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Lead(II) oxide

Lead oxide called lead monoxide, is the inorganic compound with the molecular formula PbO. PbO occurs in two polymorphs: litharge having a tetragonal crystal structure, massicot having an orthorhombic crystal structure. Modern applications for PbO are in lead-based industrial glass and industrial ceramics, including computer components, it is an amphoteric oxide. PbO may be prepared by heating lead metal in air at 600 °C. At this temperature it is the end product of oxidation of other oxides of lead in air: PbO2 293 °C→ Pb12O19 351 °C→ Pb12O17 375 °C→ Pb3O4 605 °C→ PbOThermal decomposition of lead nitrate or lead carbonate results in the formation of PbO: 2 Pb2 → 2 PbO + 4 NO2 + O2 PbCO3 → PbO + CO2PbO is produced on a large scale as an intermediate product in refining raw lead ores into metallic lead; the usual lead ore is galena. At a temperature of around 1,000 °C the sulfide is converted to the oxide: 2 PbS + 3 O2 → 2 PbO + 2 SO2Metallic lead is obtained by reducing PbO with carbon monoxide at around 1,200 °C: PbO + CO → Pb + CO2 As determined by X-ray crystallography, both polymorphs and orthorhombic feature a pyramidal four-coordinate lead center.

In the tetragonal form the four lead–oxygen bonds have the same length, but in the orthorhombic two are shorter and two longer. The pyramidal nature indicates the presence of a stereochemically active lone pair of electrons; when PbO occurs in tetragonal lattice structure it is called litharge. The PbO can be changed from massicot to litharge or vice versa by controlled cooling; the tetragonal form is red or orange color, while the orthorhombic is yellow or orange, but the color is not a reliable indicator of the structure. The tetragonal and orthorhombic forms of PbO occur as rare minerals; the red and yellow forms of this material are related by a small change in enthalpy: PbO → PbO ΔH = 1.6 kJ/molPbO is amphoteric, which means that it reacts with both acids and with bases. With acids, it forms salts of Pb2+ via the intermediacy of oxo clusters such as 4+. With strong bases, PbO dissolves to form plumbite salts: PbO + H2O + OH− → − The kind of lead in lead glass is PbO, PbO is used extensively in making glass.

Depending on the glass, the benefit of using PbO in glass can be one or more of increasing the refractive index of the glass, decreasing the viscosity of the glass, increasing the electrical resistivity of the glass, increasing the ability of the glass to absorb X-rays. Adding PbO to industrial ceramics makes the materials more magnetically and electrically inert and it is used for this purpose. PbO was used extensively in ceramic glazes for household ceramics, it is still used, but not extensively any more. Other less dominant applications include the vulcanization of rubber and the production of certain pigments and paints. PbO is used in cathode ray tube glass to block X-ray emission, but in the neck and funnel because it can cause discoloration when used in the faceplate. Strontium oxide is preferred for the faceplate; the consumption of lead, hence the processing of PbO, correlates with the number of automobiles, because it remains the key component of automotive lead-acid batteries. A mixture of PbO with glycerine sets to a hard, waterproof cement, used to join the flat glass sides and bottoms of aquariums, was once used to seal glass panels in window frames.

It is a component of lead paints. PbO was used to speed up the process to turn more profit for less time and artificially increase the quality of century eggs, a type of Chinese preserved egg, it was an unscrupulous practice in some small factories but it became rampant in China and forced many honest manufacturers to label their boxes "lead-free" after the scandal went mainstream in 2013. In powdered tetragonal litharge form, it can be mixed with linseed oil and boiled to create a weather-resistant sizing used in gilding; the litharge would give the sizing a dark red color that made the gold leaf appear warm and lustrous, while the linseed oil would impart adhesion and a flat durable binding surface. PbO is used in certain condensation reactions in organic synthesis. PbO is the input photoconductor in a video camera tube called the Plumbicon. Lead oxide may be fatal if inhaled, it causes irritation to skin and respiratory tract. It affects gum tissue, central nervous system, kidneys and reproductive system.

It can bioaccumulate in mammals. Case Studies in Environmental Medicine - Lead Toxicity ToxFAQs: Lead National Pollutant Inventory - Lead and Lead Compounds Fact Sheet Webelements PbO

The Dalles Mint

The Dalles Mint was to be a branch of the United States Mint in The Dalles in Oregon. Constructed in 1869, the planned two-story structure was never completed and the mint was never put into operation. Located in the downtown area of the city, the building was given to the state before it was sold to the public; the Mint building was most home to the Erin Glenn Winery. In 1860, gold was discovered in Idaho, this along with a gold rush in Eastern Oregon created a need for a mint in the Pacific Northwest. Although the American Civil War was underway, 80,000 prospectors headed for the gold fields in 1862. Raw gold dust was used as currency in The Dalles because gold had to be shipped to the San Francisco Mint for processing. Demand grew for a mint closer to the mines. Oregon U. S. Senator James W. Nesmith introduced an unsuccessful bill in 1862 to create a mint in Portland, Oregon. On July 4, 1864, Congress passed a bill to authorize a new branch of the mint at The Dalles for minting gold and silver coins.

