Feet of clay? The science of statues

Concept art for the Terry Pratchett statue (c) Paul Kidby

Concept art for the Terry Pratchett statue (c) Paul Kidby

Yesterday we received the exciting news that a statue to commemorate Sir Terry Pratchett and his work has been approved by Salisbury City Council. Hurrah! So, even if we don’t quite manage to get octarine into the periodic table (and thus into every science textbook for ever more), it’s looking very likely that there will still be something permanent to help keep his memory alive.

But this got me thinking about everyday chemistry (who am I kidding, I’m always thinking about everyday chemistry!) and, in particular, bronze – the material from which the statue will be made.

Bronze, I hear you say, what’s that good for apart from, well, statues? And maybe bells? Is it really that interesting?

Well, let’s see. Bronze is an alloy. Alloys are mixtures that contain at least one metal, but they’re stranger than the word ‘mixture’ might perhaps suggest. Imagine combining, say, sand and stones. You still be able to see the sand. You could see the stones. You could, if you could be bothered to do it, separate them out again. And you’d expect the mixture to behave like, well, stony sand.

Alloys aren’t like this. Alloys (other well-known examples include steel, brass and that silver-coloured stuff dentists use for filling teeth) look, on all but the atomic level, like pure metals. They’re bendy and shiny, they make pleasing ringing sounds when you hit them and they’re good electrical conductors. And unlike more simple mixtures, they’re difficult (though not impossible) to separate back into their constituents.

Perhaps the most interesting this about alloys is that their properties are often very different to any of the elements that went into making them. Bronze, in particular, is harder than either tin or copper, and hence The Bronze Age is so historically significant. Copper is one of the few metals that can (just about) be found in its pure form, and so is one of the oldest elements we know, going back at least as far as 9000 BC. But while quite pretty to look at, copper isn’t ideal for making tools, being fairly soft and not great at keeping an edge. Bronze, on the other hand, is much more durable, and was therefore a much better choice for for building materials, armour and, of course, weapons. (War, what is it good for? Er, the development of new materials?)

Hephaestus was the God of fire and metalworking; according to legend he was lame.

Hephaestus was the God of metalworking. According to legend he was lame, could it have been because of exposure to arsenic fumes?

Today we (well, chemists anyway) think of bronze as being an alloy of tin and copper, but the earliest bronzes were made with arsenic, copper ores often being naturally contaminated with this element. Arsenical bronzes can be work-hardened, and the arsenic could, if the quantities were right, also produce a pleasing a silvery sheen on the finished object. Unfortunately, arsenic vaporises at below the melting point of bronze, producing poisonous fumes which attacked eyes, lungs and skin. We know now that it also causes peripheral neuropathy, which might be behind the historical legends of lame smiths, for example Hephaestus, the Greek God of smiths. Interestingly, the Greeks frequently placed small dwarf-like statues of Hephaestus near their hearths, and this is might be where the idea of dwarves as blacksmiths and metalworkers originates.

Tin bronze required a little more know-how (not to mention trade negotiations) than arsenical bronze, since tin very rarely turns up mixed with copper in nature. But it had several advantages. The tin fumes weren’t toxic and, if you knew what you were doing, the alloying process could be more easily controlled. The resulting alloy was also stronger and easier to cast.

teaspoon in mugOf course, as we all know, bronze ultimately gave way to iron. Bronze is actually harder than wrought iron, but iron was considerably easier to find and simpler to process into useful metal. Steel, which came later, ultimately combined superior strength with a relatively lower cost and, in the early 20th century, corrosion resistance. And that’s why the teaspoon sitting in my mug is made of stainless steel and not some other metal.

Bronze has a relatively limited number of uses today, being a heavy and expensive metal, but it is still used to make statues, where heaviness and costliness aren’t necessarily bad things (unless, of course, someone pinches the statue and melts it down – an unfortunately common occurrence with ancient works). It has the advantages of being ductile and extremely corrosion resistant; ideal for something that’s going to sit outside in all weathers. A little black copper oxide will form on its surface over time, and eventually green copper carbonate, but this is superficial and it’s a really long time before any fine details are lost. In addition, bronze’s hardness and ductility means that any pointy bits probably won’t snap off under the weight of the two-millionth pigeon.

So how are bronze statues made? For this I asked Paul Kidby, who designed the concept art for the statue. He told me that he sculpts in Chavant, which is an oil-based clay. It’s lighter than normal clay and, crucially, resists shrinking and cracking. He then sends his finished work away to be cast in bronze at a UK foundry, where they make a mould of his statue and from that, ultimately (skipping over multiple steps), a bronze copy. Bronze has another nifty property, in that it expands slightly just before it sets. This means it fills the finest details of moulds which produces a very precise finish. Conveniently, the metal shrinks again as it cools, making the mould easy to remove.

And just for completeness, Paul also told me that the base of the statue will most likely be polished granite, water jet cut with the design of the Discworld sitting on the back of Great A’Tuin. I can just imagine it – it’s going to be beautiful.

