A chemically illiterate internet meme
Keith S. Taber
The challenge of popular science writing
I often enjoy reading popular accounts of science topics, but sometimes one comes across statements that are vague or dubious or confusing – or simply wrong. Some of this reflects a basic challenge that authors of popular science share with science teachers and other science communicators: scientific ideas are often complex, subtle and abstract. Doing them justice requires detailed text and technical terminology. Understanding them often depends upon already having a good grasp of underpinning concepts. That is fine in a formal report for other scientists, but is not of any value to a non-specialist audience.
So, the author has to simplify, and perhaps round off some of the irregular detail; and to find ways to engage readers by using language and examples that will make sense to them. That is, finding ways to 'make the unfamiliar familiar'.
Read about making the unfamiliar familiar in teaching
I am sure that often the passages in popular science books that I as a scientist 1 get grumpy about are well motivated, and, whilst strictly inaccurate, reflect a compromise between getting the science perfect and making it accessible and engaging for the wider readership. Sometimes, however, one does get the impression that the author has not fully grasped the science they are writing about.
"Lucy Jane Santos is the Executive Secretary of the British Society for the History of Science…"
Public engagement with radium
I very much enjoyed reading a book, 'Half lives', by the historian of science Lucy Jane Santos, about how in the decades after its discovery by Pierre and Marie Curie, radium was the subject of wide public interest and engagement. One of the intriguing observations about this newly discovered element was that it appeared to glow in the dark. We now know that actually the glow comes from nitrogen in the air, as radium is radioactive and emissions by radium 'excite' (into a higher energy state) nitrogen molecules, which then emit visible light as they return ('relax') to their 'ground' state. This production of light without heating (a phenomenon generally called luminescence), when it is due to exposure to radioactivity, is known as radioluminescence.
Today, many people are very wary of radioactivity – with good reason of course – but Santos describes how at one time radium was used (or at least claimed as an ingredient) in all kinds of patent medicines and spa treatments and cosmetics (and even golf balls). This was a fascinating (and sometimes shocking) story.
What substance(s) can you find in quinine?
I did find a few things to quibble over – although across a whole book it was, only, a few. However, one statement that immediately stood out as dodgy science was the claim that quinine contained phospor:
"Quinine contains phosphor, a substance that luminesces when exposed to certain wavelengths of light…"
Santos, 2020
This may seem an unremarkable statement to a lay person, but to a scientist this is nonsensical. Quinine is a chemical compound (of carbon, hydrogen, nitrogen and oxygen), that is – a single substance. A single substance cannot contain another substance – any more than say, a single year can contain other years. An impure sample of a substance will contain other substances (it is in effect a mixture of substances), but quinine itself is, by definition, just quinine.
Molecular structure of the chemical compound quinine (C20H24N2O2) – a pure sample of quinine would contain only (a great many copies of) this molecule.
Note – no phosphorus, and no rare earth metal atoms.
(Image source: Wikimedia)
Confusing terminology
The term 'phosphor' refers to a luminescent material – one that will glow after it has been exposed to radiation (often this will be ultraviolet) or otherwise excited. The term is usually applied to solid materials, such as those used to produce an image in television and monitor screens.
The term derives by reference to the element phosphorus which is a luminescent substance that was accordingly itself given a name meaning 'light-bearing'. The term phosphorescent was used to describe substances that continue to glow for a time after irradiation with electromagnet radiation ceases. But it is now known that phosphorus itself is not phosphorescent, but rather its glow is due to chemiluminescence – there is a chemical reaction between the element and oxygen in the air which leads to light being emitted.
The widely used term phosphor, then, reflects an outdated, historical, description of a property of phosphorus; and does not mean that phosphors contain, or are compounds of, phosphorus. There is clearly some scope for confusion of terms here. 2
| term | meaning |
| luminescence | the emission of light by a cold object (in contrast to incandescence) |
| – chemiluminescence | a form of luminescence due to a chemical reaction |
| – – bioluminescence | a form of chemiluminescence that occurs in living organisms |
| – electroluminescence | a form of luminescence produced by passing electrical current through some materials |
| – photoluminescence | a form of luminescence due to irradiation by electromagnetic radiation, such as ultraviolet |
| – – fluorescence | a type of photoluminescence that only occurs whilst the object is being excited (e.g., by exposure to ultraviolet) |
| – – phosphorescence | a type of photoluminescence that continues for some time after the object has been being excited (e.g., by exposure to ultraviolet) |
| – radioluminescence | a form of luminescence due to a material being exposed to ionising radiation (e.g., 𝛂 radiation) |
| – sonoluminescence | a form of luminescence due to a material being exposed to sound |
| phosphor | a material that exhibits luminescence |
| phosphorus | a chemical element that exhibits chemiluminescence (when exposed to air) |
A traditional medicine
Quinine, a substance extracted from the bark of several species of Cinchona, has long been used for medicinal purposes (e.g., by the Quechua people of the Americas 3), as it is a mild antipyretic and analgesic. It is an example of a class of compounds produced by plants known as an alkaloids. Plant alkaloids are bitter, and it is thought their presence deters animals from eating the plant. We might say that Quechua pain medication is a bitter pill to swallow.
