Letters: July 2020

Science is not policy

Philip Robinson rightly observes the need to ensure that the public can (and do) trust scientific advice (Chemistry World, June 2020, p6). Science is a uniquely authoritative and effective problem-solving tool. But to deserve public trust, it must be used correctly.

Robinson criticises politicians for their ‘oversimplified’ approach to science policy. Yet scientists themselves often favour such messages. On topics as varied as childhood vaccination, climate change and pandemic management, scientists publicly argue that science mandates particular actions.

Science alone, however, is insufficient to answer questions that begin ‘What should…’. Science cannot choose objectives. Science cannot make value judgements. Science cannot make moral and ethical decisions. Science rarely even provides all the evidence on a question (policy questions usually require economic evidence, for example).

To lead by example and cultivate trust, we must clearly and honestly separate science from opinion. Our arguments should be of the form ‘since science says vaccines prevent disease and I want my children to be healthy, I should vaccinate them’, not ‘science says I should vaccinate my children’. The former is clearer and more compelling, and means people who distrust the conclusion need not automatically distrust the science. For political decisions, it differentiates the science (the advisors’ domain) from the policies (the politicians’ domain).

Ian Godfrey MRSC
Penrith, UK

Slippery lies

Philip Ball’s excellent article concerning lies told to children (Chemistry World, May 2020, p17) did not cover the claim still found in school textbooks that graphite is a lubricant because its layers slip over one another. Since the dawn of aviation we have known that this cannot be the true explanation. In a vacuum, or a rarefied atmosphere, graphite becomes abrasive. I rediscovered this when I was a research student in the early 1970s grinding graphite to a high surface area with metal salts to produce electrocatalysts.

I checked the spacing between the layers was the same in a vacuum and in air to eliminate any funny business about gases nipping in between the layers as many suggested at the time. I suspected that various organic compounds produced naturally on the surface during grinding were the real lubricators. Surely someone has demonstrated this by now?

Michael Kent CChem FRSC
Haslemere, UK

Light correction

As a science teacher, I enjoy reading Chemistry World, and sometimes even manage to get to it before my FRSC husband. I was a tad disturbed to come across a blip in James Urquart’s article ‘Artificial chloroplasts turn carbon dioxide into multicarbon molecules’ (Chemistry World, June 2020, p34). The biochemistry of photosynthesis is one of my favourite topics to teach. But the article had me reaching for my green marking pen when I read that thylakoid membranes ‘convert light into energy-rich compounds’. That photons can somehow be transformed into molecular compounds is one of the misconceptions I work hard to stamp out in my A-level students. I’m sure I speak for thylakoid membranes everywhere by clarifying that they use light energy to form energy-rich compounds. Right, back to my essay marking.

Sarah Beaumont-Lall
Via email

Shopping around

As noted in the article on the effect of Covid-19 on registrations of international students at UK universities this September (Chemistry World, June 2020, p8), there may be potentially 121,000 fewer applications with a shortfall of £1.51 billion from international students and £350 million from EU students.

Maybe a partial solution would be to cut the fees for international students, who currently pay at least double those charged to UK students, to the same level as the latter for one year only. Although the reduced income generated would still mean a substantial shortfall, it might attract a number of students who might otherwise not come. And of course there would be other knock-on effects, such as income from accommodation charges and support for the local economy and shops (my wife notes that our local supermarket in Lancaster is, or was, often crowded with students from the university). University cities need students!

Phil Weston, CChem FRSC
Lancaster, UK

Floating an idea

As a long-retired academic who in his youth had to give a lecture course on liquid structure, I was intrigued by the ‘Weirdness of water’ article (Chemistry World, April 2020, p26). Has anybody studied the iso-electronic ammonium fluoride under widely ranging conditions, or its phase diagram with water?

Not for the faint-hearted, I admit. The only other solvent material I remember whose solid floats on its liquid is carbon tetrachloride.

J R Miller MRSC
Colchester, UK

Crystal methods

The article on high-throughput methods to crystallise small molecules (Chemistry World, June 2020, p41) reminded me of my PhD experiences in synthetic chemistry at Nottingham in the early 1960s. My supervisor, Bill Partridge, would not accept a solid product as being ‘pure’ unless I could show him crystals in a vial. I became quite skilled in the art of crystallisation, no doubt helped by the fact that most of my molecules contained groups such as carboxylic acid, carboxamide, nitro and heteroatoms that were conducive to intermolecular bond formation.

A common trick to initiate crystallisation was to scratch the flask with a glass rod to generate micro-shards of glass, the edges of which often promoted crystal growth. Dandruff would do the trick on occasions. Once a seed crystal had grown the rest was easy.

My skills as a crystalliser did lead to an accident when I grew a large crystal of cyanuric triazide – I know it was a stupid thing to do – that detonated when I touched it with a spatula. Apparently, unstable compounds are particularly hazardous when packed and stressed within a crystal.

I had the idea back then that if there are a finite number of crystal forms, a mixture of micronised (but still crystalline) inert inorganic minerals, representing all possible polymorphs, could provide the templates for the seed crystallisation of any small organic molecule. Sadly, I never put the idea into practice. Has anyone tried it?

Malcolm Stevens CChem FRSC
Nottingham, UK

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