§ 468. Fire patrol and salvage corps. Real property owned by a corporation organized to maintain a fire patrol and salvage corps for the public benefit, which property is used exclusively for housing or storing property used exclusively for the purpose of such fire patrol and salvage corps, shall be exempt from taxation, provided such property is used and such service rendered indiscriminately and without charge for the public benefit; provided, however, that if a portion only of the real property of such a corporation is so used, such portion shall be exempt from taxation and the remaining portion shall be subject to taxation.