Marcet was a physician and chemist who lectured at Guy's Hospital, London. Documents include: Printed resolution addressed to Marcet and hand-signed by William Livingston, naming him an honorary member of the Aberdeen Medical Society, 1808 October 20; C. Duméril, Secrétaire de la Société de Médecine de la Faculté de Paris, to Marcet, naming him a corresponding member, 1816 August 27; Acloque [a firm], Paris, to Marcet, 1820 July 14 and 1820 August 31; Henry Lemercier, pharmacien-manufacturier de produits chemiques, to Marcet, 1820 July 14; Pixii [firm], Paris, to Marcet, 1820 August 1; printed pamphlet to Fellows of the Royal Society, on the politics of electing a new Chair and discouraging private attempts to select Humphry Davy, 1820 November; handwritten copy of Marcet to C. Duméril, membre de l'Institut, Paris, [no year] September 14.