Farewell Nova Scotia got my interest because there was much discussion about the song years back in Canadian media (Confederation Centennial 1967?).
But it is "possibly" (he, he, he) in PD now since it is based on "The Soldiers Adieu," apparently written by Robert Tannahill (1774-1810), see thread 12170- Farewell
I don't think Dr. Creighton ever copyrighted the discovery of a folk version.

The new incomprehensible USA copyright regulations recently promulgated made a grab to include much written after about 1900 (if certain conditions are met).