The Chronicles of the Chronicle Flask: 2019

Happy New Year, everyone! Usually, I write this post in December but somehow things have got away from me this year, and I find myself in January. Oops. It’s still early enough in the month to get away with a 2019 round-up, isn’t it? I’m sure it is.

It was a fun year, actually. I wrote several posts with International Year of the Periodic table themes, managed to highlight the tragically-overlooked Elizabeth Fulhame, squeezed in something light-hearted about the U.K.’s weird use of metric and imperial units and discovered the recipe for synthetic poo. Enjoy!

Newland’s early table of the elements

January started with a reminder that 2019 had been officially declared The Year of the Periodic Table, marking 150 years since Dmitri Mendeleev discovered the “Periodic System”. The post included a quick summary of his work, and of course mentioned the last four elements to be officially named: nihonium (113), moscovium (115), tennessine (117) and oganesson (118). Yes, despite what oh-so-many periodic tables still in widespread use suggest (sort it out in 2020, exam boards, please), period 7 is complete, all the elements have been confirmed, and they all have ‘proper’ names.

February featured a post about ruthenium. Its atomic number being not at all significant (there might be a post about rhodium in 2020 😉). Ruthenium and its compounds have lots of uses, including cancer treatments, catalysis, and exposing latent fingerprints in forensic investigations.

March‘s entry was all about a little-known female chemist called Elisabeth Fulhame. She only discovered catalysis. Hardly a significant contribution to the subject. You can’t really blame all those (cough, largely male, cough) chemists for entirely ignoring her work and giving the credit to Berzelius. Ridiculous to even suggest it.

An atom of Mendeleevium, atomic number 101

April summarised the results of the Element Tales Twitter game started by Mark Lorch, in which chemists all over Twitter tried to connect all the elements in one, long chain. It was great fun, and threw up some fascinating element facts and stories. One of my favourites was Mark telling us that when he cleared out his Grandpa’s flat he discovered half a kilogram of sodium metal as well as potassium cyanide and concentrated hydrochloric acid. Fortunately, he managed to stop his family throwing it all down the sink (phew).

May‘s post was written with the help of the lovely Kit Chapman, and was a little trot through the discoveries of five elements: carbon, zinc, helium, francium and tennessine, making the point that elements are never truly discovered by a single person, no matter what the internet (and indeed, books) might tell you.

In June I wrote about something that had been bothering me a while: the concept of describing processes as “chemical” and “physical” changes. It still bothers me. The arguments continue…

In July I came across a linden tree in a local park, and it smelled absolutely delightful. So I wrote about it. Turns out, the flowers contain one of my all-time favourite chemicals (at least in terms of smell): benzaldehyde. As always, natural substances are stuffed full of chemicals, and anyone suggesting otherwise is at best misinformed, at worst outright lying.

Britain loves inches.

In August I wrote about the UK’s unlikely system of units, explaining (for a given value of “explaining”) our weird mishmash of metric and imperial units. As I said to a confused American just the other day, the UK is not on the metric system. The UK occasionally brushes fingers with the metric system, and then immediately denies that it wants anything to do with that sort of thing, thank you very much. This was my favourite post of the year and was in no way inspired by my obsession with the TV adaptation of Good Omens (it was).

In September I returned to one of my favourite targets: quackery. This time it was amber teething necklaces. These are supposed to work (hmm) by releasing succinic acid from the amber beads into the baby’s skin where it… soothes the baby by… some unexplained mechanism. They don’t work and they’re a genuine choking hazard. Don’t waste your money.

October featured a post explaining why refilling plastic bottles might not be quite as simple as you thought. Sure, we all need to cut down on plastic use, but there are good reasons why shops have rules about what you can, and can’t, refill and they’re not to do with selling more bottles.

November continued the environmental theme with a post was all about some new research into super-slippery coatings that might be applied to all sorts of surfaces, not least ceramic toilet bowls, with the goal of saving some of the water that’s currently used to rinse and clean such surfaces. The best bit about this was that I discovered that synthetic poo is a thing, and that the recipe includes miso. Yummy.

Which brings us to… December, in which I described some simple, minimal-equipment electrolysis experiments that Louise Herbert from STEM Learning had tested out during some teaching training exercises. Got a tic tac box, some drawing pins and a 9V battery? Give it a go!

Well, there we have it. That’s 2019 done and dusted. It’s been fun! I wonder what sort of health scares will turn up for “guilty January”? Won’t be long now…


Like the Chronicle Flask’s Facebook page for regular updates, or follow @chronicleflask on Twitter. Content is © Kat Day 2020. You may share or link to anything here, but you must reference this site if you do. If you enjoy reading my blog, please consider buying me a coffee through Ko-fi using the button below.
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Electrolysis Made Easy(ish)

Some STEM Learning trainee teachers, looking very keen!

Back in November last year (was it really that long ago??) I wrote a blog post about water, in which I described a simple at-home version of electrolysis. I didn’t think much of it at the time, beyond the fact that it was oddly exciting to do this experiment—that usually involves power-packs and wires and all sorts of other laboratory stuff—with just a 9V battery, a tic tac box and some drawing pins.

Then, hey, what do you know, someone actually read my ramblings! Not only that, read them and thought: let’s try this. And so it was that Louise Herbert, from STEM Learning (that’s their Twitter, here’s their website), contacted me last month and asked if I’d mind if they used the Chronicle Flask as a source for a STEM learning course on practical work.

Of course not, I said, and please send me some pictures!

And they did, and you can see them scattered through this post. But let’s have a quick look at the chemistry…

Electrolysis is the process of splitting up compounds with electricity. Specifically, ionic compounds: the positively-charged ion in the compound travels to the negative electrode, and the negatively-charged ion moves to the positive electrode.

Water is a covalent compound with the formula H2O, but it does split into ions.

