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Monday, 27 April 2015

Liquid mercury found under Mexican pyramid could lead to king's tomb

An archaeologist has discovered liquid mercury at the end of a tunnel beneath a Mexican pyramid, a finding that could suggest the existence of a king’s tomb or a ritual chamber far below one of the most ancient cities of the Americas.

Mexican researcher Sergio Gómez told Reuters on Friday that he had discovered “large quantities” of liquid mercury in a chamber below the Pyramid of the Feathered Serpent, the third largest pyramid of Teotihuacan, the ruined city in central Mexico.

Visitors look at the archaeological area of the Quetzalcoatl (Feathered Serpent) Temple near the Pyramid of the Sun at the Teotihuacan archaeological site, north of Mexico City. Photograph: Henry Romero/Reuters

Gómez has spent six years slowly excavating the tunnel, which was unsealed in 2003 after 1,800 years. Last November, Gómez and a team announced they had found three chambers at the tunnel’s 300ft end, almost 60ft below the the temple. Near the entrance of the chambers, they a found trove of strange artifacts: jade statues, jaguar remains, a box filled with carved shells and rubber balls.

Slowly working their way down the broad, dark and deep corridor beneath the pyramid, battling humidity and now obliged to wear protective gear against the dangers of mercury poisoning, Gómez and his team are meticulously exploring the three chambers.

Mercury is toxic and capable of devastating the human body through prolonged exposure; the liquid metal had no apparent practical purpose for ancient Mesoamericans. But it has been discovered at other sites. Rosemary Joyce, a professor of anthropology at the University of California, Berkeley, said that archaeologists have found mercury at three other sites around Central America.

Gómez speculated to Reuters that the mercury could be a sign that his team is close to uncovering the first royal tomb ever found in Teotihuacan after decades of excavation – and centuries of mystery surrounding the leadership of the cryptic but well-preserved city.

The mercury may have symbolized an underworld river or lake, Gómez postulated, an idea that resonated with Annabeth Headreck, a professor at the University of Denver and the author of works on Teotihuacan and Mesoamerican art.

The shimmering, reflective qualities of liquid mercury may have resembled “an underworld river, not that different from the river Styx,” Headrick said, “if only in the concept that it’s the entrance to the supernatural world and the entrance to the underworld.”

“Mirrors were considered a way to look into the supernatural world, they were a way to divine what might happen in the future,” she said. “It could be a sort of river, albeit a pretty spectacular one.”

Joyce said that archaeologists know that scintillation fascinated the ancient people generally, and that the liquid mercury may have held been regarded as “somewhat magical … there for ritual purposes or symbolic purposes.”

Headrick said that mercury was not the only object of fascination: “a lot of ritual objects were made reflective with mica,” a sparkling mineral likely imported to the region.

In 2013 archaeologists using a robot found metallic spheres which they dubbed “disco balls” in an un-excavated portion of the tunnel, near pyrite mirrors. “I wish I could understand all the things these guys are finding down there,” Headrick said, “but it’s unique and that’s why it’s hard.”

Water was also precious to many of the people of Mesoamerica, who knew of underground water systems and lakes that could be accessed through caves. Teotihuacan once had springs as well, though they are now dried out.

Joyce said the ancient Mesoamericans could produce liquid mercury by heating mercury ore, known as cinnabar, which they also used for its blood-red pigment. The Maya used cinnabar to decorate jade objects and color the bodies of their royalty, for instance; the people of Teotihuacan – for whom archaeologists have not agreed on a name – have not left any obvious royal remains for study.

The discovery of a tomb could help solve the enigma of how Teotihuacan was ruled, and Joyce said that the concentration of artifacts outside the tunnel chambers could be associated with a tomb – or a set of ritual chambers.

A royal tomb could lend credence to the theory that the city, which flourished between 100-700AD, was ruled by dynasties in the manner of the Maya, though with far less obvious flair for self-glorification.

But a royal tomb cold also hold the remains of a lord, which may fit with a competing idea about the city. Linda Manzanilla, a Mexican archaeologist acclaimed by many of her peers, contends that the city was governed by four co-rulers and notes that the city lacks a palace or apparent depiction of kings on its many murals. The excavation by Gomez my find one of those co-rulers, under this hypothesis.

