LA FRANCE" / Plans, croquis et photos / N° 10 – Moteur du dirigeable".
Archived from the original on 2007-08-09
Île-de-France called the région parisienne, contains the city of Paris, is the most populous of the 18 regions of France. It covers 12,012 square kilometres, or two percent of the national territory, has official estimated population of 12,213,364 as of January 1, 2019, or 18.2% of the population of France. The region accounts for nearly 30 percent of the French Gross Domestic Product; the region is made up of eight administrative departments: Paris, Hauts-de-Seine, Seine-Saint-Denis, Seine-et-Marne, Val-de-Marne, Val-d'Oise and Yvelines. It was created as the "District of the Paris Region" in 1961 renamed in 1976 after the historic province of Île-de-France, when its status was aligned with the other French administrative regions created in 1972. Residents are sometimes referred to an administrative word created in the 1980s; the GDP of the region in 2016 was €681 billion. It has the highest per-capita GDP among regions in France and the third-highest of regions in the European Union. In 2018 all of the twenty-eight French companies listed in the Fortune Global 500 had their headquarters in the Paris region.
Besides the landmarks of Paris, the region has many important historic sites, including the Palace of Versailles and the Palace of Fontainebleau, as well as the most-visited tourist attraction in France, Disneyland Paris. Although the modern name Île-de-France means "Island of France", the etymology is in fact unclear; the "island" may refer to the land between the rivers Oise and Seine, or it may have been a reference to the Île de la Cité, where the French royal palace and cathedral were located. The Île-de-France was inhabited by the Parisii, a sub-tribe of the Celtic Senones, from around the middle of the 3rd century BC. One of the area's major north–south trade routes crossed the Seine on the île de la Cité; the Parisii minted their own coins for that purpose. The Romans began their settlement on Paris's Left Bank, it became a prosperous city with a forum, temples, an amphitheatre. Christianity was introduced in the middle of the 3rd century AD by Saint Denis, the first Bishop of Paris: according to legend, when he refused to renounce his faith before the Roman occupiers, he was beheaded on the hill which became known as Mons Martyrum "Montmartre", from where he walked headless to the north of the city.
As the Frankish domination of Gaul began, there was a gradual immigration by the Franks to Paris and the Parisian Francien dialects were born. Fortification of the Île-de-la-Citie failed to avert sacking by Vikings in 845, but Paris's strategic importance—with its bridges preventing ships from passing—was established by successful defence in the Siege of Paris. In 987, Hugh Capet, Count of Paris and Duke of the Franks, was elected King of the Franks. Under the rule of the Capetian kings, Paris became the largest and most prosperous city in France; the Kings of France enjoyed getting away from Paris and hunting in the game-filled forests of the region. They built palatial hunting lodges, most notably Palace of Fontainebleau and the Palace of Versailles. From the time of Louis XIV until the French Revolution, Versailles was the official residence of the Kings and the seat of the French government; the Ile-de-France became the term used for the territory of Paris and the surrounding province, administered directly by the King.
During the French Revolution, the royal provinces were abolished and divided into departments, the city and region were governed directly by the national government. In the period after World War II, as Paris faced a major housing shortage, hundreds of massive apartment blocks for low-income residents were built around the edges of Paris. In the 1950s and the 1960s, Many thousands of immigrants settled in the communes bordering the city. In 1959, under President Charles De Gaulle, a new region was created out of six departments, which corresponded with the historic region, with the name District de la région de Paris. On 6 May 1976, as part of the process of regionalisation, the district was reconstituted and increased administrative and political powers and renamed the Île-de-France region. Île-de-France has a land area of 12,011 km2. It is composed of eight départements centered on Paris. Around the département of Paris, urbanization fills a first concentric ring of three departments known as the petite couronne, extends into a second outer ring of four départements known as the grande couronne.