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Name element 117 Octarine, in honour of Terry Pratchett’s Discworld

Sign the petition to name element 117 Octarine

UPDATE: Nature Chemistry have recently released a list of odds for the suggested new element names. Octarine is 1,000,000:1. And since, as we know: “Magicians have calculated that million-to-one chances crop up nine times out of ten,” that makes it practically a dead cert!

octarine

Octarine can famously only be seen by wizards (and witches) and cats and perhaps, now, some scientists. (Image: Discworld.com)

As you will have heard, the periodic table’s seventh row has finally been filled as four new elements have been added. Atomic numbers 115, 117 and 118 have been credited to the Joint Institute for Nuclear Research in Dubna and the Lawrence Livermore National Laboratory in California. Element 113 has been credited to a team of scientists from the Riken institute in Japan.

Period 7 is finally filled (image credit, IUPAC)

Period 7 is finally filled (image credit: IUPAC)

These elements were discovered a little while ago, but the International Union of Pure and Applied Chemistry (IUPAC) – who’s in charge of such things – have only recently verified these discoveries and asked the scientists responsible to suggest names to replace their existing temporary names of ununtrium, ununpentium, ununseptium and ununoctium.

IUPAC does have rules about naming. Namely: “Elements can be named after a mythological concept, a mineral, a place or country, a property or a scientist.”

Now, mythological concept… that might be a bit flexible, mightn’t it? What’s the definition of mythology? Well, according to dictionary.com, it’s: “a body of myths, as that of a particular people or that relating to a particular person.” And the definition of myth is “a traditional or legendary story, usually concerning some being or hero or event, with or without a determinable basis of fact or a natural explanation, especially one that is concerned with deities or demigods and explains some practice, rite, or phenomenon of nature.

I can work with that!

Terry Pratchett Terry Pratchett at home near Salisbury, Wiltshire, Britain - 04 Jun 2008

The late Sir Terry Pratchett at home near Salisbury, Wiltshire, Britain – 04 Jun 2008
(Image Credit: Photo by Adrian Sherratt/REX, (770612f), via theguardian.com)

So I propose that element 117, falling as it does in group 17 (the halogens), be named octarine, in honour of the late, great, Terry Pratchett and his phenomenally successful Discworld books. I’m also proposing the symbol Oc (pronounced, of course, as ‘ook’*).

As a halogen, 117 ought to have an ‘ine’ ending, so octarine makes perfect sense. Over 70 million Pratchett books have been sold worldwide, in 37 different languages, and lots of them concern heroes, gods and monsters. Ok, they’re not quite as old as the Greek myths, but they will be one day, right? Time is relative and all that.

Octarine, in the Discworld books, is known as ‘the colour of magic’, which also forms the title of Pratchett’s first ever Discworld book. According to Disc mythology (see, mythology), octarine is visible only to wizards and cats, and is generally described as a sort of greenish-yellow purple colour. Something that’s difficult to find and hard to observe; what could be more perfect?

So pop along and sign my petition. Maybe the Russian and American scientists are Discworld fans? You never know. If nothing else I’m absolutely certain that Sir Terry, the author of the Science of the Discworld series of books, would have a little chuckle at the idea.

“It is well known that a vital ingredient of success is not knowing that what you’re attempting can’t be done” — Terry Pratchett

* with thanks to Tom Willoughby for the pronunciation suggestion).

EDIT:

Since I started this, one or two devoted Discworld fans have commented that I should have suggested that element 118 be named octiron instead. This is because in Discworld the number 8 has special significance, and also because octiron is the metal which is the source of magical energy, and hence leads to octarine, which is just the colour of magic.

But I’m sticking with 117 and octarine. The greenish-yellow purple description seems perfect for a new halogen, and the ‘ine’ ending is just right for group 17. Although octiron also has the right ending for group 18 (‘on’), it doesn’t quite fit since it’s a metal and group 18 is technically made up of noble gases (admittedly, when you’ve only got a couple of atoms of a thing, metal vs. noble gas might be a bit irrelevant). Plus, the fact that octarine is ‘the colour of magic’ makes it seem like a more fitting tribute, this being, as I mentioned above, the title of Terry Pratchett’s first ever Discworld book.

It’s possible I’ve spent a little too long thinking about this…

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The 2015 Chronicle Flask Christmas Quiz!

Christmas preparations are well underway by now, but have you been paying attention to your chemistry? Of course you have! Well, let’s see… (answers at the bottom, this is a low-tech quiz).

  1. Let’s start with an easy one. In the nativity, the three wise men allegedly turned up at the stable with three pressies for little Jesus. But which chemical symbol could represent one of the gifts?
    a) Ag
    b) Au
    c) Al
    wisemen
  2. On the topic of chemical symbols, which christmassy word can you make out of these elements?
    carbon, radium, carbon (again), potassium, erbium, sulfur

    PT

  3. It doesn’t look like snow is very likely in most of England this year, but we can dream. And while we’re dreaming: why do snowflakes always have six sides?
    a) because water has three atoms and they join up to make six.
    b) it’s usually something do with hydrogen bonding.
    c) they don’t, it’s a myth.

    snowflakes_PNG7535

  4. Where would you be most likely to find this molecule at Christmas?
    a) In the Christmas cookies.
    b) In the festive stilton.
    c) In the Christmas turkey.
    cinnamaldehyde
  5. Mmm Christmas cookies! But which other chemical substance is often added to cakes and biscuits to help them rise?
    a) sodium carbonate.
    b) sodium hydrogen carbonate.
    b) calcium carbonate.

    christmas-cookies-wallpapers-hd-desktop-wallpaper-christmas-cookie-desktopchristmas-cookies-clip-easy-sugar-tree-cute-ideas-very-best-candy-recipes-with-pictures-martha-stewart-wallpapers-hd-desktop

