Moronic acid, windowpane, curious chloride and other silly substance names

My recent post on arsenic got me thinking about silly chemical names.  There are, in fact, asilly atom number of compounds that contain arsenic that chemists have clearly named with great glee.  In fact it seems quite likely that some of them were even deliberately synthesized purely for the opportunity to get a naughty-sounding word into a chemical name.  But it goes way beyond arsenic: there are many, many molecules with quite frankly ridiculous names.

So with such childishness in mind, here’s my top ten of silly substances:

1.  Adamantane
I have to confess that when I first met this molecule at university I though the lecturer was adamantanejoking.  He wasn’t, this rather odd-looking cycloalkane is a real molecule.  It’s existence was first suggested in 1924 but it wasn’t actually made until 1941 – either way it preceded the 1980s pop star by some years.  The arrangement of the atoms in adamantane is like those in diamond, and that’s where its name comes from: the Greek adamantinos, meaning relating to diamond or steel.  In itself adamantane doesn’t have many uses, but its derivatives are important in drug synthesis.

2.  Megaphone
YES THERE REALLY IS A MOLECULE CALLED MEGAPHONE!  It gets its name not because it’s loud, but because it’s extracted from the plant Aniba megaphylla.  It’s interesting because it has been shown to inhibit the growth of certain tumour cells.

3.  Arsole
Please remember I didn’t come up with this, it’s a real molecule.  It contains, not arsolesurprisingly, arsenic and has the rather simple formula of C4H4AsH in, ho ho, a ring-shaped structure.  It’s actually never been isolated experimentally itself but, and this just gets better and better, a class of similar molecules called arsoles have been investigated.  Arsole bonded to a benzene ring would be called benzarsole.  Ok I’ll stop now.

4.  Moronictraumaticerotic and diabolic acids
Not one, but a collection of acids (and there are more than these four with silly names, but we don’t want to be here all day).  The ‘ic’ ending for organic acids has provided rich fodder.  Moronic acid rather boringly gets its name from the Mora excelsa tree, from which it was isolated.  Traumatic acid actually gets its name from what it does – it’s a wound hormone that helps plants to repair damage.  Erotic acid is really called orotic acid, but it’s been misspelled so often that erotic acid has become an accepted name for it.  Diabolic acids are actually a class of compounds, named after the Greek diabollo, meaning to mislead, since they were particularly difficult to isolate.

On the subject of acids, honourable mention must also go to the wonderfully-named triflic acid, which sounds like something you might extract from a triffid.  It’s not obviously, but it’s still quite interesting stuff, being one of the strongest acids.  In fact it’s a superacid, which makes it sound a bit like a superhero’s deadly nemesis.

5.  Cummingtonite
This sounds like the sort of tortured name someone might invent for cocktail happy hour, but in fact it’s a greeny-brown mineral with the rather spectacular formula of (Mg,Fe)7Si8O22(OH)2.  It gets its name from the town of Cummington, Massachusetts (wouldn’t you love to live there?), where it was first discovered in 1824.

6.  Windowpane FSTRANE
You have to love this one.  The molecule actually looks like a child’s drawing of a window.  It’s more properly called fenestrane (from the Latin word for window, fenestra), and while it’s never been synthesised itself a version with a corner carbon missing has been made and, naturally, goes by the name ‘broken window’.

7.  Curious chloride
Isn’t this just the cutest thing?  Someone should write a children’s book.  CmClis more properly named curium trichloride but ‘curious’, or ‘curous’, is the trivial name for curium compounds.  A concentrated solution of curious chloride would be radioactive enough to boil itself if left alone.  Maybe not so child-friendly, then.

8.  Welshite welshite
Funny to us Brits, probably meaningless to an American, this reddish-black mineral was named after Wilfred R. Welsh, an amateur mineralogist from New Jersey.  He was a president of the Franklin Mineral Museum and this mineral was named in his honour by one of his former students.

9.  Fucitol
This sounds like something a student might say at the end of a long Friday in the laboratory, and funnily enough it’s also an alcohol.  It’s officially known, more boringly, as L-fucitol, 6-deoxy-L-galactitol.  It gets its silly-sounding trivial name because it comes from fucose, which is found in a North Atlantic seaweed with the Latin name Fucus vesiculosus (and the almost equally brilliant common name, bladderwrack).