The former département of Seine, abolished in 1968, included the city proper and parts of the petite couronne. The petite couronne consists of the départements of Hauts-de-Seine, Seine-Saint-Denis, Val-de-Marne, the grande couronne of those of Seine-et-Marne, Yvelines and Val-d'Oise. Politically, the region is divided into 8 départements, 25 arrondissements, 155 cantons and 1 276 communes, out of the total of 35 416 in metropolitan France, The outer parts of the Ile-de-France remain rural. Agriculture land and natu
The Franco-Prussian War or Franco-German War referred to in France as the War of 1870, was a conflict between the Second French Empire and the Third French Republic, the German states of the North German Confederation led by the Kingdom of Prussia. Lasting from 19 July 1870 to 28 January 1871, the conflict was caused by Prussian ambitions to extend German unification and French fears of the shift in the European balance of power that would result if the Prussians succeeded; some historians argue that the Prussian chancellor Otto von Bismarck deliberately provoked the French into declaring war on Prussia in order to draw the independent southern German states—Baden, Württemberg and Hesse-Darmstadt—into an alliance with the North German Confederation dominated by Prussia, while others contend that Bismarck did not plan anything and exploited the circumstances as they unfolded. None, dispute the fact that Bismarck must have recognized the potential for new German alliances, given the situation as a whole.
On 16 July 1870, the French parliament voted to declare war on Prussia and hostilities began three days when French forces invaded German territory. The German coalition mobilised its troops much more than the French and invaded northeastern France; the German forces were superior in numbers, had better training and leadership and made more effective use of modern technology railroads and artillery. A series of swift Prussian and German victories in eastern France, culminating in the Siege of Metz and the Battle of Sedan, saw French Emperor Napoleon III captured and the army of the Second Empire decisively defeated. A Government of National Defence declared the Third French Republic in Paris on 4 September and continued the war for another five months. Following the Siege of Paris, the capital fell on 28 January 1871, a revolutionary uprising called the Paris Commune seized power in the city and held it for two months, until it was bloodily suppressed by the regular French army at the end of May 1871.
The German states proclaimed their union as the German Empire under the Prussian king Wilhelm I uniting Germany as a nation-state. The Treaty of Frankfurt of 10 May 1871 gave Germany most of Alsace and some parts of Lorraine, which became the Imperial territory of Alsace-Lorraine; the German conquest of France and the unification of Germany upset the European balance of power that had existed since the Congress of Vienna in 1815, Otto von Bismarck maintained great authority in international affairs for two decades. French determination to regain Alsace-Lorraine and fear of another Franco-German war, along with British apprehension about the balance of power, became factors in the causes of World War I; the causes of the Franco-Prussian War are rooted in the events surrounding the unification of Germany. In the aftermath of the Austro-Prussian War of 1866, Prussia had annexed numerous territories and formed the North German Confederation; this new power destabilized the European balance of power established by the Congress of Vienna in 1815 after the Napoleonic Wars.
Napoleon III the emperor of France, demanded compensations in Belgium and on the left bank of the Rhine to secure France's strategic position, which the Prussian chancellor, Otto von Bismarck, flatly refused. Prussia turned its attention towards the south of Germany, where it sought to incorporate the southern German kingdoms, Bavaria, Württemberg and Hesse-Darmstadt, into a unified Prussia-dominated Germany. France was opposed to any further alliance of German states, which would have strengthened the Prussian military. In Prussia, some officials considered a war against France both inevitable and necessary to arouse German nationalism in those states that would allow the unification of a great German empire; this aim was epitomized by Prussian Chancellor Otto von Bismarck's statement: "I did not doubt that a Franco-German war must take place before the construction of a United Germany could be realised." Bismarck knew that France should be the aggressor in the conflict to bring the southern German states to side with Prussia, hence giving Germans numerical superiority.
He was convinced that France would not find any allies in her war against Germany for the simple reason that "France, the victor, would be a danger to everybody – Prussia to nobody," and he added, "That is our strong point." Many Germans viewed the French as the traditional destabilizer of Europe, sought to weaken France to prevent further breaches of the peace. The immediate cause of the war resided in the candidacy of Leopold of Hohenzollern-Sigmaringen, a Prussian prince, to the throne of Spain. France feared encirclement by an alliance between Spain; the Hohenzollern prince's candidacy was withdrawn under French diplomatic pressure, but Otto von Bismarck goaded the French into declaring war by releasing an altered summary of the Ems Dispatch, a telegram sent by William I rejecting French demands that Prussia never again support a Hohenzollern candidacy. Bismarck's summary, as mistranslated by the French press Havas, made it sound as if the king had treated the French envoy in a demeaning fashion, which inflamed public opinion in France.