Modern science has often adopted and developed technologies that had long been part of the 'traditional ecological knowledge' of indigenous groups – such as making extracts from Cinchona bark to use as medicines.
Sadly, the original discovers and owners of such technologies have not always been properly recognised when such technologies have been acquired, transferred elsewhere, and reported. 3
(Image by GOKALP ISCAN from Pixabay)
Quinine is an ingredient of tonic water (and bitter lemon drink) added because of its bitter taste.
(Why deliberately make a drink bitter? Quinine has anti-malarial properties which made it a useful substance to add to drinks in parts of the world where malaria is endemic. People liked the effect!)
Quinine glows when exposed to ultraviolet light. It is luminescent. To be more specific, quinine is photoluminescent. (This is responsible for the notion that someone offered a gin and tonic at a disco should test it under the 'blacklights' to make sure they have not been given pure gin to drink. Although, I am slightly sceptical about whether the kind of people that drink 'G&T's go to the kind of dances that have ultraviolet lighting.)
"I do apologise, I think I might have just splashed a tiny droplet of my tonic water on you"
(Image by Victoria_Watercolor from Pixabay)
It is reasonable to describe quinine as a phosphor in the wider sense of the term – but it does not contain another phosphor substance, any more than, say, iron contains a metallic substance or sulphur contains a yellow substance or sucrose contains a sweet substance or copper a conducting substance. So, a more accurate formulation would have been
"Quinine [is a] phosphor, a substance that luminesces when exposed to certain wavelengths of light…"
or, perhaps better still, simply
"Quinine [is] a substance that luminesces when exposed to certain wavelengths of light…"
Ask the oracle
I was intrigued at why Lucy Jane Santos might have been confused about this, until I did a quick internet search. Then I found a range of sites that claimed that quinine contains phosphors – indeed, often, rare earths are specified.
The rare earths (another unfortunate historic choice of name, as it transpired that they are neither especially rare nor 'earths', i.e., oxides) are a group of metallic elements. They are not as well known as, say, iron, copper, zinc, aluminium or gold, but they have with a wide range of useful applications.
Scandium, the first of the 'rare earth' metals. Probably not what you want in your tonic water.
(Creative Commons Attribution 3.0 Unported License, sourced from https://images-of-elements.com/scandium.php)
If something is repeated enough, does it become true?
Clearly there are not rare earths in quinine. So, the following quotes (from sites accessed on 7th March 2023) proffer misinformation.
"If you want to get a bit more scientific about it…. quinine contains rare earth compounds called phosphors. These are the substances which glow when they are hit with particular wavelengths of the EM spectrum, including UV light. Phosphors absorb UV light and then emit it in their own colour, in this case glowing blue light."
https://www.iceandaslice.co.uk/blogs/news/why-does-your-gin-and-tonic-glow-blue-in-ultraviolet-light
This claim is odd, as the previous paragraph explained more canonically: "why does quinine absorb UV light (the invisible component of sunlight that produces sun tans and sunburns!)? It is due to the structure of the quinine molecule, which enables it to take in energy in the form of invisible UV light and immediately radiate some of that same energy in the form of visible blue light." Other compounds cannot be inside a molecule – so this more canonical explanation is not consistent with quinine containing other "substances" which were "rare earth compounds."
"Quinine contains rare earth compounds called phosphors. These substances glow when they are hit with particular wavelengths of the EM spectrum, including UV light. Phosphors absorb UV light and then emit it in their own color [sic, colour]. Thus, the black light's UV radiation is absorbed by the phosphors in the quinine, and then emitted again in the form of glowing blue light."
https://sciencing.com/quinine-fluorescent-5344077.html
The following extract appeared under the subheading "Why is quinine fluorescence?" That reflects a category error as quinine is a substance and fluorescence is a process (and fluorescent the property) – so, presumably this should have read why is quinine fluorescent?
