Old Widows' Recipes is a book found in Dishonored 2.
Marnie's Secret Powders
(For bringing on Frightful Illusions, Blurred Vision, and the like)
Dry twenty purple sea slugs in the sun until they be crisped and light as feathers.
Put them in the mortar with these:
1 dried Burdock Root
4 dried Neem Leaves
1/2 measure whalebone, finely shaved
Grind until powdery. Keep very dry until ready to use. Careful not to get any in yer eyes.
Adeline's Night Drops
(For inducing night terrors, and starving yer enemies of sleep)
Soak a ripe lemon in a mug o' goat's milk for five days until the milk turns to green foam. Should be thick and pungent. Discard the lemon.
Mix the foam with a bit of honey (for taste) and bottle it up tight with a stopper. Five drops in the fellow's drink should do the trick.
The book can be found in the basement of The Crone's Hand, during the mission Dust District.