Edward Hussey Delaval (1729–1814), chemist and experimental physicist, was the third son of Captain Francis Blake Delaval and Rhoda Apreece. In 1759 he was elected a Fellow of the Royal Society. In 1766 Delaval was awarded the Society’s distinguished Copley Medal for ‘Experiments and Observations on the agreement between the specific gravities of the several Metals, and their colours when united to glass, as well as those of their other preparations’. The occasion of the award is evidently the subject of the present portrait, as indicated by the prominent position of Delaval’s certificate and the objects used in his experiments. The artist is unknown but stylistically it is somewhat reminiscent of the work of George Romney during the mid-1760s.