Chemistry jokes get the best reactions

Today, 24th March, is Red Nose Day 2017 in the UK. I decided to see if I could collect some new chemistry jokes. There are some, of course, that we’ve all heard before – we might even say that all the best ones argon.

So, I promised to donate £10 if I got sent at least five new jokes. And I did! So I have! And here are my favourite five, in no particular order. Enjoy!

“I’ll tell you a joke about a tiny amount of iron for a small Fe.”@hullodave

“Chemistry Fact: There’s really no such thing as hydrogen. The inventor of the Periodic Table just needed a place to land a tiny helicopter.”@hullodave

“Why don’t they galvanise ships to stop corrosion? …That would make them zinc.”

“Do you know why everyone wants to work with bismuth? Because there’s no bismuth like showbismuth!” — @GriceChemistry

“I know a great long Justus Von Liebig joke but it needs condensing to get it on Twitter.” — 

If you’ve enjoyed these, if they’ve even so much as made you crack a little smile, please go and donate a couple of quid to Comic Relief. It’s a brilliant charity which helps people all over the world.

Donate here

The Chronicles of the Chronicle Flask: 2016

2016 is limping to its painful conclusion, still tossing out last-minute nasty surprises like upturned thumb tacks in the last few metres of a marathon. But the year hasn’t been ALL bad. Some fun, and certainly interesting, things happened too. No, really, they did, honestly.

So with that in mind, let’s have a look back at 2016 for the Chronicle Flask….

January kicked off with a particularly egregious news headline in a well-known broadsheet newspaper: Sugar found in ketchup and Coke linked to breast cancer. Turns out that the sugar in question was fructose. Yes, the sugar that’s in practically everything, and certainly everything that’s come from a plant. So why did the newspaper in question choose ketchup and Coke for their headline instead of, oh, say, fruit juice or honey? Surely not just in an effort to sell a few more newspapers after the overindulgent New Year celebrations. Surely.

octarineThere was something more lighthearted to follow when IUPAC  verified the discoveries of elements 113, 115, 117 and 118. This kicked off lots of speculation about the elements’ eventual names, and the Chronicle Flask suggested that one of them should be named Octarine in honour of the late Sir Terry Pratchett. Amazingly, this suggestion really caught everyone’s imagination. It was picked up in the national press, and the associated petition got over 51 thousand signatures!

In February I wrote a post about the science of statues, following the news that a statue to commemorate Sir Terry Pratchett and his work had been approved by Salisbury City Council. Did you know that there was science in statues? Well there is, lots. Fun fact: the God of metalworking was called Hephaestus, and the Greeks placed dwarf-like statues of him near their Hearths – could this be where the fantasy trope of dwarves as blacksmiths originates?

MCl and MI are common preservatives in cosmetic products

MCl and MI are common preservatives in cosmetic products

My skeptical side returned with a vengeance in March after I read some online reviews criticising a particular shampoo for containing a substance known as methylchloroisothiazolinone. So should you be scared of your shampoo? In short, no. Not unless you have a known allergy or particularly sensitive skin. Otherwise, feel free to the pick your shampoo based on the nicest bottle, the best smell, or the forlorn hope that it will actually thicken/straighten/brighten your hair as promised, even though they never, ever, ever do.

Nature Chemistry published Another Four Bricks in the Wall in April – a piece all about the potential names of new elements, partly written by yours truly. The month also brought a sinus infection. I made the most of this opportunity by writing about the cold cure that’s 5000 years old. See how I suffer for my lovely readers? You’re welcome.

In May I weighed in on all the nonsense out there about glyphosate (and, consequently, learned how to spell and pronounce glyphosate – turns out I’d been getting it wrong for ages). Is it dangerous? Nope, not really. The evidence suggests it’s pretty harmless and certainly a lot safer than most of its alternatives.

may-facebook-postSomething else happened in May: the Chronicle Flask’s Facebook page received this message in which one of my followers told me that my post on apricot kernels had deterred his mother from consuming them. This sort of thing makes it all worthwhile.