Only… wait a minute… water isn’t ionic, is it? So… why does it work on water? Er. Well. Water does split up into ions, a bit. Not very much under standard conditions, but a bit, so that water does contain very small amounts of OH and H+ ions. (In fact, I can tell you exactly how many H+ ions there are at room temperature, it’s 1×10-7 mol dm-3, and, in an astonishing chemistry plot twist, that 7 you see there is why pure water has a pH of, yep, 7.)

So, in theory you can electrolyse water, because it contains ions. And I’ve more than once waved my hands and left it at that, particularly up to GCSE level (age 16 in the U.K.) because, although it’s a bit of a questionable explanation, (more in a minute), electrolysis is tricky and sometimes there’s something to be said for not pushing students so far that their brains start to dribble out of their ears. (As the saying goes, “all models are wrong, but some are useful.”)

Chemists write half equations to show what the electrons are doing in these sorts of reactions and, in very simple terms, we can imagine that at the positive electrode (also called the anode) the OH ions lose electrons to form oxygen and water, like so:

4OH —> 2H2O + O2 + 4e

And conversely, at the negative electrode (also called the cathode), the H+ ions gain electrons to form hydrogen gas, like so:

2H+ + 2e —> H2

These equations balance in terms of species and charges. They make the point that negative ions move to the anode and positive ions move to the cathode. They match our observation that oxygen and hydrogen gases form. Fine.

Except that the experiment, like this, doesn’t work very well (not with simple equipment, anyway), because pure water is a poor electrical conductor. Yes, popular media holds that a toaster in the bath is certain death due to electrocution, but this is because bathwater isn’t pure water. It’s all the salts in the water, from sweat or bath products or… whatever… that do the conducting.

My original experiment, using water containing a small amount of sodium hydrogen carbonate.

To make the process work, we can throw in a bit of acid (source of H+ ions) or alkali (source of OH ions), which improves the conductivity, and et voilà, hydrogen gas forms at the cathode and oxygen gas forms at the anode. Lovely. When I set up my original 9V battery experiment, I added baking soda (sodium hydrogencarbonate), and it worked beautifully.

But now, we start to run into trouble with those equations. Because if you, say, throw an excess of H+ ions into water, they “mop up” most of the available OH ions:

H+ + OH —> H2O

…so where are we going to get 4OH from for the anode half equation? It’s a similar, if slightly less extreme, problem if you add excess alkali: now there’s very little H+.

Um. So. The simple half equations are… a bit of a fib (even, very probably, if you use a pH neutral source of ions such as sodium sulfate, as the STEM Learning team did — see below).

What’s the truth? When there’s plenty of H+ present, what’s almost certainly happening at the anode is water splitting into oxygen and more hydrogen ions:
2H2O —>  + O2 + 4H+ + 4e

while the cathode reaction is the same as before:
2H+ + 2e —> H2

Simple enough, really, but means we use the “negative ions are going to the positive electrode” thing, which is tricky for GCSE students, who haven’t yet encountered standard electrode potentials, to get their heads around, and this is why (I think) textbooks often go with the OH-reacts-at-the-anode explanation.

Likewise, in the presence of excess alkali, the half equations are probably:

Anode: 4OH —> 2H2O + O2 + 4e
Cathode: 2H2O + 2e —> H2 + OH

This time there is plenty of OH, but very little H+, so it’s the cathode half equation that’s different.

Taking a break from equations for a moment, there are some practical issues with this experiment. One is the drawing pins. Chemists usually use graphite or platinum electrodes in electrolysis experiments because they’re inert. But good quality samples of both are also (a) more difficult and more expensive to get hold of and (b) trickier to push through a tic tac box. (There are examples of people doing electrolysis with pencil “leads” online, such as this one — but the graphite in pencils is mixed with other compounds, notably clay, and it’s prone to cracks, so I imagine this works less often and less well than these photos suggest.)

A different version of the experiment…

Drawing pins, on the other hand, are made of metal, and will contain at least one of zinc, copper or iron, all of which could get involved in chemical reactions during the experiment.

When I did mine, I thought I was probably seeing iron(III) hydroxide forming, based, mainly, on the brownish precipitate which looked fairly typical of that compound. One of Louise’s team suggested there might be a zinc displacement reaction occurring, which would make sense if the drawing pins are galvanized. Zinc hydroxide is quite insoluble, so you’d expect a white precipitate. Either way, the formation of a solid around the anode quickly starts to interfere with the production of oxygen gas, so you want to make your observations quickly and you probably won’t collect enough oxygen to carry out a reliable gas test.

In one of their experiments the STEM Learning team added bromothymol blue indicator (Edit: no, they didn’t, oops, see below) to the water and used sodium sulfate as (a pH neutral) source of ions. Bromothymol blue is sensitive to slight pH changes around pH 7: it’s yellow below pH 6 and blue above pH 7.6. If you look closely at the photo you can see that the solution around the anode (on the right in the photo above, I think *squint*) does look slightly yellow-ish green, suggesting a slightly lower pH… but… there’s not much in it. This could make sense. The balanced-for-H+ half equations would suggest that, actually, there’s H+ sloshing around both electrodes (being formed at one, used up at the other), but we’re forming more around the anode, so we’d expect it to have the slightly lower pH.

The blue colour does, unfortunately, look a bit like copper sulfate solution, which might be confusing for students who struggle to keep these experiments straight in their heads at the best of times. One to save for A level classes, perhaps.

(After I published this, Louise clarified that the experiment in the photo is, in fact, copper sulfate. Ooops. Yes, folks, it looks like copper sulfate because it is copper sulfate. But I thought I’d leave the paragraph above for now since it’s still an interesting discussion!)

The other practical issue is that you need a lot of tic tac boxes, which means that someone has to eat a lot of tic tacs. There might be worse problems to have. I daresay “your homework is to eat a box of tic tacs and bring me the empty box” would actually be quite popular.

