Section 9. The keeper, superintendent or other officer having charge of a jail, house of correction, county training school or other county public institution shall keep an invoice book, in which shall be entered, on the day of receipt, all bills for supplies for the maintenance of such institution. Such books shall be as nearly uniform as the character of the institutions will admit, and shall be kept posted up to date so that the footings shall at all times show the actual facts relating to such supplies. Such books shall be county property and remain among the records of the institutions to which they belong.