  6. Let’s think about the booze for a moment. Which fact is true about red wine?
    a) It tastes significantly different to white wine.
    b) Mixing it with other drinks will make your hangover worse.
    c) It’s mostly water.
    red-wine
  7. And why are beer bottles usually brown or green?
    a) Because these colours block blue light.
    b) Because in the old days beer was often a funny colour, and the coloured glass disguised it.
    c) Because it’s good luck.
    beer-bottles
  8. Where would you be most likely to find this molecule at Christmas?
    a) In the Christmas cake
    b) In the mulled wine
    c) In the wrapping paper

    Cellulose

  9. Let’s turn to New Year for a moment. What makes party poppers go pop?
    a) Gunpowder
    b) Silver fulminate
    c) Armstrong’s mixture

    Party_poppers

  10. And who doesn’t love a firework or two? So, which substance is used to produce a blue colour?
    a) Sodium bicarbonate
    b) Copper chloride
    c) Magnesium powder

    blue fireworks

ANSWERS

  1. b) Au – gold
  2. CRaCKErS!
  3. b) – hydrogen bonds form between the oxygen atom of one water molecule and the hydrogen atom of another molecule, causing the molecules to link up into hexagon shapes (pretty much any question to do with water can be answered with ‘something to do with hydrogen bonding’).
  4. a) – in the cookies, it’s cinnamaldehyde, which is the molecule that gives cinnamon it’s flavour and smell.
  5. b) – sodium hydrogen carbonate, also known as sodium bicarbonate, or just ‘bicarb’, breaks down when heated and forms carbon dioxide. It’s the formation of this gas which causes mixtures to rise.
  6. c) – the flavour and colour components of wine only make up about 2% of its volume. If we assume 12% alcohol, then the wine is 86% water. Still, probably best not to glug on a wine bottle after your morning run. On the other two points, there isn’t much evidence that mixing drinks makes hangovers worse (unless, as a result, you drink more alcohol), although some specific types of drinks may cause worse symptoms than others. As for taste, in this paper researchers describe an experiment where they gave 54 tasters white wine dyed red with food colouring. The tasters then went on to describe it as a red wine, suggesting that appearance was much more important than actual taste.
  7. a) – the coloured glass used in beer bottles is there to block blue light. These wavelengths can cause some of the substances in beer to react with each other, resulting in unpleasant flavours.
  8. c) – in the wrapping paper. It’s cellulose, the main constituent of paper.
  9. c) – It’s usually Armstrong’s mixture in party poppers, which is a highly sensitive primary explosive containing red phosphorous (eek). Did I trick any of the chemists out there? Silver fulminate is used in Christmas crackers.
  10. b) – Copper chloride, and also copper oxide and copper carbonate when combined with other things. Sodium bicarbonate produces yellow, and magnesium is white.

How many did you get right? Tell me in the comments, or pop along to The Chronicle Flask’s Facebook page and brag there. Merry Christmas!

Elements, compounds and misleading mercury

Elemental mercury isn't the same as mercury in compounds.

Elemental mercury isn’t the same as mercury in compounds.

Today I read an interesting article about some recent research carried out at the University of Illinois where they demonstrated that the best way to convince parents to vaccinate their children might be to show them the results of the diseases the vaccines prevent. (This, by the way, contradicts some research published in 2014 which showed that this tactic didn’t work. For an excellent discussion of the two, see here.)

Then, because I am just one of those people who can’t resist poking at ulcers with my tongue (you know what I mean) I had a quick look at some of the comments regarding that article. Reassuringly, most people were weighing in on the “yeah, vaccinate!” side of the argument. But not surprisingly there was also a small group of people posting the traditional anti-vaccine arguments. And then, this appeared:

mercury ppm

This is thoroughly silly, and I’ll tell you why.

Well, it did make be go “hmmmmm”, but for the reason you might imagine.

No, you see, what I thought was: “hmmmmm, someone else who has, possibly deliberately, failed to understood the difference between elements and compounds, and how chemical bonding changes properties.”

Allow me to start at the beginning. If you went to a school in the UK (and I would hope it’s similar elsewhere in the world) you learned about elements, compounds and mixtures when you were about 13 years old – if not before. You might have forgotten it since, but I can absolutely, categorically guarantee you that lesson happened. In fact, it was probably a few lessons.

iron sulfide experiment

The much-loved reaction between iron and sulfur.

One experiment much beloved of chemistry teachers since year dot is to take a mixture of sulfur (a yellow powder) and some iron filings (grey) and show that they can be separated with a magnet. Then heat the mixture up so that the two react, with a rather beautiful red glow, to form iron sulfide. This is a blackish solid which is in theory not magnetic (but in practice almost always is) and demonstrate that now the two elements cannot be separated.

Thus we have demonstrated that elements (the iron and the sulfur) have different properties to the compound they formed (iron sulfide), and also that mixtures can be separated fairly easily, whereas breaking compounds up into their constituent elements is much harder. Lovely. Job done.

