A recipe used by (or I should probably say
on) American sailors and soldiers in the 19th century. It probably used
salt junk (hardened salted beef) and
hard-tack as its primary ingredients, but I am unable to find a historical recipe, even in
Patrick O'Brian's nautical historical cookbook
Lobscouse & Spotted Dog.
Slum is an adulturation of "slime" and
gullion meant either stomache-ache or cess-pool, depending on your source.
It is referred to in "Two Years Before the Mast" by Richard Henry Dana, which recounts a trading mission from Boston to California and back around 1836.