Headrick suggested yet more fluid models, in which strong lineages or clans traded rule but never cemented into dynasties, or in which the rulers relied on agreements with the military to maintain power, and authority was vested more in an office than a family. Ancient Teotihuacan was a city with familiar factions vying for influence: the elite, the military, the merchants, the priests and the people.

For now, the archaeologists and anthropologists continue digging and deducing. Gomez says he hopes excavation of the chambers to be complete by October, and Headrick said that archeologists are looking at the city from new angles. Some are trying to decipher the paintings and hieroglyphics around the city, others trying to parse what may be a writing system without verbs or syntax.

Then there are the thousands of artifacts, some unprecedented and bizarre, that Gomez and his fellows are disinterring from beneath the pyramid. “It’s quite the mystery,” Headrick said. “It’s fun.”

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Monday, 20 April 2015

Silver

Silver is a chemical element with symbol Ag (Greek: άργυρος árguros, Latin: argentum, both from the Indo-European root *h₂erǵ- for "grey" or "shining") and atomic number 47. 
A soft, white, lustrous transition metal, it possesses the highest electrical conductivity of any element, the highest thermal conductivity and reflectivity of any metal. The metal occurs naturally in its pure, free form (native silver), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining.

Silver has long been valued as a precious metal. More abundant than gold, silver metal has in many premodern monetary systems functioned as coinable specie, sometimes even alongside gold. In addition, silver has numerous applications beyond currency, such as in solar panels, water filtration, jewelry and ornaments, high-value tableware and utensils (hence the term silverware), and also as an investment in the forms ofcoins and bullion.

Silver is used industrially in electrical contacts and conductors, in specialized mirrors, window coatings and in catalysis of chemical reactions. Its compounds are used in photographic film and X-rays. Dilute silver nitrate solutions and other silver compounds are used as disinfectants and microbiocides (oligodynamic effect), added to bandages and wound-dressings, catheters and other medical instruments.

Electrolytically refined silver

Thursday, 9 April 2015

On this day


1959 - NASA selects first US astronauts.
 

 
On this day in 1959 NASA announced the selection of the first seven US astronauts.
These astronauts were selected for the Mercury program to test if humans could survive in space.
Mercury astronauts had to be male, less than 40 years old and not more than 5'11" tall, less than 180 lbs. and in excellent physical condition.
The seven astronauts selected were: Scott Carpenter, Gordon Cooper, John Glenn, Gus Grissom, Wally Schirra, Alan Shepard and Donald Slayton.
For more information visit:-

Friday, 3 April 2015

Stained and Coloured Glass

Stained glass can refer to coloured glass as a material or to works created from it - most commonly seen in the stained glass windows of churches and other buildings.  Coloured glass is also found in everyday life such as green wine bottles.



As a material stained glass is glass that has been coloured by adding metallic salts during its manufacture.

There are two main types of glass - soda lime glass - commonly used in beverage bottles and the like and borosilicate glass - used in laboratory glassware and also some domestic glassware such as oven proof dishes.

Coloured glass is made in a number of ways.  There are three main ways.

The first involves introducing metallic or rare earth metal oxides to the glass as mentioned above.

Silver compounds for example such as silver nitrate are used as stain applied to the surface of glass and fired on. They can produce a range of colours from orange-red to yellow. The way the glass is heated and cooled can significantly affect the colours produced by these compounds.

Another way is by formation of colloidal particles. This means particles of a substance are suspended throughout the glass. The particles scatter light of particular frequencies as it passes through the glass, causing colouration.

Gold gives a ruby red colour, and selenium gives a pink to intense red.

The final main way in which colour can be introduced is through the addition of already coloured particles to the glass. Examples of this type of colouration include milk glass and smoked glass; milk glass is achieved by adding tin oxide.

The infographic below from Compound Interest shows what chemicals are involved in the colour process.  Click for a larger image.


Click to enlarge
For more information visit:-
http://en.wikipedia.org/wiki/Stained_glass
http://www.compoundchem.com/2015/03/03/coloured-glass/