17 Sep 2019

Liquid: life-giver and life-taker

From Afternoons, 3:07 pm on 17 September 2019

Liquids – they can kill you, save your life, or combine to make the perfect cup of tea. British scientist Mark Miodownik has written a book extolling their dangers and delights: Liquid Rules.

Mark Midow

 Mark Miodownik  Photo: Supplied

Liquids seem easy to define – for example, the sea is obviously a liquid – but things start to get more complicated with peanut butter and jam, Miodownik tells Wallace Chapman on Afternoons.

no caption

Photo: Pic's Peanut Butter

"[Liquids] seem pretty solid, you're going to spread them with a knife, but ... one of the definitions of a liquid is that it can flow into a container and it will assume the shape of that container so liquids don't have a shape of their own. They're kind of constantly borrowing shapes from other things.

"Peanut butter falls into [the liquids] category, hence if you take peanut butter on a flight it will be confiscated."

The common belief that glass is also a liquid is not strictly correct, Miodownik says.

"There's been a big argument raging about this. So glass is an amorphous solid ... what that means is half of it has the atomic structure of a liquid ...  it's chaotic and random and that's why glass is so transparent in the first place, so it's a frozen liquid in its structure."

The 'flowing' effect on older panes of window glass – where the glass becomes thicker at the bottom – is probably more to do with how it was constructed, he says. 

"We don't think it's flowed in that time span. It would take geological time.

"[At the time these windows were made] they would cast glass. They would cast it onto a steel platen, they pour it out a bit like toffee, it would flow and become flat. But there would always be a bit of camber to it because the edges will be thinner than the middle where you poured it in. 

"People would orient the panes of glass because they thought the thick bit should be at the bottom because it'd be stronger."

Blood, milk and breathable liquids 

Blood is a fascinating fluid which has several different viscosities depending on how fast it is flowing.

In an age of space travel and near-instantaneous global communications, the life-sustaining abilities of blood are yet to be replicated, Miodownik says.

"If you're in any major operation, if you have any type of trauma, if you're not near blood banks you know, one of the ... very real risks to you dying is you're just going to have too much blood loss.

"We still haven't had a good scientist who’s managed to make a liquid as good as blood to replace it."

A bag of transfusion blood

Photo: 123RF

That hasn't stopped people trying, of course, and Miodownik details the long history of research into blood alternatives in his book. 

"[People were] trying to find other liquids that can do the same job – that can absorb oxygen, deliver it to ourselves, and take out carbon dioxide. 

"So what did they do? They picked liquids that they had readily available in the hope they would do the job – and milk was one of them.

"You’d try anything, wouldn't you – I mean, if you're about to die – and milk seems such a kind of vital fluid." 

Some liquids – such as fluorocarbons – have come close to being a successful replacement, Miodownik says.

“[Fluorocarbons] are very inert, they're kind of the liquid equivalent of Teflon, right, and nothing can react with them. That's one of the characteristics you might want when injecting something into your bloodstream.

“The other thing you want it to do is carry oxygen, and these liquids carry 20 percent of oxygen.

"In fact, [fluorocarbons] are so powerful on that front that in the early experiments with them people took rats and immersed them in this liquid – the rats could breathe in the liquid, that's how much oxygen the liquid has.

"This so-called 'liquid breathing' has been also tried on other animals, including humans.” 

Mercury: alchemy, magic and trickery

As a child, Miodownik was fascinated with the chemical element mercury and played with it – without realising its toxic effects. 

No caption

Photo: А [Public domain]

“Mercury is the only element … that's a liquid at room temperature that's a pure metal ... It's got that incredible, otherworld shininess to it. It's a sort of dripping, flowing substance, but yet it's perfectly mirrored and it never seems to be corrupted.

"Because it's liquid, it can dissolve other metals really quickly … Take small bits of gold ore and if you use mercury the mercury will dissolve gold out of it, and then you can evaporate the mercury by just heating it up – and what you get left with is a nugget of gold.

It’s hard to say whether it’s irony or 'mercurial greed', but those properties have meant mercury has long been considered somewhat magical.

It's likely the source of myths about alchemy – the practise of turning base metals into gold, Miodownik says.

“We're pretty sure that … this was a trick played on some people to make them believe that someone was able to [perform alchemy]. You can take mercury, kind of alloy it with zinc and it will become an amalgam, a paste, and you can heat it up and get this gold-like substance out of it.

“It had this magical status and I guess people thought because it was magical it could heal them. Kings would imbibe it.” 

We know now that imbibing mercury is not a great idea, because the gas it produces when evaporating is poisonous.

It also causes delirium, which is the source of the phrase 'mad as a hatter', he says.

"The hatters who made bowler hats, they made them by getting mercury and using mercury to make the bowl, so they'd pour this liquid in, in order to get this perfect bowl. So those people imbibed a lot of mercury fumes and they were known as kind odd characters – mad – hence the Mad Hatter in Alice in Wonderland."

Johnny Depp as The Mad Hatter in Alice Through the Looking Glass.

 Johnny Depp as The Mad Hatter in Alice Through the Looking Glass. Photo: Disney

Water: life, death and war

The most important liquid for humans is, of course, water.

It is a contradiction of violence and vitality because we cannot live without it and yet it is the cause of much destruction and conflict both directly and indirectly, Miodownik says.

“It really is this constant threat to our environment and will, you know, make things damp and mouldy and rotten, and we are constantly trying to fight it and keep it out and yet ... we are never going to win against water because it gets everywhere."  

It’s extraordinary that this liquid – which is usually so soft and fluid – can be so solid and forceful when an object falls on it from a great height, he says. 

“When you try and make water flow with a small force – with your hand, or kicking your feet – it will flow really quite easily. But if you try and make it flow very rapidly, very instantly – and that's of course what's happening when you're hitting the water at great speed – it has to move out of your way within milliseconds.  

“It actually can't do it faster, and what that does is it creates a force backwards on you, an opposite force. And that force will break your bones; it will shatter your skull; it will split you open.” 

The destructive power of water is a force to be reckoned with as climate change continues to affect the planet, Miodownik says.

“The melting of the Greenland ice sheet in the northern hemisphere, and the Antarctic one in the southern hemisphere is raising the sea levels … As those sea levels go up, each storm gets more and more destructive and that seems inevitable for the rest of the century that that's going to get worse and worse. 

“Another thing that water does is it goes into the atmosphere, and the warm air can take more water … that means that water then comes down as rain and that means that flooding will get more severe.”

Destruction on Great Abaco Island in the aftermath of Hurricane Dorian.

Hurricanes wrought destruction on the Bahamas this year.  Photo: AFP / UK MOD / Crown Copyright 2019

The increased energy in the atmosphere will also mean more storms – another destructive example of water’s Jekyll-and-Hyde nature.  

“It will just pick up a car, float it down. If you happen to be floating in it, if that car hits you, you'll be knocked out – soon as you’re knocked out you're going to be drowning.  

“The huge number of casualties that happen as soon as you're floating around in water, or a large amount of water hits you, is really extraordinary ... and yet this stuff is absolutely vital for life.” 

Humanity's need for water as a resource may lead to war within the next century, Miodownik says.

“If you have a whole country that becomes drought-ridden and the countries nearby it – where the rivers are emanating – refuse to share their water because they perhaps are also worried, what will that population do?” 

Closeup shot of a man pouring a glass of fresh water from a kitchen faucet

Photo: 123RF