Any number of persons not less than 25 may associate together for the purpose of mutual insurance of the property of its members against loss or damage by inherent explosion, fire, lightning, riot, riot attending a strike, aircraft, smoke or vehicles, which property to be insured by companies organized or operating under this section shall embrace only farm property or property located in a village or city of less than 5,500 inhabitants used by a farmer exclusively for his own storage purposes, which property is not associated in any way with any retail, wholesale or processing operation, country churches, schoolhouses, lodge halls and town halls and their contents, in any township; and churches, schoolhouses and dwellings and accompanying outbuildings and their contents situated within the corporate limits of cities or villages having a population not in excess of 5,500 inhabitants; and any buildings and contents, located on county agricultural fairgrounds, used for fair purposes or for boys and girls club work: Provided, That such property has adequate fire protection.