The Philosophical Works of David Hume. Including all the Essays, and exhibiting the more important Alterations and Corrections in the successive Editions by the Author. In Four Volumes. (Edinburgh: Adam Black and William Tait, 1826). http://oll.libertyfund.org/titles/1728,
Vol. 1 - Treatise of Human Nature Bk 1; Vol. 2 - Treatise of Human Nature Bk 2 and 3; Vol. 3 - Essays Moral, Political and Literary; Vol. 4 An Inquiry Concerning the Human Understanding, An Inquiry Concerning the Principles of Morals, Appendix, The Natural History of Religion, Additional Essays.
The text is in the public domain.