And yet… so many people seem to have been asleep that day. Or perhaps just didn’t grasp it well enough to continue to apply the principle to other things.

pouring mercury

Elemental mercury

For example, mercury. Mercury, the element (the runny, silvery stuff that you used to find in thermometers) is a heavy metal. Like most of its compatriots, such as cadmium, lead and arsenic, it’s toxic. It can be absorbed through the skin and mercury vapour can be inhaled, so containers need to be tightly sealed. The increasing awareness of the toxicity of mercury is why older readers might remember seeing it ‘in the flesh’, so to speak, at school, whereas younger ones will not – these days it’s rarely even used in thermometers for fear of breakages.

That said, it does occur naturally in the environment, particularly as the result of volcanic eruptions – and very low levels aren’t considered harmful. The dose, as they say, makes the poison. It also occurs as the result of industrial processes, particularly coal-fired power plants and gold production, and occupational exposure is a genuine concern. In particular, chronic exposure is known to cause cogitative impairment. It might the source of the ‘mad dentist’ myth. It’s almost certainly the origin of the phrase ‘mad as a hatter‘.

So in summary, don’t mess about with elemental mercury; it’s not good for your health.

However, as I took some pains to establish, elements and compounds are different things. So what about compounds which contain mercury?

The compound thiomersal

The compound thiomersal

This is where vaccines come in. There is a substance that used to be used as a preservative in (some) vaccines called thiomersal (or thimerosal, in the U.S). You may have heard its name; it comes up quite a lot. Incidentally, it hasn’t just been used in vaccines, but also in various other things including skin-test antigens and tattoo inks.

Now, to be clear, thiomersal IS potentially toxic, however it’s quickly metabolised in the body to ethyl mercury (C2H5Hg+) and thiosalicylate and, although ethyl mercury does, clearly, still contain atoms of mercury, it does not bioaccumulate. In other words, your body gets rid of it. At very low doses (such as those in vaccines) there is no good evidence that thiomersal is harmful.

Still, due to continuing public health concerns, thiomersal has been phased out of most U.S. and European vaccines. In the UK, thiomersal is no longer used in any of the vaccines routinely given to babies and young children in the NHS childhood immunisation programme. And at the moment, all routinely recommended vaccines for U.S. infants are available only as thimerosal-free formulations or contain only trace amounts of thimerosal (≤1 than micrograms mercury per dose).

Let me just say that again. The evidence suggests it’s safe, but it’s been removed anyway as a precaution. If you live in the UK, it’s not in your child’s vaccines, and that includes the new nasal-spray vaccine for flu which has been rolled out over the last few years. If you live in the U.S. it’s probably not, and thimerosal (thiomersal) free versions exist. It does turn up most often in flu vaccines (hence the meme image at the start) but thiomersal-free versions of those also exist in the U.S.

So chances are it’s not in your vaccines. Not in there. Got it? Ok.

ethyl vs methyl mercury

methyl mercury (left) is not the same as ethyl mercury (right)

Now, you may have heard about mercury in seafood. It is an issue, particularly for women who are pregnant, trying to become pregnant or breastfeeding, and is the reason such women are advised not to eat shark and swordfish, and to keep their tuna consumption low. But here’s the thing: it’s a different kind of mercury. In this case, it’s methyl mercury (remember, thiomersal breaks down to ethyl mercury, which is not the same).

Methyl mercury is more toxic than ethyl mercury. Methyl mercury binds to parts of amino acids much more readily than its ethyl cousin, and it’s able to pass through the blood brain barrier and into nerve cells where it causes damage. In addition, ethyl mercury is much more quickly eliminated from the body than methyl mercury. Because of all this, methyl mercury does bioaccumulate (build up in the body), and that’s why large top-of-the-food-chain fish like shark and tuna can have significant levels of it, and why certain groups of people should be careful about eating them.

The FDA’s action level (the limit at or above which FDA will take legal action) for methyl mercury in fish is 1000 ppb (1 ppm). But remember, that’s for the much more dangerous methyl mercury, not ethyl mercury. I’ve been unable to find an equivalent figure for the UK, but I’d imagine it’s similar.

So, where does the 200 ppb mercury figure in the image at the top come from? Well the Environmental Protection Agency does indeed set a ‘maximum contaminant level goal’ for inorganic mercury of 0.002 mg/L or 2 ppb in water supplies. Methyl and ethyl mercury are not inorganic mercury; compounds that fall into this category include mercuric chloride, mercuric acetate and mercuric sulfide, which largely get into water as the result of industrial contamination.

In summary, that meme image at the start is basically comparing apples and oranges. The EPA limit isn’t relevant to vaccines, because it’s for inorganic mercury, which the substance in vaccines isn’t. While we’re about it, the levels applied to fish don’t apply either, because that’s methyl mercury, not ethyl mercury. They’re not the same thing. And all that aside, it’s highly unlikely (if you live in the UK, no chance at all) that there are 50,000 ppb of ethyl mercury in your flu vaccine anyway. AND, let’s not forget, there’s no evidence that the tiny quantities of thiomersal used in vaccines are harmful in the first place.

Phew.

You may note that I’ve studiously avoided the word ‘autism’ in this post so far. But yes, that’s the big concern; that exposure to thiomersal in vaccines could cause autism. Despite multiple, huge, studies in several countries looking for possible links between vaccines and autism, none have been found. Vaccines don’t cause autism. It’s time we stopped wasting enormous amounts of time and resources on this non-link and spent it instead on finding out what does cause it. Wouldn’t that be far more useful and interesting?