10.  DEAD Diethyl-azodicarboxylate
What else could I end the list with?  DEAD is the apt acronym for diethyl azodicarboxylate.  This wonderful orange stuff is rather unstable: it’s shock sensitive, light sensitive, toxic and a possible carcinogen and will explode violently if its pure form is heated above 100 degrees C.  When it’s mixed with acid and triphenylphosphine the result is called DEADCAT – brilliant.  DEAD used to be used in quite a few chemical syntheses, but thanks to its impressive list of safety hazards these uses are declining.

For even more silly-named molecules, see http://www.chm.bris.ac.uk/sillymolecules/sillymols.htm – what’s your favourite?

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After Waco: why are fertilisers so dangerous?

Yesterday there was news of a huge fertiliser explosion in the town of West, near Waco, Texas and as I write the search for survivors is ongoing.  It’s a dreadful tragedy:  the blast all but destroyed a school and a nursing home a few hundred metres away, and dozens of homes were also levelled.  More than 160 people have been injured and so far twelve have been found dead.

ammonium nitrateAt the moment the full details are still unknown.  Fertilisers have long been associated with explosives, and terrorists have been known to use fertiliser bombs (something I shall not be discussing in more detail for fear the men in dark suits might come knocking), although it seems that there’s no indication of malicious intent in this case.  Obviously factories make fertiliser all over the world, and they don’t all blow up on a regular basis, so clearly something went very wrong at 8pm local time on the 17th of April.

So why is fertiliser such potentially dangerous stuff?  Can we make it safer?

First of all, we should probably clarify what we mean by ‘fertiliser‘ (or fertilizer, for our American cousins).  Actually the clue is in the name; it’s something which makes the soil more fertile.  In essence, anything that’s added to the soil to supply one or more of the nutrients that plants need.  In particular, most fertilisers supply nitrogen.  If you were paying attention at school, you’ll remember that most of the solid stuff in plants actually comes from the air in the form of carbon dioxide (see that wooden table over there? A plant made most of that out of air. Air. How cool is that?)

However, just like us, plants also need to make protein for growth, and to do that they need nitrogen.  Unlike us, they can’t (with a few notable exceptions) get that protein from eating animals or other plants, on account of not having teeth, the ability to move and so on.  Except for triffids and that plant in Little Shop of Horrors obviously.  But good old air is about 80% nitrogen, so surely if they can get the carbon from carbon dioxide from air they can get nitrogen too?

Well, there are a few plants that can do that, but most can’t.  The problem is that the nitrogen in air, N2, has one of the strongest bonds between its atoms.  It’s very difficult to break, which means it doesn’t get involved in chemical reactions very easily.  And since growing is basically one big complicated mix of chemical reactions, plants can’t easily use the nitrogen in the air.  Before we started chucking fertiliser on the soil plants managed of course, because useable forms of nitrogen do get into the soil from natural processes.  But if you want to grow large quantities of crops year after year, you need to provide a bit of a helping hand, and that’s what fertiliser does, whether it comes from a factory or, ahem, the back of a cow.

nitrogenBut, and here’s the thing, it’s that strong, triple, bond in N2 that makes fertilisers potentially explosive.  Because if it takes a lot of energy to break those bonds, then exactly the same amount of energy is released when they’re formed.  There is no way around this: energy cannot be created or destroyed, or made to disappear.  (Not in real life, anyway – Harry Potter and co follow different rules.  But they’re not real.  Sorry.)

Why do things explode?  Essentially an explosion occurs when a chemical reaction produces lots of hot gases, very quickly.  If these gases have nowhere to go, because they’re in an enclosed space, they put immense pressure on their immediate surroundings as they rapidly expand.  Ultimately those surrounding are apt to give way, with a bang. (High explosives, like dynamite and TNT, are a little different – but fertilisers aren’t high explosives, so we’ll save that topic for another day.)

ParticleTheoryCompounds that contain nitrogen have the potential to produce nitrogen gas.  Gases take up a lot more space than solids because their particles are further apart and, as I’ve already mentioned, when that hugely strong nitrogen triple bond forms lots of energy is released.  So there you are, hot (that’s the energy bit) gas.  Lots of it.  Surround it with walls – say in a container in a factory – and you have the potential for an explosion.