In June the names of the new elements were announced. Sadly, but not really very surprisingly, octarine was not among them. But element 118 was named oganesson and given the symbol Og. Now, officially, this was in recognition of the work of Professor Yuri Oganessian, but I for one couldn’t help but see a different reference. Mere coincidence? Surely not.

July brought another return to skepticism. This time, baby wipes, and in particular a brand that promise to be “chemical-free”. They’re not chemical-free. Nothing is chemical-free. This is a ridiculous label which shouldn’t be allowed (and yet, inexplicably, is still in use). It’s all made worse by the fact that Water Wipes contain a ‘natural preservative’ called grapefruit seed extract which, experiments have shown, only actually acts as a preservative when it’s contaminated with synthetic substances. Yep. Turns out some of Water Wipes claims are as stinky as the stuff they’re designed to clean up.

Maria Lenk Aquatic Enter, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham)

Maria Lenk Aquatic Enter, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham)

August brought the Olympics, and speculation was rife about what, exactly, was causing the swimming pools to turn such strange shades of green. Of course, the Chronicle Flask knew the correct solution…

August also saw MMS and CD reared their ugly heads on social media again. CD (chlorine dioxide) is, lest we forget, a type of bleach solution which certain individuals believe autistic children should be made to drink to ‘cure’ them. Worse, they believe such children should be forced to undergo daily enemas using CD solutions. I wrote a summary page on MMS (master mineral solution) and CD, as straight-up science companion to the commentary piece I wrote in 2015.

mugsSeptember took us back to pesticides, but this time with a more lighthearted feel. Did you know that 99.99% of all the pesticides you consume are naturally-occurring? Well, you do if you regularly read this blog. The Chronicle Flask, along with MugWow, also produced a lovely mug. It’s still for sale here, if you need a late Christmas present… (and if you use the code flask15 you’ll even get a discount!)

In October, fed up with endless arguments about the definition of the word ‘chemical’ I decided to settle the matter once and for all. Kind of. And following that theme I also wrote 8 Things Everyone Gets Wong About ‘Scary’ Chemicals for WhatCulture Science.

Just in case that wasn’t enough, I also wrote a chapter of a book on the missing science of superheroes in October. Hopefully we should see it in print in 2017.

Sparklers are most dangerous once they've gone out.

Sparklers are most dangerous once they’ve gone out.

I decided to mark Fireworks Night in November by writing about glow sticks and sparklers. Which is riskier? The question may not be as straightforward as you’d imagine. This was followed by another WhatCulture Science piece, featuring some genuinely frightening substances: 10 Chemicals You Really Should Be Scared Of.

And that brings us to December, and this little summary. I hope you’ve enjoyed the blog this year – do tell your friends about it! Remember to follow @ChronicleFlask on Twitter and like on Facebook – both get updated more or less daily.

Here’s wishing all my lovely readers a very Happy New Year – enjoy a drop of bubbly ethanol solution and be careful with the Armstrong’s mixture…. 

See you on the other side!


Glow sticks or sparklers: which is riskier?

by Unknown artist,print,(circa 1605)

Remember, remember the 5th of November… (Image by Unknown artist, circa 1605)

It’s fireworks night in the UK – the day when we celebrate a small group of terrorists nearly managing to blow up the Houses of Parliament in 1605 by, er, setting fire to stuff. No, it makes perfect sense, honestly, because…. look, it’s fun, all right?

Anyway, logical or not, Brits light fireworks on this day to mark the occasion. Fireworks, of course, are dangerous things, and there’s been more than one petition to ban their sale to members of the general public because of safety concerns. It hasn’t happened yet, but public firework displays, rather than private ones at home, are more and more popular.

Which brings me to this snippet from a letter a friend of mine recently received.


