W. E. and Jennie Hutton executed a warranty deed conveying their interest in a parcel of land to the local school district. The words of conveyance stated: “This land to be used for school purposes only; otherwise to revert to grantors herein.” The property was used for a school for 32 years. Then the property was used by the school district for storage purposes. When this occurred, the heirs of the Huttons filed suit to recover the property from the school district. Who owns the land? (Mahrenholz v. County Board of School Trustees of Lawrence County, 417 N.E.2d 138, Illinois)