The fertiliser in this case appears to have been ammonium nitrate.  This is made by reacting ammonia (if you remember, Fritz Haber figured out how to produce that) with nitric acid.  Ammonium nitrate’s chemical formula is NH4NO3 – so plenty of nitrogen there.  In fact when ammonium nitrate decomposes it forms water vapour, nitrogen gas and oxygen gas (via some nitrous oxide, aka laughing gas, along the way).  Lots of gases.  Lots of heat.

The factory also contained lots of anhydrous ammonia.  Not especially surprising this, since you need ammonia to make ammonium nitrate – this was a fertiliser factory.  Anhydrous just means ‘no water’, in other words pure ammonia, NH3.  The boiling point of pure ammonia is -33 oC, so you have a bit of a problem right there if your cooling systems fail; it will quickly turn into vapour at room temperature.  This vapour is pretty nasty.  You know that smell when you use hair dye or perming solution (if you’re still in the 80s)?  That.  Times a hundred.  It’s toxic and corrosive (it poisons you while damaging your lungs), and environmentally damaging.  Oh yes, and flammable.  Not as flammable as say, petrol, but flammable enough.

Reports are that there was a fire at the plant before the explosion, so it looks as though the ammonia might have caught fire.  Ammonium nitrate isn’t easy to ignite, but if the fire is contained and it’s exposed to sustained heat it’ll start reacting.  It decomposes at about 210 oC and once it’s started it’s very difficult to stop, because the reaction gives out a lot of heat which causes the surrounding material to react, and so on in a catastrophic spiral – something chemists call a runaway reaction – ultimately leading to detonation.

So fertilisers are potentially dangerous because they contain nitrogen in a more reactive form, which plants can use.  There’s nothing you can do to make fertilisers explosion-proof.  You can’t say, put additives in to make them less explosive.  It’s in their nature.  Take away their explosiveness and you take away their ability to act as fertilisers.

Factories, though, should be following detailed safety procedures and have numerous protective backup systems to prevent disasters like this.  We don’t yet know what went wrong here, but let’s hope some serious lessons are learned.

The acid that really does eat through everything

acid burnThanks to the big screen, many of us think of acids as dangerous, burn-through-anything substances.  Think of those scenes in the Alien movies, where the alien’s blood drips through solid metal, destroying everything in its path.

Of course the vast majority of acids are much more boring.  Vinegar (which contains ethanoic acid) and citric acid (found in, guess what, citrus fruits) are common acids that we eat all the time, and they don’t burn holes in your mouth.  There’s an even stronger acid, hydrocholoric acid (HCl), in your stomach and not only does it not burn you from the inside out (usually), it actually helps you to digest your food and keeps you safe from nasty bacteria.

But there is an acid that’s really, properly scary.  And its name is hydrofluoric acid.

Hydrofluoric acid has the chemical formula HF, but unlike HCl you won’t find this one in a school laboratory, and if it turns up in your stomach you’re in very big trouble.  In true movie-acid style it’s capable of dissolving many materials, and is particularly well-known for its ability to dissolve glass (which is mainly silicon dioxide).  It will also dissolve most ceramics (which contain aluminosilicates: compounds made of chemically-bonded aluminium, silicon and oxygen).  And, like many other acids, it also reacts with metals, so storing it is a bit tricky.  Where do you put something that eats through its container? Well, these days it’s stored in special plastic bottles, but in the 17th century when it was first discovered chemists had to use glass bottles coated inside with wax, and hope the coating was a good one.

HF has been an important industrial chemical for centuries.  It’s used to etch patterns into, and clean, glass and ceramics, and also to dissolve rock samples, for example to extract chemicals or fossils from rocks.  It’s also used to clean stainless steel and, in more recent times, to prepare silicon wafers (used to make silicon chips) in the electronics industries.

The chemist Carl Wilhelm Scheele (him again – he just keeps turning up doesn’t he?) was the first person to produce HF in large quantities in 1771.  Scheele is particularly famous for his bad habit of sniffing and tasting any new substances he discovered.  Cumulative exposure to mercury, arsenic, lead, their compounds, hydrofluoric acid, and other substances took their toll on him and he died on 21 May 1786 at the age of just 43.  And that’s why your science teacher was endlessly telling you not to eat or drink in the laboratory.

