Whenever any town in lawful meeting has authorized the erection of a building for the protection of its records against fire, and the selectmen, or a committee appointed for the purpose, fail to agree upon a site for such building, or, having fixed upon a site, are unable to agree with the owner upon the amount of compensation to be paid to him, the selectmen may proceed to condemn such land in the manner provided in § 48-12; provided no town shall take for such purpose the land of any religious or ecclesiastical society, upon any part of which a church building has been erected, without the consent of such society.