So, there we are. There’s a lot of potential (haha, sorry) here: you could easily put together multiple class sets of this for a few pounds—the biggest cost is going to be a bulk order of 9V batteries, which you can buy for less than £1 each—and it uses small quantities of innocuous chemicals, so it’s pretty safe. Students could even have their own experiment and not have to work in groups of threes or more, battling with dodgy wires and trippy power-packs (we’ve all been there).

Why not give it a try? And if you do, send me photos!


Like the Chronicle Flask’s Facebook page for regular updates, or follow @chronicleflask on Twitter. Content is © Kat Day 2019 (photos courtesy of STEM Learning UK and Louise Herbert). You may share or link to anything here, but you must reference this site if you do. If you enjoy reading my blog, please consider buying me a coffee through Ko-fi using the button below.
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Non-stick toilets, synthetic poo and saving the environment

141 billion litres of water are used to flush toilets every day.

Scientists develop slippery toilet coating that stops poo sticking,” shouted newspaper headlines last week, naturally prompting comments about the state of politics, the usual arguments about the ‘right’ way to hang toilet paper rolls, and puns of varying quality.

There was also more than one person asking WHY, given everything going on at the moment, scientists are spending their time on something which seems, well, not terribly urgent. After all, ceramic toilet bowls are already quite slippery. Toilet brushes exist. We have a myriad of toilet cleaning chemicals. Surely there are higher priorities? Attempting to deal with looming environmental disaster, say?

But here’s the thing, from an environmental point of view, flush toilets are quite significant. If you’re fortunate enough to live somewhere they’re ubiquitous it’s easy to take them for granted, but consider this: flushing even a water-efficient toilet uses at least five litres of water (much more for older models, a bit less if you use a ‘half-flush’ function). Often this is perfectly clean water which has been through water treatment, only to be immediately turned back into, effectively, sewage. Now imagine you have something a bit… ahem… sticky to flush. What do you do? You flush the toilet twice. Maybe more. You break out the toilet brush and the bottle of toilet cleaner, and then you probably flush at least one extra time to leave the bowl clean.

Using toilet cleaning chemicals often results in extra flushes.

Consider that the average person uses the toilet about five times and day and multiply up by the population and, even just in the UK, we’re looking at billions of litres of water daily. Globally, it’s estimated that 141 billion litres of fresh water are used daily for toilet flushing, and in some homes it could account for a quarter of indoor wastewater production. That’s a lot of fresh water we’re chucking, quite literally, down the toilet.

It rains a fair bit in the U.K. so, except for the occasional dry summer, Brits aren’t in the habit of worrying too much about water supply. The opposite, if anything. But we need to change our ways. In a speech in March this year, Sir James Bevan, Chief Executive of the Environment Agency, warned that the U.K. could run into serious water supply problems in 25 years due to climate change, population growth and poor water management.

Even putting those warnings to one side, treating water uses energy and resources. Filters are used which have to be cleaned and replaced, chemical coagulants and chlorine (usually in the form of low levels of chlorine dioxide) have to be added. Sometimes ozone dosing is used. The pH of the water needs to be checked and adjusted. All of these chemicals have to be produced before they’re used to treat the some 17 billion litres of water that are delivered to UK homes and businesses every day. And, of course, the whole water treatment process has to be continuously and carefully monitored, which requires equipment and people. None of this comes for free.

So, yes, saving fresh water is important. Plugging leaks and using water-saving appliances is vital. And, given that everyone has to go to the toilet several times a day, making toilets more efficient is potentially a really significant saving. An super non-stick toilet surface could mean less flushing is needed and, probably, fewer cleaning products too — saving chemical contamination.

Fresh water is a valuable resource.

The new super-slippery surface was co-developed by Jing Wang in the Department of Mechanical Engineering at the University of Michigan. It’s called a liquid-entrenched smooth surface (LESS) and is applied in two stages. First, a polymer spray, which dries to form nanoscale hair-like strands. The second spray completely covers these ‘hairs’ with a thin layer of lubricant, forming an incredibly flat, and very slippery, surface. The researchers tested the surface with various liquids and synthetic faecal matter and the difference — as seen in the video on this page — is really quite astonishing.

Hold up a moment, synthetic faecal matter? I’ll bet no one embarking on an engineering degree ever imagines that, one day, they might be carefully considering the make-up of artificial poo. But actually, when you think about it, it’s quite important. Quite aside from safety aspects and the sheer horror of the very idea, you couldn’t use the real thing to test something like this. You need to make sure it has a carefully-controlled consistency, for starters. It’s the most basic principle, isn’t it? If you want to test something, you have to control your variables.

Artificial poo is surprisingly important.

Indeed, there’s even a scale. It’s called the Bristol stool scale, and it goes from “hard” to “entirely liquid”. Synthetic poo is a mixture of yeast, psyllium, peanut oil, miso (proof, if it were needed, that miso really does improve everything), polyethylene glycol, calcium phosphate, cellulose and water. The amount of water is adjusted to match different points on the Bristol scale. Aren’t science and engineering fun?

Anyway. Back to the non-stick technology. This new surface can be applied to all sorts of materials including ceramic and metal, and it repels liquids and ‘viscoelastic solids‘ (stuff that’s stretchy but also resists flow: apart from poo, PVA slime is another example) much more effectively than other types of non-stick surfaces. In fact, the researchers say it’s up to 90% more effective than even the best repellent materials, and they estimate that the amount of water needed to clean a surface treated in this way is 10% that needed for ordinary surfaces. They were also able to show that bacteria don’t stick to LESS-coated materials, meaning that even if untreated water is used to flush a toilet, it remains hygienic without the need for extra chemicals.