So why is hydrogen fluoride so nasty?  For starters the gas is a severe poison that immediately and permanently damages the lungs and the corneas of the eyes – lovely. Hydrofluoric acid solution is a contact-poison that causes deep, initially painless burns which result in permanent tissue death. It also interferes with calcium metabolism, which means that exposure to it can and does cause cardiac arrest (heart attack) and death.  Contact with as little as 160 square centimeters (25 square inches) of skin can kill – that’s about the area of the palm of your hand.

And now for a gruesome and tragic tale: in 1995 a chemist working in Australia was sitting working at a fume cupboard and knocked over a small quantity (100-230 millilitres, about the equivalent of a drinking glass full of water) of hydrofluoric acid onto his lap, splashing both thighs.  He immediately washed his legs with water, jumped into a chlorinated swimming pool at the rear of the workplace, and stayed there for about 40 minutes before an ambulance arrived.  (Should you ever need to know, the proper treatment for HF exposure is calcium gluconate gel: calcium gluconate reacts very quickly with hydrofluoric acid to form non-toxic calcium fluoride, rendering it harmless.)  Sadly, his condition deteriorated in hospital and, despite having his right leg amputated 7 days after the accident, he died from multi-organ failure 15 days after hydrofluoric acid spill.  Remember, that was a spill the size of a glass of water.

Because hydrofluoric acid interferes with nerve function, burns from it often aren’t painful to begin with. Small accidental exposures can go unnoticed, which means that people don’t seek treatment straight away, making the whole thing worse.  Do a Google image search on ‘hydrogen fluoride burns’ and you’ll see some images that will really turn your stomach.

So which would you rather meet?  An alien with acid blood and a habit of laying eggs in your stomach or an invisible gas that destroys your tissues and leaves you, if not dead from multiple organ failure, then suffering with horribly disfiguring burns?  You might stand a better chance against the alien…

Chemical conundrums: #whichelement

Recently a group of us started playing a game of #whichelement on Twitter. Yes I realise this is quite geeky but, hey, at least it’s not #YouDontKnowBeliebersTheMovie or #jeremykyle (if you think those sound more interesting, at the risk of alienating a reader you’re probably reading the wrong blog…)table

Not-really-coincidentally I have also recently become co-admin of a page on Facebook called Brain Teasers, Illusions and Fun (come along if you like puzzles in general).

So here’s a little tie-in; can identify the elements from the clues below? Feel free to post answers in comments. I’ll post my list of answers in a couple of days.

Which element…

  1. Has a clump of earth, or possibly an unpleasant person, in its name?
  2. Is not very entrepreneurial? (thanks @slhyde!)
  3. Is like a bicycle with no audible warning? (thanks @RobSomme!)
  4. Had a place named after it? (this one’s general knowledge)
  5. Has a policeman in its name?
  6. Has a medical test in its name?
  7. Contains a musical instrument?
  8. Sounds like it might drone a bit?
  9. Has a chicken in its name?
  10. Sounds like something a phishing email is trying to get you to fall for?
  11. Has a name that literally means ‘smell’? (more general knowledge)
  12. Could be something you use to take your dog for a walk?
  13. Is an anagram of livers?
  14. Has a bottom in its name?
  15. Has a name that sounds a lot like a famously smelly plant?
  16. Might be described as ‘container donkey ium’
  17. Has a very silly person in it?
  18. Are hayfever sufferers most worried about? (thanks @hullodave!)
  19. Might be a source of amateur dramatics?
  20. Has a name that means goblin? (general knowledge again)

Chemical catastrophes – who were the biggest baddies of chemistry’s past?

As a big fan of chemistry I like to encourage students to believe that it will be a huge force for good in the future, providing us with solutions to problems such as sustainable energy, currently incurable diseases and new materials.  And I hope I’m right about this.  But there’s no escaping the fact that chemistry has a dark, dirty and dangerous past.  In the days before health and safety – oh we take the mickey, but trust me you wouldn’t actually want to be without it – proper regulations and rigorous testing, chemists threw dangerous chemicals around like sweeties.  Quite literally in some cases.  They tasted and smelled toxic and dangerous substances and, worse, they released them on an unsuspecting population with barely a second thought.

baddySo with that in mind, who are my top three biggest baddies of chemistry’s past?

