Before revision: (In contrast, some base metals, notably iron, oxidize readily to form a rough porous coating of rust that adheres loosely, is of higher volume than the original displaced metal, and sloughs off readily; all of which permit & promote further oxidation.)
After revision: ,(In contrast, some base metals, notably iron, oxidize readily to form a rough porous coating of rust that adheres loosely, is of higher volume than the original displaced metal, and sloughs off readily; all of which permit & promote further oxidation.)