The potential to cut 141 billion litres of water by a factor of ten is not to be (I’m sorry) sniffed at. Plus, in some areas, ready supplies of water and the facilities to clean toilets just aren’t available. Using LESS could, potentially, reduce the spread of infection.

By Chemystery22 - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=31161897 A graft copolymer has side chains branching off the main chain — these side chains are the “hairs” described by the researchers.

So what IS this surface treatment made of? This information wasn’t widely reported, but it seems quite important, not least because applications of LESS are estimated to last for about 500 flushes, which suggests that re-application will be needed fairly regularly and, perhaps more worryingly, whatever-it-is is passing into the wastewater supply.

Not surprisingly, there’s a certain amount of vagueness when it comes to its exact make-up, but I did find some details. Firstly, it’s what’s known as a graft polymer, that is, a polymer chain with long side chains attached — these are the “hairs” described by the researchers.

Secondly, the polymer strands are based on polydimethylsiloxane, or PDMS. This may sound terrifying, but it’s really not. PDMS (also known as dimethicone) is a silicone — a compound made up of silicon, oxygen, carbon and hydrogen. These compounds turn up all over the place. They’re used contact lenses, shampoos, and even as food additives. Oh, and condom lubricants. So… pretty harmless. In fact, they’re reported as having no harmful effects or organisms or the environment. The one downside is that PDMS isn’t biodegradable, but it is something that’s absorbed at water treatment facilities already, so nothing new would need to be put in place to deal with it.

The problem of better toilets might be more urgent than you thought.

Finally, the lubricant which is sprayed over the polymer chains in the second stage of the treatment to make the surface “nanoscopically smooth” (that is, flat on a 1 billionth of a metre scale) is plain old silicone oil, which is, again, something with a low environmental impact and generally considered to be very safe.

As always with environmental considerations it’s about choosing the least bad option, and using these coatings would certainly seem to be a far better option than wasting billions of gallons of precious fresh water.

In short, silly headlines aside, it turns out that making toilets better might be quite an important problem. Maybe it’s time to rage against the latrine.


Like the Chronicle Flask’s Facebook page for regular updates, or follow @chronicleflask on Twitter. Content is © Kat Day 2019. You may share or link to anything here, but you must reference this site if you do. If you enjoy reading my blog, please consider buying me a coffee through Ko-fi using the button below.
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Refilling bottles: why it may not be as simple as you thought

Two years or so ago most of us had given relatively little thought to single-use plastics. We bought things, we used things, we put the packaging in the bin. Possibly the recycling bin. Hopefully the right recycling bin. And we thought no more about it.

Then Blue Planet II aired on BBC One, specifically episode 7, and suddenly everyone was obsessed with where all this plastic was ending up. Rightly so, since it was clearly ending up in the wrong places, and causing all sorts of havoc in the process.

People started buying reusable cups, eschewing plastic straws and demanding the option of loose fruit and vegetables in supermarkets. Wooden disposable cutlery, oven-cook food containers, and bamboo straws became increasingly common.

And people started to ask more questions about refilling containers. Why do I need a new bottle each time I buy more shampoo or washing up liquid or ketchup, they asked. Why can’t we just refill the bottle? For that matter, couldn’t I take a container to the shop and just… fill it up?

Infinity Foods allow customers to refill containers.

Shops started to offer exactly that. One such place was Infinity Foods, based in Brighton in the UK. Actually, they’d always taken a strong line when it came to recycling and reducing waste, and had been offering refills of some products for years.

Where this gets interesting from a chemistry point of view is a Facebook post they made at the beginning of this month. It said, from the 1st of November, “your empty bottle can only be refilled with the same contents as was originally intended. This includes different brands and fragrances.”

Naturally this spawned lots of comments, many suggesting the change was “daft” and saying things like “I bet it is major corporations not wanting us to reuse the bottle.

Infinity Foods argued that they were tightening up their policy in order to comply with legislation, specifically the Classification, Labelling and packaging of substances and mixtures (CLP) Regulation (EC) No 1272/2008 and others.

This post, and the comments, got me thinking. I’m old enough, just, to remember the days when random glass bottles were routinely filled with random substances. You wandered into the garage (it was always the garage) and there’d be something pink, or blue, or green, or yellow in a bottle. And it might have a hand-written label, and it might not, and even if it did, the label wasn’t guaranteed to actually be representative of the contents. The “open it and sniff” method of identification was common. The really brave might take their chances with tasting. Home-brew wine might well be next to the lawnmower fuel, and if they got mixed up, well, it probably wouldn’t be fatal.

Probably.

Bottles may be single-use, but they’ve also been designed to be as safe as possible.

You know, I’m not sure we ought to be keen to go back to that, even if it does save plastic. Sealed bottles with hard-to-remove child safety caps, nozzles that only dispense small amounts (making it difficult if not impossible to drink the contents, by accident or otherwise) and accurate ingredients lists are, well, they’re safe.

And we’ve all grown used to them. Which means that now, if I pick up a bottle, I expect the label to tell me what’s in it. I trust the label. If I went to someone else’s house and found a bottle of, say, something that looked like washing up liquid by the sink, I’d assume it was what the label said it was. I wouldn’t even think to check.

You might think, well, so what? You fill a bottle, you know what’s in it. It’s up to you. But what about all the other people that might come into contact with that bottle, having no idea of its origins? What if a visitor has an allergy to a particular ingredient? They look at the label, check it doesn’t contain that ingredient, and use it. Only, someone has refilled that bottle with something else, and maybe that something else does contain the thing they’re allergic to.

Even simpler, someone goes to a shop that sells refills, fills a hair conditioner bottle with fabric softener and doesn’t think to label it. They know what it is, right? They leave it in the kitchen, someone else picks up that bottle, and takes it into the shower. They get it in their eyes and… maybe it causes real harm.

Toilet cleaner must never be mixed with toilet bleach.

