HENRY MACKLE will be best remembered for his work in the field of thermochemistry - measurement of the energy content of materials. With a small group of talented postgraduates at Queen's University, Belfast, and few funds, he designed and built in 1951 the first modern aneroid rotating- bomb combustion calorimeters. These apparatuses were used in thermochemical studies of organic sulphur-containing compounds and were of particular significance in the petroleum refining and pharmaceutical industries.
Mackle was born in 1921 at Darrykeerin in the middle of Co Armagh fruit-growing country. He read Chemistry at Queen's University, Belfast, graduating with a First Class honours degree in 1942, followed by a PhD in May 1947. With encouragement from the then Vice-Chancellor, Sir David Lindsay Keir, Mackle applied for and was accepted to study at Magdalen College, Oxford, with Professor Leslie Sutton, obtaining a second doctorate (DPhil) in 1950.
His research project at Oxford, into the structure of molecules in gases by electron diffraction, led the world in those early days, just after the Second World War. The camera used in the research was subsequently presented to and exhibited in the Science Museum in London, representing 'the tradition of hand-made laboratory apparatus at the cutting edge of technology'.
Mackle returned in 1951 to a lectureship in Physical Chemistry at Queen's. His research in thermochemistry augmented an extensive research programme for the American Petroleum Institute at the then US Bureau of Mines, Bartlesville, Oklahoma. In addition to highlighting the value of the aneroid calorimeters, measuring devices of particular use to industry, Mackle also used them as a teaching tool. He used the results in developing ideas to aid the understanding of the chemical bonding in sulphur-containing molecules.
Mackle was a superb teacher. He once said, 'An educational system isn't worth a great deal if it teaches young people how to make a living but doesn't teach them how to live.' In 1962 he was promoted to Senior Lecturer and two years later was awarded the title of Reader in Chemistry. It was of great joy to him when in 1983 three of the aneroid calorimeters went on display in the Science Museum, making four exhibited items related to his research efforts.
Henry Mackle was a man of considerable erudition, charm and wit. He loved conversation and debate. In his youth he was a talented football player and adroit at tennis as well, representing the Irish Universities against the Scottish Universities in 1951. His skills at debating and natural Irish wit resulted in his presidency of numerous university societies.
A 'moderate nationalist', he had a love for all things Irish and especially the poetry of Yeats. On the local arts scene, he was a founder member of the Ulster Folklife Society, President of the Arts Club and a member of the literature advisory panel of the Ulster Arts Council.
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