The Chronicles of the Chronicle Flask: 2018

As has become traditional, I’m finishing off this year with a round-up of 2018’s posts. It’s been a good year: a few health scares which turned out to be nothing much to worry about, one which turned out to be a genuine danger, a couple of cool experiments and some spectacular shiny balls. So without further ado, here we go…

Things were a bit hectic at the start of this year (fiction writing was happening) and as a result January was quiet on the blog. But not on the Facebook page, where I posted a couple of general reminders about the silliness of alkaline diets which absolutely exploded, achieving some 4,000 shares and a reach (so Facebook tells me anyway) of over half a million people. Wow. And then I posted a funny thing about laundry symbols which went almost as wild. It’s a strange world.

February featured BPA: an additive in many plastics.

In February I wrote a piece about BPA (Bisphenol A), which was the chemical scare of the day. There’s always one around January/February time. It’s our penance for daring to enjoy Christmas. Anyway, BPA is a chemical in many plastics, and of course plastic waste had become – and remains – a hot topic. BPA is also used in a number of other things, not least the heat sensitive paper used to produce some shopping receipts. It’s not a harmless substance by any means, but it won’t surprise anyone to learn that the risks had, as is usually the case, been massively overstated. In a report, the European Food Safety Authority said that the health concern for BPA is low at their estimated levels of exposure. In other words, unless you’re actually working with it – in which case you should have received safety training – there’s no need to be concerned.

In March I recorded an episode for the A Dash of Science podcast, and I went on to write a post about VARD, which stands for Verify, Author, Reasonableness and Date. It’s my quick and easy way of fact-checking online information – an increasingly important skill these days. Check out the post for more info.

April ended up being all about dairy and vitamin D.

April was all about dairy after a flare-up on Twitter on the topic, and went on to talk about vitamin D. The bottom line is that everyone in the UK should be taking a small vitamin D supplement between about October and March, because northern Europeans simply can’t make vitamin Din their skin during these months (well, unless they travel nearer to the equator), and it’s not a nutrient we can easily get from our food. Are you taking yours?

May featured fish tanks, following a widely reported story about a fish-owner who cleaned out his tank and managed to release a deadly toxin that poisoned his entire family. Whoops. It turns that this was, and is, a real risk – so if you keep fish and you’ve never heard of this before, do have a read!

In June I wrote about strawberries, and did a neat experiment to show that strawberries could be used to make pH indicator. Who knew? You do, now! Check it out if you’re looking for some chemistry to amuse yourself over the holidays (I mean, who isn’t?). Did you know you can make indicators from the leaves of Christmas poinsettia plants, too?

Slime turned up again in July. And December. And will probably keep on rearing its slimy head.

July brought a subject which has turned up again recently: slime. I wrote about slime in 2017, too. It’s the gift that keeps on giving. This time it flared up because the consumer magazine and organisation Which? kept promoting research that, they claimed, showed that slime toys contain dangerous levels of borax. It’s all rather questionable, since it’s not really clear which safety guidelines they’re applying and whether they’re appropriate for slime toys. Plus, the limits that I was able to find are migration limits. In other words, it’s not appropriate to measure the total borax content of the slime and declare it dangerous – they should be looking at the amount of borax which is absorbed during normal use. Unless your child is eating slime (don’t let them do that), they’re never going to absorb enough borax to do them any harm. In other words, it’s a storm in a slimepot.

August was all about carbon dioxide, after a heatwave spread across Europe and there was, bizarrely, a carbon dioxide shortage which had an impact on all sorts of things from fizzy drinks to online shopping deliveries. It ended up being a long-ish post which spanned everything from the formation of the Earth, the discovery of carbon dioxide, fertilisers and environmental concerns.

September featured shiny, silver balls.

In September I turned my attention to a chemical reaction which is still to this day used to coat the inside of glass decorations with a thin layer of reflective silver, and has connections with biochemistry, physics and astronomy. Check it out for some pretty pictures of silver balls, and my silver nitrate-stained fingers.

In October I was lucky enough to go on a ‘fungi forage’ and so, naturally, I ended up writing all about mushrooms. Did you know that a certain type of mushroom can be used to make writing ink? Or that some mushrooms change colour when they’re damaged? No? You should go back and read that post, then! (And going back to April for a moment, certain mushrooms are one of the few sources of vitamin D.)

Finally, November ended up being all about water, marking the 235th anniversary of the day that Antoine Lavoisier formally declared water to be a compound. It went into the history of water, how it was proven to have the formula H2O, and I even did an experiment to split water into hydrogen and oxygen in my kitchen – did you know that was possible? It is!

As December neared, the research for my water piece led me to suggest to Andy Brunning of Compound Interest that this year’s Chemistry Advent might feature scientists from the last 24 decades of chemistry, starting in the 1780s (with Lavoisier and Paulze) and moving forward to the current day. This turned out to be a fantastic project, featuring lots of familiar and not quite so-familiar scientists. Do have a look if you didn’t follow along during December.

And that’s it for this year. I hope it’s been a good one for all my readers, and I wish you peace and prosperity in 2019! Suggestions for the traditional January Health Scare, anyone? (Let’s hope it’s not slime again, I’m getting really tired of that one now…)


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Marvellous Mushroom Science

Glistening ink caps produce a dark, inky substance.