Then there are the very real hazards associated with mixing chemicals. One that always worries me is the confusion between toilet cleaner and toilet bleach. Many people have no idea what the difference is. The bottles even look quite similar. But they are not the same substance. Toilet cleaner is usually a strong acid, often hydrochloric acid, while toilet bleach contains sodium hypochlorite, NaClO. Mixing the two is a very bad idea, because the chemical reaction that occurs produces chlorine gas, which is particularly hazardous in a small, enclosed space such as a bathroom.

Okay, fine, toilet bleach and cleaner, noted, check. Is anyone selling those as refills anyway? Probably not. (Seriously, though, if you finish one bottle, make sure you don’t mix them in the toilet bowl as you open the next.)

But it may not be as straightforward as that. Have you ever used a citrus-scented cleaning product? They can be quite acidic. Combine them with bleach and, yep, same problem. What if someone refilled a container that contained traces of a bleach cleaner with one that was acidic, not realising? Not only would it be harmful to them, it could also be harmful for other people around them, including employees, especially if they suffer from a respiratory condition such as asthma.

There are risks associated with the type of container, too. Some plastics aren’t suitable to hold certain substances. Infinity Foods themselves pointed out that some people were trying to find drinking water bottles and plastic milk bottles with cleaning products. These types of bottles are usually made of high-density polyethylene (HDPE). This type of plastic is a good barrier for water, but not oily substances and solvents. Cleaning products could weaken the plastic, resulting in a leak which would be messy at best, dangerous at worst. That’s before we even think about the (un)suitability of the cap.

The type of plastic used to make water bottles isn’t suitable to hold oily substances.

Plus, think of the poor salesperson. How are they supposed to judge, in a shop, whether a particular bottle is safe for a particular product? I wouldn’t feel at all confident about that decision myself. It’s not even always easy to identify which plastic a bottle is made of, and that’s before you even start to consider the potential risks of mixing substances.

In fact, the more you think about it, the more Infinity Foods’ policy makes sense. If you say that you can only refill a bottle with the exact same substance it originally contained, and you insist that the labels have to match, well, that’s easy to check. It’s easy to be sure it’s safe. Yes, it might mean buying a bottle you wouldn’t have otherwise bought, but if you’re going to reuse it, at least it’s just the one bottle.

These concerns all arise from wanting to make sure the world is a safer and healthy place. We do need to cut down on single-use plastics, but taking risks with people’s health to do so surely misses the point.


Like the Chronicle Flask’s Facebook page for regular updates, or follow @chronicleflask on Twitter. Content is © Kat Day 2019. You may share or link to anything here, but you must reference this site if you do. If you enjoy reading my blog, please consider buying me a coffee through Ko-fi using the button below.
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How are amber teething necklaces supposed to work?

Do amber beads have medicinal properties?

Amber, as anyone that was paying attention during Jurassic Park will tell you, is fossilised resin from trees that lived at least twenty million years ago (although some scientists have speculated it could be older). It takes the form of clear yellow through to dark brown stones, seemingly warm to the touch, smooth and surprisingly hard. It is certainly beautiful. But does it also have medicinal properties? And if it does, are they risk-free?

In 2016 a one year-old boy was found dead at his daycare centre in Florida. The cause of death was a necklace, which had become tangled and tightened to the point that he was unable to breathe.

Why was he wearing a necklace? Surely everyone knows that babies shouldn’t wear jewellery around their necks where it could so easily cause a terrible tragedy like this? No one needs a necklace, after all – it’s purely a decorative thing. Isn’t it?

Yes. Yes, it is. However, this particular type of jewellery was specifically sold for use by babies. Sold as a product that parents should give their children to wear, despite all the advice from medical professionals. Why? Because this jewellery was made from amber, and that’s supposed to help with teething pains.

Teething is a literal pain.

Anyone whose ever had children will tell you that teeth are basically a non-stop, literal pain from about 4 months onward. Even once your child appears to have a full set, you’re not done. The first lot start falling out somewhere around age five, resulting in teeth that can be wobbly for weeks. And then there are larger molars that come through at the back somewhere around age seven. Teenagers often find themselves suffering through braces and, even when all that’s done, there’s the joy of wisdom teeth still to come.

It’s particularly difficult with babies, who can’t tell you what hurts and who probably have inconsistent sleep habits at the best of times. Twenty sharp teeth poking through swollen gums at different times has to be unpleasant. Who could blame any parent for trying, well, pretty much anything to soothe the discomfort?

Enter amber teething necklaces. They’re sold as a “natural” way to soothe teething pain. They look nice, too, which I’m sure is part of their appeal. A chewed plastic teething ring isn’t the sort of thing to keep in baby’s keepsake box, but a pretty necklace, well, I’m sure many parents have imagined getting that out, running their fingers over the beads and having a sentimental moment years in the future.

Amber is fossilised tree resin.

So-called amber teething necklaces are made from “Baltic amber,” that is, amber from the Baltic region: the largest known deposit of amber. It is found in other geographical locations, but it seems that the conditions – and tree species – were just right in the Baltic region to produce large deposits.

Chemically, it’s also known as succinite, and its structure is complicated. It’s what chemists would call a supramolecule: a complex of two or more (often large) molecules that aren’t covalently bonded. There are cross-links within its structure, which make it much denser than you might imagine something that started as tree resin to be. Baltic amber, in particular, also contains something else: between 3-8% succinic acid.

Succinic acid is a dicarboxylic acid.

Succinic acid is a much simpler molecule with the IUPAC name of butanedioic acid. It contains two carboxylic acid groups, a group of atoms we’re all familiar with whether we realise it or not – because we’ve all met vinegar, which contains the carboxylic acid also known as ethanoic acid. If you imagine chopping succinic acid right down the middle (and adding a few extra hydrogen atoms), you’d end up with two ethanoic acid molecules.

