Published as a serial in 8 parts. The Atlantic Monthly vols. 29-30, nos. 171-78 (January to August 1872), beginning p. 5 (e-copy at HathiTrust); under the heading "Septimius Felton ; or, the Elixir of Life." (so styled in running header; in story heading identically except all caps; in both first and last instalments). A related essay later in vol. 30: G. P. Lathrop, "History of Hawthorne's Last Romance", October 1872, p. 452-60.   (quoting the lead sentence): "the latest of Hawthorne's productions which reached a tangible completeness before the author's death" George Parsons Lathrop was Hawthorne's son-in-law and the editor of his complete works. Published as a serial in 6 parts. The Saint Pauls Magazine vol. 10, January to June 1872, beginning p. 1 (e-copy at HathiTrust); under the heading "Septimius.* A Romance of Immortality." (so styled in first instalment heading, all caps, with a footnote indicated by the asterisk).