Why Quinine Glows
Quinine contains rare earth compounds called phosphors. … Phosphors absorb UV light and then emit it in their own color [sic, colour]. Thus, the black light's UV radiation is absorbed by the phosphors in the quinine, and then emitted again in the form of glowing blue light.
https://allfamousbirthday.com/faqs/does-tonic-water-make-things-glow-in-the-dark/
"Want to know one more fun fact about quinine? It glows.
https://www.mixlycocktailco.com/blogs/news/does-tonic-water-go-bad
Rare Earth compounds called phosphors in quinine glow under certain circumstances."
Why Does Tonic Water Glow Under UV Rays?
Tonic water glows and [sic] will fluoresce under UV rays because of quinine in it. Quinine is one of the most important alkaloids found in the cinchona bark, among many others. It has some rare earth compounds known as phosphors that glow when they hit certain wavelengths of the UV light. Phosphors in the quinine absorb the UV light and then reflect it or emit it again in the form of glowing blue light.
https://www.sawanonlinebookstore.com/why-does-tonic-water-glow-under-uv-rays/
Making magic mud – or not
Perhaps the most bizarre example was a site, 'emaze' which offered to show me "How to create magic mud…in 17 easy steps"
Step 1 was
"wash your potatoes!!!!"
However, perhaps due to exclamation fatigue(!), this went in a different, if now familiar, direction with step 2:
"Quinine contains rare earth compounds called phosphors. These substances glow when they are hit with particular wavelengths of the EM spectrum, including UV light. Phosphors absorb UV light and then emit it in their own color [sic, colour]. Thus, the black light's UV radiation is absorbed by the phosphors in the quinine, and then emitted again in the form of glowing blue light"
https://app.emaze.com/@AORQCIII#/16
This text was then repeated as each of steps 3-14. (Sadly steps 15-17 seemed to have been missed or lost. Or, perhaps not so sadly if they were just further repeats.) The first screen suggests this presentation was "done by Dr. Meena & Maha" but if Dr. Meena & Maha really exist (if you do, I am sorry, the internet makes me very sceptical) and 'done this', it is not clear if they got bored with their task very quickly, or whether the server managed to corrupt a much more coherent presentation when it was uploaded to the site.
According to Google, the site 'Course Hero' suggested
"Phosphors, which are found in quinine, are rare earth compounds. These chemicals glow when they are struck with particular wavelengths of the EM spectrum, …"
https://www.coursehero.com › Chemistry › 44733249–I…
but unfortunately (or perhaps fortunately given that snippet), the rest of the text seemed to be behind a pay-wall. This did not offer a strong incitement to pay for material on the site.
Toys coated with phosphorus?
Another website I came across was for a shop which claimed to be selling glow-in-the-dark objects that were made with phosoporus that needed to be illuminated to initiate a glow: a claim which seems not only scientifically incorrect (as mentioned above, phosphorus is not photoluminescent – it glows when in contact with air as it oxidises), and so unlikely; but, otherwise, dangerous and, surely, illegal.
Read about unscientific luminous creations
Defining scientific terms – badly
During my search, I came across a website (grammarist.com) offering to explain the difference between the words phosphorous and phosphorus. It did not discuss rare earths, but informed readers that
"Phosphate: Noun that means an electrically charged particle.
https://grammarist.com/spelling/phosphorous-phosphorus/
Phosphorus: Also a noun that means a mineral found in phosphate."
…We've already established that phosphorus is the simple mineral found in the particle phosphate, but phosphor is something else altogether."
So, that's 'no', 'no', 'no', and…I think at least one more 'no'.
Phosphorus is a reactive element, and is not found in nature as a mineral. To a scientist, a mineral is a material found in nature – as a component of rocks. Unfortunately, in discussing diet, the term minerals is often associated with elements, such as, for example, phosphorus, iodine, potassium and iron that are necessary for good health. However, one would not eat the element iron, but rather some compound of it. (Foods naturally contain iron compounds). And trying to eat phosphorus, iodine or potassium (rather than compounds of them) would be very hazardous.
So, whilst a nutritional supplement might well contain some minerals in the composition, strictly they are there as compounds that will provide a source of biologically important elements, and they will be metabolised into other compounds of those elements. (Iron from iron compounds will, for example, be used in synthesising the haem incorporated into red blood cells.) Unfortunately, learners commonly have alternative conceptions ('misconceptions') about the difference between mixtures and compounds and assume a compound maintains the properties of its 'constituent' elements (Taber, 1996).