French historians François Roth and Pierre Milza argue that Napoleon III was pressured by a bellicose press and public opinion and thus sought war in response to France's diplomatic failures to obtain any territorial gains following the Austro-Prussian War. Napoleon III believed. Many in his court, such as Empress Eugénie wanted a
The RATP Group known as the Régie Autonome des Transports Parisiens, is a state-owned public transport operator and maintainer headquartered in Paris, France. Formed in 1949, it has its origins as the city's public transport operator, its logo represents, in a stylized version, the Seine's meandering through the Paris area as the face of a person looking up. Today, RATP is still responsible for most of the public transport in Paris, the rest of the Île-de-France region, including the Paris Métro and bus services and part of the Réseau Express Régional network. In the Île-de-France region, RATP carries about 3 billion passengers per year; the RATP's Paris operations are still a major part of the business, but its operations have now extended to include businesses around the globe. They include involvement in the operation of bus, rapid transit and inter-city rail services in Europe, Asia and the Americas. RATP Group is the world's fifth largest operator in the public transport sector; the RATP was created on 1 January 1949 by combining the assets of the Compagnie du chemin de fer métropolitain de Paris, which operated the Paris Métro, the Société des transports en commun de la région parisienne, which operated the city's bus system.
Earlier, the CMP had absorbed the Société du Chemin de Fer Électrique Nord-Sud de Paris in 1930 and the Ligne de Sceaux in 1937, which extended commuter rail to the suburbs. The STCRP had been created on 1 January 1921 by the merger of about half a dozen independent bus and streetcar operators in the Paris area. By the time the STCRP was merged into the RATP, all of its streetcars had been replaced by bus routes. In the early years of the 21st century, a partnership with the Transdev group resulted in RATP acquiring a minority shareholding in that group, with its many worldwide transport operations. However, in 2009, the Caisse des dépôts et consignations, the majority owner of the Transdev group, started negotiations with Veolia Environnement to merge Transdev with Veolia Transport; as part of the resulting agreement, made in May 2010, it was agreed that the RATP Group would take over ownership of some of Transdev's operations in lieu of cash payment for its holdings in Transdev. This had a considerable impact on RATP's international profile.
In 2009, RATP entered the United States by purchasing transit contractor McDonald Transit Associates. McDonald operated FWTA in Texas, Votran in Florida, Waco Transit System in Texas, among others. On 1 August 2011 the RATP Group purchased Stagecoach Metrolink's contract to operate the Metrolink light rail system in Greater Manchester, England until July 2017. Two years in 2013 RATP purchased the nearby long-established coach company, Selwyns Travel, a National Express operator; the last CEOs of the RATP were Pierre Mongin and Élisabeth Borne. The actual president of the RATP, Catherine Guillouard, was nominated on 2 August 2017. In Paris, RATP operates, under its own name, on behalf of the Île-de-France Mobilités, the Paris region transit authority. RATP's services constitute, in their own right, a multi-mode public transportation infrastructure, but contribute to a larger multi-mode system extending out into the surrounding Île-de-France communities. RATP's services in the Greater Paris area include: The Paris Métro system of underground rapid transit lines, which run throughout the city, with some lines extending somewhat beyond the city boundaries.
The Métro has 16 lines with 219 km of 302 stations. Two metro lines are automated and driverless: line 1 and line 14. Orlyval, the automated metro shuttle connecting Antony station and Orly Airport. Parts of the RER, the Paris regional express rail network that runs underground in the centre of Paris and overground in the rest of the region. RATP owns and operates line A and line B, both together representing 115 km and 66 stations; the rest of the RER network is operated by SNCF. Eight out of ten lines of the Paris tram system totalizing 101.9 km and 183 stops. The extensive Paris city bus system, including the night buses of the Noctilien network. Two BRT lines: the Trans-Val-de-Marne and line 393; the Montmartre funicular. Paris bus route 341 was RATP's first line equipped with 100% electric full-size buses. RATP Dev, a 100% subsidiary of the RATP Group created in 2002, provides operations and maintenance of passenger transport services outside of the "historical" RATP network in the Greater Paris area although it operates some specialised services within Paris.
