August 2014


Cadmium correction

From Mark Booth
I read the article ‘The colourful science’ with interest – especially the section about cadmium pigments. I hoped that a reputable magazine might contextualise these pigments better and get some good science in there. However, I was appalled to read the suggestion that cadmium red may be ‘removed from the market because of its toxicity’. The Reach (registration, evaluation, authorisation and restriction of chemicals) dossier for yellow, red and orange cadmium pigments registers them as non-hazardous.
 
As you may guess, I work in the pigments industry and one of the biggest problems we face is that people, including regulators and now apparently science writers, seem to think that it is reasonable to suggest that a metal and all its compounds can be grouped together. Hence, they assume that the toxicity of cadmium metal and its key salts (which are soluble), means that every other compound must be toxic too.
 
Logically, for a pigment to be heat-, light- and weather-fast, it must not be reactive nor bioavailable, otherwise it would decolourise over time. Cadmium pigments have a structure that renders them almost completely insoluble, which is why they are such good pigments.
 
I think that a feature on the flaws of the approach in grouping all compounds of a metal together would also make an excellent article. Imagine the problems it would cause if you tried to group other elements such as carbon and all its compounds together.
M Booth MRSC
Newcastle, UK
 

Platinum pollution?

From Mark Foreman
Regarding Philip Leigh’s letter about platinum recovery, I would like to point out that both cisplatin and carboplatin have been observed in wastewater from an oncology ward. It is also important to note that cisplatin is clearly carcinogenic in rodents. 
 
Medical procedure is not a justification for totally ignoring the health, safety and environmental issues that apply to it. I support the use of platinum and other similar drugs for the treatment of cancer, but we should consider reducing the costs, which include occupational exposure of workers and environmental release. One idea would be to store the wastewater from oncology wards in a holding tank with some suitable reagent to allow the toxic drugs in the water to degrade.
 
In general, where a medical treatment is either environmentally or financially unsustainable, it is better to improve the treatment system than writing it off or banning it.
M Foreman CChem MRSC
Nuclear chemistry, Chalmers University of Technology, Sweden
 

Mary Rose sulfur puzzle settled?

From Barry Knight
I think there is a misapprehension regarding the origin of the sulfur causing problems for the conservation of the Mary Rose. This is not present as elemental sulfur and has nothing to do with gunpowder, which, as Tom Smith says, would have been prepared on land. Its origin is rather more interesting.
 
Anaerobic bacteria in the silt covering the ship metabolise sulfate in the sea water to sulfide; the sulfide reacts with Fe2+ ions derived from the corrosion of iron nails and fittings in the hull to give pyrite, FeS2, which is deposited in the ship’s timbers. This was stable all the while the ship was underwater and while it was kept wet during conservation. However, once conservation was complete and the hull was allowed to dry out, oxygen could reach the pyrite, which oxidises to give Fe2+ ions, hydrogen ions and sulfate. This highly acidic solution is responsible for the damage to the ship’s timbers and also forms orange rusty deposits of iron oxyhydroxides as it reaches the surface and oxidises further.
 
This problem has already been encountered in the conservation of the Swedish warship Vasa
 
The conservation challenge therefore is how to remove the pyrite before it oxidises, or alternatively, how to seal it in and prevent it from oxidising – neither is a simple task.
B Knight MRSC
St Albans, UK
 
From Michael Cartwright

I read the correspondence on gunpowder with interest. The medieval gun powder manufacturers were quite smart and realised that grinding the ingredients together was likely to cause an accident, so individual ingredients were finely ground before mixing. 
 
There is some evidence in the literature from the time of the Mary Rose that gunpowder was stored as separate fine powders and mixed prior to filling the charge containers in their breech-loaded cannons. These cannons generally had a lower performance than muzzle-loaded cannons, but their rate of fire was six times faster because they did not need to swab the canon out before reloading. If bulk gunpowder was stored mixed then a single cannonball in the magazine would destroy the ship. Unfortunately, the mixing was performed by unskilled personnel which meant that quality control was not very good and this process gained a variable reputation – hence most ships carried their gunpowder as ready-to-fire mixtures, but some definitely did not.
 
There is still a lot of history to be explored.
M Cartwright CChem MRSC
By email
 

Defending Shulgin

From Lionel Milgrom
Mark Peplow suggests Alexander Shulgin was naïve to deny responsibility for how his psychedelic inventions were misused and abused. Is that fair? 
 