"Compound is one or more elements mixed together"
alternative conception elicited from an Advance level chemisty student
The grammarist.com entry helpfully warned us that phosphate was "not to be confused with phosphoric acid, a chemical compound found in detergents and fertilizers". I suspect it is only found in detergents and fertilisers when something has gone wrong with the production process (notwithstanding diluted phosphoric acid has been used directly as a fertiliser) 4. It is a corrosive and irritant substance that can cause bronchitis – although tiny amounts are added to some colas. [n.b., cocaine also once featured in some cola, but that is no longer allowed.]
- An ion is an electrically charged particle
- The phosphate ion is one example of a type of ion.
- Phosphates (such as calcium phosphate) are substances that contain phosphate ions.
So, phosphates contain electrically charged particles (phosphate ions), but that does not make phosphate an electrically charged particle, just as
- blue does not mean a large marine mammal
- bank does not mean a day of celebration where people do not need to go to work
- vice does not mean a senior executive officer
- motor does not mean a two wheeled vehicle
- compact does not mean a flat circular object
- final does not mean a simple musical instrument played with the breath
- free does not mean a meal taken around noon or soon after, and
- meal does not mean a token that provides entry or service
Grammarist invited feedback: I sent it some, so hopefully by the time you read this, the entry will have been changed.
It was on the internet: it must be true
The internet is an immense and powerful tool giving access to the vast resources of the World Wide Web. Unfortunately, the downside of a shared, democratic, free to access, reservoir of human knowledge is that there is no quality control. There is a lot of really good material on the web: but there is also a lot of nonsense on the web.
One example I have referred to before is the statement:
"energy is conserved in chemical reactions so can therefore be neither created nor destroyed"
This has the form of a logical structure
X so therefore Y
which is equivalent to
Y because X:
"energy can be neither created nor destroyed because it is conserved in chemical reactions"
This is just nonsense. There is no logical reason why the conservation of energy in chemical reactions implies a general principle of energy conservation.
We can deduce the specific from the general (days have 24 hours, so Sunday has 24 hours) but not the general from the specific (January has 31 days, so months have 31 days).
Perhaps this is easily missed by people who already know that energy is always conserved.
A parallel structure might be:
"association football teams always consist of eleven players so therefore sports teams always consist of eleven players"
"sports teams always consist of eleven players because association football teams always consist of eleven players"
This is 'obviously' wrong because we know that rugby teams and netball teams and volleyball teams and water polo teams (for example) do not consist of eleven players.
Yet, if you search for "energy can be neither created nor destroyed because it is conserved in chemical reactions", you will find that this claim is included on the public websites of many schools (Taber, 2020). That is because, despite being wrong, it has authority – it is included in the English National Curriculum for Science (which I find shocking – we all make mistakes, but did nobody check the document before publication?) The English government department responsible was made aware of the error but does not think that it is a priority to make corrections to the curriculum.
Artificial (ignorant) intelligence
But what about quinine containing rare earth compounds? A notion that is structurally similar to claiming that
- France contains South American countries, or
- 'Great Expectations' contains Jane Austin novels, or
- February contains Autumn months, or
- Cauliflower contains citrus fruits, or
- Beethoven's 5th Symphony contains Haydn concerti
(in other words, something obviously silly to someone who has a basic understanding of the domain – chemistry or geography or literature or the calender or botany/horticulture or music – because it suggest one basic unit contains other units of similar status).
How does this error appear so often? Quite likely, a lot of website now are populated with material collected and collated by machines from other websites. If so, it only takes one human being (or government department) to publish something incorrect, and in time it is likely to start appearing in various places on the web.
There is currently a lot of talk of how artificial intelligence (AI) is getting better at writing essays, and answering questions, and even drafting lectures for busy academics. AI seemingly has great potential where it is provided with high quality feedback. Perhaps, but where the AI is based on finding patterns in publicly available texts, and has no real ability to check sense, then I wonder if the www is only going to become more and more polluted with misinformation and nonsense.
I do not know where Lucy Jane Santos got the idea that there are other substances in the single substance quinine (akin to having other countries in France), but if she did a web-search and relied on what she read, then I am in no position to be critical. I use the web to find things out and check things all the time. I am likely to spot gross errors in fields where I already have a strong background…but outside of that? I do seek to evaluate the likely authority of sources – but that does not mean I could not be taken in by a site which looked professional and authoritative.