Fritz Haber (1868 – 1934)
The German chemist Fritz Haber gets the number three slot.  In some ways, he’s a bit of double-edged sword.  He did good along with the bad, inventing – along with Carl Bosch – the Haber Bosch process for making ammonia.  No matter what your feelings about inorganic fertilisers, we have to accept that without them we wouldn’t be able to feed the population of this country, let alone the world.  There just isn’t that much pooh out there.  Some people would argue that the population rise Haber’s process facilitated has been a disaster in itself.  But this is to conveniently forget that, had he not developed it, they probably wouldn’t be here to complain about it.

Haber wasn’t entirely a misunderstood genius though.  He’s also been described as the father of chemical warfare for his work on the use of chlorine and other poisonous gases during World War I.  His work included the development of gas mask filters, but he also led teams developing deadly chlorine gas used in trench warfare.  He was even there to supervise its release.  He was a patriotic German and believed he was doing the right thing, supporting his country in the war effort.  During the second world war Haber’s skills were initially sought out by the Nazis, who offered him special funding to continue his work on weapons.  However Haber was Jewish, so in common with other scientists in a similar position he ended up leaving Germany in 1933.

Famously, Haber’s first wife disagreed vehemently with his work on chemical warfare.  In fact, perhaps unable to cope with the fact that he had personally overseen the successful use of chlorine in 1915, she committed suicide by shooting herself with his service revolver.  That same morning, Haber left again to oversee gas release against the Russians, leaving behind his grieving 13 year-old son.

Haber was awarded the Nobel prize for Chemistry in 1919 for his work on the Haber Process.  So the story goes, other scientists at the ceremony refused to shake his hand in protest at his work with chemical weapons.  A tragic story all round.

Carl Wilhelm Scheele (1742 – 1786)
We’ve seen Scheele’s name come up before of course.  In his short – thanks to his bad habit of tasting and sniffing toxic chemicals – life he made a lot of chemical discoveries, but didn’t get the recognition for many of them because he always seemed to publish after someone else.  The ones he is remembered for always seem to be the horribly dangerous ones (maybe no one else wanted the credit).  For example he discovered hydrogen cyanide (a poison beloved of many an Agatha Christie villain, hydrogen fluoride (a highly toxic gas that forms the incredibly dangerous hydrofluoric acid when dissolved in water) and hydrogen sulfide (toxic, highly flammable and stinks of rotten eggs).

But his most harmful contribution to the world was undoubtedly Scheele’s Green, the arsenic-based yellow-green dye that was used to colour fabrics, paints, candles, toys and even, most tragically of all, foodstuffs in the 1800s.  It’s impossible to count but it was undoubtably responsible, directly and indirectly, for huge numbers of deaths in the 19th century.  Essentially he invented a deadly poison that ended up in thousands of homes all around the world.  Aren’t you glad we have safety testing these days?

Thomas Midgely (1889-1944)
Who was worse, Scheele or Midgely?  It’s a tough call, but I think Midgely takes it, particularly because he had some inkling exactly how damaging at least some of his work might turn out to be.

Midgely is famously responsible for synthesising the first CFC, freon.  CFCs, or chlorofluorocarbons, are neither toxic nor flammable, so were considered much safer than other propellants and refrigerants used at the time.  In fact, he was even awarded the Perkin Medal in 1937 for his work.  This, of course, was some time before the terrible consequences of CFCs were realised.  As we now know, they turned out to very damaging to the ozone layer, and in 1989 twelve European Community nations agreed to ban their production, and they have since been phased out across the world.

Although CFCs were a disaster, Midgely could at least be defended for having no way of knowing how disastrous they would ultimately turn out to be.  Not so for his other famous invention.  Whilst working at General Motors he discovered that adding tetraethyllead, or TEL, to petrol (aka gasoline) prevented ‘knocking‘ in internal combustion engines, which is when the air/fuel mixture ignites at slightly the wrong time.  Knocking makes the engine much less efficient, and so preventing it was a big issue.  You’d think Midgely might have accepted that lead in petrol was a bad idea when he had to take a vacation to recover from severe lead poisoning, but no.  In fact he appeared to have been pretty cynical about the whole thing, pouring TEL over his hands at a press conference in 1924 to demonstrate its apparent safety (its not, and he had to take more time off afterwards to recover).

Unfortunately burning fuel with TEL in it disperses lead into the air where it’s readily inhaled by innocent bystanders, and it’s particularly harmful to children.  Lead exposure has been linked to low IQ and antisocial behaviour, and recently researchers suggested that the ban on leaded petrol across the world in the early 2000s might now be leading to a reduced crime rate.