Shulgin’s psychedelic ‘cookbooks’ Pihkal and Tihkal were originally published outside ‘the cloisters of academe’, and are still bestsellers. So some blame him for deaths among youthful clubbers and criminal elements ‘breaking bad’ in the drug scene. But far worse is now freely available: a cursory glance at the internet will tell you all you need to know about how the 7/7 bombers managed to wreak so much devastation on the London underground.
 
Along with several other high profile scientists-turned-psychonauts, Shulgin was a child of his time. They believed passionately in the absolute right of the individual to explore the limits of their own consciousness, free of government interference.And herein lies the rub. More than Shulgin’s purported naïvety, it was the blanket ban on psychoactive substances, and the concomitant criminal activity such bans inevitably engender, which ramped up their misuse and abuse. Whether or not this might be an argument for their legalisation, taxation and control misses the point. Criminalising psychoactive substances in the first place represented arguably one of the greatest losses to science and humanity.
 
Since the beginning of human history, if not before, psychoactive substances (or entheogens – literally, ‘generating the divine within’) have been used to complement religious, shamanic and spiritual practices. The explosion of interest in them during the 1950s and 1960s, especially in psychological and psychotherapeutic contexts, was just beginning to open up the scientific mapping of these inner spaces. Sadly, all that outlawing psychoactives ever did was to deny a generation proper supervision, and the opportunity to learn how to navigate these domains in safety. Coupled with today’s ‘street’ drugs with their lack of purity and provenance, is it any wonder the number of deaths (and grieving relatives) is on the increase?
 
If the 20th, and now 21st centuries have taught us anything, it is that there are far greater crimes against humanity than exploring the spaces between our ears. Or to paraphrase (badly) a line from Shakespeare, ‘The fault, dear Mark(us), lies not in our drugs, but in ourselves...’
L R Milgrom CChem FRSC
London, UK 
 

Perils of privatisation

From Barrie Skelcher
Privatising, in part or in whole, the Food and Environment Research Agency (Fera) will be a disaster for society. 
 
Public authorities are devoted to serving the public interest, but once private investment becomes involved that changes to short-term considerations for maximising profit. This scenario is well illustrated by what happened to the once publicly owned electricity industry in the UK. This industry’s priority is no longer to provide a secure supply for the country but to provide a profit to foreign companies, often at our expense. It was privatised in stages, probably similar to what some politicians have in mind for Fera.
 
When privatisation of the electricity supply took place, we were told it would bring great benefits. And for the brokers in the city of London it did, but not for the rest of us. There is now a lack of public planning and control and we are faced with the dangerous strategy of building massive nuclear power stations on unsuitable sites. I have tried to alert the government to the danger of concentrating power generation in just a few locations, but they would not listen. So I wrote a short novel to illustrate my concerns: The day England died.
 
Why am I so concerned? When you have worked in the nuclear and electricity industry all your working life, you get worried when you see things going wrong.
B Skelcher MRSC 
Suffolk, UK
 

The Choshu five

From Alwyn Davies
There has been an interesting sequel to the commemoration last year of the arrival in 1863 of the UK’s first Japanese university student. These students were cared for during their stay by Alexander Williamson, and when they returned to Japan, they became the founders of the modern Japanese state.
 
I received a message from John Fison, the great grandson of Williamson, saying that he and his niece, Sally-Anne Lenton, had some items that might interest us.
 
One of these is Williamson’s Royal Medal from the Royal Society, which he was awarded in 1862. Another is the bronze plaque commemorating his election to the Italian Lincea Academy in 1883. But the most interesting item is a beautiful silver incense burner in the form of a lion; this was given to Williamson and his wife, Catherine, by the Japanese students they had fostered.
 
It is 97mm high and weighs 475g, and has some small precious stones inset round the collar. The head comes off and inside is a dish in which the incense is burned, the smoke coming out through the lion’s mouth, nose, eyes and ears. On the base, in Japanese characters, is the name of the artist, Joun Oshima. He lived from 1858 to 1940 and was a master craftsman of the Meiji era, so it seems likely that the lion dates from the last quarter of the 19th century. We can find no record elsewhere of the existence of this beautiful and historically important object.
 
The medal and plaque have generously been donated to the University College London chemistry department and the lion has been given to us on long-term loan.
A G Davies CChem FRSC
University College London, UK
 

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