If an agreement can be negotiated for less than the appraised market value, purchase of all or a part of such real estate is hereby authorized, without the exercise of the power of eminent domain. Such lands shall be acquired in the name of the state of Kansas, and the state historical society shall not issue a voucher in payment therefor until the seller shall furnish an abstract showing a merchantable title, and a warranty deed conveying a fee simple title thereto to the state of Kansas nor until such abstract and deed have been approved by the attorney general. In the event such an agreement is entered into, it shall not become effective until approved by the attorney general, nor until such abstract and deed are approved as hereinbefore provided for nor until placed in escrow pursuant to an agreement approved by the attorney general. Said tracts may be acquired separately either by negotiation or condemnation.