So for knowingly poisoning people worldwide with lead, and unknowingly taking out a chunk of the ozone layer, Midgely gets my award as biggest chemical baddy.

Would you pick someone else?

Another famous female chemist…

Today I was reminded of another, very, famous female chemist I somehow forgot about when I wrote my blog post on the topic a little while ago.

thatcher ice creamYes, Margaret Thatcher: born 13th October 1925, died today, 8th April 2013.  She read Chemistry at Oxford between 1943-1947.  How could I, a child of the 80s, forget her?  It’s true, she became famous for things other than chemistry, but nevertheless that was her subject.

So never mind the politics.  What did she do as a chemist?

In her final year at Oxford, she specialised in X-ray crystallography under the supervision of Dorothy Hodgkin (another shameful omission on my part – Hodgkin developed the technique of protein crystallography, confirming the structure of penicillin and then determining the structure of vitamin B12, for which she was awarded a Nobel prize).

After graduating Thatcher, née Margaret Roberts, worked for BX Plastics.  After moving to Dartford, she worked as a research chemist for J. Lyons and Co. in Hammersmith, as part of a team developing emulsifiers for ice cream.

So what do emulsifiers do?  Well, as everyone knows, oil and water don’t mix.  At least, not permanently.  You can shake them together temporarily, but they’ll gradually separate.  Emulsifiers act as a sort of bridge between the oil and the water.  They have a hydrophobic (‘water hating’) end and a hydrophilic (‘water loving’) end.  The hydrophobic bit buries itself into oil droplets, whereas the hydrophilic bit hangs out with the water molecules.  Emulsifiers keep everything working together; they’re the mediators of the molecular world.

There are lots of natural emulsifiers.  After all, living things contain fats and water, and it could be potentially problematic if everything kept separating out.  In particular, egg yolks contain an emulsifier called lecithin (don’t worry vegans, there’s a soy version too).  Next time you’re eating pretty much anything with fat in it (chocolate, ice cream, sauces, salad dressing) check out the label – lecithin is probably on there, or its E number, E322.

Anyway, back to Thatcher.  What did she do?  J. Lyons and Co. tasked her with getting more air into ice cream.  The difficulty was keeping it stable, so that it didn’t just collapse into a watery puddle.  The type of the ice cream that Thatcher worked on is what we call today ‘soft serve‘ ice cream – the stuff that gets squirted out of those machines ice cream vans lug around, and into which you stick a delicious chocolaty flake.  Soft serve is has less milk fat (strangely appropriate, given that Thatcher later became famous as the ‘milk snatcher’) and is produced at a higher temperature than normal ice cream, both of which make it cheaper.

Thatcher’s team managed to double the amount of air that could be crammed into the mix, and so those big squirty machines and Mr Whippy was born.

So no matter what you think of her politics, remember that without her work you wouldn’t be able to enjoy a 99 flake from the ice cream van in the summer.  If we see summer this year…

Bronze, humbugs, wallpaper and electronics: what’s your favourite element?

As a chemistry teacher I’m sometimes asked for my favourite element. Don’t tell anyone, but I don’t really have a single favourite. That would be a terribly boring answer though, so I usually pick something to make a relevant point. Carbon, for example, for being the stuff of life, for having a whole third of chemistry – organic chemistry – devoted to its compounds, and because diamonds are fascinating and really very pretty things. Or sometimes I go for xenon, for being a noble gas, for its potential use as an anaesthetic, and just because its name starts with an X (have a go at this: name five words that start with X without googling*).

And then, if I think we’ve got time for a story, I might go for the famous and much-maligned element number 33: arsenic (As).  After all, if it weren’t one of the world’s most famous poisons you’d have to love it just for having the word ‘arse’ in its name.

arsenic poison bottle

So, a little background. It’s the 20th most common element in the Earth’s crust, and is actually one of the oldest known elements. It was officially first documented around 1250 by a Dominican friar called Alvertus Magnus but it’s been used for more than 3000 years, going back as far as the bronze age when it was added to bronze to make it harder. It’s a metalloid, which means it’s neither quite metal nor non-metal, and these days its most important use is in the electronics industry.

