Gregory, an influential teacher, first isolated morphine in a usable form (though it took twenty years for its great advantages as a painkiller to be appreciated). Having graduated in medicine in Edinburgh, Gregory studied under Liebig on his famous chemistry course in Giessen; Liebig became a good friend, Gregory doing much to make his pioneering work on organic chemistry available in Britain. Gregory assisted Turner in London for a year; Liebig and he later collaborated on an extensively updated edition of Turner’s ‘Elements of Chemistry.’ Crum Brown was one of Gregory’s Edinburgh students.