Succinic acid (the name comes from the Latin, succinum, meaning amber) is produced naturally in the body where it is (or, rather, succinate ions are) an important intermediate in lots of chemical reactions. Exposure-wise it’s generally considered pretty safe at low levels and it’s a permitted food additive, used as an acidity regulator. In European countries, you might see it on labels listed as E363. It also turns up in a number of pharmaceutical products, where it’s used as an excipient – something that helps to stabilise or enhance the action of the main active ingredient. Often, again, it’s there to regulate acidity.

Basically, it’s mostly harmless. And therefore, an ideal candidate for the alternative medicine crowd, who make a number of claims about its properties. I found one site claiming that it could “improve cellular respiration” which… well, if you’ve got problem with cellular respiration, you’re less in need of succinic acid and more in need of a coffin. Supposedly it also relives stress and prevents colds, because doesn’t everything? And, of course, it allegedly relieves teething pains in babies, either thanks to its general soothing effect or because it’s supposed to reduce inflammation, or both.

Purporters claim succinic acid is absorbed through the skin.

The reasoning is usually presented like this: succinic acid is released from the amber when the baby wears the necklace or bracelet and is absorbed through the baby’s skin into their body, where it works its magical, soothing effects.

Now. Hold on, one minute. Whether this is true or not – and getting substances to absorb through skin is far less simple than many people imagine, after all, skin evolved as a barrier – do you really, really, want your baby’s skin exposed to a random quantity of an acidic compound? Succinic acid may be pretty harmless but, as always, the dose makes the poison. Concentrated exposure causes skin and eye irritation. Okay, you might say, it’s unlikely that an amber necklace is going to produce anywhere near the quantities to cause that sort of effect, but if that’s your logic, then how can it also produce enough to pass through skin and have any sort of biological effect on the body?

The answer, perhaps predictably, is that it doesn’t. In a paper published in 2019, a group of scientists actually went to the trouble of powdering Baltic amber beads and dissolving the powder in sulfuric acid to measure how much succinic acid they actually contained. They then compared those results with what happened when undamaged beads from the same batches were submerged in solvents, with the aim of working out how much succinic acid beads might conceivably release into human skin. The answer? They couldn’t measure any. No succinic acid was released into the solvents, at all. None.

Scientists submerged Baltic amber beads in solvents to see how much succinic acid they released.

They concluded that there was “no evidence to suggest that the purported active ingredient succinic acid could be released from the beads into human skin” and also added that they found no evidence to suggest that succinic acid even had anti-inflammatory properties in the first place.

So amber necklaces don’t work to relieve teething pains. They can’t. Of course, there could be a sort of placebo effect – teething pain is very much one of those comes-and-goes things. It’s very easy to make connections that just aren’t there in this kind of situation, and imagine that the baby is more settled because of the necklace, when in fact they might have calmed down over the next few hours anyway. Or maybe they’re just distracted by the pretty beads.

And, fine. If wearing the jewellery was really risk-free, then why not? But as the story at the start of this post proves, it is not. Any kind of string around a baby’s neck can become twisted, interfering with their breathing. Most necklaces claim to have some sort of “emergency release” mechanism so that they come apart when pulled, but this doesn’t always work.

Don’t fall for the marketing.

Ah, goes the argument. But it’s okay, because we only sell bracelets and anklets for babies. They don’t go around the baby’s neck. It’s completely safe!

No. Because I don’t care how carefully you make it: the string or cord could still break (especially if it’s been chewed), leaving loose beads to pose a serious choking hazard. Not to mention get jammed in ears or nostrils. Even if you’re with the baby, watching them, these sorts of accidents can happen frighteningly quickly. Letting a baby sleep with such an item is nothing short of asking for disaster, and no matter how good anyone’s intentions, babies do have a habit of dozing off at odd times. Will you really wake the child up to take off their bracelet? Every time?

In summary, don’t fall for the marketing. Amber necklaces may be pretty, but they’re not suitable for babies. The claims about succinic acid are completely baseless, and the risks are very real.


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The UK’s Unlikely System of Units

The novel Good Omens was first published in 1990. And this is my original copy.

Unless you’ve been asleep for the last few months (if so, are you a snake, by any chance….?) you will have noticed that there’s recently been a very popular television adaptation of the much-loved book by Terry Pratchett and Neil Gaiman: Good Omens.

I have always loved this book, and I love the TV show even more. Obsessed? Erm. Anyway. Can I wring a science-themed post for my blog out of a story about a demon and an angel saving the world from Armageddon? Of course I can.

Here goes. There’s a moment in the second episode of the TV adaptation* when the demon, Crowley, is driving his Bentley very, very fast, and the angel, Aziriphale, says: “You can’t do ninety miles an hour in central London!”

This caused a bit of confusion for some non-British viewers§. Not the idea that you can’t, or at least shouldn’t, drive extremely fast in a built-up area, but rather the fact that Britain is a European country, isn’t it? At least, for the moment. Don’t the Europeans use the metric system? Shouldn’t he have said one hundred and forty-five kilometres per hour?

So you thought Brits used the metric system? Haha.

I mean, okay, we do. Scientists in particular are quite keen on it. But we also use imperial units really quite a lot. And coincidently, this all arose just after the politician Jacob Rees-Mogg issued a style guide to his staff declaring that they must “use imperial measurements” — which at first sounds typically Victorian of Rees-Mogg, but actually… if your aim is to at least try to be consistent, he might, just might, have a point…

Allow me to try to explain.

Firstly, a little clarification: the “metric system” is an internationally-recognised decimalised system of measurement, that is, a system where units are related by powers of ten. I stress this because “metric” and “decimal” do not mean quite the same thing, which is relevant when it comes to money. The metric system takes base measurements — kilograms, metres and so on — and says that all versions of those measurements can only be connected by powers of ten, and must not introduce new conversion factors. So, grams (1000th of a kilogram) and tonnes (1000 kilograms) are both metric, but a pound (0.454 of a kilogram) is not. Scientists know this as the SI system of measurements. Okay? Right. Let’s get on to the amusing cocktail of units the British have to cope with in their every day lives…

Britain loves inches.