In case you can’t read it, it says:

“NO SPARKLERS PLEASE – with so many children runni[ng] around, we believe it is too dangerous fro children to be [words missing] lighted sparklers around.
Last year we had a few incidents of children drinking the [words missing] glowsticks – please advise against this.”

Now there are some words missing here, but it’s fairly clear that sparklers are prohibited at this event, and it seems to be suggesting that children have managed to get into, and swallow, the contents of glowsticks. But they, by contrast, haven’t been banned. Indeed, parents are merely being asked to “advise” against it.


Does this seem like an appropriate response? Well, let’s see…

1024px-sparklers_moving_slow_shutter_speedWhat are these things? Let’s begin with sparklers. They’re hand-held fireworks, usually made of a stiff metal wire, about 20 cm long, the end of which is dipped in a thick mixture of metallic particles, fuel and an oxidising agent. The metal particles are most commonly magnesium and/or iron. The fuel usually involves charcoal, and the oxidiser is likely to be potassium nitrate. Sometimes metal salts are also added to produce pretty colours.

Sparklers are designed to burn hot and fast. The chemical-dipped end can reach temperatures between 1000-1600 oC, but the bit you hold doesn’t have time to heat up before the firework goes out (although gloves are still recommended). The sparks, likewise, are extremely hot but burn out in seconds. This makes sparklers relatively safe, if they’re held well way from the face and body, and if the hot end isn’t touched.

If. Every year there are injuries. Sparkler injuries aren’t recorded separately from other firework injuries in the UK, but the data we do have suggest we might be looking at a few thousand A&E admissions each year, and probably a lot more minor injuries which are treated at home.

Sparklers are most dangerous once they've gone out.

Sparklers are most dangerous after they’ve gone out.

The biggest danger comes from people, usually children, picking up ‘spent’ sparklers. The burny end takes a long time to cool down, but once the sparkles are finished and it’s stopped glowing it’s impossible to judge how hot it is just by looking.

The burns caused by picking up hot sparklers are undoubtedly very, very nasty, but they’re also relatively easy to avoid. Supply buckets of cold water, and drill everyone to put their spent sparklers into the buckets as soon as they go out. Hazard minimised. Well, assuming everyone follows instructions of course, which isn’t always a given. Other risks are people getting poked with hot sparkers – which can be avoided by insisting sparkler-users stand in a line, facing the same way, with plenty of space in front of them – and people lighting several sparklers at once and getting a flare. Again, fairly easily avoided in a public setting, where you can threaten and nag everyone about safety and keep an eye on what they’re doing.

Although I do understand the instinct to simply ban the potentially-dangerous thing, and thus remove the risk, the idea does worry me a little bit. I was born in the 70s and I grew up with fire. I remember the coal truck delivering coal to us and our neighbours. I was taught how to light a match at an early age, and cautioned not to play with them (and then I did, obviously, because in those days it was usual for kids to spend hours and hours entirely unsupervised – but fortunately I emerged unscathed). Pretty much everyone kept a supply of candles in a drawer, in case the lights went out. And bonfires were a semi-regular event – this being long before garden waste collections.

These days things are very different. It’s not unusual to meet a child who, by age 11, has never lit a match. If their home oven and hob are electric, they may never have seen a flame outside of yearly birthday cake candles. But so what? You may be thinking. Aren’t fewer burns and house fires a good thing?

Of course they are, but people who’ve never dealt with fire tend to panic when faced with it. If the only flame you’ve ever met is a birthday cake candle, your instinct might well be to blow when faced with something bigger. This can be disastrous – it can make the fire worse, and it can spread hot embers to other nearby flammable items.

I’m personally of the opinion that children ought to be taught to handle fire safely, how to safely extinguish a small fire, when to call in the experts, and not to disintegrate into hysterics the presence of anything warmer than a cup of tea. Sparklers, I think, can be part of that. Particularly if they’re used in a well-supervised setting, with plenty of safety measures and guidance on-hand. (As opposed to, say, picking them up for the first time at university with some drunk mates, setting fire to half a dozen at once and immediately dropping them.)

