30 ILCS 605/1.04

"Transferable property" means and includes all tangible personal property belonging to the State of Illinois in the possession, custody or control of any responsible officer or agency, which is not needed or usable by said officer or agency, including all excess, surplus, or scrap materials; provided, however, that "textbooks" as defined in Section 18-17 of the School Code shall not constitute transferable property after those textbooks have been on loan pursuant to that Section for a period of 5 years or more.