Length
The length of small-ish objects is measured in centimetres and millimetres. Sometimes. Except the diameter of pizzas, the sides of photos and photo frames, and the diagonal of laptop screens and televisions — all of which are almost always given in inches. Screws, as in woodscrews, are often given in  fractions of inches. Let’s not get into jewellery, for that way madness lies.

Longer objects are measured in metres and centimetres, except for the height of people, which is almost always quoted in feet and inches. Chippies (that is carpenters, not people that cook fish and chips — keep up) tend to colloquially use feet and inches for planks of wood. For example, “I need a bit of six by nine” — meaning a piece of wood 6 feet long and 9 inches thick.

What do you mean, how do you know which one is 6 and which one is 9? You’d hardly have a 9 ft piece of wood that was only 6 inches thick, would you?

People do sometimes use metres for short walking distances, e.g. “it’s fifty metres to the shops”, however Brits also like to use yards, a yard being 3 feet. But that’s okay, because a yard is close enough to a metre as to make little difference to a casual walking estimate, so they’re pretty interchangeable.

Marathons are measured in miles. Shorter road races use kilometres.

The sorts of distances involved in lengthy travel are always measured in miles. The distance from Oxford the city to Oxford Street in London, for example, is about 55 miles. No British person would ever describe this as 88.5 km. Speed, as we saw in Good Omens, is thusly described in miles per hour (mph). For the record, the speed limit in a built-up area such as Oxford Street would normally be 30 mph, or sometimes (more and more frequently) 20 mph. Crowley was indeed driving ridiculously fast, but then, he has demonic magic to help him avoid both pedestrians and police.

Miles are also used for marathons. However, not for shorter running races, which are often described as “5k” or “10k” meaning, obviously, 5 kilometres or 10 kilometres. The cynics may wonder whether this is because 5 kilometres sounds longer than 3 miles, but I’m sure runners aren’t concerned about such vanities.

Is all of that clear? Okay, let’s move on…

Weight
Weight (physicists: I mean mass, yes, you’re very clever, shhh now) of people is measured in stones and pounds (there are 14 pounds in a stone). Except for babies, which are little and are therefore measured in pounds, because everyone knows a baby ought to weigh somewhere in the region of 7 pounds or so, and if you quote a baby weight in kg, Brits have no idea whether to gasp, coo, or wince sympathetically.

The weight of food is mostly measured in kilograms and grams (or possibly grammes; it’s essentially the same thing) these days, although a lot of people still favour pounds and ounces. This leads to oddities, such cake recipes which call for 225 g of butter (half a pound). There are, by the way, 16 ounces in a pound, because it would be far too easy if it were consistent with the pounds/stones thing, wouldn’t it. Oh, and Brits have quarter pounder beefburgers in restaurants — none of that ‘Royale with cheese‘ business for us, thanks.

Larger weights are mostly quoted in tonnes, because that’s easy, but sometimes we use tons as well, which has the added amusement of sounding exactly the same when you say it out loud. 1 tonne is about 1.1 tons, so it’s not too much of a problem unless you’re planning a really big building project. Very large amounts are sometimes given in hundredweight, which sounds metric, doesn’t it? It’s not. A hundredweight is 50.8 kg, or 112 pounds. Did you think it would be 100? Yes, well, there are reasons.

Once again, let’s not get into jewellery. If we start on carats we’ll be here all day.

Beer, blood and milk are measured in pints.

Volume
Small volumes of liquids tend to be measured in millilitres or (particularly for wine) centilitres. The exceptions are beer, blood and milk — which are given in pints. Wandering into a British pub and asking for half a litre of beer is guaranteed to cause everyone to stop what they’re doing and stare at you. As will asking for pint of blood, for different reasons.

Larger volumes are measured in litres. We’ve mostly given up on gallons, now that all the fuel stations quote their prices in pence per litre because it looks cheaper that way.

Chemists like to be awkward, though, and use cubic centimetres — written cm3 or occasionally cc just for fun — for small volumes of liquids, and dm3 (cubic decimetres) for litres. 1 cm3 is 1 ml and 1 dm3 is 1 litre, so there’s really no reason for any of this other than to confuse students.

Temperature
Temperatures are mostly quoted in Celsius (aka centigrade, well, more-or-less), and most Brits these days have a fairly good feel for that scale. But Fahrenheit still gets rolled out when either a person or the air gets hot. A midsummer’s day might reach ‘100 degrees’ (that is, a little under 38 oC) and someone with a fever might also be described as ‘having a temperature of over a hundred’. Once it gets chillier, however, we’re firmly back to Celsius, because ‘minus five’ sounds a lot more dramatic than 23 oF.

In case you’re wondering, no, I did not choose this particular picture of a thermometer by accident.

In case you thought you were on safe ground here, don’t forget there’s also Kelvin (where 0 oC = 273 K) which is the SI unit of temperature and very popular with physicists. And, if you’re cooking, the mysterious ‘gas mark‘ — which is more-or-less unique the U.K. and which is based on some sort of occult formula. (Gas mark 6 is about 200 oC or 400 38 oF.)

Energy
Energy is measured in Joules. Except when it comes to food, where it’s measured in calories. Actually, kilocalories, but everyone just calls them calories. There’s meant to be a capital C to help tell the difference, but no one ever remembers. This is all fine.

Pressure
Are you sure you want to go here? Okay. FINE.

Tyre pressures are quoted in pounds per square inch, that is, PSI. Most British car owners can probably tell you roughly what their tyre pressures ought to be in PSI, even if (having learned metric at school) they have a somewhat shaky grasp of what either inches or pounds are.

