How Cold Is It in Canada? Niagara Falls Has Frozen Over – Mental Floss

Subtle silver gets pushed aside next to gold, but in many ways it outranks its lustrous competition. The cool-toned element is more conductive and more reflective, and boasts properties absent in other metals, like a reaction with light that put the “silver” in “silver screen.” Read on for more.

1. HUMAN USE OF SILVER DATES BACK TO 3000 BCE.

Archeological records show humans have mined and used silver (or Ag, number 47 on the periodic table) for at least 5000 years. Silver shows up in slag heaps at ancient mines in Turkey and Greece, as well as in deposits in China, Korea, Japan, and South America. Its visible shine made it popular in jewelry, decorative objects, and practical tools like the aptly named silverware. Its rarity gave it high value. Silver coins are credited with fueling the rise of classical Athens, and Vikings used “hacksilver”—chunks of silver bullion chopped off a larger block of the metal—as money.

2. SOME INDIGENOUS CULTURES WERE EXPERTS AT SILVERSMITHING.

As a soft, pliable metal, silver is easily smelted, but the process still requires moderate heat. Metal workers in the precolonial Americas didn’t have bellows to pump oxygen to a fire; instead, several people would encircle the fire and blow on it through tubes to increase its intensity. The Inca of the Andes became expert silversmiths. They believed gold was the sweat of the sun, and silver came from the tears of the moon.

3. SILVER CONDUCTS ELECTRICITY BETTER THAN ANY OTHER METAL.

Of all metals, silver is the best conductor of heat and electricity, so it can be used in a wide variety of applications. Metal solder, electrical parts, printed circuit boards, and batteries have all be made with silver. But it’s expensive: In electrical wiring, copper is often used instead.

4. ITS REACTIVITY TO LIGHT MADE EARLY PHOTOGRAPHY POSSIBLE.

In the 1720s, German physicist Johann Heinrich Schulze produced the first images with silver. Having discovered that a piece of chalk dipped in silver nitrate would turn black when exposed to sunlight, Schulze affixed stencils to a glass jar filled with a mix of chalk and silver nitrate. When he brought the jar into the sun, the light “printed” the stencil letters onto the chalk. A century later, Louis-Jacques-Mandé Daguerre created photographic prints on silver-coated copper plates. At the same time, British chemist William Henry Fox Talbot devised a method for developing an exposed image on silver iodide-coated paper with gallic acid.

“The effect was seen as magical, a devilish art. But this mystical development of an invisible picture was a simple reduction reaction,” science reporter Victoria Gill explains on the Royal Society of Chemistry’s podcast Chemistry in its Element. “Hollywood could never have existed without the chemical reaction that gave celluloid film its ability to capture the stars and bring them to the aptly dubbed silver screen.” Silver salts are still used in rendering high-quality images.

5. THAT SAME REACTIVITY CAN ALSO CAUSE TARNISH.

Silver reacts with sulfur in the air, which forms a layer of tarnish that can darken or change the color of a silver object. The tarnish interferes with how silver reflects light, often turning the object black, gray, or a mix of purple, orange, and red. An at-home experiment can demonstrate the process: Put a shelled and quartered hard-boiled egg (preferably still warm) in the same container as a silver object, like a spoon, and seal the container closed. The tarnish should appear within an hour, thanks to the egg’s release of hydrogen sulfide gas, and grow darker as time goes on.

6. RESEARCHERS ARE STILL EXPLORING SILVER’S ANTIMICROBIAL PROPERTIES.

According to a 2009 review, silver was one of the most important anti-microbial tools in use before the discovery of modern antibiotics in the 1940s. The ancient Macedonians were likely the first to apply silver plates to surgical wounds, while doctors in World War I used silver to prevent infections when suturing battlefield injuries. Silver is toxic to bacteria, but not to humans—unless it’s consumed in large quantities. Ingesting too much silver can cause argyria, a condition where the skin permanently turns gray or blue due to silver’s reactivity with light.

A 2013 study in Science Transitional Medicine looked into the mechanisms behind silver’s anti-microbial powers. The findings suggested that silver makes bacterial cells more permeable and interferes with their metabolism. When antibiotics were administered with a small amount of silver, the drugs killed between 10 and 1000 times more bacteria than without it. “It’s not so much a silver bullet; more a silver spoon to help [bacteria] take their medicine,” lead researcher James Collins, a biomedical engineer at Boston University, told Nature.

7. SILVER IODIDE HELPS MAKE IT RAIN.

When regions need rain after a prolonged drought, scientists can “seed” clouds by spraying silver iodide particles into the atmosphere. In the 1940s, Bernard Vonnegut (brother of the author Kurt Vonnegut) demonstrated in a lab that silver iodide provides a scaffold on which water molecules can freeze, which (theoretically) would lead to precipitation in the form of snowflakes. In a 2018 study, researchers from the University of Colorado in Boulder and other institutions demonstrated the process in actual clouds. The team sent out two planes; one to spray silver iodide and the other to track its course and measure how water responded. The second plane recorded a zigzagged line of water particles freezing in the same flight path as the plane spraying silver, confirming silver iodide’s role in cloud seeding.

Bernard Vonnegut had made his discovery while he and his brother both worked for General Electric in Schenectady, New York. The two discussed the idea of water stabilized as ice at room temperature—a concept that Kurt Vonnegut went on to explore as ice-nine in his novel Cat’s Cradle.

8. SILVER IS RESPONSIBLE FOR A LOT OF GHOST TOWNS.

The United States established a “bimetallic” currency during George Washington’s presidency. The policy required the federal government to purchase millions of ounces of silver each year to mint coins or set the value of paper currency. Government demand for silver contributed to the boom of Western mining towns in the mid-19th century, encouraged by the 1890 Sherman Silver Purchase Act, which increased the federal purchase of silver.

But falling values in relation to gold eventually led to the repeal of the Sherman act, and the price of silver crashed. The mining settlements shrank from hundreds of residents to just a handful—and some were completely abandoned. Ghost towns (or minimally populated near-ghost towns) with names like Bullionville, El Dorado, Potosi, and Midas can still can be explored in Nevada, the Silver State.

Source: http://mentalfloss.com/article/571434/how-cold-it-canada-niagara-falls-has-frozen-over

Comments