RATP Dev is present in 14 countries, namely Algeria, France, Italy, the Philippines, Saudi Arabia, South Africa, South Korea, the United Kingdom, the United States. Wholly and owned operations include the following: Agglobus, the urban bus network of Bourges in the Cher department Aléo, the urban bus network of Moulins in the Allier department Cars Jacquemard, a coach operator in the Eure department Cars Perrier, one of the operators of the Sqybus network serving the Saint-Quentin-en-Yvelines suburb near Paris The CTRL network of Lorient Agglomération in the Morbihan department Com'Bus and Val-d'Oise departments The Impulsyon urban bus netw
Wind tunnels are large tubes with air moving inside. The tunnels are used to copy the actions of an object in flight. Researchers use wind tunnels to learn more about. NASA uses wind tunnels to test scale models of spacecraft; some wind tunnels are big enough to hold full-size versions of vehicles. The wind tunnel moves air around an object, making it seem like the object is flying. Most of the time, powerful fans move air through the tube; the object to be tested is fastened in the tunnel. The object can be a small model of a vehicle, it can be just a piece of a vehicle. It can be spacecraft, it can be a common object like a tennis ball. The air moving around the still object shows what would happen if the object were moving through the air. How the air moves can be studied in different ways. Smoke or dye can be seen as it moves. Threads can be attached to the object to show. Special instruments are used to measure the force of the air on the object; the earliest wind tunnels were invented towards the end of the 19th century, in the early days of aeronautic research, when many attempted to develop successful heavier-than-air flying machines.
The wind tunnel was envisioned as a means of reversing the usual paradigm: instead of the air standing still and an object moving at speed through it, the same effect would be obtained if the object stood still and the air moved at speed past it. In that way a stationary observer could study the flying object in action, could measure the aerodynamic forces being imposed on it; the development of wind tunnels accompanied the development of the airplane. Large wind tunnels were built during World War II. Wind tunnel testing was considered of strategic importance during the Cold War development of supersonic aircraft and missiles. On, wind tunnel study came into its own: the effects of wind on man made structures or objects needed to be studied when buildings became tall enough to present large surfaces to the wind, the resulting forces had to be resisted by the building's internal structure. Determining such forces was required before building codes could specify the required strength of such buildings and such tests continue to be used for large or unusual buildings.
Still wind-tunnel testing was applied to automobiles, not so much to determine aerodynamic forces per se but more to determine ways to reduce the power required to move the vehicle on roadways at a given speed. In these studies, the interaction between the road and the vehicle plays a significant role, this interaction must be taken into consideration when interpreting the test results. In an actual situation the roadway is moving relative to the vehicle but the air is stationary relative to the roadway, but in the wind tunnel the air is moving relative to the roadway, while the roadway is stationary relative to the test vehicle; some automotive-test wind tunnels have incorporated moving belts under the test vehicle in an effort to approximate the actual condition, similar devices are used in wind tunnel testing of aircraft take-off and landing configurations. Wind tunnel testing of sporting equipment has been prevalent over the years, including golf clubs, golf balls, Olympic bobsleds, Olympic cyclists, race car helmets.
Helmet aerodynamics is important in open cockpit race cars. Excessive lift forces on the helmet can cause considerable neck strain on the driver, flow separation on the back side of the helmet can cause turbulent buffeting and thus blurred vision for the driver at high speeds; the advances in computational fluid dynamics modelling on high speed digital computers has reduced the demand for wind tunnel testing. However, CFD results are still not reliable and wind tunnels are used to verify CFD predictions. Air velocity and pressures are measured in several ways in wind tunnels. Air velocity through the test section is determined by Bernoulli's principle. Measurement of the dynamic pressure, the static pressure, the temperature rise in the airflow; the direction of airflow around a model can be determined by tufts of yarn attached to the aerodynamic surfaces. The direction of airflow approaching a surface can be visualized by mounting threads in the airflow ahead of and aft of the test model. Smoke or bubbles of liquid can be introduced into the airflow upstream of the test model, their path around the model can be photographed.