Yesterday I had the fantastic experience of a “fungi forage” with Dave Winnard from Discover the Wild, organised by Incredible Edible Oxford. There are few nicer things than wandering around beautiful Oxfordshire park- and woodland on a sunny October day, but Dave is also an incredibly knowledgeable guide. I’ve always thought mushrooms and fungi were interesting – living organisms that are neither plants nor animals and which we rely on for everything from antibiotics to soy sauce – but I had lots to learn.

Did you know, for example, that fungi form some of the largest living organisms on our planet? And that without them most of our green plants wouldn’t have evolved and probably wouldn’t be here today?

And from a practical point of view, what about the fact that people once used certain fungi to light fires? I’ve always imagined fungi as being quite wet things with a high water content (unless they’re deliberately dried, of course), but some are naturally very dry. Ötzi, the mummified man thought to have lived between 3400and 3100 BCE, was found with two types of fungus on him: birch fungus, which has antiparasitic properties, and a type of tinder fungus which can be ignited with a single spark and will smolder for days.

Coprine causes unpleasant symptoms, including nausea and vomiting, when consumed with alcohol.

Then, of course, there’s all the interesting chemistry. Early on in the day, we came across some glistening ink caps.The gills of these disintegrate to produce a black, inky liquid which contains a form of melanin and can be used as ink. And there’s more to this story: as I’ve already mentioned, fungi are not plants and they can’t photosynthesise, but it seems that some fungi do use melanin to harness gamma rays as energy for growth. Extra mushrooms for the Hulk’s breakfast, then?

Moving away from pigments for a moment, a related species to the glistening ink cap, the common ink cap, contains a chemical called coprine. This causes lots of unpleasant symptoms if it’s consumed with alcohol, similar to Disulfiram, the drug used to treat alcoholism. For this reason one of this mushroom’s other names is tippler’s bane. The coprine in the mushrooms effectively causes an instant hangover by accelerating the formation of acetaldehyde (also known as ethanal) from alcohol. Definitely don’t pair that mushroom omelette with a nice bottle of red and, worse, you’ll need to stay off the booze for a while: apparently the effects can linger for a full three days.

Yellow stainer mushrooms look like field mushrooms, but are poisonous.

We also came across some yellow stainer mushrooms. These look a lot like field mushrooms, but be careful – they aren’t edible. They cause nasty gastric sympoms and are reportedly responsible for most cases of mushroom poisoning in this country, although some people seem to be able to eat them without ill effect. They had a slightly chemically scent that reminded me “new trainer” smell – sort of rubbery and plasticky. It’s often described as phenolic, but I have to say I didn’t detect that myself – although yellow stainers have been shown to contain phenol and this could account for their poisonous nature. Anyway, it was an aroma that wouldn’t be entirely unpleasant if I were opening a new shoebox, but it wasn’t something I’d really want to eat. Apparently the smell gets stronger as you cook them, so don’t ignore what your nose is telling you if you think you have a nice pan of field mushrooms.

4,4′-Dimethoxyazobenzene is an azo dye.

The real giveaway with yellow stainers, though, is their tendency to turn yellow when bruised or scratched, hence the name. This, it seems, is due to 4,4′-dimethoxyazobenzene. The name might not be familiar, but A-level Chemistry students will recognise the structure: it’s an azo-dye. Quite apart from being a very useful word in Scrabble, azo compounds are well-known for their characteristic orange/yellow colours. It’s not really clear whether it forms in the mushroom due to some sort of oxidation reaction, or whether it’s in the cells anyway but only becomes visible when the cells are damaged. Either way, it’s something to look out for if you spot a patch of what look like field mushrooms.

The blushing wood mushroom.

We also came across several species which are safe to eat. One I might look out for in future is the blushing wood mushroom. As is often the way with fungi, the name is literal rather than merely poetic. These mushrooms have a light brown cap, beige gills, and a pale stem, but they turn bright red when cut or scratched due to the formation of an ortho-quinone. It’s quite a dramatic colour-change, and makes them pretty easy to identify. Apparently they’re normally uncommon here, but we found quite a lot of them, which might be something to do with this year’s unusally hot and dry summer.

Red ortho-quinone causes blushing wood mushrooms to literally blush.

I tried to find out the reasons for these colour-changes. In the plant and animal kingdoms pigments are usually there for good reason: camouflage, signalling and communication or, as with chlorophyll, as a way of making other substances. Fruits, for example, often turn bright red as they ripen because it makes them stand out from the green foilage and encourages animals to eat them so that the seeds can be spread. Likewise, they’re green when they’re unripe because it makes them less obvious and less appealing. But what’s the advantage for the mushroom to change colour once it’s already damaged? Perhaps there isn’t one, and it’s just an accident of their biology, but if so it seems strange that it’s a feature of several species. I couldn’t find the answer; if any mycologists are reading this and know, get in touch!

Velvet shank mushrooms.

Other edible species we met were fairy ring champignons, field blewits and jelly ear fungus – which literally looks like a sort of transparent ear. I’ll definitely be looking out for all of these in the future, but it’s important to watch out for dangerous lookalikes. Funeral bell mushrooms, for example, look like the velvet shank mushrooms we found but, once again, the name is quite literal – funeral bells contain amatoxins and eating them can cause kidney and liver failure. As Dave was keen to remind us: never eat anything you can’t confidently name!


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