Now. Onto glowsticks. They’re pretty neat, aren’t they? We’ve already established that I’m quite old, and I remember these appearing in shops for the first time, sometime in the very early 90s, and being utterly mesmerised by that eerie, cold light.


Diphenyl oxalate (trademark name Cyalume)

They work thanks to two chemicals. Usually, these are hydrogen peroxide (H2O2 – also used to bleach hair, as a general disinfectant, and as the subject of a well-known punny joke involving two scientists in a bar) and another solution containing a phenyl oxalate ester and a fluorescent dye.

These two solutions are separated, with the hydrogen peroxide in a thin-walled, sealed glass vial which is floating in the mixture of ester and dye solution. The whole thing is then sealed in a tough, plastic coating. When you bend the glowstick the glass breaks, the chemicals mix, and a series of chemical reactions happen which ultimately produce light.

How Light Sticks work (from - click image for more)

How Light Sticks work (from – click image for more)

Which is all very well. Certainly nice and safe, you’d think. Glowsticks don’t get hot. The chemicals are all sealed in a tube. What could go wrong?

I thought that too, once. Until I gave some glowsticks to some teenagers and they, being teenagers, immediately ripped them apart. You see, it’s actually not that difficult to break the outer plastic coating, particularly on those thin glow sticks that are often used to make bracelets and necklaces. Scissors will do it easily, and teeth will also work, with a bit of determination.

How dangerous is that? Well… it’s almost impossible to get into a glowstick without activating it (the glass vial will break), so it’s less the reactants we need to worry about, more the products.

And those are? Firstly, carbon dioxide, which is no big deal. We breathe that in and out all the time. Then there’s some activated fluorescent dye. Now, these vary by colour and by manufacturer, but as a general rule they’re not something anyone should be drinking. Some fluorescent dyes are known to cause adverse reactions such as nausea and vomiting, and if someone turns out to be allergic to the dye the consequences could be serious. This is fairly unlikely, but still.

Another product of the chemical reactions is phenol, which is potentially very nasty stuff, and definitely not something anyone should be getting on their skin if they can avoid it, let alone drinking.

Inside every activated glowstick are fragments of broken glass.

Inside every activated glowstick are fragments of broken glass.

And then, of course, let’s not forget the broken glass. Inside every activated glowstick are fragments of broken glass – it’s how they’re designed to work. If you break the plastic coating, that glass is exposed. If someone drinks the solution inside a glow stick they could, potentially, swallow that glass. Do I need to spell out the fact that this would be a Bad Thing™?

The thing with hazards is that, sometimes, something that’s obviously risky actually ends up being pretty safe. Because people take care over it. They put safety precautions in place. They write risk assessments. They think.

Whereas something that everyone assumes is safe can actually be more dangerous, precisely because no one thinks about it. How many people know that glowsticks contain broken glass, for instance? Probably not the writer of that letter back there, else they might have used stronger language than “please advise against this.”

So glowsticks or sparklers? Personally, I’d have both. Light on a dark night, after all, is endlessly fascinating. But I’d make sure the sparkler users had buckets of water, cordons and someone to supervise. And glowstick users also ought to be supervised (at least by their parents), warned in the strongest terms not to attempt to break the plastic, and all efforts should be made to ensure that the pretty glowy things don’t fall into the hands of a child still young enough to immediately stuff everything into his or her mouth.

The most important thing about managing risks is not to eliminate every potentially hazardous thing, but rather to understand and plan for the dangers.

Like the Chronicle Flask’s Facebook page for regular updates, or follow @chronicleflask on Twitter. In need of a groovy new mug? Check out this page.

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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
  2. On the topic of chemical symbols, which christmassy word can you make out of these elements?
    carbon, radium, carbon (again), potassium, erbium, sulfur


  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.


  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.
  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.


