Obituary: D. T. Lewis

David Thomas Lewis, chemist, born 17 March 1909, Government Chemist 1960-70, CB 1963, died 1 July 1992.

D. T. LEWIS was a South Walian with an enthusiasm for and a gifted imagination in chemistry. These two features formed the basis of his notably varied career. He was, at times, schoolteacher, university lecturer, civil servant and Defence Ministry nuclear-weapons boffin, the Government Chemist, and, in his last phase, part-time university academic professor. In all these catergories - and especially as Government Chemist - he left an above-average mark, and always many appreciative colleagues and friends.

Starting as the son of a miner from a typical 'County (quasi-grammar) School', at Brynmawr in Breconshire, David Lewis took first-class honours in chemistry at the University College of Wales, Aberystwyth. There he acquired a tutor and research director who greatly influenced his outlook. Lawson John Huddleston retained a military orientation from his 1914-18 years, when he ended as a captain on the Western Front. That experience had given him far more than an academic outlook and his lively mind injected an imaginative approach to his subject, hallmarks which became part of Lewis's professional character. Lewis's Ph D research was on the reactions and equilibria in solutions of hydrofluoric acid. As this medium immediately etched and eventually dissolved glass, the work required the construction of all apparatus from hard paraffin wax. Unconventionality in the science field always appealed to Lewis.

In 1983, when he left university, the country was in the middle of a depression. He took a post, for which there were over 300 applicants, paying little more than pounds 200 a year, as chemistry master at Quaker's Yard, in Mid Glamorgan. Soon he moved to a junior lectureship at University College of South Wales Cardiff. With the outbreak of war in 1939, he was recruited and rapidly promoted as a scientific officer in the Ministry of Supply Armament Division. Experience with explosives there singled him out as a group leader in the team assembled by William Penney to produce UK nuclear weapons at Aldermaston. He was in charge of the chemical side. This involved all aspects of analytical control but it also allowed him to demonstrate his uncanny ability to delineate the most effective - the most direct and least wasteful - method of preparing a variety of chemicals. It also embraced the effectiveness of the implosion to achieve 'instantaneously' the greater-than-critical mass for nuclear reaction to occur. Such key interests led to his presence at various UK nuclear weapons tests. Lewis, one of the warmest-hearted of men, was yet in his element.

His versatility and ready acceptance of responsibility, a preparedness to define, and if necessary, to defend his position, made him an effective choice as the Government Chemist in 1960. The almost limitless normal interests of this laboratory, which are extended when it has to act in a consultative role on unusual problems, were matched by Lewis's predisposition, he was interested in all and every aspects of the chemistry of materials. Unsurprisingly, he was a considerable success.

His decade as Government Chemist saw many developments in instrumental recording, and spectroscopic methods for precision analysis. Inevitably the computer made a significant impact. Lewis's enthusiasm for his subject meant that the newer methods were effectively deployed and the status of the laboratory was much enhanced. Typically, he saw the need to alert the public to the likely consequences of the unrestricted use of pesticides and herbicides. These were established to enter the human food-chain from fruit and vegetables. Civil-service caution would not have been his top priority: Lewis was more anxious to share outcomes likely to impinge on the public weal.

At Penney's behest Lewis wrote items for the Aldermaston house journal describing in simple terms the variety of sub-atomic particles: collected together, these appeared as a book, Ultimate Particles of Matter (1959). This also led to much effort separated from his professional activities. Lewis seemed convinced by the sophisticated mathematical deductions and physical experiments confirming the characteristics of such sub-atomic entities. Physics was not his strong point, and this accounted for his persisting over many years in representing these particle masses in terms of the highest common sub-multiples. It was an arithmetic exercise of a Pythagorean-Eddingtonian character. Lewis never abandoned his conviction in his units, the tamaid (morsel) and the bach (small), but it was not shared by others.

When he left the Government Chemist's Laboratory in 1970, Lewis was appointed to the first honorary professorship in the University of Wales. This took him back to his cynefin (original home) when he gave courses in modern aspects of analytical chemistry at Aberystwyth. One series of lectures on the chemistry of the environment was, for its date, of the greatest value. Regretfully, it was not published.

David Lewis was a charming person. His Welshness was never more in evidence than in his writing and publishing verse, replete with imaginative touches and benign humour.

(Photograph omitted)