Auditors and their deputies may administer oaths necessary in the performance of their duties and in all other cases where oaths are required by law to be administered and take acknowledgments of deeds and other instruments in writing: PROVIDED, That any deputy county auditor, in administering such oath or taking such acknowledgment, shall certify to the same in his or her own name as deputy, and not in the name of his or her principal, and shall attach thereto the seal of the office: PROVIDED, That all oaths administered or acknowledgments taken by any deputy of any county auditor certifying to the same in the name of his or her principal by himself or herself as such deputy, prior to the taking effect of chapter 119, Laws of 1893 be and the same are hereby legalized and made valid and binding.