All articles purchased or exchanged by a junk dealer, as defined in Section717.01
shall be retained by him for at least thirty days before disposing of the same. Such articles shall be kept in an accessible place in the building where such articles are purchased or received. A tag shall be attached to each article in some visible and convenient place, with the number written thereon corresponding to the entry number on the book required by Section 717.10.
(1973 Code §118.12)