Tag: metal

Posted in Science & Nature

Silver

Posted on by Jinavie

Historically, silver has been associated with cleansing, healing, the moon and warding off evil. For example, it is said that some monsters such as werewolves would only die if it is shot by a silver bullet. The Greek goddess of hunting and the moon, Artemis, carries a silver bow. Although it is always seconded to gold when it comes to precious metals, silver is a fascinating metal.

It is the most reflective metal on Earth and has the highest conductivity for heat and electricity. It is ductile and malleable, making it a good choice of metal for making coins, jewellery and silverware (hence the name). Because of how reflective it is, it is also used in solar panels and special mirrors, such as those in telescopes.

Another useful characteristic of silver is its chemical reactivity. Thanks to this property, silver forms many different compounds with varying applications. Silver halides are photosensitive and turn dark when they are exposed to light. This is the basis of film photography, where the light shone on a film coated with silver halides leaves a photographic imprint. Silver oxides are sometimes used in batteries and silver/mercury alloys are used for dental fillings.

Silver also plays a role in medicine. Silver ions have been shown to inactivate bacteria such as E. coli, making silver nanoparticles a useful antiseptic that can be impregnated into different materials such as wound dressings. Silver nitrate sticks are used in emergency departments as applying it to a bleeding vessel in the nose will release nitric acid, which cauterises (burns off) the vessel to stop a nosebleed. In medieval Korea, silver spoons were used to test if a food has been poisoned with arsenic, as arsenic reacts with silver to form a black tarnish. If a person has too much silver build-up in their body, they can develop argyria (silver poisoning), which turns the skin an eerie bluish-grey colour.

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Posted in History & Literature

Sweat Like A Pig

Posted on by Jinavie

The English idiom to describe profuse sweating is sweating like a pig. However, pigs lack the ability to sweat properly due to ineffective sweat glands, which is why they roll in mud to cool their bodies. The idiom is not wrong though, as it is not referring to the animal, but pig iron.

When refining iron, the iron ore is smelted in a furnace until it is liquid. As the liquid metal is extremely hot, it is poured into a mould where it can cool. The iron was set in a branching mould that apparently resemble many piglets suckling from a mother sow – hence the name: pig iron.

Back in the old days when technology was not as advanced, it was difficult to tell when the pig iron was cool enough to transport safely. This is where science came in handy. As the metal cools, the surrounding air reaches a dew point, causing droplets of water to form on the pig iron as condensation. The condensation made it look like the pig iron was “sweating”, hence the idiom. When the pig iron sweats, it is a sign that is cool enough to be moved safely without spilling and burning everything around it.

Posted in Science & Nature

Lava

Posted on by Jinavie

Death by lava is an often-used trope in films, most likely because of its slow, dramatic nature and the poetic beauty of being engulfed by liquid fire. But unfortunately as with so many things in the film world, most movie scenes depicting a person slowly sinking into lava until they are completely submerged is completely unscientific.

Lava is essentially molten rock. Just as ice and rock have different densities (try smashing two together for comparison), water and lava have completely different densities. In fact, lava is just over three times denser than water and somewhere between 100,000 to 1,000,000 times thicker (viscosity). The extremely high viscosity is why lava does not flow well, much like thick syrup and pitch. Density matters because less dense objects float when placed in a denser substance. Human beings are slightly denser than water (1010kg/m³ vs 1000kg/m³), meaning we can float if we have enough air in our lungs to provide the buoyancy. However, we are far less dense than molten lava. Even if we were as dense as lava, the extreme viscosity would make it very difficult for us to sink as the lava would not flow away from you that quickly. Ergo, if you were thrown into a pool of lava, you would not sink into a dramatic death.

Instead, you would most likely experience an even more horrific death as you stay afloat on the lava, as the surface of your body touching the lava is burned. Typical lava is between 1100~1200°C – well beyond the ignition point of human flesh. Not only will the skin, fat and muscle melt and peel away, but it will light up like a wick. The flame will soon cover the entire person and they will not only burn, but combust. Ultimately, only ash and completely dried up bone will be left floating on the lava, which will also end up igniting eventually.

Unfortunately, objects made of material such as steel and most other metals are denser than lava. This means that the Terminator would actually sink as dramatically as it did in the ending of Terminator 2 if he were to descend into a pool of lava.

(NB: It is important to note that in the movie, he descends into a vat of molten steel, not lava. Therefore, the accuracy of that scene hinges on whether the Terminator is made of a metal alloy denser than molten steel)

Posted in Science & Nature

Metal

Posted on by Jinavie

Next to the discovery of fire and the wheel, the discovery of metals and the mastery of metalworking was arguably one of the most important advances for prehistoric humanity. Metal was far superior to rock, clay, wood or any other natural resource known to man in terms of strength and sharpness. Because of these properties, metal soon became a valuable commodity. It can be seen how much impact metal had on humanity’s history, considering that the stages of human prehistory were named after the type of metal (or lack thereof) that was mastered then: Stone Age, Bronze Age and Iron Age.

The discovery of metal came in two ways.