Atmospheric pressures are usually quoted in atmospheres, because everyone knows what that means (sea level is one atmosphere, give or take). Of course, that’s not the SI unit, which is Pascals: 1 atmosphere is 101,325 Pascals, which is a bit unwieldy, so scientists often use bars, where 1 bar is 100,000 Pascals, and thus 1 atmosphere is more-or-less 1 bar, which, for once, is sort of helpful (no, really).

Blood pressure is usually quoted in mmHg

But then there’s also Torr, which arises from the historical practice of using mercury to measure pressure. 760 Torr is 1 atmosphere, while 1 Torr is 133.32 Pascals. Blood pressure, of course, was traditionally measured with a mercury sphygmomanometer, but just in case you thought you were on top of this, 1 Torr is nearly, but not quite, the same as the measurement in that case, which is mmHg, 1 of which is equal to 1.000000142466321 Torr.

Money
British money is decimal (but not metric, for the reasons described back at the start there), but only became so in 1971. If Rees-Mogg has his way I’m sure we’ll be back to pounds, shilling and pence before we know it.

It’s all your fault, isn’t it, Crowley?

In summary….
Since no one in this country is going to give up miles any time soon, if you want to be consistent about units it makes a certain kind of sense to insist on sticking to imperial, I suppose. As much sense as imperial measurements make anyway, which is not much.

You do have to wonder how we ended up with such a confusing mixture of measurements. It’s almost… demonic….


* Page 51 of the original print edition, second line up from the bottom. Obsessed? No idea what you mean.
§ And possibly non-British readers of the book in the 1990s, but Twitter didn’t exist then, so any puzlement went largely unnoticed. It was a quieter time.
would# you? I don’t bloody know. Apparently it’s obvious.
# or, indeed, wood.


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Would you like to listen to the lovely Alasdair Stuart and me natter on about how utterly brilliant Good Omens is, and all the clever little things we spotted in the show for about an hour or so? Of course you would! It’s part of the premium content bucket at the EA Podcasts Patreon. Please do consider supporting Escape Artists podcasts; they produce truly brilliant fiction podcasts on a weekly basis. If you’ve never heard of them (where have you been?) why not subscribe to their free podcasts: Podcastle (fantasy), Pseudopod (horror), Escape Pod (science fiction) and Cast of Wonders (young adult).


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A natural remedy that’s full of chemicals?

Blossoms

The summer holidays are here! A time when parents of small children find themselves exploring every park in their local vicinity, quite probably several times (whilst hoping against hope that it doesn’t rain). On just such a quest myself, I recently visited one particular park that was filled with a gorgeous smell.

What was it? A bit of sniffing around quickly identified this tree. Now, I am not a botanist (or even much of a gardener), so I immediately resorted to the rather wonderful Seek app by iNaturalist, which uses some very clever image recognition software to identify plants and animals (disclaimer: accuracy is not guaranteed — don’t eat anything based on this app!)

Seek told me that this was a lime tree, or a linden (genus Tilia). A bit of cross-referencing (thanks Dad!) suggested that it had identified the tree correctly. It’s not an uncommon plant: you’ll probably come across it yourself if you go looking (or smelling).

The name ‘linden’ was more familiar to me. The wood is soft and easily worked, and is used to make musical instruments because it has good acoustic properties. It’s also used to make wooden blinds and other pieces of furniture because it’s lightweight, stable, and holds stains and finishes well.

Linden blossoms can be used to make tea.

But let’s go back to the flowers and their delicious scent. The tree blooms during July and August in the Northern hemisphere. The flowers are sometimes described as mucilaginous — which is a fabulous word meaning, basically, thick and sticky. More specifically: “containing a polysaccharide substance that is extracted as a viscous or gelatinous solution and used in medicines and adhesives.”

Linden flowers are a ‘natural remedy’ with a list of applications in herbal medicine as long as your arm. They contain lots of different substances. One that comes up a lot is farnesol, which is actually a type of alcohol. Of course, it’s nothing like the alcohol we’re familiar with from drinks, which is the much simpler ethanol — but it’s important to remember that ‘alcohol’ actually refers to a class of compounds (which, in simple terms, contain an -OH group like the one in the image here) and not a single substance.

The chemical structure of farnesol

Farnesol turns up in lots of essential oils, such as citronella, rose and lemon grass. It’s used in perfumes to enhance floral scents. But plants don’t make substances just to please humans (well, it’s complicated…). It acts as a pheromone for several insects. Sometimes this doesn’t work out so well for the insects, as it confuses their mating behaviour and effectively acts as a natural pesticide. On the other hand, it actively encourages others: bumblebees release farnesol when they return to the hive to spur other bees into action. It’s the bee equivalent of shouting, ‘oi! Move it you lot, pollen this way!’

Farnesol acts as a pheromone for bumblebees.

Linden flowers also contain one of my all-time favourite chemicals, benzaldehyde. That’s the one that smells of almonds and isn’t a deadly cyanide salt. Its delicious almondy-ness is the reason it’s used as a flavouring and scent, but it’s also a starting material for loads of different chemicals, for example the dye malachite green, which is used to give a green colour to leather, fabric and paper. A form of this dye called ‘brilliant green‘ is mixed with a second, violet, dye to make ‘Bonney’s blue,’ a disinfectant dye used to mark skin for surgeries. Benzaldehyde is also used to make styrene, which is of course used to make the well-known packing material, polystyrene.

And these are just a couple of the substances found in those yummy-smelling flowers. They also contain arabinogalactans, uronic acid, tannins, rutin, hyperoside, quercitrin, isoquercitrin, astragalin and others. In short, a veritable cocktail of different chemicals.

So next time you smell the scent of a lovely flower, just think about all the amazing chemical substances the plant is making. All natural, of course!


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