The board of supervisors of any county holding in trust the property of any agricultural society organized under any law of this state for the purpose of the holding and maintaining of agricultural, industrial and mechanical fairs, is hereby authorized and empowered to purchase and acquire, from such agricultural society, all the beneficial right, title and interest of such agricultural society, in and to any or all of the lands, or property, so held in trust by such county, and to thereafter have and hold said lands and property in fee simple and free from such trust.