  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.
  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.
  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


  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


  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


  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!

Merry Chemistmas!

It’s December! All that American Black Friday/Cyber Monday nonsense aside, like it or not once the calendar turns to the 12th month it’s time to stop putting off the Christmas shopping. So with that in mind, here are some present ideas for the chemist(s) amongst your family and friends:

  1. anandamide necklace
    This beautiful necklace represents the anandamide molecule. It’s a little bit simplified (can you pick out the nitrogen?) but we can forgive that. After all, to paraphrase the late, great Terry Pratchett (badly, sorry): Taint what anandamide looks like, it’s what anandamide be. This particular neurotransmitter takes its name from the Sanskrit word ananda, which means “joy, bliss, delight” and, of course, ‘amide‘ (which means a molecule that contains a nitrogen atom joined up to some other stuff). Anandamide is important for all sorts of functions in the body: it’s linked with pleasurable reward systems (hence the ‘bliss’), ovulation, and may even inhibit breast cancer. Fabulous all round, and it looks very pretty too.


    Anandamide necklace, from store.madewith.molecules

  2. the Compound Interest book
    If you follow my Facebook and Twitter feeds you’ll know I’m a huge fan of Andy Brunning and his beautiful Compound Interest graphics (don’t forget to check out the Chemistry Advent Calendar). His book, Why Does Asparagus Make Your Wee Smell?, is equally gorgeous, and it’s really much nicer to flick through the glossy, full-colour pages than squint at them on a screen. It would make a lovely pressie and it’s (currently) less than a tenner on Amazon. What’s not to like?


    Why Does Asparagus Make Your Wee Smell book, available from

  3. Wirdou ‘Be Like Him’ t-shirt
    Wirdou is an extremely talented graphic artist who specialises in all things geeky and sciency. His work is so good I’ve even forgiven him for choosing a name that’s impossible to type without Google, Amazon, WordPress and every spell checker ever insisting on changing it to ‘weird’ or ‘word’. Anyway, he has many, many fabulous designs that are well-worth browsing through, but if I had to choose one, it’d be this. The non-chemists will probably spot the reference to neon lights. Chemists will enjoy feeling super smart about understanding the octet rule.


    Be Like Him t-shirt, from

  4. periodic table lunch box
    No list of chemistry presents would be complete with a periodic table-emblazoned item of some sort, and I’ve plumped for this one. It’s delightfully industrial in appearance, looking like it might just contain a collection of questionable substances rather than sandwiches, so you never know – it may even deter your co-workers from nicking your lunch for fear of accidental poisoning.


    Periodic table lunch box, available from

  5. science lab beaker pinafore
    For the little (future) chemist in your house, here’s a lovely dress from the wonderful Sewing Circus. All their clothes are handmade, unisex, and promote STEM (science, technology, engineering and mathematics) themes. I can vouch for the fact that, although they are a little more expensive than some children’s clothes, they are excellent quality, wash brilliantly and last really well. Plus, not a bit of sparkly pink in sight. Well worth it.


    Science lab beaker pinafore, from

  6. Chem C3000 chemistry set
    Of course you can wander into a toy shop or even, possibly, a supermarket and pick up a chemistry set for a tenner. But, I’m gong to paraphrase again (hey, why stop once you’ve started): Those aren’t chemistry sets. THIS is a chemistry set. Yes indeed, while those cheap sets consist of little more than baking soda and PVA glue, if that, this one has proper good stuff in it, such as luminol, potassium permanganate, sodium thiosulfate, copper sulfate and ammonium chloride. And something called ‘litmus power’, which I suspect is a typo, but you never know. Yes it’s pricy, but if you have a interested child of pretty much any age at home it would be marvellous. Unlike school experiments, which necessarily have to stop at the end of the lesson, with this you could mix things together for hours. It also comes with a detailed experiment manual, so parents can reassure themselves that the kitchen table will still be (mostly) in once piece at the end of the day. Go on, you know you want to.

