Encyclopaedia corner: elements, bad smells, and purples

28 July 2020

Interview with 

Adam Murphy, The Naked Scientists

PURPLE_FABRIC

Purple silk.

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Adam Murphy took Phil Sansom through some extra credit 'material' from the Chemistry & Materials round...

Phil - Adam - now that we've had Chemistry & Materials, can you give us the scores just for that round, please?

Adam - Okay. Just for that round, we have: Bhavesh got two in that round, then Megan with six, and Chris with a pretty fantastic seven.

Phil - Wow. Came from not backing himself to an excellent performance. Well done Chris, but also to the other two. Now, Adam, over in encyclopaedia corner, what would you pick out from that?

Adam - So one of the things I was looking at was elements. And we said there are 118 elements; that 118th element is called - hang on, let me get it right - oganesson.

Phil - Oganesson.

Adam - Yeah. And it was discovered all the way back in 2002. So it's an 18 year old element, but we didn't get a name for it until 2016.

Phil - Now can you tell me anything about it? Is it bizarre and radioactive, and lives for half a moment, or what?

Adam - All those elements that are that side live for really low level times. Even if you go and look up sheets about it, you get "it will have this property. Maybe. We think."

Phil - Right, right. Oganesson then - what's the symbol for that?

Adam - It's Og. So it is the OG element.

Phil - The OG element! That's helpful though, because you get some elements that are... well, presumably not designed with us English speakers in mind, because their letter acronyms don't actually match the letters in their English name.

Adam - Yeah, that's very true. One great example of that is lead. Lead's symbol on the periodic table is Pb. But if you go into Latin, the Latin word for lead is 'plumbum'. And that's where we get that Pb from. And as well as that, in Latin they used to coat their drainpipes in lead, and they used to coat the pipes that brought water around the place. So the people who would take care of those water pipes under the ground were 'plumb-ers'.

Phil - Well that makes sense, but now I'm really worried for their health, because lead is toxic...

Adam - They didn't know quite how toxic it was! But it's why we have the word plumber, and why it has that weird, random 'b' stuck in the middle of it silently.

Phil - Oh how interesting. Elements aside, anything else from that round take your fancy? Any interesting answers?

Adam - Well just with all the weird chemicals that have come through, can I tell you about one of my favourite chemicals?

Phil - Absolutely.

Adam - So there's a chemical called thioacetone, and it is the stinkiest chemical we have ever discovered. In 1890 it got out in Leeds, and the smell was described as "fearful".

Phil - Jesus!

Adam - And then in Esso research south of Oxford - and I have this written down to tell you - "two of our chemists, who had done no more than investigate the cracking of minute amounts of trithioacetone, found themselves the object of hostile stares in a restaurant and suffered the humiliation of having a waitress spray the area around them with deodorant.

Phil - Oh my goodness. So this is some real stink bomb stuff, right?

Adam - Oh yeah. In a town in Freiburg, you could smell it nearly a full kilometre away when a few drops of this stuff sprayed out.

Phil - Why were these scientists even using this chemical? Were they creating the world's best stink bomb?

Adam - It generally is what happens when you take this other thing called trithioacetone, which is actually used a lot in flavouring compounds.

Phil - How strange is that!

Adam - Yeah, so something that we actually have as tasty, if you make it wrong or it breaks the wrong way, it becomes the stinkiest thing we know of - or one of.

Phil - Just before we move on - any other facts for us from that set of questions back there?

Adam - One of the things that we've talked about in chemistry - a lot of the questions had what colour the elements were. And one of my favourite stories when it comes to colour in science is the making of purple. So for years, purple was only worn by emperors and kings and queens; the Queen's robes are often purple. And that's because it's almost impossible to get a purple that both looks really, really purple, and stays for a really long period of time. So where do you think that purple came from?

Phil - Is it from a... is it from a rock?

Adam - It's something that moves nearly as slowly as a rock! So we get it from a kind of snail.

Phil - From its shell?

Adam - No, you have to boil the poor snail to get it.

Phil - Oh really!

Adam - Yeah. So it's this kind of snail called a Murex snail, and it's actually a predatory snail. And it shoots this stuff out to sedate its prey before it eats it, so it's sleepy and it can eat it. Underwater, that chemical is cloudy and milky. But above water, when it's exposed to oxygen, it turns into this really, really deep purple. And for years, this was the purple for all fancy robes. It's called Tyrian purple. And it took thousands of snails to make grams of dye. So that's why it was so hugely expensive.

Phil - Do you know what changed? Do we still boil snails to get our lovely violets?

Adam - What happened was -we don't still boil snails, the snails are left to have a good time underwater - but in the 19th Century, this guy William Henry Perkin, he was working on his schoolwork. Well, his undergraduate work - he was in college. And he was trying to come up with something that could be replaced with quinine, because quinine has some medicinal properties. And he screwed it up, and he made this just horrible black mass; or as he later checked, a very, very, very dark purple mess. That became the first synthetic purple dye, called mauvine. And then that became the replacement dye, and then people from that discovered loads of synthetic purples. Purple used to be illegal to wear, and now I can go down to Primark and just grab a purple shirt if I want to.

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