Chiefly correspondence with Alexander John Gaspard Marcet on chemistry, with references to Sir Joseph Banks, Jean Francois Berger, Johan Jakob Berzelius, Jean-Baptiste Biot, and others; a few letters to and from John Bostock, Thomas Cooper, John Wilson Croker, Giovanni Fabbroni, and Henry Penneck.

This collection of Morton letters forms part of a bound volume of incoming correspondence. It is a companion volume to the original letters in the Morton collection at the American Philosophical Society, which were also originally bound. Most of the subjects of the two collections overlap, but additional subjects in the microfilmed collection include American Indians, archaeology, Egyptology, and phrenology.