    The Chem C3000 chemistry set, from

Merry Christmas from The Chronicle Flask! Follow me on Facebook for regular updates and other interesting bits and pieces.

The Chronicle Flask’s festive chemistry quiz!

Tis the season to be jolly! And also for lots of blog posts and articles about the science of christmas, like this one, and this one, and this one, and even this one (which is from last year, but it’s jolly good).

But here’s the question: have you been paying attention? Well, have you? Time to find out with The Chronicle Flask’s festive quiz! I haven’t figured out how to make this interactive. You’ll have to, I don’t know, use a pen and paper or something.

Arbol_de_navidad_con_adornos_de_personajesQuestion 1)
Which scientist invented a chemical test that can be used to coat the inside of baubles with silver?
a) Bernhard Tollens
b) Karl Möbius
c) Emil Erlenmeyer

Question 2)
Reindeer eat moss which contains arachidonic acid… but why is that beneficial to them?
a) a laxative
b) an anti-freeze
c) a spider repellant

1280px-ChristmasCrackers_2Question 3)
Which chemical makes crackers and party poppers go crack?
a) gunpowder
b) silver fulminate
c) nitrogen triiodide

640px-Glass_of_champagneQuestion 4)
We all like a glass of champagne at this time of year, but what’s in the bubbles?
a) carbon dioxide
b) nitrogen
c) oxgyen

Question 5)
What’s the key ingredient in those lovely bath salts you bought for your grandma?
a) calcium carbonate
b) magnesium sulfate
c) citric acid

The Bird - 2007Question 6)
Which chemical reaction is responsible for both perfectly browned biscuits and crispy, golden turkey?
a) Maillard reaction
b) Hodge reaction
c) Caramel reaction

Question 7)
Sucrose-rodmodelWhere are you most likely to find this molecule at this time of year?
a) in a roast beef joint
b) in the wrapping paper
c) in the christmas cake

Question 8)
Let it snow, let it snow, let it snow… but which fact about (pure) water is true?
a) It glows when exposed to ultraviolet light
b) It expands as it freezes
c) It’s a good conductor of electricity

Ethanol-3D-ballsQuestion 9)
Where are you likely to find this molecule on New Year’s Eve?
a) in a champagne bottle
b) in the party poppers
c) in the ‘first foot’ coal

OperaSydney-Fuegos2006-342289398Question 10)
Who doesn’t love a firework or two on New Years Eve?  But which element is most commonly used to produce the colour green?
a) magnesium
b) sodium
c) barium

(Answers below…)

1a) Bernhard Tollens (but his science teacher was Karl Möbius).
2b) It’s a natural anti-freeze.
3b) Silver fulminate (it always surprises me how many people guess gunpowder. That would be exciting).
4a) carbon dioxide.
5b) magnesium sulfate which, funnily enough, also causes ‘hard’ water.
6a) the Maillard reaction, although Hodge did establish the mechanism.
7c) In the cake – it’s sucrose (table sugar).
8b) it expands as it freezes and is thus less dense than liquid water (which is why ice floats). We take this for granted, but most things contract (and become more dense) as they turn from liquid to solid. You should be grateful – live probably wouldn’t have evolved without this peculiar behaviour.
9a) In the champagne – it’s ethanol (or ‘alcohol’ in everyday parlance).
10c) barium – copper produces green flames too, but barium salts are more commonly used in fireworks.

So how did you do?
Less than 4: D, for deuterium. It’s heavy hydrogen and it’s used to slow things down. Enough said.
4-6: You get a C, by which I mean carbon. Have another slice of coal.
7-8: You’ve clearly been paying attention. B for boring, I mean boron.
9-10: Au-ren’t you clever? Chemistry champion!

Happy New Year everyone! 🙂

Creepy combustion chemistry…

Halloween pumpkins

We’re burning!

So it’s October and I’m trying to think of a blog post topic. Hmm.

