The clerk of the county commission shall have power and is authorized to administer oaths and affirmations in all matters and proceedings incident to the exercise of the powers and duties of his office, and incident to the powers and proceedings of the county commission of which he is clerk; and shall have power and authority to administer oaths and affirmations, and to take and certify depositions within the respective counties in all cases where oaths or affirmations are required by law to be administered. And, when required, he shall affix thereto his jurat and the seal of the county commission of which he is clerk.