Section 16. In a conveyance of real estate the words ''warranty covenants'' shall have the full force, meaning and effect of the following words: ''The grantor, for himself, his heirs, executors, administrators and successors, covenants with the grantee, his heirs, successors and assigns, that he is lawfully seized in fee simple of the granted premises; that they are free from all encumbrances; that he has good right to sell and convey the same, and that he will, and his heirs, executors, administrators and successors shall, warrant and defend the same to the grantee and his heirs, successors and assigns forever against the lawful claims and demands of all persons''.