Well, the Nobel prize for Chemistry was announced earlier this month. But it went to some guys who’d developed a microscopy technique for seeing single molecules, specifically molecules involved in cell interactions. All very nice, but that’s biophysics isn’t it? Why did it get the Chemistry Nobel? (Biology famously doesn’t have it’s own Nobel prize, so maybe the committee just had to sneak it in somewhere?)

What else happens in October? Halloween of course! I love Halloween. But I’ve done pumpkins before. And I’ve written about sugar and chocolate, so that’s tick or treating more or less covered… hmmmm… candles, vampires, ghosts, the paranormal…


Is anyone else hot? (The Human Torch, art by Adi Granov)

Ahah! Inspiration! Spontaneous human combustion. What else?

If there’s any paranormal topic that touches on the edges of chemistry, it has to be this one. If you’ve never heard of it, spontaneous human combustion refers to the idea that humans can (or, er, maybe not – bear with me) suddenly and unexpectedly burst into flame and be reduced to ashes in a matter of moments. There is apparently no external source of this flame – it seems to come from nowhere.

It’s a creepy idea. I remember one of my chemistry professors at university, who had turned up to lecture us in his chemical-stained lab coat, with bushy white hair and too-dark eyebrows sticking out in all directions, pausing on his way out to tell us that we should think carefully when deciding whether chemical reactions would happen spontaneously or not under real world conditions. “After all,” he said cheerfully, “spontaneous human combustion has a negative Gibbs free energy, and you haven’t all burst into flame. Yet.”† And with that he gave us all an ever-so-slightly crazed grin and sauntered out of the room, leaving us looking around uneasily for traces of smoke.

Gibbs free energy change is a measure of how energy changes during a chemical reaction. It’s linked to couple of very important physical laws that pretty much describe how the world works. In short, do a bit of maths and, if you get a negative number, it tells you whether a chemical reaction can occur spontaneously but, and this was my lecturer’s point, not necessarily whether they actually will. It’s a subtle distinction, and one that’s easily forgotten. (Crucially, activation energy needs to be considered as well – if you want to know more about these terms, follow the links.)

Theatrically-minded chemistry lecturers aside for a moment, the idea that people, and things, might unexpectedly start burning is an old one. You can track it right back to the Old Testament, where there was quite a lot of suddenly bursting into flames going on, for example the angel of the Lord appearing to Moses in flames of fire from within a bush. Mind you, that was an angel rather than a human being, and they might be flame retardant of course. But you get the point. Fire has always been important to humans as a source of vital light and heat – indeed many would argue that the ability to control fire was a key turning point in human evolution – but at the same time it can be horrifyingly destructive. It’s hardly surprising that fire has found its way into so much of our history and mythology.

Let’s think about what the combustion part of ‘spontaneous human combustion’ means. The definition of combustion is a chemical reaction between a fuel and an oxidant (commonly oxygen) that gives out heat.


This applies to you, unless you’re a silicon-based lifeform.

There is more than one type of fuel, but the most familiar ones (coal, oil, gas, fats, wood and so on) are made of largely of carbon, hydrogen and oxygen. You are made up of the same elements (assuming you’re not some kind of alien life-form who’s stumbled over my blog – in which case, welcome). Of course you do have some other elements thrown in as well, notably nitrogen, calcium and phosphorous, but most of you is carbon, oxygen and hydrogen.

When you burn these kinds of fuels, this happens:

fuel + oxygen –> carbon dioxide + water (+ lots of energy)

Fuels give out lots of energy when they burn, and so, in theory, would you. Particularly if you have plenty of fat, because fats burn really nicely. After all, what were candles made of before paraffin wax? Largely tallow – which is a processed form of animal fat, usually from cows or sheep. And we all know that candles burn really well, that’s sort of the point.

