point — Wouters, Manual of Moral Theology
Point III. On Accession
803.
I. Notion. Accession is the right by which we acquire whatever is united with our thing.
804.
II. Modes of accession. Accession can occur by alluvion, by planting, sowing, and building, by commixture and confusion. It is useful to hand down certain notions.
Alluvion is had when, from an overflowing river, something of land accrues to someone's estate.
Commixture is had when solid things, and confusion when liquid things, belonging to different owners, are mixed together.
What right accrues to the owners in individual cases, you should draw from the civil laws.