Now… if you’re hardcore anti-vaccine and you’ve read this far, and you’re about to hit the comment button and tell me that all this research is just Big Pharma covering things up so they can make money from the ‘million(/billion/trillion) dollar vaccine industry’, just wait a moment.

Stop.

Think about this: how much money could the medical industry make from people actually catching measles, mumps, polio, TB, whooping cough and all the others? Just think of all the money they could make selling antivirals and antibiotics, all the money to be made from painkillers, antipyretics, drugs to treat respiratory symptoms of one kind or another, and everything else? Believe me, it would be much, much more than they make from a single 2 ml dose of vaccine. Why ‘cover up’ research that’s, if anything, reducing their profits?

All these diseases are horrible, and some can be fatal or have genuinely life-changing consequences. That’s proven. Please vaccinate your children, and yourself.

—-

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Are we really wasting a valuable natural resource at parties?

Solar_eclipse_1999_4_NR

This particular inert gas was discovered by an astronomer observing a solar eclipse.

A couple of weeks ago I wrote a (tongue in cheek) post about a very inert gas, nitrogen. Silliness aside though, nitrogen is a bit, well boring. I mean, we’ve known about it for nearly 250 years, it makes up nearly 80% of our atmosphere and it mostly just sits around doing nothing. Even plants, who’ve mastered the spectacular trick of making solid stuff out of sunlight and carbon dioxide, can’t do much with it in its gaseous form (with a few exceptions).

There are much more interesting inert gases. There’s one that wasn’t even discovered on Earth. In fact, it was first spotted on the Sun by Jules Janssen, an astronomer who was taking advantage of a total solar eclipse to study the Sun’s atmosphere. After some more experiments astronomer Norman Lockyer and chemist Edward Frankland named the element after the Greek word for the Sun. It was the first element to be discovered somewhere other than Earth.

Helium_spectrum

Spectral lines of helium

As it turns out, this element is the second most abundant element in the universe (after hydrogen), but one of the least abundant elements on Earth – with a concentration of just 8 parts per billion in the Earth’s crust.

Today, almost all of us meet it as very young children. In balloons.

It’s helium, the second-lightest element in the periodic table and also, perhaps, the ultimate non-renewable resource.

Most of us meet this element as children.

We all learnt what ‘non-renewable’ means in school: it refers to something we’re using up faster than we can ever replace it. Almost anyone can tell you that crude oil is non-renewable. But the thing is, there are alternatives to crude oil. We can use bioethanolbiodiesel and their cousins to power vehicles and provide power. Bioethanol can act as a route to plastics, too. Scientists are also investigating the potential of algae to produce oil substitutes. These alternatives may (at the moment) be relatively expensive, and come with certain disadvantages, but they do exist.

We have no way to make helium. At least, no way to make it in significant quantities (it’s a by-product in nuclear reactors, but there we’re talking tiny amounts). And because it’s so light, when helium escapes into the atmosphere it tends to float, well, up. Ultimately, it escapes from our atmosphere and is lost. Every time you get fed up with that helium balloon that’s started to look a bit sorry for itself and stick a pin in it (perhaps taking a few seconds to do the squeaky-voice trick first) you’re wasting a little bit of a helium.

But so what? We could all live without helium balloons right? If we run out, balloons will just have to be the sinking kind. What’s the problem?

Liquid helium is used to cool the magnets in MRI machines.

Liquid helium is used to cool the magnets in MRI machines.

The problem is that helium has a lot more uses than you might realise. Cool it to -269 oC – just 4 degrees warmer than absolute zero, the lowest termperature there is – and it turns into a liquid, and that liquid is very important stuff. It’s used to cool the superconducting magnets in MRI (magnetic resonance imaging) scanners in hospitals, which provide doctors with vital, non-invasive, information about what’s going on inside our bodies. MRI techniques have made diagnoses more accurate and allowed surgery to become far more precise. Nothing else (not even the lightest element, hydrogen) has a lower boiling point than helium, so nothing else is quite as good for this chilly job. Scientists are working hard on developing superconducting magnets that work at warmer temperatures, but this technology is still in its infancy.

There’s another technology called NMR (nuclear magnetic resonance) which chemists use all the time to help them identify unknown compounds. In fact, MRI was born out of NMR – they’re basically the same technique applied slightly differently – but the medical application was renamed because it was felt that patients wouldn’t understand that the ‘nuclear’ in NMR refers to the nuclei of atoms rather than nuclear energy or radiation, and would balk at the idea of a ‘nuclear’ treatment. Possibly imagining that they’d turn into the Hulk when they went into the scanner, who knows.

Since it works in essentially the same way, NMR also relies on superconducting magnets, also often cooled with liquid helium. Without NMR, whole swathes of chemical research, not to mention drug testing, would run into serious problems overnight.

It doesn’t stop there. Helium is also used in deep-sea diving, in airships, to cool nuclear reactors and certain other types of chemical detectors. NASA also uses massive amounts of helium to help clean out the fuel from its rockets. In summary, it’s important stuff.

But if we can’t make it, where does all this helium come from?

The Earth’s helium supplies have largely originated from the very slow radioactive alpha decay that occurs in rocks, and it’s taken 4.7 billion years to build them up. Helium is often found sitting above reserves of natural oil and gas. In fact that’s exactly how the first helium reserve was discovered: when, in 1903, an oil drilling operation in Kansas produced a gas geyser that wouldn’t burn. It turned out that although helium is relatively rare in the Earth overall, it was concentrated in large quantities under the American Great Plains.

