The bulk of the Hunt papers consists of scientific correspondence, with a fairly large component of notes on scientific subjects. Most of the material dates from after Hunt's departure for the United States. With the exception of a letter of appointment to the Geological Survey of Vermont in 1845, all Hunt's correspondence (incoming, with copies of some outgoing) dates from the period 1863-1891, with the majority of items from the 1880s. There are a few letters of a social or personal nature, but most concern scientific matters: geological and chemical research problems, exchange of specimens, Hunt's theories and the controversies they stirred, his publications, negotiations for patents on some of his discoveries, the business of various scientific societies, and in particular the organization of the Geological Congress. Amongst his correspondents were James D. Dana (with whom he engaged in a heated quarrel over scientific theory), James Hall, Persifor Frazer, J.W. Dawson, and various members of the Geological Survey of Canada, such as G.M. Dawson, Robert Bell, Henry Y. Hind, and George Iles. Hunt's scientific notes mostly deal with special topics in chemistry, geology, mineralogy, railways, coal products and the controversy with Dana. There are also reading notes for geological texts, lecture notes for courses in geology, 1876, and chemistry, and indexes, apparently for Hunt's books. A manuscript on "Benjamin Franklin's Autobiography: an episode in its history", notes for a lecture on "People I have met", and sketches of family history represent Hunt's wider interests. There are also clippings of reviews of books and lectures by Hunt, biographical notices, reports on scientific themes and institutions, and news of the Geological Survey.