One was through mining, where prehistoric people discovered that shiny, hard objects were buried in the ground. They later discovered that with enough heat, they could melt the metal out of ores (copper and tin were the first metals to be gathered this way) and mould them into any shape. After smelting technologies developed, our ancestors found that mixing copper and tin produced bronze – a much stiffer and more durable metal than either of its components. A mixture of metals is called an alloy. This was the start of the Bronze Age. Bronze was extremely useful and people quickly came up with innovative ways of using it, such as farming equipment and weapons.

Some other metals used during this age were: gold, silver, lead and mercury. It is likely that gold was one of the earliest metals used as it comes in pure nuggets and is easily workable thanks to its chemistry. However, given that gold is rather soft and was treated more as jewellery than a practical metal, it was not used as much to advance technology.

The second way mankind came upon metals was in the form of “gifts from the gods”. A prime example is iron. Although the Iron Age began around 1200BC at the earliest, there are iron objects (mainly jewelleries) that have been dated back to 5000BC. How could this be? This was before mankind had the technology to smelt iron ores (which is more difficult and needs much higher temperatures than copper or tin ores), so the iron could not have been gathered through mining. The answer to this conundrum lies in meteorites. About 6% of meteorites contain iron and nickel, which prehistoric civilisations may have stumbled onto and taken the shiny pieces back to their tribe. The people would have considered the gathered iron a “gift from the gods”, as it had crashed down from the “heavens”. Because of this reason, iron was considered more valuable than gold or silver and was frequently used for jewellery. This is reflected in Arthur C. Clarke’s science fiction short story, The Songs of Distant Earth, where sentient sea scorpions hoard metal objects stolen from the humans and wear it proudly as a badge of honour.

The history of iron and how it was believed to be a gift from the heavens relates to a common superstition of how finding a penny (or any coin) represents good luck. As “metal” (mainly iron) was considered a holy gift bestowed unto mankind, finding a piece of metal was believed to be a blessing and some form of protection against evil. This is also represented in various traditions such as hanging horseshoes over doorways and wearing charm bracelets with metal on it.

Although it sounds like a silly superstition, it clearly shows how metals have been an integral part of the development of civilisation.

Posted in Psychology & Medicine

Pica

Posted on by Jinavie

Occasionally, there are news stories about a man who eats steel or a girl who likes to eat plastic. Such a condition where the person develops an appetite for a non-food substance is called pica. Pica is more common than one would think. The most common cases are those of dirt, clay and chalk, with the disorder being much more prevalent in children or pregnant women. Although pica is officially a mental disorder (possibly related to OCD), it is possible that it is a neurological mechanism to cure a certain mineral deficiency. For example, patients with coeliac diseases or hookworm infections tend to be iron-deficient and the substances they eat tend to contain iron. It is unclear how the brain knows what “food” to eat to cure a disease, but there are many cases where people subconsciously consume foods that would improve their health. According to a study, between 8% and 65% of people have had a sudden urge for a very strange appetite. However, as substances commonly involved in pica (such as dirt and ice) are solids, they can damage the oesophagus and the digestive tract. Also, they may contain toxic chemicals which can cause poisonings, making pica a potentially dangerous condition.

Posted in History & Literature

Elements: Wu Xing Of The East

Posted on by Jinavie

In ancient China and Korea, there are five, not four, basic elements (Japan also has five but they are slightly different). In the East, these five elements are called “oh hang (오행, 五行)” in Korean and “wu xing” in China. These are (read in Korean): hwa (火, fire), su (水, water), mok (木, wood), geum (金, metal), and toh (土, earth). When you combined with the theory of Yin and Yang, the concept is known as the Yin-Yang and the Five Elements theory (eum yang oh hang sul, 음양오행설). Wu Xing is quite different from the Four Elements of ancient Greece in that it explains the changes in life and the universe rather than being the building blocks of matter (“wu xing” translates to “five ways”). To first understand Wu Xing, one must understand that each element is more of an abstract concept than the actual object. For example, “mok” does not mean wood per se, but rather a symbol for the life force of a growing tree.

There are two relationships between the elements in Wu Xing: Creation (상생, 相生) and Destruction (상극, 相剋). Creation refers to the cyclic principle of what generates what, and Destruction refers to what overcomes and represses what. The Creation and Destruction of Wu Xing are as follows:

  • 목생화(木生火): Wood creates Fire. Wood feeds Fire.
  • 화생토(火生土): Fire creates Earth. Fire makes ash which becomes Earth.
  • 토생금(土生金): Earth creates Metal. Earth bears Metal.
  • 금생수(金生水): Metal creates Water. Metal carries Water.
  • 수생목(水生木): Water creates Wood. Water nourishes Wood.
  • 목극토(木剋土): Wood beats Earth. Wood takes roots in Earth.
  • 토극수(土剋水): Earth beats Water. Earth absorbs Water.
  • 수극화(水剋火): Water beats Fire. Water quenches Fire.
  • 화극금(火剋金): Fire beats Metal.  Fire melts Metal.
  • 금극목(金剋木): Metal beats Wood. Metal chops Wood.