The National Helium Reserve

Show me the way to… The National Helium Reserve

Of course this meant that the United States quickly became the world’s leading supplier of helium. The US started stockpiling the gas during World War I, intending to use it in barrage balloons and later in airships. Helium, unlike the other lighter-than-air gas hydrogen, doesn’t burn. This made things filled with helium safer to handle and, of course, more difficult to shoot down or sabotage.

In 1925 the US government set up the National Helium Reserve in Amarillo, Texas. In 1927 the Helium Control Act came into force, which banned the export of the gas. At that point, the USA was the only country producing helium, so they had a complete monopoly (personally, I’d quite like to see a Monopoly board with ‘helium reserves’ on it, wouldn’t you?). And that’s why the Hindenburg, like all German Zeppelins, both famously and tragically had to use hydrogen as its lift gas.

Helium use dropped after World War II, but the reserve was expanded in the 1950s to supply liquid helium as a coolant to create hydrogen/oxygen rocket fuel during the Space Race and the Cold War. The US continued to stockpile helium until 1995. At which point, the reserve was $1.4 billion in debt. The government of the time pondered this and ended up passing the Helium Privatization Act of 1996, directing the United States Department of the Interior to empty the reserve and sell it off at a fixed rate to pay off the cost.

Right now, anyone can buy cheap helium in supermarkets and high street shops.

Right now, anyone can buy cheap helium in supermarkets and high street shops.

As a result cheap helium flooded the market and its price stayed fairly static for a number of years, although the price for very pure helium has recently risen sharply. This sell-off is why we think of helium as a cheap gas; the sort of thing you can cheerfully fill a balloon with and then throw away. Pop down to a large supermarket or your local high street and you might even be able to buy a canister of helium in the party section relatively cheaply.

The problem is that this situation isn’t going to last. The US reserves have been dramatically depleted, and at one point were expected to run out completely in 2018, although other reserves have since been discovered and other countries have set up extraction plants. It is also possible to extract helium from air by distillation, but it’s expensive – some 10,000 times more expensive. None of these alternatives are expected to really ease the shortage; they’ll just delay it by a few years.

So are helium party balloons truly an irresponsible waste of a precious resource? Well… the helium that’s used in balloons is fairly impure, about 98% helium (mixed with, guess what? Yep, we’re back to nitrogen again!) whereas the helium that’s needed for MRI and the like is what’s called ‘grade A’ helium, which is something like 99.997% pure, depending on whom you ask. Of course you can purify the low-grade helium to get the purer kind but this costs money, which is why grade A helium is so much more expensive.

NABAS logo

The National Balloon Association (‘the voice of the balloon industry’ – you can’t help wondering whether that’s a very high-pitched voice, can you?) argues that balloons only account for 5-7% of helium use and that the helium that goes into balloons – which they prefer to call ‘balloon gas’ because of its impurities – is mainly recycled from from the gas that’s used in the medical industry, or is a by-product of supplying pure, liquid helium, and therefore using it in balloons isn’t really a problem.

Dr Peter Wothers argues that helium balloons should be banned.

Dr Peter Wothers argues that helium balloons should be banned.

On the other hand, more than one eminent physics professor has spoken out on the subject of helium wastage. It costs about 30-50p to fill a helium balloon, but Professor Robert Richardson of Cornell University argued (before his death in 2013) that a helium party balloon should cost £75 to more accurately reflect the true scarcity value of the gas. Dr Peter Wothers of Cambridge University has called for an outright ban of them, saying that in 50 years’ time our children will be amazed that we ever used such a precious material to fill balloons.

Is it time to call for a helium balloon boycott? Perhaps, although it will probably take more than one or two scientifically-minded consumers refusing to buy them before we see any difference. Realistically, the price will sky-rocket in the next few years and, as Peter Wothers suggests, filling balloons with helium will become a ridiculous notion because it’s far too expensive.

Will images like this make no sense in the future?

Will images like this make no sense in the future?

It’s strange to think though, that in maybe 50 years or so the idea of a floating balloon might simply disappear. Just think of all the artwork and drawings that will no longer make sense.

Perhaps this quotation by the late Sir Terry Pratchett is even more relevant than it first appears:

“There are times in life when people must know when not to let go. Balloons are designed to teach small children this.”

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Is a noxious gas really being added to your food?

Daniel Rutherford named nitrogen "noxious air".

Daniel Rutherford named nitrogen “noxious air”.

Today I’m writing about a potentially dangerous, but surprisingly rarely discussed, substance. It’s a gas at room temperature, with a molecular mass of 28. It sits next to oxygen in the periodic table, but these two could not be more different. When it was discovered by Daniel Rutherford in 1972 he named it ‘noxious air’. Other scientists called it ‘burnt air’, ‘mephitic air’, and ‘azote’ – from the Greek word meaning lifeless – because animals died when they were exposed to it. Today we call it nitrogen.

Let me tell you more. It’s an industrial chemical which is used to make fertilisers and explosives, and to fill tyres. Does that sound like something that you should be exposed to on a daily basis?

Nitrogen is used to fill aeroplane and car tyres.

Nitrogen is used to fill aeroplane and car tyres.

