Where any deed of conveyance, or mortgage, or other instrument in writing affecting real estate, heretofore executed, purporting to be the act and deed of a corporation or of a joint stock or partnership association or limited partnership or registered partnership, or specifically therein naming the corporation or the joint stock or partnership association or limited partnership or registered partnership as the grantor or party of the first part, shall have been erroneously executed by failure to affix the corporate seal or otherwise, or shall have been erroneously acknowledged by any officer or officers of such corporation or such joint stock or partnership association or limited partnership or registered partnership, or shall have been executed and acknowledged by the officers of such corporation or such joint stock or partnership association or limited partnership or registered partnership in the manner prescribed by law for the execution and acknowledgment of deeds and mortgages by individuals or otherwise, but in such manner as to show that they were signing or acknowledging the said deed or mortgage in their official capacity, or was executed, acknowledged and delivered after the expiration of the period of its existence fixed by its charter or by its articles of association, such deed or mortgage is hereby ratified, confirmed and made valid, as the act and deed of the corporation or of the joint stock or partnership association or limited partnership or registered partnership, and shall be taken to be of the same validity and effect as if properly executed and acknowledged in the manner prescribed by law for the execution and acknowledgment of deeds and mortgages by corporations or by joint stock or partnership associations or limited partnership or registered partnership: Provided, That no case now in litigation shall be affected by this act.