There are many, many interesting stories associated with arsenic. One of my personal favourites, if that’s the right word, is the story of the Bradford Sweets Poisoning. Back in 1858 a Bradford confectioner known as ‘Humbug Billy’ was buying his mint humbugs from another local character called Joeseph Neal. At the time, sugar was expensive so Neal was in the habit of cutting it with something called ‘daft’, a mysterious substance that could contain anything from limestone to plaster of Paris. Neal sent his lodger to the local pharmacy to collect the daft. The druggist was ill, and somehow or other his assistant managed to sell Neal’s lodger 12 pounds of arsenic trioxide (you might imagine this was an expensive error, but arsenic was actually surprisingly cheap: half an ounce cost about the same as a cup of tea).

The mistake went undetected, despite the sweetmaker who worked for Neal suffering symptoms of illness during the sweet-making process, and despite the resulting humbugs looking so different from normal that Humbug Billy managed to buy them from Neal at a discount. Humbug Billy himself promptly became ill after eating the sweets, but nevertheless still sold 5 pounds of them from his market stall that day. Subsequently about 20 people died and a further 200 became ill. To start with the deaths were blamed on cholera, common at the time, but soon they were traced to the sweet stall. Later analysis showed that each humbug contained enough arsenic to kill two people.

This tragic tale led to The Pharmacy Act 1868 and the requirement for proper record keeping by pharmacists. Ultimately it also led to legislation preventing the adulteration of foodstuffs, such as for example, oh I don’t know, sneaking horse into something labelled beef.

Historically arsenic was also used in dyes and pigments, perhaps most famously Scheele’s Green – also known as copper arsenite and invented by Carl Wilhelm Scheele in 1775 – produced a wonderful green colour that was used to dye wallpaper, fabrics, added to paints, children’s toys and even sweets. Many poisonings in Victorian times were linked to toxic home furnishings and clothing. In fact, this probably explains the superstition that green is an unlucky colour, especially for children’s furnishings and clothes. Arsenic poisoning being very unlucky indeed. Next time you’re near a baby store, have a look: even today (arsenic pigments now long defunct, thank goodness) you still don’t see that many green things.

One of the most famous people to die from arsenic poisoning was probably Napoleon. Originally thought to have been deliberately poisoned, analysis of his hair samples in 2008 demonstrated that his exposure had been long-term rather than sudden, and was probably due to the lovely green wallpaper and paint decorating the room in which he’d been confined.

Then there’s George III, the famously ‘mad King George’. His episodes of madness and physical symptoms were linked to the disease porphyria, and 2004 studies of samples of his hair also found very high levels of arsenic which may well have triggered his symptoms. Ironically, he may have been exposed to arsenic as part of his medical treatment.

In fact historically arsenic was used to treat many medical complaints. It’s even been used as an aphrodisiac, thanks to the fact that small doses stimulate blood flow. In 1851 it was reported that peasants in Styria, a remote region in Austria, were in the habit of swallowing solid lumps of the stuff that, fortunately, passed through their digestive system relatively intact. However they absorbed just enough to given the women a rosy glow and the men an increased libido – resulting in something of a population boom. Upon hearing about this British manufacturers immediately began selling arsenic-containing beauty products, including soap and skin treatments, with predictably tragic results.

Thanks to its toxicity arsenic is used in pesticides, herbicides and insecticides, although these uses are gradually being phased out. Despite being notoriously poisonous to most organisms, there are interestingly some species of bacteria whose metabolism relies on arsenic. Arsenic turns up naturally in groundwater and is absorbed by plants such as rice, as well turning up, in the form of arsenobetaine, in mushrooms and fish. Don’t worry though, this particular arsenic compound is virtually non-toxic.

Today gallium arsenide, with the brilliant chemical formula GaAs, is one of biggest uses of arsenic. It’s a semiconductor, used in the manufacture of many electronic devices, including solar cells. Its electronic properties are, in some ways, superior to silicon so despite its inherent dangers its important stuff.

So it definitely has one of the most fascinating histories of any of the elements, and I’ve only mentioned a tiny number of the many, many arsenic-related stories out there.  From the bronze age to the computer age, arsenic has been with us, both friend and foe, and will be with us for a lot longer yet.

So, what’s your favourite element? Tell me and maybe I’ll write about it in a future post!

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* betcha said xenon (of course), xylophone, xi and xu if you play Scrabble, x-ray and maybe xylem. Am I right?