Well I’ve got news for you, you are. Nitrogen is in the air around us. That’s right, this gas which, let me reiterate, was discovered when it was found to kill small animals, is all around us. The concentration of it is fairly stable now, but it has increased dramatically in Earth’s past.

NitrogenRencer

A nitrogen molecule. Not actual size.

Breathing air with more than about 0.8 bar partial pressure will make you really ill or even kill you and yet, pure nitrogen is regularly used to package our foods. Those salad bags you thought were so fresh and healthy? Full of pure nitrogen. That nitrogen is obtained by a process known as fractional distillation. Petrol, diesel and bitumen – the stuff used to cover our roads – are produced by exactly the same method.

Nitrogen is invisible, tasteless and odourless, and companies don’t have to label it on their packaging. Some of the more reputable manufacturers do state that their food is ‘packaged in a protective atmosphere’, but since there is no regulation to force companies to include this label, its absence is no guarantee. You could be eating nitrogen-drenched lettuce right now, and you’d have no idea. And for those salad-dodgers out there breathing a sigh of relief, crisps (chips, for my American readers) are also packaged in this stuff.

Nitrogen can be used in food preparation.

Nitrogen is often used in over-priced food preparation.

It gets worse. When it’s cooled nitrogen becomes a liquid, and this form is also used in food preparation. Some chefs have famously used it to make gourmet ice-cream. But in its liquid form nitrogen is even more dangerous. It’s extremely volatile. Exposure to liquid nitrogen causes severe and painful burns which can leave permanent scars. People who need to handle it should wear thick, industrial-strength gloves and eye protection. It’s so dangerous that one Australian liquor authority recently ordered bars to stop serving drinks containing liquid nitrogen after a patron became seriously ill.

Surely we should be asking the question: should something this harmful REALLY be involved in food preparation at all, anywhere in the world?

Screen Shot 2015-03-31 at 23.20.43

The Food Doll. She knows about this stuff.

Health food campaigners and ‘wellness warriors’ are increasingly setting their sites on this new menace. In an interview, ‘Food Doll’ Eyna Noscience said, “During my research into this stuff I found out that food companies sometimes mix it with carbon dioxide, and we all know that’s killing the ozone layer. We should all be campaigning for better labelling.”

She went on to add: “It’s a pnictogen. I don’t know what that means, but it sounds suspiciously like carcinogen to me. Nothing that unpronounceable can be good for you, right? I always say, if you can’t read it, you shouldn’t be eating it. Or breathing it.”

The spectrum of nitrogen. It's totally irrelevant but it is pretty.

The spectrum of nitrogen. It’s totally irrelevant but it is pretty.

Great-student-demonstration-slogans-ladynottingham-17775214-500-334

Cease the Ugly Nitrogen Terror campaigners staged a peaceful demonstration, and were arrested for “offensive slogans” (not shown).

Despite clearly knowing nothing whatsoever about anything, it’s possible that Eyna Noscience has a point. Perhaps consumers should have the choice over whether they want to buy products saturated with nitrogen? The organisation Cease the Ugly Nitrogen Terror certainly think so. They recently held a peaceful demonstration outside a well-known supermarket in London. Several of their supporters, who were holding placards bearing the initials of the organisation, were arrested for allegedly “offensive slogans”. Clearly yet another example of the food industry having far too much power.

What do you think? Should nitrogen be banned from foods? Leave your comments below.

GNU Terry Pratchett.

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Note: now, in case it’s not entirely obvious, this post is a joke (I say this because some people have asked me, believe it or not). But truth, as they say, is stranger than fiction. After I wrote this I found out that the ‘Food Babe’, aka Vani Hari, had actually written a post (she has since deleted it, but the internet is great for making it difficult to hide such things) in which she demonstrated a fabulous misunderstanding of chemistry and physics. In particular (from here, 6th paragraph):

“The air you are breathing on an airplane is recycled from directly outside of your window. That means you are breathing everything that the airplanes gives off and is flying through. The air that is pumped in isn’t pure oxygen either, it’s mixed with nitrogen, sometimes almost at 50%. To pump a greater amount of oxygen in costs money in terms of fuel and the airlines know this! The nitrogen may affect the times and dosages of medications, make you feel bloated and cause your ankles and joints swell.”

I don’t know about everyone else, but personally I’d be a bit worried about a 50% oxygen atmosphere, particularly in an aeroplane. Let’s just hope she’s wrong, eh?

Low on battery?

2001 a space odyssey

It’s 2015. Where’s my spaceship?

The other day I was reminded of something that happened, if my memory serves me correctly, in 2001. It seems like a long time ago doesn’t it? Strange to think that it seemed so futuristic to Arthur C. Clarke in 1968 that he named his classic science fiction novel with that date. Time is funny like that.

Anyway, back in 2001 I went into a mobile phone shop to get a new phone (yes young people, they did exist 14 years ago). I was shown one of the smaller, lighter phones on the market which was still, certainly by today’s standards, a rather blocky piece of kit. The salesman told me that phones just wouldn’t get much thinner than the model he was trying to convince me to sign up for, because that was the thinnest the batteries could be made.

How wrong was he? Perhaps not quite wrong on the scale of Bill Gate’s infamous (and since strenuously denied) “640K ought to be enough for anybody” line, but pretty wrong. Just a couple of years later lithium ion batteries became widely available, and everything changed.

Lithium-Ion-battery

Argh, my battery is down to 5%!