The idea that you can burn a human isn’t surprising, after all people have been using fire to dispose of human remains for thousands of years. But spontaneous human combustion (SHC) is something different. In these cases, the person burns without any (obvious) source of ignition. At this point, you might be imagining a person suddenly bursting into flame right in front of shocked witnesses, but in truth reliable eyewitness accounts are pretty rare. Instead, what generally seems to happen is that a body is discovered, badly burnt but usually with very little damage to the surrounding furniture or even, sometimes, parts of the victim’s clothes. Observers of the scene then draw their own conclusions, some more rational than others, as to how the burning occurred.

Possibly one of the most famous cases like this is that of Henry Thomas. He was a 73 year-old man whose remains were discovered in the living room of his council house in South Wales in 1980. His entire body had been incinerated, leaving only his skull and a section of each leg. Bizarrely, sections of his socks and trousers were relatively unscathed, as was half of the chair he’d been sitting in, and most of the rest of the room except for some smoke damage.

Could ball lightning cause people to catch fire?

Could ball lightning cause people to catch fire?

There are various theories to explain this kind of gruesome discovery, from ball lightening, to flammable intestinal gases (namely methane, which is the same gas in your kitchen cooker), to acetone building up in the body. The most famous, and probably best accepted of the more scientific theories, is ‘the wick effect‘, popularised in a BBC QED documentary in 1998. This idea likens a clothed human body to a candle, but with the wick (clothes) on the outside. The person’s fat is the fuel source, and the theory goes that the person’s fat melts and burns slowly, like a candle, over a period of several hours. The burning is very localised, which explains the lack of damage to the surroundings. Police forensic officers decided that Henry Thomas’s death was most likely an example of the wick effect in action.

It is often the case that apparent SHC victims are elderly, have low mobility due to illness or obesity, and are smokers (in other words, had a source of ignition in the vicinity). The logic goes that they are somehow incapacitated, perhaps a heart attack or stroke, perhaps excessive alcohol consumption, drop their cigarette and burn slowly.

But there are cases where the burning seemed to be a lot more sudden, and even a few where someone else was on the scene. For example, the most recent (suspected) case of spontaneous human combustion in the UK was that of Jeannie Saffin, who died in 1982. She was a 61 year-old woman, but had the mental capacity of a child due to birth defects. She was sitting with her father in the kitchen of their family home. He wasn’t looking directly at her when she caught fire but, according to his account, something caught his eye and he turned to find her suddenly ablaze. He and his son-in-law put out the fire using water, and then called an ambulance. She eventually died in hospital despite treatment. The coroner refused to accept the suggestion of spontaneous human combustion saying there was “no such thing”, and recorded an open verdict.

Jeannie Saffin’s case clearly wasn’t an example of the wick effect; it happened too fast. As far as I can find out, no one has ever really been able to explain why she caught fire so suddenly. She was in a kitchen, and kitchens do typically contain sources of ignition. Perhaps something went unrecorded: matches, alcohol, use of a gas oven. But even if it did, why did she burn so quickly and so violently? Flammable clothing perhaps? The truth is, we will probably never know.

Not too much now.

Not too much now.

Searching around I found other examples, but in every ‘sudden’ case I found the victim was in close proximity to something flammable or something that could, conceivably, provide a source of ignition. Or both. In particular, there are several cases of apparent SHC happening in cars. Usually a fire crew has investigated and found no traces of petrol in the wrong place. But… this seems like too much of a coincidence to me. Petrol is extremely flammable – could a small trace be present, perhaps from filling up the tank? If something were to ignite it, it could cause other things to burn, like synthetic fibres or, an even more likely culprit, hair products like gel or hairspray. Hair coated in product can burn really quickly. It doesn’t entirely explain every detail, but then it’s hard to know what is and isn’t an accurate account in these cases.

The truth is that spontaneous (if that really is an appropriate adjective) human combustion remains a bit of a mystery.

Just be careful around those jack-o-lanterns.

† I may be misquoting, it was a long time ago, but I’m sure I’ll be forgiven if I am.