The next year another bill unsuccessfully attempted to change the location for the mint to Portland. William Logan was appointed as superintendent of the planned mint, but he died in the shipwreck of the S. S. Brother Jonathan en route to The Dalles. Mary Laughlin donated a block of land on June 6, 1865, as a site for the mint and in 1869, construction began with Harvey A. Hogue as the superintendent of construction. However, the project was delayed, as the gold rushes waned and the Central Pacific Railroad opened, the mint become obsolete before the building could be completed and the minting equipment could be installed; the basement and first floor were completed in 1869, but in 1870 the construction was suspended, abandoned in 1873. A fire destroyed much of the city in 1871, but the fact the mint was in the middle of the city block served as a firebreak and helped stop the fire. In 1875, the federal government gave the structure to the State of Oregon, who in turn sold it to private interests in 1889.

By 1940, the building was being used by the Columbia Warehouse Company. A fire in 1943 damaged the mint building; the structure was owned by Ralph's Transfer & Storage Co. before becoming the home of the Erin Glenn Winery in 2007 after a $1.5 million renovation. The single story, 35-foot high granite building has a basement; the building has a flat roof, with arched windows. Stone for the building was shipped by wagon to the site; the building measured 50 feet by 60 feet and cost $105,000. Built in the center of the block, the original plans called for a two-storey building to be 90 feet by 51 feet. A concrete block section was added to the north side of the original structure; the building is eligible for the National Register of Historic Places, but is just outside the NRHP-listed The Dalles Commercial Historic District. National Register of Historic Places listings in Wasco County, Oregon Carson City Mint Image of the building Downtown The Dalles Historical Commercial District

Penygraig

Penygraig is a village and community in the Rhondda Valley in the county borough of Rhondda Cynon Taf, Wales. As a community Penygraig contains the neighbouring districts of Dinas, Edmondstown and Williamstown. Penygraig is within the historic county boundaries of Glamorgan; the name Penygraig is Welsh for'head of the rock'. The original settlement which in now Penygraig was called Ffrwd Amos, though as with the rest of the Rhondda before industrialisation the only settlements were farmsteads. In 1832, one of the first baptist chapels in the Rhondda was built at Penygraig by preacher David Williams. Coal mining began in Penygraig in 1857. In 1858 Moses Rowlands and Richard Jenkins discovered a seam at Penygraig and would form the Penygraig Coal Company; the Company sank the first deep pit in The Penygraig Colliery. After the Penygraig Colliery showed a successful profit the Naval Colliery Company opened a second deep pit, The Pandy, which reached the steam coal seam in 1879; the Pandy was sold to the New Naval Colliery Company after three disasters, which opened three more deep mines The Ely, the Nantgwyn and the Anthony Pits.

The New Naval company would become part of the Cambrian Combine, owned by Viscount Rhondda. The Ely Colliery would be the centre of the Cambrian Combine dispute, which in turn would lead to the Tonypandy Riot; the first of three disasters to occur at the Naval Colliery happened on 4 December 1875 when a flood broke through into the mine, resulting in two miners drowning and the lives of many others placed at risk. On 10 December 1880 a gas explosion took the lives of 101 miners out of the 106 who were working in the mine at the time; this was followed on 27 January 1884. These disasters are factors in the Naval Colliery Company selling the mine in 1887; the Penygraig community is coterminous with the electoral ward of Pen-y-craig which elects two county councillors to Rhondda Cynon Taf County Borough Council. Since 1995 representation has been either by the Labour Party or Plaid Cymru. Between 2004 and 2017 both councillors were from the Labour Party, though at the May 2017 election Plaid Cymru won both seats.

Penygraig is home to rugby union team Penygraig RFC, which during the late 19th and early 20th century was one of the most notable rugby clubs in the Rhondda, producing Wales international players Dai Evans and Jack Rhapps, was the early club of British Isles rugby representative Percy Bush. See Category:People from PenygraigPenygraig, like many of the villages of the Rhondda produced notable boxers, including Tom Thomas, who in 1908 became the first British national middle-weight champion, in 1909 was the first winner of the Lonsdale Belt at the same weight. Leanne Wood, the former leader of Plaid Cymru, still lives in Penygraig. Gwyn Martin and author, grew up in Penygraig. Ricky Wright, Master of Ceremonies for professional boxing and Mixed Martial arts. Rhondda Cynon Taf Library Services, Heritage Trail:Penygraig