(Image source: http://cadfluence.deviantart.com/)

Posted in Science & Nature

Microwave

Posted on by Jinavie

The following are some strange things that happen when certain objects are placed in a microwave (and then turned on).

  • Never put metallic objects in a microwave. Metals act as an antenna, collecting the microwave and creating an electric current. This causes the metal to heat up, burning the food or melting plastic containers. Also, if the metal is pointy, it may cause an electric arc (sparks) which can be very dangerous. 
  • Ice alone does not melt in a microwave. This is because microwaves cause vibrations of particles to generate heat, but in ice the water molecules are tightly bonded and so vibration does not occur. 
  • Microwaves can cause something called superheating of liquids. This means that the liquid is heated to beyond its boiling temperature without boiling. A superheated liquid can spontaneously begin to boil in an explosive manner when disturbed. This is dangerous as it can mean that a cup of boiling hot water may suddenly explode in your face.
  • Certain foods are known to generate sparks in a microwave. For example, when two oblique slices of chilli pepper are placed near each other point-to-point, a flame sparks between the two points from the arcing electricity. Grapes do the same thing.
  • Some foods such as grapes and eggs explode in a microwave. This is because of the pressure building up within it from all the steam being released all at once. This is amplified with something like an ostrich egg where the shell is strong enough to contain an immense pressure. But when a certain pressure is reached, the egg will literally explode and send shrapnels of microwave pieces flying out like a bombshell.
  • A piece of garlic will spin rapidly in a microwave as garlic has a thin tube running on one side. As water evaporates, the vapours rush towards both ends causing the garlic to spin. Also, if you cut the bottom of a clove of garlic then microwave it for about 15 seconds, the pieces of garlic will pop out easily.
  • As explained above, metal conducts microwaves and generates a current. This is most obvious when a CD is placed in a microwave, where sparks dance on the surface (assuming the reflective surface is facing up). Similarly, a fluorescent tube will light up in a microwave from the electricity generated.
  • Placing an open flame, such as a lit candle, inside a microwave produces a very strange phenomenon. The naked flame will become ionised plasma and shoot up to the ceiling of the microwave. This is observed as a ball of light floating around. Note that this is extremely dangerous and most likely will destroy the microwave.

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Posted in History & Literature

Printing

Posted on by Jinavie

Most Westerners are familiar with Johannes Gutenberg, who invented the printing press in 1450 which allowed the mass-production of books, namely the bible. In fact, the printing press is thought of as one of the crucial factors that triggered the Renaissance in Europe.
However, what most people do not know is that the movable type – a printing machine where individual letters can be rearranged and reused – was invented in Korea during the Goryeo Dynasty two centuries before Gutenberg.

Before the movable type, Buddhist monks would carve out wooden blocks so that they could copy out religious texts with ease. But as this involved the monks having to carve out the entire text (often very long), it was extremely labour-intensive and everyone sought an easier method of mass-producing texts. The concept of the movable type was experimented with throughout the centuries, but it was found that woodblocks would wear out too fast. Although metal was the obvious choice, the technology was not developed enough to produce the fine letters.

In 1234, a Korean man called Choe Yun-ui finally devised the technology to invent the first metal movable type in the world. The process was very complicated, involving the making of durable clay moulds to hold the molten metal without breaking.
This was revolutionary as it meant that texts could easily be printed as all the printers had to do was rearrange pre-made letters in order rather than laboriously carving each one out. Metal movable types are also extremely durable and give a very clean print, unlike the wooden counterpart that tends to wear out or smudge. The metal movable type allowed for the mass-production of books which greatly boosted Goryeo’s culture and education within the poorer classes.

Korea was the leading innovator in the printing industry throughout history, with the earliest woodblock prints dating back to 751. The motivation to develop this technology was partly thanks to Buddhism. To ensure that Buddha’s teachings could be spread far and wide, Buddhist monks worked day and night to produce these texts. This was a critical job during the 13th century when the Mongol Empire was rampaging through the whole of Eurasia. As military force was insufficient to repel the invaders, the people turned to spirituality for power. Furthermore, due to the destructive nature of the Mongols, it was crucial to replace damaged texts to ensure that precious cultural heritages would not be destroyed. This was the main motivation for the creation of the metal movable type and to this day we can see the evidence of the state-of-the-art printing device in books from the 13th and 14th century.

One limitation still remained with the movable type – Chinese characters. At the time, Korea still used Chinese characters to record the Korean language (similar to how Chinese characters can be transcribed in pinyin form). As there are literally tens of thousands of characters, a massive amount of individual types had to be produced.
This problem was solved by King Sejong the Great of the Joseon Dynasty, who invented Hangul – the Korean alphabet. Hangul only contains 24 letters and is extremely logical in its construction, ergo it was a perfect system for recording language. It also meant that much less individual types were needed, making the printing process even more efficient.

Although the 20th and 21st century saw the Western Hemisphere leading science and technology innovations, it is important to remember that the East dominated the field for millennia before.