The web started with imperfect people (because we all are) posting all kinds of material – with all kinds of motivations. I expect most of it was well-meaning, and usually represented something the poster actually believed; and indeed much of it was valid. However, a 'bot' can search, copy, and paste far quicker than a person, and if the internet is increasingly authored by programs that are indiscriminately copying bits and pieces from elsewhere to collage new copy to attract readers to advertising, then one cannot help wonder if the proportion of web-pages that cannot be trusted will be incrementally coming to dominate the whole network.
I (a fallible, but natural intelligence) hope not, but I am not very optimistic.
Work cited:
- Santos, Lucy Jane (2020) Half lives. The unlikely story of radium. Icon.
- Taber, K. S. (1996). Chlorine is an oxide, heat causes molecules to melt, and sodium reacts badly in chlorine: a survey of the background knowledge of one A level chemistry class. School Science Review, 78(282), 39-48. [ Download this article]
- Taber, K. S. (2020). Conceptual confusion in the chemistry curriculum: exemplifying the problematic nature of representing chemical concepts as target knowledge. Foundations of Chemistry, 22: 309-334. https://doi.org/10.1007/s10698-019-09346-3 [Open Access – download for free]
Notes:
1 Although my own research has been in science education and not one of the natural sciences, I am pleased that the learned societies (e.g. the Institute of Physics, the Royal Society of Chemistry, etc.) and the UK's Science Council, recognise the work of science educators as professional contributions to science.
2 One internet site suggests:
Luminescence is caused by various things like electric current, chemical reactions, nuclear radiation, electromagnetic radiation, etc. But phosphorescence takes place after a sample is irradiated with light.
• Phosphorescence remains for sometime even after the lighting source is removed. But luminescence is not so.
https://www.differencebetween.com/difference-between-luminescence-and-vs-phosphorescence/
The second paragraph is nonsensical since phosphorescence is a type of luminescence. (It should be, "…fluorescence" that does not.) The first paragraph seems reasonable except that the 'but' seems misplaced. However 'in the light of' the second sentence (which sees phosphorescence and luminescence as contrary) it seems that the (contrasting) 'but' was intended, and whoever wrote this did not realise that light is a form of electromagnetic radiation.
Another, more technical, site suggests,
Luminescence is the emission of light by a substance as a result of a chemical reaction (chemiluminescence) or an enzymatic reaction (bioluminescence).
https://www.moleculardevices.com/technology/luminescence
Here again a contrast is set up:
- chemiluminescence (due to a chemical reaction) versus
- bioluminescence (due to an enzymatic reaction).
However, the keen-eyed will have spotted that "an enzymatic reaction" is simply a chemical reaction catalysed by an enzyme. So, bioluminescence is a subtype of chemiluminescence, not something distinct.
3 Some sources claim that the medicinal properties of cinchona bark were discovered by Jesuit missionaries that travelled to South America as part of European imperial expansion there.
Nataly Allasi Canales of the Natural History Museum of Denmark, University of Copenhagen is reported as explaining that actually,
"Quinine was already known to the Quechua, the Cañari and the Chimú indigenous peoples that inhabited modern-day Peru, Bolivia and Ecuador before the arrival of the Spanish…They were the ones that introduced the bark to Spanish Jesuits."
https://www.bbc.com/travel/article/20200527-the-tree-that-changed-the-world-map
Learning about the history of indigenous technologies can be complicated because:
- often they are transmitted by an oral and practice culture (rather than written accounts);
- traditional practices may be disrupted (or even suppressed) by colonisation by external invaders; and
- European colonisers, naturalists and other travellers, often did not think their indigenous informants 'counted', and rather considered (or at least treated) what they were shown as their own discoveries.
4 This again seems to reflect the common alternative conception that confuses mixtures and compounds (Taber, 1996): phosphoric acid is used in reactions to produce fertilizers and detergents, but having reacted is no longer present. It is a starting material, but not an ingredient of the final product.
Just as we do not eat iron and phosphorus, we do not use washing powders that contain phosphoric acid, even if they have been prepared with it. (Increasingly, phosphates are being replaced in detergents because of their polluting effects on surface water such as rivers and lakes.)
5 This gives the impression to me that the Department of Education sees schooling as little more than a game where students perform and are tested on learning whatever is presented to them, rather than being about learning what is worth knowing. There is surely no value in learning a logically flawed claim. Any student who understands the ideas will appreciate this statement is incorrect, but perhaps the English Government prefers testing for recall of rote learning rather than looking for critical engagement?