Aerodynamic forces on the test model are measured with beam balances, connected to the test model with beams, strings, or cables. The pressure distributions across the test model have been measured by drilling many small holes along the airflow path, using multi-tube manometers to measure the pressure at each hole. Pressure distributions can more conveniently be measured by the use of pressure-sensitive paint, in which higher local pressure is indicated by lowered fluorescence of the paint at that point. Pressure distributions can be conveniently measured by the use of pressure-sensitive pressure belts, a recent development in which multiple ultra-miniaturized pressure sensor modules are integrated into a flexible strip; the strip is attached to the aerodynamic surface with tape, it sends signals depicting the pressure distribution along its surface. Pressure distributions on a test model can be determined by performing a wake survey, in which either a single pitot tube is used to obtain multiple readings downstream of the test model, or a multiple-tube manometer is mounted downstream and all its readings are taken.
The aerodynamic properties of an object can not all remain the same for a
Communes of France
The commune is a level of administrative division in the French Republic. French communes are analogous to civil townships and incorporated municipalities in the United States and Canada, Gemeinden in Germany, comuni in Italy or ayuntamiento in Spain; the United Kingdom has no exact equivalent, as communes resemble districts in urban areas, but are closer to parishes in rural areas where districts are much larger. Communes are based on historical geographic communities or villages and are vested with significant powers to manage the populations and land of the geographic area covered; the communes are the fourth-level administrative divisions of France. Communes vary in size and area, from large sprawling cities with millions of inhabitants like Paris, to small hamlets with only a handful of inhabitants. Communes are based on pre-existing villages and facilitate local governance. All communes have names, but not all named geographic areas or groups of people residing together are communes, the difference residing in the lack of administrative powers.
Except for the municipal arrondissements of its largest cities, the communes are the lowest level of administrative division in France and are governed by elected officials with extensive autonomous powers to implement national policy. A commune is city, or other municipality. "Commune" in English has a historical bias, implies an association with socialist political movements or philosophies, collectivist lifestyles, or particular history. There is nothing intrinsically different between commune in French; the French word commune appeared in the 12th century, from Medieval Latin communia, for a large gathering of people sharing a common life. As of January 2015, there were 36,681 communes in France, 36,552 of them in metropolitan France and 129 of them overseas; this is a higher total than that of any other European country, because French communes still reflect the division of France into villages or parishes at the time of the French Revolution. The whole territory of the French Republic is divided into communes.
This is unlike some other countries, such as the United States, where unincorporated areas directly governed by a county or a higher authority can be found. There are only a few exceptions: COM of Saint-Martin, it was a commune inside the Guadeloupe région. The commune structure was abolished when Saint-Martin became an overseas collectivity on 22 February 2007. COM of Wallis and Futuna, which still is divided according to the three traditional chiefdoms. COM of Saint Barthélemy, it was a commune inside the Guadeloupe region. The commune structure was abolished when Saint-Barthélemy became an overseas collectivity on 22 February 2007. Furthermore, two regions without permanent habitation have no communes: TOM of the French Southern and Antarctic Lands Clipperton Island in the Pacific Ocean In metropolitan France, the average area of a commune in 2004 was 14.88 square kilometres. The median area of metropolitan France's communes at the 1999 census was smaller, at 10.73 square kilometres. The median area is a better measure of the area of a typical French commune.
This median area is smaller than that of most European countries. In Italy, the median area of communes is 22 km2. Switzerland and the Länder of Rhineland-Palatinate, Schleswig-Holstein, Thuringia in Germany were the only places in Europe where the communes had a smaller median area than in France; the communes of France's overseas départements such as Réunion and French Guiana are large by French standards. They group into the same commune several villages or towns with sizeable distances among them. In Réunion, demographic expansion and sprawling urbanization have resulted in the administrative splitting of some communes; the median population of metropolitan France's communes at the 1999 census was 380 inhabitants. Again this is a small number, here France stands apart in Europe, with the lowest communes' median population of all the European countries; this small median population of French communes can be compared with Italy, where the median population of communes in 2001 was 2,343 inhabitants, Belgium, or Spain.