These days the only time most people think about batteries is when they’re cursing them for running down too quickly and scrabbling about looking for a charging cable. They’re part of modern life; something we take for granted. I’m writing this on a laptop that’s running on a battery. Pretty much everyone has a mobile phone with a battery. Lots of other devices in our households have batteries, either as their primary power source or as a backup to mains electricity. Electric cars, like the Nissan Leaf, run on batteries, and scientists are even investigating the possibility of putting large storage batteries into our houses to store any excess power generated from solar panels on our roofs.

And the majority of those batteries are lithium ion. Stop and think about that for a moment. Smartphones, tablets, eReaders and the like have changed our lives hugely over the last few years and yes, of course, they are the sum of lots of different strands of technology, including touch-screens and increasingly tiny processors. But the fact remains they probably just wouldn’t exist without the humble lithium ion battery, which provides a lightweight, thin and long-lasting (it is, really) source of captive electricity.

Lithium really doesn't place nicely with water.

Lithium really doesn’t play nicely with water.

Lithium batteries were first proposed in the 1970s, and the first ones actually contained lithium metal. Now, even if you’ve forgotten everything else you did in your school chemistry classes, you probably do remember your teacher dropping lithium, sodium and potassium metal into water and watching them suddenly burst into red, orange and purple flames respectively. It’s bad enough accidentally dropping your phone in the loo, imagine if didn’t just stop working but actually exploded. That really would spoil your day.

Lithium reacts spectacularly with oxygen too, so although nice in theory it was ruled out pretty much straight away on safety grounds. Researchers quickly started investigating lithium compounds, and lithium cobalt oxide, LiCoO2, was next up. As a general rule, very reactive elements produce much more stable compounds – and lithium cobalt oxide is much easier to handle than lithium metal.

Unfortunately it does still have poor thermal stability. Which means it has a nasty habit of blowing up if it gets too hot. A bit like that beltric acid stuff in Superman III, only without the turning into strawberry jelly and causing supercomputers to go rogue thing. At high temperatures lithium cobalt oxide starts to generate oxygen, and although oxygen itself isn’t flammable (we all knew that, right?) it does make everything else burn really, really well. Like, say, the plastic cover on your phone, or your curtains. So, that was a problem.

nissan leaf

The Nissan Leaf runs on lithium ion batteries. Big ones.

Not to worry: it didn’t take too long before Rachid Yazami found a way to reversibly insert lithium ions into graphite. The fact that the process is reversible is important: as you charge the battery the lithium ions are absorbed into the graphite, forming LiC6, and as you use it they are slowly released. The electrode that he discovered is still one of the most commonly used ones in commercial lithium ion batteries. These batteries are safe and affordable. The graphite does break down over time, in a process called exfoliation (not the facial wash type). There are ways to reduce this but as we all know from experience, while most lithium ion batteries can happily survive a few years worth of charge cycles, they still don’t last forever. It probably comes as no surprise that there are plenty of researchers out there working on new battery technologies. One of the newer types is the lithium vanadium phosphate battery (LVP), which is increasingly being used in electric cars.

Speaking of cars, we all learned at school that crude oil (the source of petrol and diesel) is a non-renewable resource. This is true, but there are alternatives to producing fuels from crude oil. Bioethanol is relatively easy to produce, diesel vehicles can run directly from plant oil fuel, and there are types of algae which can produce fuels. These alternatives also have the advantage of absorbing carbon dioxide as the plants or algae grow, so reducing the total amount of carbon dioxide that ends up being released into the atmosphere. That’s good, because pretty much everyone agrees now that global warming is a Bad Thing (even Republicans).

If you think about it, no metal is renewable. We can’t make metals (well, beyond a few atoms in a supercollider), and often there’s no really good alternative to using a particular type of metal. Having said that, scientists are working on sodium ion batteries, but they’re not commercially viable just yet. So right now, to feed our desire for new laptops, phones and even cars, we need lithium. Lots and lots and lots of it.

lithium triangle Salde Vida Map

The lithium triangle. Where batteries mysteriously disappear (not really).

Because lithium is so reactive it’s never found in its pure state; it has to be extracted from its compounds. Most of the world’s supply comes from a small group of places colloquially known as the ‘lithium triangle’, which includes the Atacama Salt Flat in Chile (generally considered to produce the best quality lithium in the world) and the Hombre Muerto Salt Flat in Argentina. Most of it, some 40-50% of the world’s reserves, is thought to be in Bolivia, where mining only began a few years ago.

It takes 750 tons of brine, and 24 months, to obtain just ton of lithium from these salt flat locations. The energy cost is high, although lithium itself is still relatively cheap (right now). It can of course be recycled: 20 tons of spent batteries can also provide one ton of lithium. So be good and recycle your phone responsibly. And next time you’re cursing your battery, just stop for a second and think of all the time and energy that went into making it. Pretty amazing, really.

The Salar de Arizaro. Beats a wet January in the UK, that's for sure.

The Salar de Arizaro. Beats a wet January in the UK, that’s for sure.

And if you’re a student thinking about career options, spare a thought for chemical engineering. Our demand for metals is only going to increase and someone needs work on more efficient ways of getting at them. You won’t be short of a job, and you might even get to visit some pretty nice locations along the way.

Now funnily enough, and I swear I’m not just saying this for artistic licence, my laptop battery has just hit 7%. Where did I leave my charging cable…?