The Prose Works of Percy Bysshe Shelley from the original Editions. Edited, Prefaced, and Annotated by Richard Hearne Shepherd, in Two Volumes (London: Chatto & Windus, 1906). http://oll.libertyfund.org/titles/2582,
A 2 volume collection of prose writings. Vol. 1 includes 2 youthful prose romances, the Refutation of Deism, his Declaration of Rights, an essay on electoral reform, and other short pieces. Vol. 2 includes A Defence of Poetry, On a Future State, Speculations on Metaphysics, and Letters from Italy.
The text is in the public domain.