The median population given here should not hide the fact that there are pronounced differences in size between French communes. As mentioned in the introduction, a commune can be a city of 2 million inhabitants such as Paris, a town of 10,000 inhabitants, or just a hamlet of 10 inhabitants. What the median population tells us is that the vast majority of the French communes only have a few hundred inhabitants. In metropolitan France just over 50 percent of the 36,683 communes have fewer than 500 inhabitants a
Clay is a finely-grained natural rock or soil material that combines one or more clay minerals with possible traces of quartz, metal oxides and organic matter. Geologic clay deposits are composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to particle size and geometry as well as water content, become hard and non–plastic upon drying or firing. Depending on the soil's content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red. Although many occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, some overlap in particle size and other physical properties; the distinction between silt and clay varies by discipline. Geologists and soil scientists consider the separation to occur at a particle size of 2 µm, sedimentologists use 4–5 μm, colloid chemists use 1 μm.
Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits. ISO 14688 grades clay particles as being smaller than 2 silt particles as being larger. Mixtures of sand and less than 40% clay are called loam. Loam is used as a building material. Clay minerals form over long periods of time as a result of the gradual chemical weathering of rocks silicate-bearing, by low concentrations of carbonic acid and other diluted solvents; these solvents acidic, migrate through the weathering rock after leaching through upper weathered layers. In addition to the weathering process, some clay minerals are formed through hydrothermal activity. There are two types of clay deposits: secondary. Primary clays remain at the site of formation. Secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Clay deposits are associated with low energy depositional environments such as large lakes and marine basins.
Depending on the academic source, there are three or four main groups of clays: kaolinite, montmorillonite-smectite and chlorite. Chlorites are not always considered to be a clay, sometimes being classified as a separate group within the phyllosilicates. There are 30 different types of "pure" clays in these categories, but most "natural" clay deposits are mixtures of these different types, along with other weathered minerals. Varve is clay with visible annual layers, which are formed by seasonal deposition of those layers and are marked by differences in erosion and organic content; this type of deposit is common in former glacial lakes. When fine sediments are delivered into the calm waters of these glacial lake basins away from the shoreline, they settle to the lake bed; the resulting seasonal layering is preserved in an distribution of clay sediment banding. Quick clay is a unique type of marine clay indigenous to the glaciated terrains of Norway, Northern Ireland, Sweden, it is a sensitive clay, prone to liquefaction, involved in several deadly landslides.
Powder X-ray diffraction can be used to identify clays. The physical and reactive chemical properties can be used to help elucidate the composition of clays. Clays exhibit plasticity. However, when dry, clay becomes firm and when fired in a kiln, permanent physical and chemical changes occur; these changes convert the clay into a ceramic material. Because of these properties, clay is used for making pottery, both utilitarian and decorative, construction products, such as bricks and floor tiles. Different types of clay, when used with different minerals and firing conditions, are used to produce earthenware and porcelain. Prehistoric humans discovered the useful properties of clay; some of the earliest pottery shards recovered are from Japan. They are associated with the Jōmon culture and deposits they were recovered from have been dated to around 14,000 BC. Clay tablets were the first known writing medium. Scribes wrote by inscribing them with cuneiform script using a blunt reed called a stylus. Purpose-made clay balls were used as sling ammunition.
Clays sintered in fire were the first form of ceramic. Bricks, cooking pots, art objects, smoking pipes, musical instruments such as the ocarina can all be shaped from clay before being fired. Clay is used in many industrial processes, such as paper making, cement production, chemical filtering; until the late 20th century, bentonite clay was used as a mold binder in the manufacture of sand castings. Clay, being impermeable to water, is used where natural seals are needed, such as in the cores of dams, or as a barrier in landfills against toxic seepage. Studies in the early 21st century have investigated clay's absorption capacities in various applications, such as the removal of heavy metals from waste water and air purification. Traditional uses of clay as medicine goes back to prehistoric times. An example is Armenian bole, used to soothe an upset stomach; some animals such as parrots and pigs ingest clay for similar reasons. Kaolin clay and attapulgite have been used as anti-diarrheal medicines.
Clay as the defining ingredient of loam is one of the oldest building materials on Earth, among other