An Irish scientist noted for his work on gases. He studied chemistry at the University of Glasgow before undertaking further studies in Paris. He then attended Trinity College, Dublin before completing his medical studies in Edinburgh and then returning to Belfast to set up practice as a physician. When Queen’s College opened in 1845, he was appointed professor of chemistry, and also the first vice president of the college. During this time, he carried out his most important studies on gases. His three main areas of work concerned thermochemistry, the nature of ozone, and the continuity of liquid and gaseous states of matter. He was offered a knighthood but declined on the grounds of ill health.