You write to us about the periodic table, Buzz Aldrin and aluminium doors

Early periodic tables

In the February issue we recounted our discovery at the University of St Andrews of a very early example of a periodic table wallchart, produced in 1885 (Chemistry World, February 2019, p68). We asked if there were any other surviving tables of that era or perhaps any that predated the St Andrews Table.

It has come to our attention that there is a periodic table displayed high in a lecture theatre at St Petersburg State University, Russia. This is a one-off hand-painted table, possibly commissioned by Dimitri Mendeleev himself, and is dated 1876. Igor Dmitriev, the director of the Mendeleev museum and archives at the university, indicates that the table was originally located in another teaching building where Mendeleev taught, and was moved to its current location when a new chemistry laboratory was constructed in 1894.

The St Petersburg table was restored in 2006. Given this was created only seven years after the important disclosure of Medeleev’s system in 1869, it seems likely it is the earliest periodic table wallchart. The St Andrews table, produced nine years later, appears to be the earliest surviving copy of a commercially printed periodic table wallchart.

David O’Hagan, Alan Aitken and M. Pilar Gil
St Andrews, UK

The article on the art of the periodic table in the recent Chemistry World (Chemistry World, April 2019, p25) attributes the non-acceptance of chemists to the ‘telluric screw’ because it appeared in a geology journal. Alexandre-Emile Béguyer de Chantcourtois was a geologist, but the article was actually in Comptes rendus. Importantly, a key diagram was not included in the journal article so, the next year, de Chantcourtois printed it privately on his own press.

The rarity of these copies make them very valuable. I saw one recently at a stunning exhibition held St Catharine’s College, Cambridge, UK to celebrate the International Year of the Periodic Table, which is now on tour.

Gordon Woods CChem FRSC
Oakham, Rutland

‘The art of the periodic table’ was, quite rightly, more about continuous representations of the periodic system than about tables, which are the format that offers least scope to artistry. However, it missed out the beautiful ‘lemniscates’ of Charles Janet, 1928; the ‘wound ribbon’ of George Gamow, 1940; and the most widely influential of all spirals – John Clark’s 1949 redrawing of his ‘arena’ for Life. This inspired both Theodor Benfey’s ‘snail’ and the beautiful spiral designed by the artist Edgar Longman for the Festival of Britain, 1951, with its elliptical outline and dynamic upward tilt.

Longman’s mural was regrettably tiled over at the end of the Festival but, in skeletal form, it has been republished several times; in 2004 the Royal Society of Chemistry paid for the printing of 6000 copies of my updated version, ‘Chemical Galaxy’, to be sent to every school and college in the UK.

Philip Stewart
Oxford, UK

Aldrin and Aldrin

Having read the Named Reaction article on the Diels–Alder reaction (Chemistry World, May 2019, p71) it would be remiss of me not to mention the two chlorinated insecticides, Aldrin and Dieldrin, which were named in honour of the two discoverers of the reaction. Those names, together with those of their isomeric brothers Isodrin and Endrin, are engraved on my heart.

Aldrin is made by the Diels–Alder reaction between hexachlorocyclopentadiene and bicycloheptadiene. Dieldrin is made by epoxidation of Aldrin. Isodrin is made from cyclopentadiene and hexachlorobicycloheptadiene, and Endrin by epoxidation of the product. My PhD thesis was on the metabolism of those substances. I am delighted to recall that I was working on the metabolism of Aldrin while Buzz Aldrin was walking on the moon!

These insecticides were banned because of toxicological and environmental problems, but I am pleased to report that I continue to enjoy good health despite working with them and other equally toxic substances for many years.

Michael Baldwin CChem FRSC
Sittingbourne, UK

The door is open…

Aluminium-framed doors and windows incorporate a layer of solid resin between the inner and outer leaves, typically 2cm thick. This is known in the industry as a ‘thermal break’. If a resourceful chemist could find a means of creating a resin foam rather than homogeneous layer, it would bring at least three benefits: improved insulation value, reduced cost (since less resin would be used) and less weight. It is unknown whether such a porous structure could be created by injected air or other gas (argon has a lower thermal conductivity), or whether one could incorporate a gas-forming chemical within the resin formulation. But, at a time when we are all striving for increased energy efficiency, such a development would surely be received with open arms.

Anselm Kuhn MRSC
Stevenage, UK

Mercury risk

I was interested to read the article in about dimethylmercury (Chemistry World, April 2019, p71). In the 1960s I worked for a company producing a range of inorganic and organic mercurials including mercury (II) oxide and phenylmercury compounds. In one laboratory, work was carried out on methylmercury and dimethylmercury: these were considered to be so dangerous as to necessitate only one worker in the laboratory at a time. This laboratory was remote from the production plant and the rest of the laboratories. The dangers of methylmercury were well known at the time, and the company had had problems with inadvertent exposure of a worker to mercurials resulting in neurological damage.

The person working in the laboratory wore full protective clothing and multiple layers of gloves as the permeability of latex was understood. The chemist on duty, and other workers with mercurials, were monitored frequently for absorption of mercury by blood and urine tests, which involved the destruction of the organic material and complexing the mercury with dithizone for spectroscopy. In addition, the methylmercury workers were tested for any neurological symptoms at what is today the Royal London Hospital.

Fortunately no problems were encountered with the plant and laboratory workers during my time. The site also produced lead compounds. Exposure to these was monitored by measuring the concentration of coproporphyrin IV in urine through a tedious solvent extraction process, followed by UV spectroscopy.

John Chamberlin MRSC
North Shields, UK