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 section 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.