How to Remove Freckles
Apply a saturated solution of borax in rose-water five or six times a day and allow to dry upon the face. This will be successful in mild cases.
Moisten the finger tips and dip in finely powdered saltpeter and apply to the freckles. Repeat until freckles are gone.
Poultice the face lightly, or soften with almond paste and rub a freshly cut lemon over the surface.
--from the 20th Century Cookbook--